CA1105409A - Workpiece storage system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
For use in a work processing line for work-pieces, a workpiece storage system including a topo-logically closed loop track means having downwardly sloping surfaces coupled with elevators and lowerators in the loop, and work holding, gravity-operated pallets to run on said tracks having track engaging wheels equipped with retarding means responsive to wheel angular velocity and utilizing wheels of different diameters on the track depending on the loaded or loaded condition of the pallets to control the speed of the pallets. Auxiliary track means, pallet loaders and unloaders, and switching mechanisms are incorporated in the system with elevators and lowerators to allow the storage system to function between multiple work process-ing lines, between single and multiple lines or between multiple and single lines to increase the flexibility of a work processing activity and reduce downtime.

Description

This invention relates to a Workpiece St'~rageSystem between sPctions of a multiple section workpieca processing line and the further utilization of this work-piece storage system as a means of transferring workpieces between parallel transfer lines and the division and com-bining of workpieces on transfer lines requiring this function~

Backqround In the field of automatic machining, assembly, and other forms of workpiece processing, it is customary practice to use transfer machines which employ a multi plicity of stations which operate se~uentially on a given workpiece, with a line of workpieces progressively trans-ferred along the line of stations, by an automatic txans~
fer mechanism;
For illustrative purposes, and by way of example, there exist in industry transfer lines for machini.ng the cylinder heads for internal combustion engines, referred to as head lines. ~he total number of individual stations in such a head line may exceed 100~ It will be ~nderstood that each station performs a givèn operation on each head - (workpiece), and, at ~he end of a given cycle, the heads are indexed foxward one station increment; and when a head is discharged from the line, all operations will have been performed on it.
suilding such a line as a single tran5fer machine creates two significank problems: the first is the practical problem of building a txansfer system capable of accurately and reliably transferring such a large number of heavy workpieces along a single trans-fer machine. The second concerns the likelihood of downtime. If a single station of a transfer machine is down or inoperative for a varie~y of reasons, among which are broken or dull tools, electrical, hydraulic, or mechanical malfunction, then the entire line, of which such a down station is a part, is down or non operative as a result. m is situa~ion has long been recognized in the industry, and, as a result, overall processing lines incorporating a large number of sta-tions are generally subdivided into multiple sections which may range from 2 to 12 or more. Each such sec-tion is then operated as a single machine with its ownindependent transfer mechanism for transferring parts between its multiplicity of stations. Between such 5`~

machine sections, there is generally i~corporated an independent workpiece transfer system, which may be a roll conveyor, accumulating conveyor, power and free conveyor, monorail conveyor, and even manual labor, for transfer o~ the workpieces from the last station of the upstream ~ection to the first station o~ the downstream section. In almost all cases, some degree of automatic or manual workpiece storage between sections is thereby achieved.
With some degree of workpiece storage between machine sections, it will be seen that when one station of a single section goes down,that entire section goes down, but the other sections may continue to operate for as long as there are workpieces stored in the lS between-section transfer system immediately downstream of the non-operative section and as long as there are spaces available in the between-section trans~er ~ystem immediately upstream of the non-operative section.
As a broad qeneraIization, the greater the amount of between-section transfer system storage capacity, the longer a given section may be down without causing the other sections to go down, and, as a second broad generalization, the larger the number of sections into which a given line is subdivided, the less likeli-hood a given section will be inoperative at any given S time.
It is one objective of this invention to create a system of workpiece storage between sections which is more flexible, more economical, in terms of cost per part stored, and less wasteful of floor space than the systems presently in use.
In high production situations, it is not un-common to find multiple parallel lines operating adja-cent to one another in a given plant. Hypothesizing that there exist three parallel lines, A, B, and C, each of which i5 divided into six sections, 1, 2, 3, 4, 5, and 6, there arise many occasions in which, for example, sec-tion 1 of line A is down while at that same time, section 5 of line B is down, and at thak same ti.me, section 3 of line C is down. Under such conditions, it can be seen that with sultable cross-trans:Eerring between lines, the productivity of all three lines can be maintained at 2/3 of the theoretical full productivity of all three lines, even though each line, as a continuous system, is down.

~s~

This technique of crossfeeding between corresponding "between-sectlon" ~ransfer systems of multiple parallel lines to maintain partial production when non-correspond-ing sections of multiple lines are simultaneously down has also long been known and utilized by industry.
It is a further object of this invention to create a storage system which, by its nature, provides a simple means to transfer workpieces between correspond-ing points of multiple parallel processing lines.
I0 In the processing of many types of workpieces, there often exist sections of transfer lines which are significantly slower in operation than the remaining sections of that same transfer line. In such cases, it is common practice to utilize two parallel identical sections, each of which operates on approximately half of the workpieces as compared to the remaining sections of the line.
It is a further objective of this invention to provide a means of dividing the flow from a single section of a transfer line to a multiplicity of parallel substantially identical sections of a transfer line in addition to the storage function of this invention; and, conversely, to provide a means of recombining the outputs from a multiplicity of substantially identical sections of a ~ransfer line into a single inpu~ to a subsequ n~
sec~ion.
Other objectives and features of the inven-tion will be apparent in the ~ollowin~ description, claims, and accompanying drawings in which the prin-ciples o~ opexation and use are set forth in connec-tion with the best modes presently contemplated for the practice of the invention~
DRAWINGS accompany the disclosure and the various views thereof may be briefly described as:
FIGURE 1, a segmental view of a pallet sys-tem showing pallet and track.
FIGURE 2, an end view of the segment of FIGURE 1.
FIGURE 3, a view of a support roller with an àlternate track relationship.
FIGURE 4, a velocity force vector diagram.
FIGURE 5, a view of an alternate wheel track arrangement.
20 - FIGURE 6, a view of the wheel arrangement simi~
lar to FIGURE 5 on an alternate wheel diameter.
FIGURE 7, a side view of the arrangement of FIGURE 5 .

FIGURE 8, a view of a hanger mounting con-struction.
FIGUkE 9, a side view of an alternate roller transfer means.
FIGURE 10, an end view of ~he assembly in FIGURE g.
FIGURE 11, a diagrammatic plan vi2w of a storage system between two transfer line sections.
FIGURE 12, an elevation view of an elevator section.
FIGURES 13 ana 14, sectional views of the elevator taken on lines 13 13 and 14--14 of FIGU~E 12 FIGURE 15, a top plan view of the elevator section.
FIGURE 16, a side view of the elevator chain guides.
FIGURE 17, a view on line 17W-17 of FIGURE 15.
FIGURE 18, a side view of a pallet loader and unloader.
FIGU~E l9o a sectional view of line 19-~19 o FIGURE 18 .
: FIGURE 20, a side view of a second embodiment of loading and unloading mechanism.
FIGURE 21, an end view of the loader o FIGURE 20.

FIGURE 22, a plan view of a switching sec-tion of a conveyor track.
FIGURE 23, a side view of the switching sec-tion of FIGURE 22.
S FIGURE 24, a plan view of a modified track circuit.
FIGURE 25, a plan view of another modifica-tion of a track circuit with parallel lines and storage on each line.
FIGURE 26, a view of a helical down track to replace the lowerator sections.
EIGURE 27, a side view of an elevator for direct lift or lowering of workpieces taken on line 27--27 of FIGURE 28.
FIGURE 28, a partial horizontal section of a part lifter and load and unload tracks.
FIGURE 29, diagrammatic view of a part and pallet storage, load, and unload system using a single parts elevator.
FIGURE 30, a diagrammatic view of a track layout utilizing two elevators for transfer of bare parts from one machine section to another.
FIGURE 31, a view similar to FIGURE 30 with delivery to two machine sections.

FIGURE 32, a bottom view of a modified~part carrier.
FIGURE 33, an end view of the part carrier shown in FIGUR~ 3 2 .
FIGURE 34, a side view of the parts carrier Of FIGURE 32.
FIGURE 35, a seetlonal view of a modiied roller and guide arrangement.
~IGURE 36, a sectional view o~ another modi-fied cons~ruction for a pallet guide.
FIGURE 37, a front elevation of a modified pallet elevator.
FIGURE 38, a side elevation on line 38--38 of the modified elevator of FIGURE 37.
~IGURE 39, a front elevation of another modi~
fication of a pallet elevator.
FIGURE 40, a side elevation on line 40-~40 of the modified elevator illustrated in FIGURE 39.
FIGURE 41, a side view of a pallet escalator.
20 . FIGURE 42, a sectional view on line 42--42 of FIGURE 41.
FIGURE 43, a modified escalator design shown in cross-section.
FIGURE 44, a side view of a still further modi-fication o-f a monorail, hanger type pallet escalator.
FIGURE 45, ar, end view of the monorail escalator.

FIGURE 46, a sectional view of a chain actuated upslope conveyor.
FIGURE 47, a modified structure to provide differential resistance dependent on direction of movement.
FIGU~E 48, a belt actuated pallet mover.
FIGURE 49, a secondary track lit to nullify a retarding device~
FIGURE 50, a side view of the track lift of FIGURE 49.
FIGURE 51, a plan view o~ a pallet elevator design.
FIGURE 52, a side view of the structure of FIGURE S Ln FI~URE 53, a work pallet level changer utilizing a vertically reciprocating actuator.

One basic element of this system is a pallet or workpiece holding carrier which is a means for supporting a workpiece during storage, crOss-transferring, dividing, or recombining. A given S pallet is unpowered but moves along a downwardly sloped track system on wheels, at least one of which is retarded by a braking system governed to maintain a controlled speed.
A first embodiment of a pallet and a short section of suppor~ing track is shown in FIGURES 1 and

2. A pallet frame 2 supports a workpiece 4 in a nest configuration; the workpiece 4 is transversely located by a locator 6, as part of the nest. The pallet frame 2 in turn is supported by two hangers 8 whose lower ends support the pallet frame 2, and whose upper ends are formed into an inverted U structure, in which are journalled axles 10. On each axle 10 is mounted a wheel assembly 12 designed to operate on two different rolling diameters, with each rolling diameter termi- -nated by a pair of guiding flanges. In FIGURE 2, awheel 12 is shown rolling on a track 14 consisting of a rectangular tube with its major axis vertical; in this condition, the wheel 12 is rolling on diameters 16 and guided with respect to the track 14 by flanges 18;

~5~

the track 14 is in turn supported from a suitable struc-ture by intermittently spaced hangers, one o~ which is shown as hanger 20. It will be noted that pallet ~ to track 14 configuration is such that workpiece 4 is made vertically captive in the pallet 2 by the underside o~
the track 14 i.e~, the presence of track 14 prevents the workpiece 4 from being vertically removed from its nest in pallet 20 ~he axle 10 of at leas~ one of the wheels 12 is governed as to speed of rotation by an assembly made up of a body 22 attached to the pallet hanger 8, which in turn supports a seal 24 in which is journalled the shaft 10. A retarding disc 26 is fastened to,the end of shaft 10 and a sealing cover 28 is bolted to case 22. A
small but controlled space exists be~ween one face of disc 26 and case 22, and between disc 26 and cover 28. This space is filled with a viscous fluid exhibiting substan-tially Newtonian characteristics, such as a silicone oilO
It will be understood that in such a ~ewtonian fluid~ the shear force required to shear the fluid is directly propor-tional to the time rate of shear exerted on the fluida Therefore, the retarding torque exerted on the axle 10 by the disc 26 is directly proportional to the angulax velocity of the axle 10. The factor o proportionality is dependen-t on the viscosity of the fluid, the diameter of the disc 26 and the thickness Of the f luid space on the sides of the disc~

Whereas the retarders described in connecti~
with FIGU~ES 2, 5 and 46 all employed a viscous fluid operating in shear between a rotor and a housing to create a retarding torque subs~antially p~opor~ional to the rotor angular velocity, the well-known principle of magnet and eddy current xetardation can also be utilized. As related to ~I~URE 2, a permanent magnet or group of them would be mounted in the cover 28 or housing 18 or both to create a magnetic field perpen-dicular to the plane of the disc 26 which would bemade of a suitable conductor such as aluminum. Rota~
tion of the disc 26 would induce electrical currents therein proportional to the angular velocity, which in turn would create a proportional retarding torgue.
15 A comparable design, analagous to FIGURE 46, would employ a cylindrical sleeve as a rotor as opposed to a disc. In either case, because of the lower torques attainable with eddy current retardation as compaxed wi*h viscous retardation, a step~up gear ratio from t~e wheel shaft to the retarder shaft would be ad-visable.

