US2975247A - Time delay relay - Google Patents

Description

March 14, 1961 B E FACKLER ET AL 2,975,247

TIME DELAY RELAY Filed April 27, 1955 2 Sheets-Sheet 1 lllllllllnu m' III FlG.

INVENTORS BERNARD E. FACKLER GEORGE B. SODEN BY l bmg fm,

March 14, 1961 B. E, FACKLER ET AL 2,975,247

TIME DELAY RELAY 2 Sheets-Sheet 2 Filed April 27, 1955 INVENTORS BERNARD E. FACKLER GEORGE B. SODEN 27 ATfoERNEYflygjyll States Patent O TIME DELAY RELAY Bernard E. Fackler, Waterbury, and George B. Soden, Wolcott, Conn., assignors to Consolidated Electronics Industries Corp., Waterbury, Conn., a corporation of Delaware Filed Apr. 27, 195s, ser. No. strinse s claims. (ci. zoo-38) This invention relates to timing devices and more particularly to a motor-driven, switch-operating timing device or time delay relay provided with means for accurately varying the length of the period timed thereby.

Motor driven switch operating timing devices of the general type in which is included the device of this invention have heretofore of course been available. However, of those heretofore available, most do not possess the high degree of accuracy which has now become necessary for certain uses such as are found, for example, in the aircraft and guided missile industries. This lack of accuracy in prior devices results sometimes from a lack of accuracy in the constancy of the speed of the motor employed for driving the device. In other instances it results from lost motion in the clutching means employed to couple the output shaft of the motor used for the actuating mechanism of the timer. It also sometimes results from a time lag between the initiation of the operation of the clutching or coupling means and the completion thereof. The components employed and their structural arrangement in the device of this invention minimize or eliminate completely the aforementioned and other sources of inaccuracy.

ln the majority of the presently employed timing devices which fall in the category into which the timing device of this invention would be properly placed, and in fact in all such timing devices with which we are familiar, adjustment of the period to be timed is accomplished by adjustment of the rest or starting position of the motor driven actuator thereof. With a view to improving the accuracy of the period of the timing device of this invention, we, however, employ an adjustment for the timed period which involves adjustable mounting of the switch to be actuated at the end of the timed period. This is so because the return stop for the actuator must be sufficiently solidly mounted in order to remain accurately fixed in position even after many cycles of the timing device. This is difficult where the return stop is adjustably mounted. The forces imposed by the actuator upon the switch lor switches, however, is relatively small and hence the tendency for them to move from an adjusted position, even though adjustably mounted, is much less than in the case of an adjustable stop.

With the above and other improvements in the structural arrangement which will appear more fully hereinafter, we provide, in accordance with the invention, a timing device having a rated accuracy of plus or minus l() milliseconds over time periods of from 2 to l0 seconds and of plus or minus 1% over time periods of l0 to seconds, both at normal (room) temperature, pressure, etc.

For a more detailed description of our invention, reference may be made to the accompanying drawings which illustrate a preferred embodiment thereof and in which:

Fig. 1 illustrates in partial embodiment of the device of axial section the preferred the present invention;

Fig. 2 shows in a section taken along line 2-2 of "ice Fig. l the clutching structure of the present invention;

Fig. 3 shows in a section taken along line 3-3 of Fig. 1 the support tabs for the preferred switch of the present invention;

Fig. 4 is a section taken along line 4-4 of Fig. l showing the preferred form of actuator and support arm of the present invention and part of the gear train coupling the actuator to the drive;

Fig. 5 shows in side elevation a preferred form of switch supporting member employed in this embodiment of the present invention;

Fig. 6 is a detailed view partially in section of the position of the switch in normal (unactuated) position; and

Fig. 7 illustrates schematically the electric circuitry of the preferred embodiment of the present invention.

Referring to the drawings, in the preferred embodiment of the present invention, a D.C. motor 10 is employed as the drive. A governor which is preferably of the type disclosed in Haydon Patent 2,523,298 and is housed in a casing 11 is employed to control the speed of the motor. The governor, as will be understood from reference to the aforementioned patent, is of a type which maintains the speed of the motor constant to a high degree of accuracy despite varying input voltage and load. The motor-governor assembly is supported on supporting declc 12 of the frame.

The frame may be as simple or as complex as required for the support of the structure of the present invention. In the preferred embodiment illustrated the support frame is quite simple, consisting essentially of parallel decks and intermediate support columns. For the sake of clarity, however, the columns have been omitted from the drawings. The casing 13 which encloses the motor, the governor and most of the rest of the structure is also part of the frame. The various supporting decks might be supported by said casing in some embodiments of the invention, and, for the purpose of visualizing an operable structure, such support may be presumed. ln building the commercial embodiment of the present invention, however, it is preferred to make the casing removable for easy access to the parts.

