US3534690A - Fluid pressure actuated conveyor system - Google Patents

Description

United States Patent Inventor James F. Lockard North Tarrytown, New York Appl. No, 691,502

Filed Dec. 18,1967

Patented Oct. 20, 1970 Assignee OHM Manufacturing Inc.

Hawthorne, New York a corporation of New York FLUID PRESSURE ACT L'AT El) CONVEYOR SYSTEM 10 Claims, 14 Drawing Figs.

'52} L'.S.Cl 104/155, 104/165 [51] Int.C1 ..1i6lb13/12; B65g25/08 [50) Fieldol'Search 104/155, 162,165,172,178

156] References Cited UNITED STATES PATENTS 250,787 12/1881 Conger 104/165 3,014,459 12/1961 Gustairs 104/155 3,045,611 7/1962 Murray 104/155 Immury Exuminer Arthur 1.. La Point Assistant Examiner- Robert Saifer A1lnmey-Barnett and Barnett ABSTRACT: A pliably collapsible elongated conduit has a traveler adapted to compress a portion of the conduit thereat into a constriction. A fluid pressure is applied within the conduit to expand the constriction against the traveler for propulsion therealong. Valve means selectively applies the fluid pressure from a source to either of opposite ends of the conduit to determine the direction ofmovement of the traveler, the latter being adapted to engage a vehicle for propulsion on a track paralleling the conduit or may comprise the vehicle, per .i'e. Automatic means actuated by the traveler at the end of a predetermined run reverses the valve means.

Patented Oct. 20, 1970 Sheet H NN INVENTOR.

JAMES F. LOCKARD Patented Oct. 20, 1970 Sheet or 4 FIG,4

Patented Oct. 20, 1970 3,534,690

Sheet 5 of4 FIG.8

FI G.I4

INVENTOR.

JAMES F. LOCKARD A TTOR NE Y Patented Oct. 20, 1970 Sheet 1 of 4 3w Ev L W Q Q 5 F M E I I I I I I I IH H IH NH H IH I I I I I I I I I v $1 mw mv m2 AM" mm Ev 3v m w n 1 Q 2 Ev mv N ow NEE ATTORNEY FLUID PRESSURE ACTUATED CONVEYOR SYSTEM BACKGROUN D OF TH E INVENTION 1. Field of the Invention The invention relates to the utilization of fluid pressure as a prime mover in a propulsion device for a vehicle along a predetermined course and more particularly is directed to the combination of a collapsible conduit for the fluid under pressure and a traveler mounted for movement there along, said traveler having means to compress the conduit forming a constriction which under fluid pressure progressively propels the traveler along the conduit.

2. Description of the Prior Art The invention satisfies the long felt need for a readily controllable prime mover for conveyor systems. One example of such need is for the controlled propulsion of merchandise racks or trolleys along a rail system in manufacturing facilities and particularly in distribution warehouses where merchandise, such as garments, may be received and placed on hangers suspended on such trolleys. Conventional chain or belt driven means using electric motors with or without clutch control mechanisms have been found to be clumsy, inefficient, expensive, and difficult to adapt to existing overhead track systems with the result that movement of the trolleys along overhead track systems from station to station, for example, for ticketing, selection, sorting for distribution to various stores, holding for loading, and final movement to loading docks is done manually.

The simplicity of the propulsion device embodying the invention not only permits use of power in place of manual operation but greatly facilitates the adaptation of controls thereto for automatic or semiautomatic operation of the conveyor systems.

SUM MARY OF THE INVENTION Among the objects of the invention is to utilize fluid pressure as a prime mover in a novel propulsion device which shall comprise relatively few and simple basic parts which can be readily and economically adapted as a conveyor system per se or serve as an accessory for track and trolley conveyor systems, for example, of the overhead type used in manufacturing and distribution warehousing facilities.

The basic combination embodying the invention comprises an elongated readily collapsible conduit for a fluid medium under pressure and a traveler mounted for movement along the length of the conduit and having means compressing the latter into a substantially closed-off constriction. Fluid medium pressure from a suitable source, such as compressed air, is applied to an end of the conduit, acting to expand the constriction, causes an undulation thereof against the compressing means which propels the traveler in advance of the undulation. A valve means may selectively apply the fluid pressure to either of opposite ends of the conduit to determine the direction of movement of the traveler and automatic reversal of the latter may be achieved by its actuation of electric switch means at the end of a course in one direction.