s~

In FIC,URE 3 is shown the wheel track arrange-ment for supporting and guiding a pallet when a pallet is moving along a track empty, i~e., without carxying a workpiece. In this case, the rectangular tubular track 14a is arranged with its major axi~ horizontal, and the wheel 12 rolls on the track 14a on the larger diameters 23 and is guided by flanges 25. The use of different diameters of rolling on the wheels permits the independent control of speed between full and empty lQ pallets, including~ but not restrlcted to, having full and empty pallets descend the downward sloping tracks at subs~antially identical speeds. Other uses of this feature will be subseguently described.
The effect of the rolling diameter on the speed of descent may be understood by reerence to FIGURE ~, a schematic velocity and force vector diagram o a wheel supporting a weight Wl having a diameter Dl, and rolling down a track inclined to the horizontal at an angle CC, and moving with an angular velocity ~
and linear velocity V. It can be seen that the force, parallel to the track, causing the wheel to move for-ward is:

This in turn creates a torque on the wheel T F Dl Dl Wl sin ~C

~ s the wheel rolls down the track at a constant angle and substantial equilibrium is reached, i.e., the wheel is neither accelerating nor declerat-ing, the forward torque TF and the retardlng torque TR
are equal tand opposite). The retarding torque may be expressed as:

TR 3 KlC~) Since ~ = D

where V is the equilibrium velocity, TR -- 2 Kl V

Since TF = TR

Dl 2 K V
- Wl sin oC 3 Solving for V

sin V = ~K Wl ~15--~s~g This equation indicates that the equili~rium forward rolling velocity is proportional to the weight and the square of the rolling diameter. In ~he speci-fic case where it is desired to have the rolling velo-city of an empty pallet equal the rolling velocity ofa full pallet, it can be seen that:

W DE2 = WF DF2 where WE and WF are -the empty and full weights respec~
tively and DE and DF are the rolling diameters for the empty and full conditions respectively. This condition can be expressed also as:

DE DF ~

The multi diameter wheel technique is also useful in other areas to be covered in the ensuing de-scriptio}l.
Referring again to FIGURES l and 2, there aremounted on the bottom of the pallet, two wheels 30, free to rotate on shafts 32. These wheels 30, which oper~te in a horizontal plane about vertical axes, perform a variety of functions to be subsequently described.

5~

Ordinarily, the weight of the pallet, w~h or without the workpiece, is nlaintained and guided on the track by the wheel flanges 18 or 25. As a safety against jumping the track, a bar 34 is mounted on each pallet hanger 8. This bar would contact the underside of the track 14 be~ore the wheel flange could ride over the top of the track, due to unforeseen circumstances;
the pallet assembly is therefore totally captive on the track.
Since there are many conditions in which successive pallets abut one another while moving, or when a moving pallet runs into a stationary one, suit-able bumpers 36 are mounted on each end of a pallet to absorb the contact forces encountered.
An alternate wheel track arrangement is shown in FIGURES 5, 6, 7 and 8. In this embodiment, the upper end of each pallet hangers 8a is formed into an open hook 50 which engages a circular groove 52 in a package or cartridge type wheel, axle, retarder assembly. The hook is closed and made captive on the cartridge by a bolt 53 and nut 54.

~17 ~ ~r~ 9 Referring to FIGURE 5, the cartridge consists of a body 55 in which is journalled a shaft 56 through a bearing 58. A wheel 60 is mounted on one outboard end o~ shaft 56; this wheel 60 is further journalled to the outside of body 55 through bearing 62, w~ich is the primary load carrying bearing. The oukside of wheel 60 is formed into ~wo double flanged grooves having two separate rolling diameters. In FIGURE 5, ~he wheel 60 is shown engaging the track 64 with its larger rolling diameter 66; in FIGURE 6, the wheel 60 is shown engag-ing the track 64 with its smaller rolling diame~ter 68.
The track 64 is comprised of a thin bendable ribbon of suitable material punched with holès or slots for mounting~ ~his track is mounted from a suitable sup-port by multiple hangers 70 throu~h spacers 72 ox 74 and bolt.s 76 or 78 and nuts 80. A material particularly de-sirable for use as a track is a high carbon, hardened steel given a chemical or heat treatment for corrosion resistance and known in the industry as "blue steel".
The retarder assembly is comparable to that shown in FIGURE 2. Referring to FIGURE 5, a disc 82 is astened to and rotates with ~he other end of the wheel -- shat 56. The retarder housing 84 is mounted coaxially to the cartridge body or made integral with it and con-4~9 tains a seal 86 to the shaft 56. The retarder cover 88 is fastene~ to ~he housing 84 to foxm a ~ealed cavi-ty for the retarding fluid w~ich fills the interspace between the two faces of the disc 82, housing 8~ and cover 88, thereby creating a retarding torque on the shaft 56 which is substantially proportional to the angular velocity thereof.
FIGURES 7 ~nd 8 show sid views of the assemblies illustrated in FIGURES 5 and 6.
The primary means of supporting and guiding the pallets as they move through the system are the wheels 12 or 60 mounted thereon usually, but not always, with a re-tarder as shown in FIGURES 2 and 5. For reasons to be described, it is convenient and necessary to have the pallets move through the system part of the time by other means.
One such other means is shown in FIGURES 9 and 10. 'rwo structural rails lOO are suitably supported by columns 102 at appropriate intervals. On these rails are mounted a series o~ two rows o free running rollers 104 through spacers such as 106~ The upper surfaces o these rollers 104 form a nominal plane slightly above the upper surfaces of the rails lOO. 'rhe inner faces of the rails ~ lOO constitute a channel which forms a guide for the pallet mounted rollers 30 (FIGS. 1 and 2). A pallet 2 will, there-fore, reely roll on and be guided by such an alternate track system.

In FIGURES 9 and 10, a pallet is shown ln transition from a track system employing the station-ary track 64 and pallet suppoxt wheels 60, to the support and guidance system employing stationary roll-ers 10~ and guide rollers 30 which will be furtherreferred to as a roller bed track. To maintain align ment between the stationary track 64 and the roller bed track, an alignment frame 108 is connected between them.
While FIGURE 9 shows a pallet 2 in transi-tion from stationary track 64 to roller bed track 100, it is clear that the inverse transition from roller bed track to stationary track 64 can be made with equal ease. The roller bed track can be curved by suitable curving of the structural rails 100, in which case the upper surfaces of the rollers generate a helical rather than a plane surface.
An illustrative system to accomplish work-piece storage between two sections of a transfer line is shown schematically in FIGU~E 11. Under normal operation, i.e., when the lask section 150 of the upstream transfer line is delivering workpieces 152 - and the first section 154 of the downstream transfer line is accepting workpieces 152, the flow of wor]cpieces 152 from one sec~ion to the other is along a powered roll conveyor 156, or its equivalent, such as a walking beam conveyor, power and free conveyor or the like. As the workpieces 152 arrive at the 5 entrance of the machine section 154, they are metered by an escapement mechanism consisting of cylinders 158 and 160 which operate gates 162 and 164 respective-ly. At appropriate times in the automatic cycle of ma-chine section 154, an automatic loader, comprised of cylinder 166, and pushex 168, slides a workpiece 152 into the first station of machine section 154, Erom ~"hich point it is transEerred through the machine sec-tion 15~ by its internal transfer system. This portion of FI(;URE 11 is a typical and normal technique presently 15 in use in industry.
As a convention in the representation oE the storage system, all pallets which are carrying work-pieces are represente by circles crossed by a double lin~ as at 170 and referred to as full, and all pallets 20 which are not carrying workpieces are represented by open circles 172 and referred to as empty. The storage system utilizes pallets 170 or 172, which previously have been described (pallet 2 in FIGURES 1 and 9)O Dual func-tion elevator-loweratoxs 174 and 188 in the storage system ~5f~

cooperate with a topological closea loop track system, the func~ion of which will now be described. meiele-vator~lowerator 174 accepts empty pallets 172 at an up-per level track 176 from an escapement 178 and delivers them to a lower level track 180, and simultaneously ac-cepts loaded pallets 170 from a lower level ~rack 182 and delivers them to an upper level track 18~; a pallet loader mechanism 186 transfers a workpiece 152 from the conveyor 156 to a pallet on the lower level track 180-182 transforming a p~llet from empty 172 to full 170; a sec-ond dual function elevator-lowerator 188 accepts full pallets 170 at an upper level track 190 from an escape-ment 192 and delivers them to a lower level track 194 and simultaneously accepts empty pallets 172 from a lower level track 196 and delivers them to an upper level track 198, a pallet unloader mechanism 200 trans-fers a workpiece 152 from a pallet on the lower level tracX 194 196 to the conveyor 156, thereby transforming a palle~ from full 170 to empty 172; and a gating and sensing mechanism on the conveyor 156 with a limit switch 202 signals the pallet unloader mechanism 200 that an open space is available on the conveyor 156. A cylinder 204 operates a gate 206 to stop workpleces 152 on conveyor - 156 during operation of pallet unloader 200, and a second gate 208 operated by cylinder 210 controls the flow of a workpiece 152 to a further downstream position on ~on-veyor 156. Such a gating and sensing mechanism may also be employed with tne pallet loader mechanism 186.
The lower level track in the topological closed loop system whic~ operates from 180 to 182, and is associated with the pallet unloader 186, descends at a substantially uniform angle from its beginning at 180 to its ending at 182; the exit level of the empty pallet 172 from lowerator 174 ls therefore appropriately higher than the entry level o-f the full pallet 170 into ele-vator 174. Similarly, the lower level track which oper-ates from 194 to 196 has a difference in exit and entrance levels from and to the lowerator elevator 188 to generate ~ the required descending flow.
While the lower level tracks lB0-182 and 194-196 of the closed loop system are near the floor and at a specific height required by the characteristics of the pallet loader 186 and the pallet unloader 200, the two upper level tracks 184-190 and 198-176 are not as con-strained. To conserve floor space, these upper level tracks 184-190 and 198-176 will be at a height above the normal passage level requixed by personnel, lift trucks, etcO The routings shown in FIGURE 11 are for illustrative purposes only. The routings may extend over either or both of the machine sec-tions 150 or 154, or wherever is most convenient or eco-.

~5~

nomical. The structural support may be from the machine sections, from floor mounted columns, from the ov~r-head plant structure, or some combination thereof.
Full pallets 170 exit from the elevator 174 to enter the full pallet storage track, which runs from 184 to 190 with a substantially uniform descend-in~ slope, and form a queue thereon, to be released as required by escapement 192. As the lead full pallet 170 is released into the lowerator 188, the remainin~
full pallet queue advances one pallet length due to the slope of the track 184-190. A high level switch 212 senses when this track is fully loaded with full pallets.
Similarly, empty pallets 172 exit from the elevator 188 to enter the empty pallet storage track, which runs from 198 to 176 in a substantially uniform descending slope, and form a queue thereon to be re-leasPd as required by escapement 178. As the lead empty pallet 172 is released into the lowerator 174, the remaining empty pallet queue advances one pallet length due to the 510pe o-f the track 198-176. A
high level swi.tch 214 senses when this track is full of empty pallets.

~24-Functional schematic drawings of a comblna-tion elevator-lowerator as exemplified by 174 in FIGURE 11 are shown in FIGURES 12~17. ~eferring to thes~ figures, two ver~ical channel frames 230 are spaced by lower headers 232 and upper headers 234.
An upper sprocket shaft 236 is journalled in pillow blocks 238 mounted in the frames 230 and a lower sprocket shaft 240 is similarly journalled in pillow blocks 242 mounted in the frames 230. Two chain sprockets 244 are mounted on the upper shaft 236 and two chain sprockets 246 ~FIGURE 13) are mounted on the lower shaft 240; the lower shaft 240 is driven by a motor 248, gear reducer 250, sprocket 252, chain 254, and sprocket 256 on shaft 240. Alternately, the shaft lS 240 may be driven from the gear reducer 250 by an inter-mittent drive mechanism of the type shown in my U. S.
Patent No. 3,789,676 or my U. S. Patent No. 3,859,862.
A pair of chain loops 258 operate between the upper sprockets 244 and the lower sprockets 246. A
pallet carrier or bucket 260 is intermittently suspended from each chain loops 258 by an extended pin 262 (FIGURE
15). These pins are stabilized in guides 264 by auxiliary rollers 266 on the straight vertical chain runs. Each bucket 260 is additionally stabilized against sway-ing about its pin connection to ~he chain 258 by a roller 268 mounted on the lower end of each side of a bucket 260 and guided by the guides 264. The guides 264 have a bell-mouth configuration 271 at each end of their vertical straight run to facilitate entry of the rollers 266 and 268~
Each bucket 260 is arranged to accept both a full pallet 170 and an empty pallet 172, both simul-taneously and separatelyj one side of each bucket 260 is allocated to carry full pallets 170~ and the other side is designated to carry empty pallets 172n The entry of pallets, empty or full, into . an elevator or lowerator is controlled by gates which may be fixed or movable; similarly, the exit of pallets, empty or full, from an elevator is also controlled by gates which may be fixed or movable.
A pallet, empty or full, is primarily movable through the system on sloplng fixed tracks and pallet mounted wheels as described in connection with FIGURES 1, 2 and 3. A pallet, empty or full, can also move on a roller bed track as described in connection with FIGURES
9 and 10. It is on this roller bed track that pallets, empty or full, enter and exit the elevator-lowerator such as 174.

Referring to FIGURES 14 and 15, the buckets 260 are in the descending flight, and the buckets 270 are in the ascending 1ight. Relating to FIGURE 11, the track 176 carrying empty pallets becomes a roller 5 bed track 272 shortly before abutment to the elevator.
Closely abutting the stationary roller bed track 272 is a movable section of such track. A channel section 274 carries a group of two sets of rollers 276 the open upward side of the channel is to control the cen--10 ter guide rollers 30 on the pallets. This channel sec-tion is supported by a shaft 278 mounted in pillow blocks 280 on the frame 230.
Referring to FIGURE 17, the shaft 278 ex-tends beyond the frame 230 and has mounted to it an 15 actuator clevis arm 282, the outboard end of which is pivotally connected to an actuator 284 operated by a cylinder 286 attac~ed to the frame 230. When the cylinder 286 is extended, as shown in FIGURE 17, the actuator arm 282 is positioned against a stop 288, a~
20 which time the movable section 274 of the roller bed mounted on the shaft 278 is in effect a continuation of the fixed roller hed 272 at substantiaLly its same slope, and the section 274 extends into an open slot oE a bucket 270. A pallet released by the escapement, as at 178 in ~27-FIGURE 11 will roll down the roller beds 272 and ~7 and will be picked up by the bucke-t 270 on surfaces 290 as the bucket 270 move upward in its vertical path.
With the cylinder 286 in its retracted posi-tion, the actuator arm is rotated approximately 95 counterclockwisa until it rests against stop 292.
With the shaft 278 in this posit.ion, the movable sec-tion of the roller bed mounted on channel 274 is in the position 296 shown in FIGURE 14. In this position, pallets cannot be loaded into the buckets 270, but buckets which have already been loaded can move upward through the gate space without interference. These conditions will be subsequently described.
Similarly, on the descending flight of buckets 260, empty pallets can be removed from the buckets by a movable gate 2g8 mounted on shat 300, which is actuated by a mechanism substantially iden-tical with the mechanism shown in FIGURE ].7. With the exit gate in the position 298 shown in FIGURE 14, empty pallets are stripped from the vertically downward moving buckets and roll out onto the fixed exit roller track 180 as related to FIGURE ll. With the exit gate in its retracted position 302, empty pallets in the buckets 260 move past the exiting level for another trip around the chain J.c)op.

.-28-

3~

In some instances, in which there exists only a single entry point and a single exit point, the gates may be fixed rather than movable; this requires that every pallet will be stripped out as its carrying bucket moves past the fixed exit gate level. Therefore, all buckets reaching the entry gate level will always be empty of a pallet and the entry gate may be fixed without danger of interference.
The diagram of FIGURE 14 represents that por-tion of a combined elevator-lowerator which handles the empty pallets and is termed a lowerator. When carrying an empty pallet, each bucket carries such a pallet on the surfaces 290 (FIGURE 15).
Each bucket may simultaneously and separately carry a full pallet on surfaces 304 (FIGURE 15). The section shown in FIGURE 13 schematically represents this construction and function as related to traclcs 182 and 184 of FIGURE 11. Full pallets enter from track 182 through a gate substantiall~ similar to the gate asso-ciated with the empty pallets. Full pallets are lifted up and over the sprockets 244, to be discharged at the upper track level 184, again by a gate mechanism substan-tially similar to the one associated with empty pallet discharge.

~29-In essence, a single chain loop mechanism, as described above, is capable, through the use of dual function buckets, of simultaneously acting as an elevator for full pallets and a lowerator for empty pallets, as schematically depicted by 174 in FIGUR~
11.
In FIGURE 11, it will also be noted that the combination elevator-lowerator 188 accepts full pallets at an upper level track 190 and discharges them at a lower level track 194, while accepting empty pallets . at a lower level track 196 and discharging at an upper level track 198. This is the inverse of the function described in connection with FIGURES 12-17. But it is easily seen that the function of elevator-lowerator 188 is met by merely reallocating the bucket functions, such as by carrying full pallets on surfaces 290 and empty pallets on surfaces 304 of the buckets 270 shown in FIGURE 15.
While it is generally more convenient and economical to have a single mechanisrn perform the dual function of elevator and lowerator, applications arise in which single units only are employed. In such cases, a bucket can carry only a single pallet, either ull or empty.

In FIGURE 11, the schematic plan of an illus-trati.ve storage system, are shown a pallet loader 186 and pallet unloader 2Q0. Either of these operations can be ~erformed by the mechanism shown in FIGURES 18 and 19. Referring to these figures, a workpiece 152 is moved along a roll conveyor 156 (FIGURES 11 and 18) comprised of closely spaced rollers 310 mounted on shafts 312, which are journalled in pillow bloclcs 314 and driven by chain sprockets 316 from a suitable and conventional motor and gear reducer. The workpieces are moved along this conveyor in their normal progress from machine section 153 to machine section l54 shown in FIGURE 11.
The pallet loader mechanism consists of a lS base 311 (FI~URE 18), on which is mounted a bracket 313 containing two pivot points about which the link-age mechanism operates. A box link 315 is pivotally connected to the bracket 313 by a shaft 317 at one end:
and at its other end, the box link supports the beam link 318 with a pivot connection at shaft 320~ The other end of beam link 318 mounts a nest assembly com-prised of a horizontal beam 321, on which are mounted two arms 322 and 324 (FIGURE 19), which in turn carry split nests 326 and 328 through spacers 330 and 332.

~31-The beam link 318 is controlled and driven by a driver link 334 through a pivot connection at shaft 336 and bearing 338. ~he other end of the link 334 is pivot connected to a control link 340 through a shaft 342; and -the other end of the link 340 is pivot connected to the bracket 313 by a shaft 3~13 .
In the general area of the center of link 334, but at a specific point determined by geometric layout, the link 334 is connected by bearing 344 to the output shaft 346 of a mechanism, such as shown in my U. S. ~atent No. 3, 857 ,479 capable of generating a substantially square path of its output shaft. Such a mechanism, mounted on the base 311, causes the shaft 346 and the corresponding polnt B on the link 334, shown at position B0, to move along the path BO, Bl, B2, B3, B4. Through the action of the llnkage, ~he point C, shown at position CO, on the split nests 326 and 328 moves along a path C0, Cl, C2, C3, C4. The roll conveyor 156 is provlded ~ith slots between the rollers through which the splik nests 326 and 328 can move during the traverse of this path.

~'~35~

Also mounted on the base 311 on one side of the linkage mechanism, and spaced between split nests 326 and 328 is mounted a section of roller bed track 331 which corresponds to a section of the lower level track 180 in FIGURE 11. An empty pallet moves down this roller bed track to be stopped by a stop pawl 348, which i~ pivot mounted to the track 331 and actuated by a cylinder 3S0 mounted on the base 311.
When an excessive number of workpieces accu-mulate on the roller conveyor 156, as determined by limit switches khereon, the pallet loader mechanism operates through a cycle from a starting position in which point C on the split nests 326 and 328 is at the position C1 and moves along the path Cl, C2, C3, C4, C0, Cl. As the split nests approach the position C3, they pass upwardly through the rollers 310, some of which are cantilevered at the sprocket end, and they lift a workpiece 152 vertically upward from the roller conveyor 156; continued movement of the nests to point C4 moves the workpiece substantially horizontally clear of the conveyor and subsequent movement to the point C0 lowers the workpiece into the waiting empty pallet 172, thexeby transforming it into a full pallet 170, as shown in FIGURE 18. The linkage and split nests 326 and 328 continue moving until point C reaches Cl, at which time the pallet ~35~

loader mechanism is comp1etely clear of the now full pallet 170i the pallet loader linkage now stops to await the next cycle. The cylinder 350 retracts the stop pawl 348, and the full pallet now rolls down the track 330 to the pallet elevator. In some instances, the roller nest type track may have a transition to fixed rail type track for this run, either before or after the load position, or both; However, it can be seen that at the load point, a section of roller nest track mu~t be used too since the fixed track would interfere with the loading path of the workpiece.
Shortly after the now full pallet 170 has moved away from the load position, the stop pawl 348 is returned to the stop position shown, to await the arrival of the next empty pallet. Referring to FIG-U~E 11, the full pallet rolls down the track to the entry point 182 on elevator 174. With the pallet posi-tioned slightly ahove the lifting bucket, the elevator 174 indexes one bucket pitch lifting the full pallet one pitch. Simultaneously, an empty pallet is lowered to the discharge point at track end 180.

.

-3~-~$~

For long cycle operations, about 15 seconds or more, the use of only one pallet at a time in the track section 180-182 is sufficient. To achieve high-er cycling rates, two, three or more pallets will S simultaneously be on this same track section 180-182;
and with multiple pallets on this track section, addi-tional control points are required, specifically an upstream stop or escapement for empty pallets, such as shown by stop 352 (FIGURE 18), and an escapement at the entry into the eleva-tor for full pallets at track position 182.
The mechanism shown in FIGURES 18 and 19 has been described in connection with the loading of work-pieces from the roller conveyor to a waiting empty lS pallet. This same mechanism is also usable to lift workpieces from a full pallet to the roll conveyor, as required of the pallet unloader 200 in FIGURE 11.
To operate as a pallet unloader, full pallets roll down the roller nest txack to be stopped by pawl 348. The unloader linkaye is moved in the opposite direction; i.e., poi.nt B of the square generating . mechanism traverses i.ts path in the sequence Bl, B0, B4, B3, B2, Bl; and point C on the split nests 326, 328 ~5~ ~

tr~verses its path in the sequence Cl, CO, C4, c3, c2, Cl. At the point CO, the split nests 326-328 engage the workpiece 152 in the pallet, lift it up-ward and free of the pallet while movin~ to C4, and move it horizontally over the roll conveyor 156 in movin~ to C3. Shortly after moving past C3, the split nests deposit the workpiece onto the xoll con-veyorj they then continue empty to point C2 and finally to point Cl to await the next pallet unload cycle.
The now empty pallet may be released at any time after the point C reaches C4 and the workpiece is clear of the pallet proper.
The mechanism of FIGURES 18 and 19 usable to either load or unload pallets is provided as one example.
Other mechanisms employing cylinders may also be used;
or the linkage mechanism may be~replaced by slide mecha-nisms.
An alternate system for loading or unloading t~orkpieces from the roll conveyor to the pallets is shown in FIGURES 20 and 21. A section of roller bed track 331 is still used to support and guide the pallet 170, 172 which is stopped for loading tor unloading) previously described.