The collapsible conduit may be provided in at least two different forms; namely, as a collapsible hose which has a rigid support formed as, but not limited to, a housing in which the traveler is mounted and supported, the traveler having a pair of compressing rollers between which the hose extends; or as an elongated rigid backing plate with an overlying strip of elastic sheet material secured to the plate along the opposite longitudinal edges thereof, the elastic material being inflatable by introduction of the fluid pressure medium between the rigid plate and elastic sheet, the backing plate extending sub stantially through the traveler, the latter having a roller pressing the elastic sheet against the backing plate.

The propulsion device will be seen to have a wide range of versatility in that the traveler may be formed as a vehicle for carrying a load directly or may be provided with a projecting track system adjacent the conduit.

The fluid pressure provides a smooth and dependable propulsive force to the traveler capable ofmoving its intended load both on level and inclined tracks and has the ad vantageous characteristic of permitting stop and go control by the simple imposition of an obstruction in the path of the vehicle without causing any excessive shock. strain or wear on the equipment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary perspective view of a portion of an overhead suspension trolley system having mounted thereon a propulsion device embodying the invention, parts being broken away to show interior construction, direction of travel from left to right being indicated by the arrow.

FIG. 2 is a transverse section taken on line 2-2 in FIG. I showing the traveler mounted within the housing and the hose compressed between the rollers.

FIG. 3 is an enlarged transversesectional view through the compressing rollers showing in full lines constriction of the hose thereby with fluid pressure being exerted in the hose from the left end toward the right to propel the traveler along the hose to an instantaneous advanced position illustrated in broken lines.

FIGS. 4 and 5 are enlarged end and side elevational views, respectively, of the traveler removed from the housing showing details of construction.

FIG. 6 is a transverse sectional view of the traveler taken on line 6-6 in FIG. 5.

FIG. 7 is a fragmentary perspective view of a portion of a propulsion device shown in FIG. 1 in which the housing is formed to parallel a trolley system (not shown) having curved and inclined sections.

FIG. 8 is a fragmentary enlarged view, partly in section, showing an end portion of the housing of the propulsion device wherein one end of the hose is supported and connected to a line to the fluid pressure source.

FIG. 9 is a diagrammatic representation of propulsion device hose shown in FIG. 1 with its line connections to a reversing valve and electric wiring for automatic reciprocation of the traveler.

FIG. 10 is an illustrative diagram of a trolley system having an automatic reciprocating propulsion device arranged to move trolleys from station A to station B.

FIGS. 11 and I2 are side elevational and top plan views, respectively, of a modified propulsion device embodying the invention wherein a rigid supporting structure serves as part of the conduit and the traveler is illustrated as a load carrying vehicle.

FIG. 13 is an enlarged transverse sectional view taken on line 13-13 in FIG. II, and

FIG. 14 is a perspective view of a propulsion device, similar to that shown in FIG. 11, adapted as an endless closed track conveyor system.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring in detail to the drawings, 10 denotes a power propelled trolley system shown in FIG. 1 to comprise an overhead suspension trolley system ll having mounted thereon a propulsion device 20 constructed to embody the invention.

Overhead trolley system II may be of any conventional construction, such as, the type installed in manufacturing or distribution warehousing facilities for station to station conveyance of articles in the process of manufacture or of merchandise through the various receiving, sorting, tagging, storing, and reloading operations in such warehousing. As shown in FIG. I trolley system I] has a plurality of spaced apart suspenders 12 which are suitably anchored at their upper ends to ceiling beams or the like (not shown) and terminate in C-brackets 13. The latter support the rail or track 14 which may extend horizontally from station to station on a single level and may include inclined portions connecting multiple levels and branches terminating in dead ends, all in the well understood manner. A plurality of vehicles are adapted to run on track 14 and may be suitably equipped as required, for example, with baskets for carrying small articles. hooks for meat carcasses, or as here shown as trolley 15 having a pair of spaced grooved wheels 16 journaled in frames 16a from which brackets 16); depend. the latter supporting therebetween a rack 17 on which hangers 18 for garments (not shown) may be carried.

Propulsion device 20, shown in FIGS. 1 and 2 as an accessory to trolley system 11, comprises an elongated tubular housing 21, a collapsible conduit in the form ofa hose 22 extending therethrough, and a traveler 23 mounted for reciprocation in housing 21 and for compression of hose 22 into a constriction 22a thereat. Housing 21 may be suitably mounted as by brackets 12a connected to suspenders 12, to parallel track 14 in spaced relation thereto and has an elongated side opening 21a facing track 14 through which a pusher arm 24 extends from traveler 23 to engage trolley 15 for movement therewith along track 14.