-A pusher bar 360 i5 mounted on the rod of an air or hydraulic cylinder 362 which in ~urn is mounted from the base plate of the power roll con-veyor 156 through a riser 364~ Two transverse slide rails 366 are mounted on the power roll conveyor 156, interspaced between rollers 310 and extending beyond the power roll conveyor in a direction towards the stopped pallet 170, 172~
The base 310a is modi:Eied relative to base 311 of FIGURE 18. On the base 310a are mounted two guide blo`cks 368 in which are slidably supported two guide rods 370, which in tuxn support and guide a lifter base plate 372, on which are mounted two lifter rails 374. The lifter base plate 372 is connected to and driven by the rod 375 of an air or hydraulic cyl-inder 376 mounted on the base 310a.
`When the rod 375 of cylinder 376 is retracted as shown in FIGURES 20 and 21, the tops o-f the li.fter rails 374 lie below the lower plane of the workpiece 152 when it is nested in the pallet 172. When -the rod 375 of cylinder 376 is extended, the lifter base plate 372 and lift rails 374 are moved vertically upward, as guided by rods 370, such that, at the end of the stroke, the upper ~5~

surfaces of the lift rails 372 are substantially"~O-planar with the top surfaces of the slide rails 366.
It will be noted that the lift rails 374 straddle the roller nest conveyor 331 during such a lift move-ment.
To accomplish the loading of a pallet 170 from the power roll conveyor 156, an empty pallet 172 is stopped in the position shown in FIG~RE 20, and the lift rails 374 are extended to their upper position.
The pusher 360 is extended, sliding the workpiece transversely across the rollers 310 and across the slide rails 366 and onto the upper suriaces of the lift rails 374, reaching the intermediate workpiece position 152a. The lift rails 374 are then lowered, carrying the workpiece 152a downward with them and into the paliet nest. Shortly before the lift rails 374 reach their fully retracted position, the work-piece 152a is fully nested by the pallet 170. The pallet 170 is now loaded; it is released to be replaced by the next empty pallet 172, and the cycle can repeat with the arrival of a new workpiece 152 on the power roll conveyor 156.

, y~s~

It can be seen that this mechanism must be slightly altered to be used to unload workpieces from the pallets to the roll conveyor. The pusher bar 360 and its actuating cylinder 362 must be mounted on the other side of ~he intermediate work-piece po~ition 152a al~d push in the opposite direction, i.e., from right to left. To unload a pallet, the lift-er rails 374 move upward lifting a workpiece 152 from a loaded pallet 172i upon reaching their upper posi-tion, the revised pusher bar slides the workpiece ontothe roll conveyor. Pusher and lifter return, the now empty pallet 172 is released to be replaced by a full pallet 170.
The mechanism of FIGURES 20 and 21 is pro-vided as one example. It can be used with a belt con-veyor or a power and free conveyor as well as the power roll conveyor shown. Other methods of loading and un-loading pallets will be subsequently described.

~Sfl~9 When this system is employed for the simple storage of workpieces between two sections of a ma-chine as shown in FIGURE 11, no switching of pallets, either full or empty, is required. Switching is de-ined as the means of optionally routing a pallet mov-ing along a given track to one or more alternate tracks, or as the means for routing pallets moving on two or more individual tracks onto a single track.
When this system is employed to crosstransfer workpieces between parallel processlng lines, in addi-tion to storage, or when it is used to divide the work-piece flow from one number of sections of a line to a larger number of following sections of that line, or when it is used to combine -the workp.iece flow of mul~
tiple paraliel sections of a line to a smaller number of following sections, some type of switching is re-quired for both the empty pallets and the full pallets.
One type of switching employs the elevators .which are already in use. Referring to FIGURE 13, a second output for loaded pallets may be added as at 390, or a second input for loaded pallets may be added as at 392. Similarly, and referri.ny to FIGURE 14, a second output for empty pallets may be added as at 394, or a second input for empty pallets may be added as at 396.. These additions ~o FIGURES 13 and 14 are for illustrative purposes and it will be understood that the points of addition and the heights at which they occur will be dependent on the specific applica-tion.
It can be seen that when muItiple inputs or outputs are used for any given elevator flight, the elevator itself can function as a switch and combine the flow from multiple inputs or selec-tively control the flow to multiple outputs by selection of the gate operations.
Switching may also be performed while the pallets are rolling on their own wheels on a section of ixed track as shown in FIGURES 22 and 23. A section of track 400 is suitably supported by hangers 402 as pre-viously described, with an overhanging portion 404 de~
pendent on its own vertical stiffness for support. A
-cylinder 406, suitably supported from the track support structure, has its rod end pivot connected to a clevis 408 mounted to the overhanging portion of the track 404.
Two other fixed portions of track 410 and 412, which re-repsent the ends of alternate track loops, are also suit-ably supported from the structure. Each of these tracks ~41--410 and 412 carry stops 414 and 416 respectively which limit the travel of -the track portion 404.
~s shown in FIGURE 22, with the cylinder 406 extended, the track portion 404 is held against stop 414 aligning tracks 400 and 410. When the cylinder 406 is retracted, the track portion 404 is deflected or bent until it reaches stop 416, as at 404a, which aligns track 400 with track 412. It will be noted that the track is relatively unstiff and resilien-t enough in the horizontal plane to permit the deflection within the elastic limit of the material.
This simple deflection track switch is usable to divide pallet flow or to combine it dependent on the direction of dowhflow incorporated. Switches using hinge points in lieu of track deflection are also usable.
Switches of comparable design may also be incorporated into the roller nest type track, but because of greater complexity are not as favored as flexible fixed track switches~

~2-FIGURE 24 shows a track circuit layout for an application in which the flow is divided from the output of a single section of machine 420 and trans-ferred, with storage, to the input of two identical S parallel following machine sections 422 and 424. A
pallet loader 186 removes workpieces 152 from the last station of machine section 420 and deposits into -a waiting empty pallet on the lower track level 426, 428. It will be noted that the last station of the machine internal transfer system is adapted to this operation, and that there is no power roll conveyor.
The lower level track is pitched downward from 426 to 428 and the track at the pallet load point is of the roller nest type.
lS ~u;Ll pallets 170 enter the elevator 430 at the lower track level 428 ~rom which point they are carried upward to be selectively discharged at one or the other of the two upper level tracks 432 and 434, This selection is made by the two discharge gates on the elevator, and is controlled by the two high level contact switches 436 and 438 which cut off the flow to a given track when that track is sufficiently full to actuate the switch. In the absence of a signal from either high level switch, the loaded pallets may be al ternately routed or folLow any other appropriate sch~dulin~.

-Full pallets 170 entering track 434 join the end of the queue from whose forward end, escape-ment 440 releases the full pallets one at a time to enter the lowerator portion of elevator 442. They are subsequently discharged at the lower track level 444 to roll by gravity to the stop position 446, at which point they are unloaded by pallet unloader 200.
This pallet unloader 200 delivers the workpiece 152 directly to the load station of machine section 424, from which station the internal machine transfer sys-tem pulls it directly into the machine. An empty pallet 172 then proceeds to the end of the lower level track 448, enters the elevator portion of elevator 442 to be discharged at the upper level track 450. From this point, an empty pallet rolls by gravity to the end of the queue controlled by escapement 452 at elevator ~30.
Full pallets 170 which enter the track 432 follow an analagous path through escapement 454, elevator 456, lower level track 458, ~60, to return as empty pallet 172 on upper level track 462, the workpieces 152 having been delivered to machine sec-tion 422.

~Lf~~S~

It will be noted that two separate queues of empty pallets 172 controlled by escapements 452 and 464 enter the elevator 430 at the upper track levels. The control of this flow is by gates such as 274 and 396 in FIGURE: 14. Selection will ordi-narily be alternately from each track queue unless a given high level switch 466 or 468, for empty pallets, indicates an excessively long queue, at which time, empty pallets from that queue only will enter the lowerator portion of elevator 430.
Empty pallets from either upper level queue are discharged at the lower level track 426 to be re-loaded with a workpiece 152 to begin another travel cycle through one loop or the other.
It will be noted that on the average, the elevators 456 and '142 will cycle only at half the rate as elevator 430. It will be further noted that this system can be inverted, i.e., two machine sections will feed into a single machine section. One way to visualiYe the situation with respect to FIGURE 24 is to reverse the roles of empty and full pallets 172 and 170, to consider the flow from machines 422 and 424 to a - single downstream machine 420 and to consider mechanisms 200 as pallet loaders and mechanism 186 as a pallet un-loader.
.

_~5--5~

FIGU~E 25 shows a track layout for two parallel lines, with storage on each given line and the addition of cross flow tracks for crossfeeding of workpieces between lines when conditions warrant.
The normal on-line upper level storage tracks are shown as dotted lines and correspond identically with the tracks so numbered in FIGURE
11, when applied to one of the two parallel lines, consisting of machine sections 150 and 154 and con-veyor 156.
A second parallel line consisting of machine sections 150a and 154a and conveyor 156a employs on line upper level storage tracks numbered as on the first line except for the suffix "a".
lS The lower level tracks in FIGURE 25 corres-pond identically with those of FIGURE 11 and are num-bered as in FIGURE 11 for the line 150, 154, and with the suffix l'a" for the line 150a, 154a.
When the lines are operating without cross-flow, the storage function and description of each linestorage syste~ is as described for FIGURE 11.

~5~

To achieve crossflow, four additional u~per level tracks are added as sh~wn; no changes are re-quired of the lower level tracks 180-182, 194-196 on which the pallets are loaded and unloaded. For cross-feeding full pallets 170 from line 150a, 154a to line 150, 154, upper level track 480-482 is added from ele-vator 174a to elevator 188. For crossfeeding ull pallets 170 from line 150, 154 to line 150a, 154a, upper level track 484-486 is added from elevator 174 to elevator 188a. For returning empty pallets 172 ~rom line 150a, 154a, to line 150, 154, upper level track 488, 490, is added from elevator 188a to ele-vator 174; and for returning empty pallets from line 150, 154, to line 150a, 154a, upper level track 492, 494, is added from elevator 188 to elevator 174a.
It will be noted that the addition of these four crossflow tracks adds an additional upper level input and upper level output to each of the four com-bination elevator lowerators 174, 18~, 174a, and 188a.
This requires two gates at each such point in place of the one required where only on line storage is required.
The control of these gates is again through the use of appropriate queue length-determining limit switches.

-47~

In some applications, a slightly different arrangement is preferred; this is shown in FIGURE 26.
In this embodiment, the lowering function of the ele-vators is deleted and replaced by sections of helical S positioned track which spiral downward from the upper traclc level to a level suitable for the loading (or unloadlng) of pallets.
Refexring to FIGURE 26, which is a schematic representation of a single line storage system, a power roll or equivalent transfer conveyor 500 is employed to transfer workpieces 152 between two sec-tions of a transfer line, as previously described.
When workpiece storage is called for by the line re-quirements, a pallet loader 502 removes workpieces from the conveyor 500 and deposits them one at a time into empty pallets 17~ which then become full pallets 170.
The empty pallets 172 which are waiting to be loaded are queued and stored on a helical track section 504 which extends from the upper track level to khe pallet load level. Loaded pallets 170 roll down a short track sec-tion 5Q6 to be picked up by buckets on an elevator 508 which discharges them onto an upper level track 510 on which they progress to the top of a helical storage track 512 used for storing and lowering loaded pallets 170.

-~8--r ~len the line requirements call for work-pieces to be delivered to the conveyor 500 a pallet unloader 514 unloads the full pallets 170 from the helical storage track 512, one at a time, delivering the workpieces 152 to the conveyor 500 and discharg-ing the now empty pallets 172 to a short track sec-tion 516. From here, the empty pallets are picked up by the buckets ~f an elevator 518 which discharges them on an upper level track 520 on which they progress to the top of the helical storage track 504, completing the to~al pallet travel loop.
The system described in connection with FIG-URE 26 is for the storage and delivery of workpieces from and to a single line. It can also be used Eor lS crosseedin~ between parallel lines, for dividing flow or for recombining flow. Alternate inputs 522 for full pallets 170 can be introduced on the ascending :Elight of elevator 508 to accept full pallets from adjacent lines or to achi.eve combining of workpieces from two machine sections; this in turn requir~s the alternate distribution of empty pallets 172 from the descending flight of elevator 518 as schematically shown at 524.

~9w Similarly, full pallets 170 can be delivered away from the subject line by providing alternate out-puts 526 on the descending rlight of elevator 508; and this in turn requires the acceptance of empty pallets 172 at the alternate inputs 528 on the ascending flight of elevator 508; this is required for crossfeeding or ~or dividing flow to a larger number of following ma-chine sections.
As previously described, these alternate in-puts and outputs are controlled by gates which respond to -the queue lengths at the various pallet waiting points in the system.
~1hile the system described uses two discreet elevators, it is easily seen that both elevators can lS be combined into a single mechanical unit having buckets capable of simultaneously supporting full pallets and empty pallets as shown in FIGURES 13 and 15. Additionally, the lower level tracks 506 and 516 would need to be routed to be substantially parallel at their entry into such a double elevator.

--.,0--.

Each of the previous system embodiments em-ployed a lower level track system and a discrete mecha-nism for the loading and unloading of the pallets at that level. ~dditionally, the elevators, and lowering systems operated on the pallets and through them indi-rectly on the workpieces. In the embodiment of FIG-U~ES 27 and 28, the workpieces themselves are directly elevated from the conveyor, or lowered to it, and the pallet loadinq and unloading accomplished by this same operation.
Referring to FIGURES 27 and 28, two elevator side plates 540 support two sprocket shafts S42 suit-ably journalled therein; one of these shafts is driven by an intermittent drive mechanism such as that oE my prior U. S. Patents, Nos. 3,789,676; 3,859,862 and ~,075,911.
Each of these shafts 542 has mounted on it two sprockets 544 spaced apart on the shafts; these sprockets in turn drive and support two chain loops 546 and 548, with the straight flights of these chains operating in substantially vertical paths. A æeries of workpiece carriers 550 are pin connected to each chain 546, 548 with nominally equal spacing, and they ?ivot with respect to the chains to maintain a constant hanging (dependent) attitude. Each carrier is com-prised of two cantilevered arms 552, which are con-toured to support and maintain location of a work-piece 152, and a structural cross-connection 554 be-tween sald arms. A guide roller 556 is mounted on each connecting pin between chains 546, 548 and car-riers 550; and the rollers 556 are guided in channel members 558 mounted to the elevator side plates 540.
Auxiliary guide rollers 560 are mounted directly to the carriers 550 and aIso operate in the channel mem-bers 558 to prevent free swinging of the carriers 550 during their movement along the vertical paths. The carriers 550 are free to swing as pendulums while tra-versing the reversing arcs created by the sprockets;
lS suitable bell mouths (not shown) at the ends of the channel members 558 guide the rollers 556 and 560 into the ends of the channels.
The workpieces 152, in traversing from one machine section to the next, progress along a power roll conveyor 156 (FIGURE 11) as previously described.
This power roll conveyor 156 is adapted to operate with the elevator by incorporating slots 562 (FIGURE 28) -- between the rollers through which the carrier arms 552 ~Q~

are free to pass while delivering workpieces 152~to, or removing them -from, the conveyor.
An upper level track (see FIGURE 29) carry-ing full pallets 170 terminates at the elevator with a short section of roller nest track 564i full pallets arriving at this point are held in the position 170a (FIGURE 27) by a suitable escapement previously 'shown.
A gate section 566, comprising a short section of roll-er nest track, is mounted on a shaft 568 actuated by a mechanism as in FIGURE 17. This gate 566 leads to a fixed section of curved roller nest track 570 which directs pallets rolling thereon out one side of the elevator. A suitable stop is provided on the gate section 566 to stop a pallet in position 170b.
A second upper level track carrying empty pallets 172 'also terminates at the elevator with a short section of roller nest track 572; empty pallets arxiving at this point are held in the position 172a by a suitable escapement. After a short gap, a sec-tion of roller nest track 574 e~tends through the elevator and also curves out the side of the elevator (FIGURES 27, 28, 2g); and a second stop is provided to halt a pallet in position 172b.

It will be noted that a gap 576 exists be-tween track 564 and gate 566 in its down position;
and that a similar gap 578 exists between track 572 and track 574. These gaps are small enough to permit a pallet to confortably bridge as 1~ rolls across, but large enough to permit the carrier structure 554 to pass through vertically. It will further be noted that the carrier arms 552 are spaced further apart than the width of an empty pallet, and therefore, when an empty pallet is positioned as a-t 172b, or 170b, the empty carriers SS0 can move vertically through these positions without interference.
Though lt is not inherently necessary to use an indexing motion for the chain elevator, it is very convenient to do so, and further it is most convenient to have the stopped or dwell position of the carriers 550 positioned as shown in FIGU~E 27, i.e., with the points of pickup or deposition of workpieces 152 to or from the roll conveyor 156 or to or from pallets 170 or 172 approximately midway between the carriers stopped position. This permits operation of the gates to proceed without any interference with adjacent carriers (buckets) or workpieces, and further permits movement of workpieces on the conveyor without inter-ference with the adjacent carriers.

With the points of pickup and depositio~ of the workpieces midway between the stopping points of a carrier or bucket, it is very advantageous to uti-lize an index distan~e or stroke, as generated by the indexing drive and as related to the drive sprocket periphery, which is one-half of the carrier spacing on the chain. In this way, a given carrier will be at or near zero velocity when a worXpiece is picked up or deposited by said given carrier at the conveyor or with respect to a pallet. Stated another way, the chain and its carriers move through a double acceleration-deceleration cycle while moving through a distance equal to one carrier pitch on the chain.
Similaxly, and to minimize the number oE
carriers on the total chain length, the carrier pitch distance on the chain can be three, or four, o~ even more integral multiples o~ the distance moved by the chain during an acceleration-deceleration cycle created by the aforesaid indexing drive. This is the case pro-vided that the workpiece pickup or deposition point co-- incides with a carrier position at one oE the inter-mediate momentary stopping points or dwells separating the multiple acceleration~deceleration cycles.

~55~

The unloading of workpieces from the full pallets 170 queued on track 564 to the roll conveyor 156 proceeds as follows: the gate 566 is lowered and a full pallet in position 170a is released by the actuation of the appropriate escapement and is per-mitted to roll down to position 170b where it is again stopped. The sprockets 544 are then indexed counterclockwise through one carrier pitch distance causing the flight of carriers on the left to move downward and the flight of carriers on the right to move upward. The lowermost carrier above the roll conveyor at the start of index deposits the workpiece 152 it was carrying onto the conveyor rollers and pro-ceeds to the next position below the roller conveyor as an empty carrier. Simultaneously, an empty carrier di-rectly below the full pallet in position 170b lifts a workpiece 152 from the full pallet, converting it into an empty pallet 172, and this carrier proceeds to a position directly above gate 566. The now empty pallet 2t) on ~ate 566 is released by the stop and rolls out on track 570 to proceed to the end of the empty pallet queue. The workpiece deposited on the roll conveyor 156 is carried away by the power rolls and the system awaits the next delivery command from the machine re-quirements. This cycle can be repeated whenever the carrier workpiece deposit position on the roll con-veyor is empty and as long as there are full pallets waiting to be unloaded on track 564. After the last full pallet has been emptied at position 170b, those carriers still carrying workpieces 152 can deliver those workpieces to the roll conveyor; and the sub-sequent arrival of additional full pallets will then re~uire additional cycling to refill the gaps so gene-rated ln the workpieces in the carriers, which are above and between the roll conveyor and the pallet un-load position.
Whereas workpieces are unloaded from full pallets in position 170b, workpieces are loaded into empty pallets in position 172b. To unload workpieces 152 from the roll conveyor 156 to the empty pallets, the gate 566 is open and full pallets in the queue on track 564 are held baclc by their escapement. An escapement on the roll conveyor 156 holds a workpiece in a position 152a and the sprockets of the elevator are indexed clockwise a distance equal to one carrier pitch. This causes the left flight of carriers to move ~5~

upward and the right flight of carriers to move down-wa~d. The carrier immediately below the roll conveyor moves through it (opening 562) lifting the workpiece 152 upward with it. At this time, or during a sub-sequent unload cycle, depending on the initial condi-tion of the intermediate carriers, the carrier immed-iately above the empty pallet at 172b, in moving down-ward during a clockwise conveyor unload cycle, will, if it is carrying a workpiece, deposit that workpiece into the waiting empty pallet in position 172b. As soon as a workpiece is received by an empty pallet, it becomes a full pallet, and is released by the stop and rolls out on track 574. The first empty pallet in the queue on track 572 in position 572a is then released by its controlling escapement and stopped again in posi-tion 172b. It will be noted that the presence of an empty pallet in position 172b may exist even durlng pallet unloading at position 170b, since there is no interference between rising empty carriers moving up-ward past an empty pallet in this position.
The operation of this system may be summarizedas follows:

;~

~s~

1. To deliver workpieces to the conveyor 156, the sprockets 544 index counterclockwise one carrier pitch.
2. To remove workpieces from the conv~yor 156, the sprockets 544 index clockwise one carrier pitch.
3. Prior to a delivery cycle, the gate 566 is lowered and a full pallet (if available) is allowed to move to position 17Ob to be emptied as part of a delivery cycle.

4. After a delivery cycle, the now empty pallet in position 17Ob is released to rnove out on track 570.

5. After a removal cycle, if the pallet in position 172b was loaded with a workpiece, the now full pallet is released to move out on track 574, and is immediately replaced with an empty pallet from position 172a.
It can be seen that if no empty pallets are available at position 172b, and if the carrier immed iately above track 57~ is carrying a workpiece, the storage system has absorbed its full complement of workpieces and no more removal of workpieces from conveyor 156 is permitted. Similarly, if no full ,r :

pallets are available at position 170a and if the carriers be~ween position 170b and the roller con-veyor 156 are empty, the storage system has delivered its full complement of workpieces and no additional deliveries can be made.
It will be noted that full pallets emerge from the elevator on track 574 and reappear at the track 56~ which is higher. Referring to FIGURE 29, a track plan schematic, a pallet elevator 580 for full pallets must be added to the track loop which begins at track 574 and ends at 564, in order to compensate for the di-fference in elevation between the ends of the track plus the height lost due to the downward slope of the track. This elevator which is termed a booster elevator may be of a design comparable to the design of the elevator described in connection with FIGURES 12-15 except that the buckets need carry only full pallets and the elevator is proportionally narrower. In the simple non-switching application of FIGURE 29, no gates are required and a single low level input for full pallets arriving on track 574, and a single high level output for full pallets discharging onto track 564 is sufficient.

~L~t~

Since empty pallets emerge on track 570 which is higher than track 572, the requirement for an empty pallet elevator, shown in dashed lines as 582 is dependent on each application, specifically on the 5 height differential between tracks 570 and 572. and the length of track between them which in turn is dependent on the desired empty pallet storage capacity. If these requirements demand the usage of ~n empcy pallet ele-vatox, its construction would be similar to ~hat for full pallets, except for lift height. Furthermore, if~the physical track routing permits, the full pallet elevator 580 and empty pallet ele~ator, when xequired, can be combined into a single elevator as in FIGURE 150 A variation of the bare parts loading and un-loading elevator of FI~URE 27, which is possible, and in some cases desirable, may be achieved by combining ~he position of pallet unloading and the position of pallet loading into a single position on the elevator. Tracks 564 and 570 and gate 566 are deleted; a combining track switch, such as in FIGURES 22 and 23 is added ahead of track section 572 and is used to select empty or full pallets from their respective waiting queues, and a second dividing track switch, such as in FIGURES 22 and 23, is added to track 574 to direct empty or full pallets to their respective tracks.
In this way, empty or full pallets can be positioned at 172b, and this single position is utilized either to load or unload the respective pallets, according to the demands of the main line.
The foregoing description of a pallet loader-unloader built in the form of an elevator applies to its use with substantially conventional power roll conveyor wllich exist between machine sections. The same mechanisms with only minor modifications can be used directly between machine sections in the absence o the power roll conveyor.
FIGURE 30 shows a schematic track and system layout for the transfer and storage of woxkpieces di-rectly rom the last station of machine section lSO to the first station of machine section 154. A bare part elevator 584 is used to elevate the bare un-pallitiæed workpieces from the last station of ma-chine section 150, into which a workpiece is trans-5 ferred by the internal machine transfer system; thislast station is suitably adapted with slots for the carriers of the elevator unloader 584 to move through in lifting a workpiece vertically out of this station.
The elevator 584 is substantially identical with the 10 elevator of FIGURES 27 and 28 except that the full pallet entry track 564, gate 566, and empty pallet exit track 574 are deleted, and the elevator indexing is always clockwise, to remove workpieces :from the last station of the machine section 150 and to load them into 15 empty pallets at position 172b.
After the now full pallets 170 leave the ele-vator 584 on track 574, they progress to a pallet ele-vator 580, (or booster elevator), and then to the end of the queue awaiting entry into elevator 586, whose 20 function it is to unload full pallets 172 and deliver the workpieces into the first station of machine sec-tion 154. Elevator 586 is also substantlal identical "
with the elevator of FIGURES 27 and 28, e~ccept that the --63~

~s~

empty pallet entry track 572 and full pallet exit track 574 are deleted and that the elevator indexing is always counterclockwise to remove workpieces from full pallets at position 170b and deliver them to the first station of machine section 154. Since the re-quirement to lower full carriers 550 downward through position 170b no longer exists, it is further possible to delete the gate 566 and make that portion of the roller nest track integral with exit track 570. Empty pal~ets are discharged to track 570 to roll b~ gravity t,o the end of the ernpty pallet queue awaiting entry into elevator 58~, with or without going through an empty pallet booster elevator 582, depending on the fall available, and, distance between exit track 570 on ' elevator 586 and entry track 572 on elevator 584.
Furthermore, since the entry and exit tracks on each elevator 584 and 586 are no longer related as they must be on a single elevator, it is possible to arrange these heights to delete the booster elevator 580 for full pallets and use only a booster elevator 582 for empty pallets. The first station of machine section 154 is slotted to permit the vertical downward motion of a carrier 550 as it deposits a workpie~e into tilis sta-tion. From this deposit position, the workpiece is

-6~

,r transferred into the machine directly by the machine internal transfer system.
While the track and system schematic lay-outs of FIGURES 29 and 30 apply only to single lines, as between machine sections 150 and 154, it is also possible to a~apt this pallet loader or unloader as a bare part elevator technique to crossfeeding between multiple parallel lines as previously illustrated in FIGURE 25. Indeed, greater system design flexibillty exists. FU11 or empty pallets can be switched, not only by track switches, or by the use of gates in the pallet Ibooster) elevators, as has been previously described, but such switching can now also be accom-plished by adding additional entry tracks, e~it tracks, and movable gates to the bare part elevators, whose pri-mary function is the loading and unloading of pallets as in FIGURES 27 and 28 and elevators 584 and 586 in FIGURE
30.
FIGURE 31 illustrates a track and system schematic layout for a situation in which the work-pieces from a single machine section 150 are divided .~ and delivered to two following machine sections 154 which is analagous to the system of FIGURE 24.