As seen in FIGS. 4, and 6, traveler 23 may comprise a tubular frame having opposite side walls 23a, 23b, a bottom wall 230, a top wall 23d, and a substantially open front and rear through which hose 22 extends between a pair of compressing rollers 25 mounted for free rotation on a pair of shafts 25a extending between opposite side walls 23a, 2317. Any suitable means may be provided to properly centralize traveler 23 for propulsion through housing 21 with a minimum of friction, here shown as a pair of longitudinally spaced wheels 26 supported from bottom wall 23c and eight side thrust rollers or wheels 27, one mounted adjacent each corner of each of the side walls 23a, 23b to freely rotate on four shafts 27a extending between top wall 23d and bottom wall 23c. Where required, as for example, when housing 21 is formed with curved portions, a guide roller 27b for hose 22 may be mounted on each shaft 270 between wheels 27.

Hose 22 is supported solely at opposite ends thereof in any suitable manner for proper alignment with respect to the space between compressing rollers 25 of traveler 23 and for proper connection to a fluid pressure source, which in this em bodiment is compressed air. To this end, hose 22 is shown in FIG. 8 connected by a clamp 28a to a reducing coupling 28 which may be mounted by a bracket 21b in tubular housing 21 located beyond each end of the course traversed by traveler 23. The smaller end of coupling 28 may carry a T-fitting 29, one branch of which connects to air hose 32, the other branch to a quick release valve 31. Hose 22 is similarly mounted at both ends, one end connecting to air hose 32, the opposite end to an air hose 33, as illustrated in FIG. 9. Air hoses 32 and 33 in turn are alternately connected to a compressed air tank 35 through a suitable four-way valve which may be manually operable, or as shown diagrammatically in FIG. 9, may be the solenoid operated valve 30 of an automatic reversing control for traveler 23.

In the embodiment of the invention shown in FIGS. 1 to 3, inclusive, traveler 23 is required to effectively push one or more trolleys along a portion of track 14 in only one direction. To this end, pusher arm 24 is shown mounted as a detent to pivot on a pin 24a from a normally extended position across the path of trolley 15 biased by tension spring 24b to a trolley clearing position shown in broken lines in FIG. 1. An angle bar 240, attached to traveler side wall 23b, supports pusher arm 24 so that in its normally extended position leading edge 24d thereof, disposed substantially perpendicular to the path of travel, engages trolley wheel frame 16a for forward movement by traveler 23 and angularly disposed trailing edge 24e serves as a cam surface for deflective pivoting of pusher arm 24 by wheel frame 16a against action of spring 24b permitting traveler 23 to pass by trolleys 15 when moving in a reverse direction.

A simple control for automatic reciprocation of traveler 23 is shown in FIG. 9 as comprising four-way valve 30 operated by solenoids 30a and 30b in parallel circuits 30a and 30f to an electric power source through normally open microswitches 301' and 30d. Solenoid 30a shifts valve 30 to a first position connecting main air hose 34 from tank 35 to hose 32 and venting hose 33 at port 30g while solenoid 30b shifts valve 30 to a second, alternate position connecting main air hose 34 to hose 33 and venting hose 32 at port 303 in the well understood manner.

Propulsion device 20 is readily adaptable to serve a trolley system having various curved and inclined sections. As indicated in FIG. 7, housing 21 may comprise a plurality of sections, for example, straight sections 210, horizontally curved sections 21d and 210 turning to the right and left, respectively, and vertically curved sections 21f which may serve both for the lower and upper ends of an incline. These sections are joined together in any suitable manner to provide a smooth duct for traveler 23 and support for hose 22 which is placed to extend therethrough in a relatively loose manner being supported at the opposite ends thereof by brackets 21h in the manner shown in FIG. 8.

The utility and operation of the invention will be apparent from the description of an installation of propulsion device 20 having an automatic control of a type shown in FIG. 9 for reciprocation of traveler 23. Device 20 propels trolleys l5 along a section of an overhead suspension system 11 illustrated in FIG. 10 as extending between stations A and B in a distribution warehouse wherein, for example, at station A garments, previously hung on hangers l8 suspended on racks 17, are ticketed and at station B the garments on racks 17 are staged for loading into trucks for distribution to the various stores.