A bare part elevator 588 lifts workpieces vertically upward from the last station of machine 150 which is ` again adapted for this operation. The elevator 588 is agaln substantially identical with the elevator of FIGURES 27 and 28, except that the indexing is always clockwise to unload workpieces from the last station of machine 150. However, in this application of a bare parts unloader elevator, tracks 564 and 570 and gate 566 are not deleted but used as an alternate position for loading empty pallets. Empty pallets are queued on track 564 as well as on track 572 and the loading of an empty pallet can occur at either position 170b or 172b, and full pallets can exit at tracks 570 or 574.
lS Tracks S70 and 574 proceed to two entry points of a pallet booster elevator 584 from which two exit tracks 586 and 588 route full pallets to the respective queues leading to the two elevators 586, each of which unloads workpieces from full pallets and ?O delivers them to the first station of its associated machine section 154 as previously described. The empty pallets discharged from the two pallet unloaders 586 proceed on downward sloping tracks to the two empty pallet queues 587a and S87b assoclated with pallet loader elevator 588.

No booster elevator for empty pallets is shown in FIGUR~ 31. If one were used, it could operate with a single output and two inputs, thereby combining the empty pallets from the ~wo unloaders 586, and deleting the multiple input function of elevator pallet loader 588. Numerous other arrange-ments are possible, with any given choice dependen-t on the specific parameters of a given situation.
The techni~ue of FIGURE 31 for the division of workpiece flow, can, with obvious modifications, be used for the combination of workpiece flow, and, with other modifications, be used for crossfeeding between multiple lines. In essence, the use of an elevator type pallet loader or unloader does not decrease the system options but increases them.
For workpieces such as cylinder heads, crankshafts, cam shafts, and comparable parts dis-tinguished by a relatively large ra~io of length to width, pallets which incorporate a hanger structure at each end to operate on a fixed overhead track through flanged retarded wheels are appropriate. For other types of workpieces, pallets which mount their own retarded support wheels, to operate on a fixed track, on the underside of said pallets are more appropriate.

-67~

5~

In either caseO and depending on workpiece size and configuration, it may be advantageous for a given pallet to locate and support two or more work-pieces, with all elements of the system adapted to handle such a condition.
An illustrative construction of ~he underside of a pallet to ride over a fixed track, as opposed to hanging from it, is shown in FIGURES 32-36. It will be understood that the upper surface of the pallet, not shown, is contoured to support and locate the specific workpiece or workpieces for which it was designed.
Referring to FIGURES 32~34, a pallet body 600 has mounted on its underside two cartridge type retarder assemblies 602 which support dou~le flanged wheels 604 having mul-tiple rolling diameters. The wheels 604 roll on and areguided by a stationaxy track 606 ~FIGURE 33) intermittent-ly supported by a structural support member 608. It will be understood that the track 606 will have a slig7nt down-slope in the direction the pallets rolling thereon are intended to travel.
Since the center of gxavity of the pallet, with or without ths workpiece it carries, will normally be above the contact points between wheels 604 and track 606, the pallet is unstable and will tend to tilt one way or the other about the said contact points.
Therefore, two auxiliary wheels 610 are mounted on pallet base 600 to roll on auxiliary tracks 612 which ~6~-~s~

are suitably structurally interconnected with the structure member 608. It will be noted that the contact surfaees of the auxiliary tracks 612 are horizontal so lateral alignment in the horizontal plane can be imprecise. vertical alignment i~ also very non-critical, provided only that tracks 612 as shown in FIGURE 33 do not both become high enough to lift the pallet off the primary track 606.
In normal construction, both tracks 612 will be mounted ~ome reasonable distance below their theore-tical position for simultaneous contact with both wheels 610. It is of no concern that the pallet 600 tilt through some reasonable angle be~ore stab~lity i9 regained through contact of one wheel 610 or the other with its associated track 612; furthermore, it is of no concern that the pallet tilt back and forth between the two limits established by tracks 612~
In FIGURE 33, the location of auxiliary tracks 612 is under the auxiliary wheels 610. As shown in the inset of FIGUR~ 35, it is also possible to locate ~he auxiliary tracks 614 above the auxiliary wheels 610, it being understood that both tracks must be above or both tracks below the auxillary wheels 610. The arrange-ment of FIGURE 35 i~ advantageous in khat it is least susceptible to dirt pickup.

;3S~ 9 In some areas of pallet travel, especially as pallets move through switches of the type shown in FIGURES 22 and 23, it is desirable to provide stabili-ty through only one or the other of wheels 610. Such an arrangement is shown in FIGURE 3~. In this case, a single wheel 610 is trapped between an upper and a lower rolling surface as in a channel member 616~
The methods of providing stability, through wheels 610, as illustrated by FIGURES 33, 35 and 36, may be alternated on a given track section to suit specific conditions~
The underside of the pallet body 600 is de-signed to incorporate longitudinal strips of substan-tially flat surfaces which are intended to support the pallet in such areas where it operates on roller nest type track, or for support in bucket type palle~ ele-vators. Two center guide rollers 618 are mounted on the underside of the pallet body, operating on vertical axes, to provide lateral guidance on the center channel of a typical roller nest type track.

At the four corners of the pallet body 600 are mounted four adapters 620, which are intended to operate with pins on a specialized ~ype of elevator to be described. These adapters 620 are in effect S inverted U type structures suitable ~or mating with stub pins on an elevator chain. It will be under-stood that these adapters 620 can also be incorporated in the pallets employing overhead wheels and hangers.
All e~lbodiments of pallet elevators already described employ buckets which are pivot-suspended from the two chain loops to lift pallets from one level to another. An elevator for lifting pallets without the use of buckets is illustrated in FIGURES 37 and 38.
Two side frames 630 are interconnected by spacers 632.
Two lower shafts 634 and 636 are suitably journalled in the sideframes 630; and each of the shafts mount two sprockets 638. The two lower shafts 634 and 636 are interconnected to rotate in the same direction by sprockets 640, mounted thereon, and chain 642. Four upper sprockets 644 are mounted on stub shafts 646 which are journalled in the sideframes 630. It will be noted that the upper sprocket shafts 646 do not span the dis-tanc~ between the two sideframes 630, but that the ., :

~s~9 ~

sprockets 644 are mounted on the short cantilever shafks 646 and that the interspace between the upper sprockets is open for the passage of pallets. Two chain loops 648 operate between the lower sprockets 638 mounted on shaft 634 and their corresponding up~
per sprockets 644; two other chain loops 650 operate between the lower sprockets 638 mounted on shaft 636 and their corresponding upper sprockets 644. All four chain loops rotate in unison as driven by an indexing 10- drive, as previously noted, by one or the other of tha interconnected lower shafts 634 or 636.
On each of the four chain loops 648 and 650 are mounted a series of pins 652, which may be simple extensions of the hinge pins of the chain, or short stub pins othexwise connected to the chains. For a given position of all four chain loops, and for a given position of a given pin on one chain, the other three chains on their corresponding flights will carry pins which lie substantially in the same hori-zontal plane as the given pin. Then as the sprockets are rotated in unison, such a set of four pins, one mounted to each chain loop, will continue to lie in a su~stantially horizontal plane, which moves as the ~72--chains move. This coplaniarity of a set of four pins remains true, even as the pins traverse the peri-phe~ies of the upper sprockets 644 or lower sprockets 638.
A short section of roller nest track 654 is suitably mounted between the chain loops 648 and through one flight of chain loops 650; this is the entry point for palle~s to be elevated. A stop 655 is moun~ed at the end of this track 654 to halt a pallet in the proper position for pickup by the pins 652. Similarly, a short section of roller nest track 656 is mounted to the frame 630, and extends not quite through the chain loops 650 this track 656 is used to carry away the pallets after they have been elevated.
To elevate the pallets, all sprockets rotate clockwise as viewed in FIGURE 38~ A pallet 658 is re-leased by an escapement on the input track 654, and allowed to roll down against stop 655. In this posi-tion, the adapter receptacles 620 on the pallet are in alignment with the paths of the four pins mounted on the chains 648 and 650. To accomplish a lift cycle, the sprockets rotate clockwise through one pin pitch. The pins on the ascending flights of chain loops 648 and 650, i.e., the left hand vertical flights as viewed in FIGURE 38, engage the adapters 620 on the pallet 658, and lift it vertically upward from track 654.
The pallets 658, shown in FI~URE 38, are shown in an intermediate position after the pallet 658 has been lifted from the ~rack 654. Near the en~ of the index, the leadin~ pallet 65~, which has been carried over the top of the sprockets 644, al-ways moving parallel to itself, now moves downward on the descending ~lights of the chain loops 648 and 650, i.e., the right hand flights as viewed in FIG-URE 38~ This downward movement causes the pallet 658 to be stripped from the pins 652 by the roller track 656, on which the pallet 658 rolls away. It will be noted that the descending pins on the chain loop 648 clear the body of the pallets 658 still moving up on the pins of the ascendin~ chain ~lights since they clear the adapters 620 which extend beyond ~he basic body outline.
Pallets intended ~or use with an elevator of the type shown in FIGURES 37 and 38 must incorporate adapters as illustra~ed by the adapters 620 in ~IGURES
32-34, and such adapters can be added to the previous pallet embodiments shown.

Furthermore, while the adapt~rs on the pallets are shown as inverted "U's" to be engaged by pins on the chain, it is equally feasible to make the adapters as pins on the pallets, while the chain is fitted with U fittings to engag~ those pallet adapter pins. Indeed, it is possible to devise a variety of male-female combinations of pallet adapters and corres-ponding chain fittings to accomplish the desired chain to pallet engagement.
Another embodiment of an elevator suitable for elevating pallets is shown in FIGURES 39 and 40.
This is again a ~our chain loop elevator, but in this embodiment, two chain loops ro~ate in one direction, while the other two chain loops rotate in the other direction.
Two sideframes 660 are interconnected by spacers 662. Two lower shafts 664 and 666 are suit-ably journalled in sideframes 660~ ~nd Pach has mounted on it two sprockets 66~ and 670, respectively. These shafts 664 and 666 are suitably interconnected to rotate in opposite directions and are again driven by an index-ing drive system as previously noted. Two upper shafts 672 are also journalled in sideframes 660, and each in turn supports two sprockets 674. Four chain loops operate between the upper and lower sprockets; two chain loops 676 operate between lower sprockets 668 and the corresponding upper sprockets 674, and two chain loops 678 opera~e between lower sprockets 670 and the corresponding upper sprockets 674~
At substantially equal intervals of their total loop lengths, the chains of chain loops 676 have angular lift brackets 6~0 transversely suspended between the two chain loops. Similarly, a group of identical lift brackets 682 is suspended between the chain loops 678.
A section of roller nest track 684, suit-ably mounted to the frames 660 extends between the chain loops 676 and 678, and a stop 686 is attached to the end thereof. A pivoted gate 688, comprised of roller nest track, is mounted to a shaft 690 which is rotated as in FIGURE 17. Wit~ t~e gate in its extended position, shown in dashed lines, it is sub6tantially coplanar with a section of fixed roller nest track 692 suitably connected to the frame 660. With the gate 688 in its returned position as shown in solid lines in FIGURE 39, it does not interfere wi~h pallets being elevated.

. . .

:

A pallet 694 enters th~ elevator of track 684 to be halted by stop 686 in proper position to be picked up and elevated by a bracket 68V on chain loops 676 and a corresponding bracket 682 on chain loops 678. It will be noted that to elevate a pallet 694, the sprockets 668 rotate countercloekwise and sprockets 670 rota~e clockwise, through equal peri-pheral increments. At the end of a given elevating index of the chain loops 676 and 678, a pallet 694 reaches the uppermost position on the elevator. At the end of the index, the g~te 688 is extended, slight-ly lifting said pallet 694, whereupon it rolls out onto track section 692.
~11 of the elevating methods previously de-scribed employ elevators in which the pallets arY
lifted through a substantially vertical path. The height differential or head is xequired only to supply the gravitational ~nergy to the system to create the movement of the pallets along the unpowered, down-sloping tracks, and this height differential can alsobe created by sloping, rat-her than vertlcal, elevators which will be termed pallet escalators.

A side view of a generalized pallet escalator is shown in FIGURE 41. A pulley 700 is mounted on a shaft 702 suitably journalled in a frame of conven-tional construction; at the othex end of the escalator, a similar pulley 704 is mounted on a shaft 706, also suitably journalled in the same frame. Either shaft 702 or shaft 706 or both are driven in a clockwise direction by an appropriate drive systsm.
Referring also to an illustrative cross-section in FIGURE 42, two belts 708 encircle the pulleys 700 and 704; these belts 708 are supported in their upper flight by a plate 710, also mounted to the frame, on which they slide~ Two fixed rails 712 are mounted to this plate 710 to form a channel for guid~
ing the center guide roller5 of a typical pallet.
A section of fixed track 714 converts to a short section of roller nest track 716 which abuts the belts at an obtuse angle. At the other end of the escalator, another short section of rollsr nest track 718 is tangential to the belt on pulley 704 and then converts to the beginning of the fixed track 720. It can be seen that a pallet 722 moving down track 714 on its own retarded wheels will transfer to the roller nest ~78-"~ -~L~S4~

track 716 on which it rolls until its leading lower edge contacts the upward moving belts 708~ Friction between the belts and the bottom of the pallet will carr~ the pallet up the inclined surface until it is stripped off by the roller nest 718, on which it rolls downward to xeturn to a fixed track 720 at a higher level than at 714. During its movement on the tracks 716 and 718 and belts 708, the pallet 722 is guided by its center guide rollers between channels 712.
The belts 708 may be of any suitable formable ~aterial with a smooth or ribbed surface, or even a fiber material. The belt may also be a metal chain or belt with or without protuberances to increase friction.
An alternate escalator cross-section is shown in FIGURE 43. In this embodiment, two series of xollers 724 are mounted on the upper surface of the plate 710 between strips 711, which in effect create a substan-tially continuous section of rollar nest track. At the uphill section of this track, the pallets are pushed up the slope by two chains 726 having extended pins engag-ing appropriate protuberances 728 on the pallets 722 co~-parable to the adapters 620 previously described. The _ 19_ .

~`5~

chains 726 are supported by rails 730 and spacers 732 from plate 710.
Another e~bodiment of escalation which drives the pallets uphill on the fixed track is shown in FIG-URES 44 and 45. In this instance, a conventional mono-rail 74 0, monorail chain 74 2, and monorail hangex 744 having supporting rollers 74 5 is employed to provide the uphill drive for a pallet on its fixed track. ~ pusher pawl 746 ls pivoted to the underside of monorail hanger lo 744 and maintained in a driving position by a spring 748. The monorail track besomes suitably ~angent to the fixed track at the beginning of an upslope, at which time a pusher pawl randomly engages a pallet hanger 8 or 8a, as previously illu~trated in FIGURES 1, 2, 5 and 6, and through it drives a pallet 2, up the slope of a rail 14 until the desired height is reached, at which time the fixed track supporting the pallet eurves downward to its normal unpowered slope.
It can be seen that this type of escalating pusher can also be adapted to pushing on the underside of the pallet in such applications where this is ad-vantageous.

_~

Another means of achieving pall~t escala tion is through a series o~ closely sp~ed power driven rolls comparable to the power roll conveyor used for the unpalletized workpieces as shown at 156 in FIGUR~S 20 and 28. Such an escalating power roll conveyor for pallets would obviously require rolls wide enough to accommodate the width of the pallet support surface, and spaced closely enough to provide a continuously stable support for this same surface.
All of the previously described systems for pallet escalation are equally usable for the horizontal transport of pallets, as is sometimes desirable for manual operations on the workpieces, including manual loading and unloading.
Another means of causing a pallet to move along an upslope is shown in FIGURE 46, which also illu trates a cylindrical type of retarder a5 opposed to a disc type o~ retarder.
A chain strand 750 operates over two sprockets 752, which are arranged comparably to the pulleys 700 and 704 in FIGURE 41. The chain strand 750, ~herefore, is moved upward at an inclined angle as i8 belt 708 in FIGURE 41: a back-up bar, as 710, may be provided to prevent chain sag over long spans.

Ref~rring to FIGURE 46, a sprocket 754 is concentrically moun~ed to the wheel 60 mounted on shaft 756 of a cylinarical type cartridge retarder, which is comprised of housing 758, bearings 760 and 762, seal 764, and a ro$or 766 mounted on the shaft 756. The interspace between the housing 758 and the rotor 766 is filled with a viscous fluid creating a cylindrical shear area 768 between the rotor 766 and housing 758. This cylindrical cartridge retarder also creates a torque proportional to the angular velocity of shaft 756.
~he housing 758 is connected to the pallet by a hanger 8a and hook 50 as in FIGU~ES 5-8; or it may be configured with a mounting boss 770 making it usable with an undersupported pallet as in FIGURE 33.
For downslope operation, the pallet rolls on one o the rolling diameters of wheel 60 as pre~
viously described. For upslope operation, the track brings the pallet into line with the chain strand 750 and the sprocket 754 finds its way into engagement with the chain 750 it will be noted that a double strand chain is used, with one strand engaging the driving sprockets 752 and the other strand engaged by the pallet sprocket 754, thexeby precluding sprocket-to-sprocket interference.

As the chain 750 is driven uphill, it drives the sprocket 754 with it; this sprocket 754 may rotate with respect to the housing 758 with the aforementioned torque speed ratio. The retarder now functions as a slip clutch. It can be see~ that as the sprocket 754 is pulled uphiLl by the chain 750, the pallet rolls backwards with respect to the up-ward moving chain as determined by the retarder characteristics. ~he true pallet uphill velocity will be less than that of the chain. As a good approximation, the pallet rolls backward at a rela-tive velocity with respect to the chain as if it were rolLing downhill at that same angle of inclina tion, and in order to achieve a given upward velocity o~ the pallet, the kotal chain velocity must be the sum o~ this relative velocity and the given net upward velocity.
Thi5 technique is useful or moderate upward inclination angles comparable to or somewhat greater than the downhill angles at which the pallet rolls on the ~racks, and for which the retarder was designed.
miS is caused by the fact that the retarder torque angular velocity ratio is the same in both directions of rotation. It can be seen that the retarder torque is generated by one direction of rotation of the shaft 756 _~3-when the pallet is moving downhill, and generated by the opposite direction of rotation of the shaft 756 when the pallet is being moved uphill by the chain 750.
An illustrative means of building a retarder which has a given torque angular velocity ratio when the shaft is rotated in one direction, and a hi~her torque angular velocity ratio when the shaft is ro-tated in the opposite direction, is shown in FIG~RE
47, which comprises an addended section of FIGURE 46.
Referring to FIGURE 47, ~he housing 758a and shaft 756a are lengthened to crea~e additional space adjacent to the rotor 766 mounted on shaft 756a and bearing 760. A secondary rotor 772 is journalled on the shaft 756a through bushings 774. Additionally, the secondary rotor 772 is connected to the shaft 756a through an overrunning clutch 775, such as a sprag clutch or a roller clutch; such clutches are character-ized by permitting free rotation of the shaft 756a with respect to the rotor 772 for one direction of shaft 756a rotation with respect to the rotor 772, and locking the rotor 772 to the shaft 756a for the opposite direction of rotation.

It can be see~, therefore, that for one direction of rotation of the shaft 756a, the retard-ing torque is generated by shear of ~he fluid between rotox 766 and housing 758a, with rotor 772 disconnected ~rom shat 756a, while for the o~her direetion of rota-tion of the shaft 756a, the retarding torque is gene-rated by the shear of the fluid between both rotors 766 and 772 and the housing 758a. Sta~ed another way, the torque angular velocity ratio is greater for one direc-tion of rotation of shaft 756a than ~or the other di-rection of its rotation.
This construction can be usefully employed by arranging these characteristics such that only rotor 766 rotates to create the retarding toxque during the 15 downhill movement of a pallet, and both rotors 766 and 772 rotate during the uphill pulling of chain 750~ The higher torque angul~r velocity ratio created by the re tarder during this uphill pulling permits steeper uphill inclination ~or a given amount of slippage~ It will be understood that this type of double rotor construction is equally applicable to the disc type retarder shown in FIGURES 2 and 5 by using multiple discs, including concentr.ic discs, one of w~ich is attached to the sha~t through an overrunning clutch.

--~3S--.f'~ .

~s~

Another me~hod for pulling the pallets uphill throuyh the use of the retarder shaft is shown in FIG-URE 48. ~o pulleys 780 are mounted in an arrangement such as pulleys 700 and 704 in FIGU~E 41. A belt 782 is driven by pulleys 7~0 at an inclined angle such as belt 708 in FIGURE 41. ~he bel~ 782, shown in section in FIGURE 48, is configured to run over ~he pulleys 780 and also to engage one of the diameters of wheel 60 on retarder 758~ Therefore, as the belt 7ao moves uphill, the palle~ is also pulled uphill at a lower velocity, due to the slippage o~ ~he retarder, anala-gously to the chain sprocket system of FIGURE 46.
The systems for moving pallets uphill at in-clined angles through the retarder, with its attendent slippagej is useful in that it is a simple and inex-pensive method of lifting pallets through moderate distances while still retaining the non-jamming charac-teristics of the simple downhill track. Pallets may even orm part of a queue ~n the chain or belt without 20 harmful consequ~nces.

The technique of moving the pallet through the retarder by a chain and sprocket as in ~IGURE 46 or by a belt on the existing wheel as in FIGURE 48, is also applicable for hoxiæontal travel of the pallets. In such a case, the sprockets 752 or pulleys 780 are arranged horiæontally. This is useful for si-tuations where manual loading and unloading of the pallets is desired or where some manual operation is to be per~ormed on the workpiece.
Another outgrowth of ~his technique is that in situations where downhill angles of travel are re-quired that exceed the friction capacity of the wheel on a track of the type shown in FIGU~ES 5 and 7, it is feasible to incorporate a fixed section of chain to be engaged by the sprocket 754, it being undarstood that ~his fixed chain would be mounted parallel ~o the track and in proper relationship to the track to ~e engaged by sprocket 754 when wheel 60 is on or slightly above ~he track. The wheel to track ~riction would be of no conse~u~nce because of the positive chain to sprocket engagement or retardation.

Similarly, in such steeper downhill appli-cations, a fixed section o~ belt, suitably supported, could be used as a track, it being understood that the wheel belt holding riction is greater than the wheel track friction of FIGURE 5.
Another use~ul technique is illustrated in FIGURES 49 and 50. In this instan~e, a secondary wheel 786 is mounted to the shaft 755 through a bearing 788. This wheel engages an auxiliary track 790 mounted parallel to the modified primary track 64a on modified supports 72a. It can be seen that when a pallet is supported by wheel 786 rolling on auxiliary track 790, the retarding torque of the retarder 758 is effectively cancelled since the wheel 786 is free to rotate on bearing 788. This is a means o~ turning off the retarding effect as a pallet rolls down some portion of the inclined track. It is use-fully employed going around sharp corners which create a natural retarding effect, or for moving away ~rom a stopped position, such as at an escapement, where mini-mum departure time is desirable, or wherever a non-retarded situation is desirable.