After the garments are tagged at station A, trolleys 15 are advanced around the curved portion of track 14 onto track portion 14a which lies along the path of pusher arm 24 of reciprocating traveler 23. As traveler 23 approaches the end of its return run, that is. its travel in a direction from right to left as seen in FIGS. 1, 9 and 10, it engages microswitch 30c closing circuit 30c to energize solenoid 30a and shift valve 30 to a position connecting air hose 32 to main hose 34 to supply air pressure from tank 30 to the left end of hose 22 and simultaneously venting hose 33 through port 30g to relieve the pressure at the right end of hose 22. The air pressure introduced into the left end of hose 22 causes it to inflate and imparts an expanding force to the left side of constriction 22a. The simultaneous release of air pressure on the right side of constriction 22a creates an inequality in pressure which propels rollers 25 toward the right. Traveler 23, now advancing in its load carrying direction from left to right, engages the first of the trolleys 15 on track portion 14a with pusher arm 24 and propels the entire group to station B where track 14 curves away from housing 21 permitting clearance of pusher arm 24. Traveler 23, in completing its run, engages microswitch 30d energizing solenoid 30b to shift valve 30 to its alternate position wherein hose 32 is vented and hose 33 supplies air pressure to the right end of hose 22 reversing traveler 23. Any trolleys 15 on track portion 14a will offer no obstruction to the return of traveler 23 because of the detent action of pusher arm 24 which pivots against the action of spring 24b to the retracted, clearance position shown in broken lines in FIG. 1. Upon arrival at microswitch 30c, traveler 23 initiates its next forward run in its continous automatic reciprocation, moving the succeeding group of trolleys 15 from station A to station B.

In order to reduce resistance to the forward motion of traveler 23 in its progressive constriction of hose 22, the venting of air is accomplished immediately adjacent the ends of hose 22 with the aid of quick release valves 31 used in the manner shown in FIG. 8. Valves 31, which are of conventional construction, close when a predetermined internal pressure is applied and open when the internal pressure is relieved. Thus, when air pressure is applied through hose 32 or 33 by fourway valve 30, the respective valve 31 closes but when the pressure is relieved by hose 32 or 33 being vented through fourway valve 30, the respective valve 31 opens for quick venting of air being forced out of hose 22 by the approach of traveler 23, whereby the length of hose 32 or 33 to vent 30g is bypassed after the initial release of pressure through vent 30g.

A conveyor system 40 is shown in F168. ll, 12 and 13 as a modification embodying the invention comprising a track 41 along which a load carrying traveler 43 is propelled. Track 41 is constructed to carry the weight of traveler 43 and its intended load and also to provide a collapsible and inflatable conduit for the propulsion device. To this end, track 41 is formed as an elongated rigid backing plate 41a having a strip 42 of elastic sheet material mounted on one face thereofforming an inflatable cavity or conduit thcrebetween. Strip 42 is suitably joined along its edges as by joints 41h which may be formed by edge borders of plate 41a being folded over to clampingly grip the edges of strip 42 leaving the center portion thereof free for expansion by fluid pressure introduced between plate 41a and strip 42 through suitable pipe fittings 41c terminating in openings 41d in plate 41a adjacent opposite ends of track 41. Fittings 41c may be connected to a fluid pressure source, such as, to air hoses 32 and 33 to the left and right ends of track 41, respectively, as indicated in H6. 11. Track 41 may be supported from a floor, or as shown, may be hung from a ceiling by suspenders 41a having angularly disposed ends attached to a central portion of backing plate 41a at spaced intervals therealong.

Traveler 43, substantially surrounding track 41, has top and bottom walls 43a and 43b, respectively, interconnected by a front wall 430 and two small opposite side walls 43d. A pair of opposing wheels 46 are mounted in suitable openings in top and bottom walls 43a and 43b and have grooved surfaces conforming to the rounded edges ofjoints 41b on which wheels 46 ride A compressing roller 45 freely rotates on shaft 45a ex tending between top and bottom walls 43a and 43b and is opposed by two pairs of thrust rollers 47 mounted on stub shafts 47a extending inwardly from top and bottom walls 43a and 43b.Rollers 47, riding on the rear surface of backing plate 4la,coact with compressing roller 45 which may be centralized between each pair of rollers 47, as is clear from H6. 12. Compressing roller 45 rides on elastic strip 42, extending across the width thereof, to provide a constriction 42a in the inflatable cavity between backing plate 41a and strip 42, constriction 42a functioning in the same manner as hereinbefore described for constriction 22a in hose 22 formed between rollers 25 of traveler 23. A load carrying suspending basket 48 is suitably attached to bottom wall 43b by a bracket 48a or where track 41 is disposed near the floor, top wall 43a may be constructed to carry a desired load above track 41.