~s~

Also illustrated in FIGURE 49 is a capping member 792 mounted on the modified primary track 64a.
This capping member 792, which may be bolted to track 64a or merely pressed over it, accomplishes two func-tions; it is an expendable wear member which is easily and economically replaced, and it can create two angular contact ~ines with the wheel 60, thus increasing the wheel to track effectlve contact force.
The crossover from a situation in which a pallet is rolling on the unretarded wheel 786 on track 790 to the situation in which that pallet in rolling on the retarded wheel 60 on ~rack 64a with capping member 792 requires no moving parts other than the pallet movement itself as it rolls downhill.
Referring to FIGURE 50, wheel 786 is sho~n rolling on track 790 and rolling downward to the right.
As both wheels continue to the right, as a pair, the wheel 60 contac~s its track 64a, 792, at a point 794 and rolling thereon is established. Simultaneously, wheel 786 lifts from ~rack 790; track 790 tapers off slightly, then terminates completely.

It can be seen that the capping member 792 is not relevant to ~his track shift other than to pro-vide a replaceable wear surface on track 64a, i.e., the track shift could also be accomplished with an un-capped track such as shown by 64 in FIGURE 5.
It can also be seen that the shift from theretarded rolling of wheel 60 on track 64 to ~he unre-tarded rolling of wheel 786 on track 790 can be accom-plished by adding another segment of track 790 provided with a tapered entry which is the inverse of the con-figuration shown in FIGURE 50.
Several means for transferring workpie~es from ~he line to the pallets and then from the pallets back to the line have already been described. Another technique suitable for certain workpiece configurations involves moving a pallet directly through the on-line station, where an empty pall~t is moved vertically up-ward through the station to pick up a workpiece, or a full pallet is lowered through the station to deliver a workpiece.
FIGURES 51 and 52 illustrate this technique as it relates to movement of a pallet which is being moved vertically in a chain t.ype elevator of the type \

5~

illustra~ed in FIGUR~S 27 and 28, with the exception that the buckets are designed to carry palle~s as opposed to bare woxkpieces.
Referring to FIGU~ES 51 and 52, the work-piece 152 is shown in position at the point of inter-change; it is supported on the interrupted slide rails 800 and 802. It will be understood that these rails 800 and 802 are part o the main line transfer sys-tem and that the workpiece 152 reaches the position shown by being pushed into ~his position by a machine transfar bar or by an auxiliary transfer barO It will be urther noted that the gap be~ween.rails 800 and 802 is sufficiently small for the workpiece to bridge as it is slid across in the direction of arrow 804.
A pallet 806 is supported by an elevator bucket 808 which in turn is guided b~ xollers 556 and 560 in elevator channels 558 and carried by chains 546 and 548 as detailed in FIGURES 26 and 27. Referring to FIGURES 51 and 52, it will be noted that the pallet 806 is configured t~ vertically pass through the gap between the rails 800 and 802; the elevator bucket 808 is similarly configured to pass through this same gap.

--gl--It will be ~urther noted that the pallet 806 overhangs the bucket sufficiently to be capable of being lifted from the bucket by a fixed track or swinging gate of the roller nest type, not having the center guide S (which is of no consequence for a short distance).
For the loading of workpieces into the pallets, it will be understood that empty pallets are loaded into the elevator and full pallets discharged therefrom by tracks and gates as previously described.
The elevator buckets 808 carry empty pallets 806 up-ward through the main line rails 800 and 802, thereby loading a workpiece into a pallet. With th2 pallet 806 and bucket 808 clear of the now empty interchange position, the elevator stops. The main line transfer system now slides the next workpiece 152 into the inter-change p~sition and another elevator index takes place rai~in~ the next empty pallet on its bucket through the interchange and it now becomes loaded.
- The transfer of workpieces 152 from the pallets to the main line transfer involves exactly ~he inverse operations. Full pallets are loaded into the elevator and empty pallets discharyed ~herefrom by tracks and gates as previously described. Full pallets are lowered by the ele~ator ~hrough the in~erchange posi-tion whereb~ the worXpieces 152 are deposited on the rai~s 800 and 802. After each such deposition, a workpiece is carried away by the main line transfer 5 bar.
Separate elevators can be used for pallet loading and unloading, ox by the combining of tracks and gates, a single elevator can be used for both pallet loading and unloading by change of direction.
A variation of the technique of moving the pallet through the main line slide rails 800, 802 is illustrated in FIGURE 53O In this instance, a vex-tically reciprocating actuator~ rather than a chain type elevator, is employed. Referring to FIGURE 53, an empty pallet rolls down fixed track 812 to be deposited on roller nest track 814 where it is stopped in the position, shown at 806, by a stop 816~
A workpiece 152 is brought into the inter-change position on slide rails 800 and B02 as described before. An elevator platform 818 is mounted on an actuator 820 which is compri~ed of a cylinder, or equivalent, and appropriate guide rods, slides or equivalent ~not shown), through which ~he platform ~93-5~9 818 is mov~d through ~he necessary vertical stroke.
As the platform 818 is raised by the ackuator 802, it passes between the two series o rollers of the roller nest track 814 and contacts and lifts the empty pallet 806. After a short further lift, the pallet 806 reaches the position 806a at which point the pallet 806 contacts and lifts ~he workpiece 152 from the rails 800, 802. The upward movement of the platform 818 continues until the pallet it i~ carry l(i ing, now loaded, reaches the full up po3ition shown as 806b. With the pallet held in thi~ position by the fully extended actuator 820 and platform 818, a roller nest ga~ke 822 is pivoted to position 822a by a torque tube 824 actuated as described in connection with FIGURE 17. The roller nest track is split to clear the platform 818 and its rollers contact the underside of the loaded pallet at 806b. The actuator 8~0 and platform 818 return to their lowermost po~,ition as shown, and the loaded pallet in position 806b rolls downward to the right on the roller nest track 822a and 826 and makes contact with f ixed track 830 on which it is carried away into ~he trackage system. Finally, the roller nest gate is returned to its position 822 and the mechanism is ready for the next cycle. The supporting structure *or the various elements is not shown but is of simple conventional design~

_9~_ i;4~

me same t~chr~ique is usable :for unloading full pallets. The inclina~ion o~ tracks 81~, 8~.4, 826, 830 and 822a and platorm ~18 are reversed, i.e., they slope downward to the left instead of to the right.
A full pallet now rolls down to position 806b (though oppositely inclined) from tracks 830 and 826 on roller nest track 822 in position 822a (again oppositely in-clin~d). The platform 818 is lited to a position under pallet 806b by actuator 820; the roller nest track swings to position 822, and ~he plat~orm 818 lowers the full pallet, When position 806a is reached, the workpiece 152 is deposited on the slide rails B00, 802 an~ the now empty pallet and platform 818 continues downward~ Near the end of the downstroke, the roller nest track 814 strips ~he empty pallet from the plat-form 818, and the empty pallet rolls away on fixed track 812. The roller nests 822 return to position 822a to await the arrival of the next ull pallet. The work-piece 152 is carried away on slide rails 800, 802 and the mechanism is ready for its next cycle.

Specification Summary As can be seen from the foregoing drawings and descriptions of the various embodiments and com-binations, the essential elements of this workpiece transfer and storage system are:
A. A yroup of substantially identical pallets, each of which:
1~ Locates and supports the workpiece or workpieces to be stored or trans-ferred;

2. Moves downhill on a fixed track on its own wheels which guide on the track, at least one of which is speed governed, and optionally capable of being governed at diffex-ing speeds by selection of di~ferent rolling diameters on these wheels;

3. Can also move downhill on a track consisting of a group of rollers whose upper surfaces constitute a plane or helical surface with the -g6--rollers spaced closely enough to support the pallet in a stable manner. This requires a suitable surface on the underside of the pallets, and sui~able guide roll-ers to guide itself with respect to such a roller track;

4. Can be elevated on a conventional type bucket elevator, or with spe-cial adapters be elevated by a non-bucket elevator.

B. A powered type elevating system or sys-tems which can elevate vertically, or escalate at an upward angle, full pallets or empty pallets, includ ing escalating syctems which utilize the fixed or roller nest type track.

C. One composite topological closed loop track, approximately half fox full pallets, and the re-mainder for empty pallets, which is comprised ofO a f~xed track on which the pallets roll on a downward slope on their own, self guided and speed governed wheels; a roller bed track on which the pallets roll on track rollers contacting substantially fla~ surfaces on the pallets; and elevating or escalating systems suitably situated in ~he ovexall composite track loop.

D. Pallet loader and unloader systems which transfer workpieces into and out of the pallets, includ-ing loaders and unloade~s which elevate and lower the workpieces in eleva~ors and thereby eliminate at least a portion o the pallet elevators required in their ab~
sence. It will be understood that the loaders and un loaders divide the composite topological closed loop track into a portion for e~pty pallets and a portion for full pallets.

E. Where crossfeeding between multiple parallel lines is required, or where workpiece flow division on a single line is required, or where work-piece flow combining on a single line is required, the provision of track switches, where such switches are in the fixed txack, roller track, or as multiple exit and entry txacks on the elevators.

-98~

It will be appreciated that the pallet carry-ing means, namely, the track means, forms a topological closed loop, and this term is used in the claims to de-fine the loop. This loop may include rising and descend-ing portions such as elevators and lowerators and variouslifting and lowering mechanisms and portions of the loop may overlie each other. Topologically, however, the loop or loops are closed and include segments for loaded pallets and segments for unloaded pallets.

_99_

Claims (9)

1. A conveyor having a downwardly sloping main track on which workpieces are conveyed by means of pallets having upowered wheels engaging the track, at least one of the wheels having retarding means asso-ciated therewith to create a speed-to-retarding force ratio for the pallet characterized in that said one wheel has multiple diameter portions adapted for roll-ing engagement with the track so that said force ratio varies in accordance with the diameter portion of the wheel in rolling engagement with the track.

2. A conveyor according to claim 1 characterized in that the track has different successive sections on which the multiple diameter portions of said one wheel are adapted to roll.

3. A conveyor according to claim 2 characterized in that the track includes segments which form auxiliary tracks and the pallet is provided with auxiliary support means.

4. A conveyor according to claim 3 characterized in that said main track comprises a monorail from which the pallet is suspended by means including said unpower-ed wheels, said auxiliary track segments being vertically offset below an adjacent section of the main track and comprising a series of rollers, said auxiliary support means comprising a support face on the pallet body dis-posed at a level below said unpowered wheels and adapted to engage the rollers as the unpowered wheels roll off the adjacent end of the monorail.

5. A conveyor according to claim 4 characterized in that the pallet body includes a workpiece support sur-face disposed vertically intermediate between the unpow-ered wheels and said support face, said unpowered wheels being spaced apart both fore and aft of said support sur-face to enable the workpiece supported on the pallet to be displaced vertically upwardly between said unpowered wheels when the pallet is supported on the auxiliary track segments.

6. A conveyor according to claim 3 characterized in that the unpowered wheels are mounted on the pallet body at a level below the position of the workpiece on the pallet body whereby the pallet body rides over the main track and is not stable as supported solely by the unpowered wheels, said auxiliary support means on the pallet comprising auxiliary wheels mounted on the pallet body outboard of the unpowered wheels and in engagement with the auxiliary tracks, said auxiliary tracks having contact surfaces thereon adapted to be engaged by the auxiliary wheels which extend substantially parallel to the main track.

7. A conveyor according to claim 3 characterized in that the auxiliary tracks comprise a pair of spaced sprockets journalled on a supporting framework; a con-tinuous chain loop running over said sprockets; drive means for driving said chain and in which said auxiliary support means on said pallet comprises pallet sprockets mounted concentrically on said primary wheels to engage and be driven by said chain, whereby said pallets are moved along the path of said chain in a non-positive connection through the retarding torque of said retard-ing means, said auxiliary track means inclining upwardly to form a lifting means for the pallets.

8. A conveyor according to claim 3 characterized in that the auxiliary tracks comprise a pair of spaced pulleys journalled on a supporting framework; a continu-ous belt running over said pulleys; drive means for driv-ing said belt and in which said auxiliary support means comprise surfaces on said primary wheels to engage and be driven by said belt, whereby said pallets are moved along the path of said belt in a non-positive connection through the retarding torque of said retarding means, said auxiliary track means inclining upwardly to form a lifting means for the pallets.

9. A conveyor according to claim 1 characterized by a secondary wheel on said pallet freely rotatable independently of the retarded primary wheel and adapted to selectively engage a section of said main track to cancel the effect of said retarding means when said secondary wheel rolls on said track means.