A conveyor system 50 is illustrated in FIG. 14 utilizing a track 51, of similar construction to track 41, having a backing plate 510 and elastic strip 52. Although shown as circular in shape, it is to be understood that track 51 may be of any closed configuration with the ends of plate 510 brought together and joined at 50a to form a smooth track structure on which traveler 53 may be propelled continuously in one direction. Strip 52 is closed off at the juncture 50a separating pressure medium inlet 54 from outlet 55 which are located adjacent opposite sides of juncture 50a.

An appropriate means is required to carry traveler 53 across the juncture 500 which otherwise would obstruct its progress. A suitable spring loaded mechanical device actuated by the forward movement of traveler 53 as it approaches juncture 50a will serve such purpose. Another such means utilizes the fluid pressure from the source supplying inlet 54 and is diagrammatically indicated to comprise cylinder 60 having a reciprocatable piston rod 61 carrying a puller arm 62 for engaging a protruding rod 63 on traveler 53, microswitches 64 and 65, and hoses 66 and 67 which connect to a four-way solenoid operated valve (not shown) similar to valve 30.

In its clockwise advance along track 51, as traveler 53 approaches juncture 50a, protruding rod 63 deflects and passes puller arm 62, the latter being pivotally mounted for such deflection as indicated in broken lines. Microswitch 64 is positioned to be closed by traveler 53 as soon as puller arm 62 clears rod 63 and springs back to its operative position. The closing of microswitch 64 shifts the solenoid operated valve to deliver pressure to hose 66 which moves piston rod 61 toward the right, as seen in H0. 14, to the position shown in broken lines, whereby puller arm 62 engages rod 63 carrying traveler 53 across juncture 50a and beyond inlet 54. Traveler 53, now being propelled by the pressure from inlet 54, engages microswitch 65 shifting the solenoid operated valve to an alternate position to supply pressure to hose 67 which returns piston rod 61 to its extended position ready for the next cycle. In this manner continuous motion in the same direction is imparted to traveler 53,

It will now be apparent that propulsion of travelers 43 and 53 is achieved in a manner similar to that of traveler 23. namely, by the introduction of a fluid, such as air, under pressure between plate 41a and strip 42 to expand the latter against one side of constriction 42a, This pressure propels roller 45 and its traveler 43 over the uninflated portion of strip 42. the constriction 42a advancing under roller 45 as a progressing undulation.

The collapsible-inflatable conduit combined with a supporting means for the traveler as a prime mover accessory to a conveyor system such as hose 22, housing 21 and trolley system 11 or formed as the self-contained conveyor systems 40 and 50 may be further modified within the contemplated scope of the invention to serve particular conveyor needs. Thus, for example, housing Zl may be reduced to a supporting plate upon which hose 21 rests with a traveler resembling the construction of traveler 43 having compressing roller 45 constricting the hose against the plate. A platform may be provided on such traveler to carry a desired load. Likewise, traveler 43 may be fitted with a pusher arm to serve in a manner similar to pusher arm 24 of traveler 23, and tracks 41 and 51 may be arranged to be in a horizontal instead ofa vertical plane as shown.

The mounting of pusher arm 24 on traveler side wall 23b may be constructed to facilitate reversing the direction in which trolleys 15 are propelled along track 14, as for example, by a suitable mounting enabling angle bar 240 to be readily inverted.

To propel travelers 23 pushing a group of loaded trolleys 15, air pressure on the order of 20 to 40 p.s.i. has been found to render satisfactory results. Greater or lesser pressures may be used depending upon load requirements, inclines in the track, and desired speeds, which pressure may be controlled by suitable valves (not shown) interposed in the various air supply lines, as for example, in main air hose 34 or in hoses 32 and 33. it is thus apparent that a versatility of the invention includes the wide range of speeds that may be developed in travelers 23, 43 and 53 which speeds are controlled by simple adjustment of a conventional air pressure control valve.

lt is also contemplated that the movement of travelers 23, 43 and 53 and trolleys 15 be controlled by the imposition of a suitable obstruction in the path of movement thereof since the prime mover permits the stopping of travelers 23, 43 and 53 without adjustment or cutoff of fluid pressure, and also permits the resumption of movement of the travelers 23, 43 and 53 when the obstruction is removed. Excessive buildup of fluid pressure behind such stalled traveler may be prevented by providing suitable pressure safety relief valves (not shown) at the ends of the conduit.

The improved fluid pressure prime mover and conveyor systems herein disclosed are seen to achieve the several objects of the invention and to be well adapted to meet conditions of practical use. As various possible embodiments might be made of this invention, and as various changes might be made in the disclosed constructions, it is to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.

lclaim:

1, A propulsion device comprising a collapsible-inflatable conduit disposed along a predetermined path between opposite ends thereof, a traveler mounted for movement along said path and having means compressing the conduit into a constriction thereat, air pressure means applied to one of said opposite ends of the conduit to inflate the latter and expand said constriction as an undulation progressing against said compressing means propelling said traveler along said path toward said other conduit end. in combination with a trolley system having a track portion paralleling said conduit and a trolley mounted on said track for movement therealong. said traveler having projecting means engaging said trolley for propulsion along said track by said traveler, said air pressure means, conduit, traveler and trolley system being so constructed and arranged to permit stoppage of the traveler and trolley by interposition along said track of an obstruction to trolley advancement and continued forward movement of the traveler and trolley upon removal of said obstruction.

2. The propulsion and trolley system combination defined in claim 1 in which said projecting means has a detent action permitting the traveler to engage and propel the trolley in a predetermined direction and to pass by the trolley when the traveler is moving in an opposite direction.

3, The propulsion and trolley system combination defined in claim 1 including means for adjusting the air pressure applied to said first conduit end to control the speed of said traveler.

4. The propulsion and trolley system combination defined in claim 1 including means for selectively applying said air pressure to one of the opposite ends of said conduit and simultaneously venting the other end to propel said traveler toward said conduit other end and for reversing the respective application of pressure and venting to propel the traveler in an opposite direction, control means for said selective air pressure applying means responsive to the approach of said traveler to either end of said path to effect said reversal of pressure and venting providing automatic reciprocation of said traveler.

5. The propulsion and trolley system combination defined in claim 1 including a pressure relief valve located at opposite ends of said conduit preventing excessive pressure buildup when the traveler is stalled by said interposition of an obstruction to the forward movement of the trolley.

6. A propulsion device comprising a collapsible-inflatable hose disposed along a predetermined path between opposite ends thereof, a traveler mounted for movement along said path, said traveler having a pair of rollers supported by said traveler between which the hose passes compressing the hose into a constriction thereat, fluid pressure means applied to one of said opposite ends of the hose to inflate the latter and expand said constriction as an undulation progressing against said rollers propelling said traveler along said path toward the other of said opposite hose ends, a supporting duct through which said hose extends defining said path, said traveler being sized and shaped for support in and movement through said duct.

7. The propulsion device defined in claim 6 in which said traveler has thrust rollers engaging opposite sides of said duct stabilizing said traveler against yawing.

8. The propulsion device defined in claim 6 in which said duct has a longitudinal extending side opening, a trolley system having a track portion paralleling said side opening and a trolley mounted on said track for movement therealong, said traveler having means extending through said opening engaging said trolley for propulsion alongsaid track by said traveler.

9. A propulsion device comprising a collapsible-inflatable conduit disposed along a predetermined path between opposite ends thereof and formed as an elongated rigid backing plate having an overlying elastic strip joined to the plate along opposite longitudinal edges thereof providing an inflatable cavity therebetween, longitudinal edges of said backing plate being folded over to clampingly grip longitudinal edges of said elastic strip as said joining thereof. a traveler mounted for movement on said conduit.said traveler having a pair of opposed grooved wheels riding on the surface of said folded edges and having a roller extending across said strip urging the latter against said backing plate as a constriction thereat. fluid pressure means applied to one of said opposite ends of the conduit to inflate the latter and expand said constriction against said roller propelling said traveler along said path toward the other of said opposite conduit ends.

10. A propulsion device comprising a collapsible-inflatable conduit disposed along a predetermined path between opposite ends thereof, a traveler mounted for movement along said path, said traveler having means compressing the conduit into a constriction thereat, fluid pressure means applied to one of said opposite ends of the conduit to inflate the latter and expand said constriction as an undulation progressing against said compressing means propelling said traveler along said path toward the other of said opposite conduit ends, said conduit opposite ends terminating adjacent each other so that said path defines an endless circuit having a juncture between said opposite ends, said traveler being mounted to bridge said juncture for continuous movement around said circuit, and auxiliary propulsion means actuated by the approach of said traveler to said other opposite conduit end for propelling said traveler across said juncture and beyond said first mentioned conduit end for continued propulsion along said path by said fluid pressure application to said first mentioned conduit end.

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