The output shaft 1S of the motor is offset from the axis of the motor 10 because of the use of speed reduction gears (not shown) within housing 16. The output shaft 15 has iixed to it a pinion 17. This pinion, in turn is meshed with spur gear 18 which is mounted to rotate freely on stud shaft 19 supported on arm 20. Fixed to spur gear 18 is gear 21. Gear 21 is meshed with a rotatable gear 22 which is coaxially supported on a bearing 24 staked on the face of housing 16 and through which the drive shaft 15 extends. Gear 22 has a rearwardly extending integral extension 22 which surrounds bearing 24 and is fixed to drum member 23 which advantageously consists of a planar circular member having a cylindrical rim at its outer periphery. The drum 23 is spaced from supporting deck 12 by extension 22 of gear 22. The gear 22 and the drum 23 are held on bearing 24 by a ring 25, which is allixed to the bearing 24.

"Fig 2 shows especially well the brake drum and its related structure. A brakeshoe 2'7 is provided with a surface which corresponds to the contour of the rim of brake-drum 23. ln this case the shoe is concave and tits the outer surface 28. Thel outer surface in this instance may be covered with rubber or any other suitable material having high frictional properties. The brakeshoe is normally held barely out of contact with the brakedrum. The support for shoe 27 is ultimately lever arm 29. Lever arm 29 is Aarranged to be 'actuated by a solenoid 3l). At least that part of arm 29 which cooperates with the solenoid is accordingly composed of some ferromagnetic material. This solenoid has conventional electrical connections (not shown), and it may position occupied when the actuator arm lies against s advantageously be supported on support deck l2 by means of a bracket. The lever arm 29 rotates about a pin 31 which is part of a stud on the support frame, as a fulcruni. That end of levcr arm 2,9 which is moved by the solenoid is normally held out of `contact with solenoid 3G by means of spring 32 which extends between the `lever and a post 33 extending from supporting deck 1,2 of the frame. Accordingly shoe 27 is normally held out of Contact with drum 23. The means for applying pressure to the shoe is a rotating block34 which is mechanically an integral part of the lever arm. Block 34 is attached to the brakeshoe 27 by a pin 3S which is parallel to pin fulcrum 3l, through flange 27a, which lies perpendicular to pin 35. The pin 35 is located approximately in the middle of the shoe` and the spacing between pin 31 and pin 35' constitutes a highly powerful lever arm which is quite short compared to the lever arm between pin 31 and solenoid 39. Since the longer and `shorter lever arms are not aligned, the structure acts like a bell crank rotating about pin 31.y In operation, as the solenoid is excited, the end of lever arm 29 will be attracted to said solenoid causing rotation about pin 31 of all its associated parts including block This rotation will move pin 35 and hence brakeshoe 27 toward the drum. Because of its close spacing the shoe will engage surface 23 of the brake-drum almost instantly. Because of the short lever arm, a great deal of force will be applied to stop the drums rotation. A spring 27b is provided to normally maintain brakeshoe 27 always in place in the arcuate cavity in the surface of block 34.

As previously mentioned, the distance that the brakeshoe has to move in accomplishing the stopping of drum 23 is very small indeed. The small clearance between the shoe and the drum makes possible a fast braking action which increases the accuracy of the timing device. This spacing may be adjusted by the use of frame reference member, such as post 36, in conjunction with an adjustable member, such as screw 37, which extends lthrough block 34 and. terminates against post 36. This screw member 37 may be adjusted inwardly, in order to decrease vthe spacing between the shoe and the drum, or outwardly, in order to increase said spacing. ln this manner it is possible to obtain an optimum spacing.

Referring again to Fig. l, it will be observed that arm 20 which supports gears 18 and 2l is itsel'.F supported by a hollow shaft 39. Shaft 39 is coaxially arranged withV drive shaft and is in contact with the drive shaft at a bearing surface, but it is not fixed to said drive shaft. In fact, shaft 39 rotates independently of drive shaft 1S in response, for example, to movement of arm. 20. VAt the end of shaft 39 remote from the drive shaft is a pinion 40. Pinion 4@ preferably lies on the other side of supporting bushing di from drive shaft porting bushing 4i is, in turn, supported by a part of the frame supporting deck (l2. Pinion iti drives gear 43 which is advantageously mounted to rotate about a supporting axle located on the major axis of the device. A radially extending arm i4 is advantageously iixed to gear 43 so that it will rotate with said gear. This arm 44 supports the switch actuator and hence is referred to as the actuator arm.

A stop member 4S is provided on the supporting frame to define one limiting means .for the actuator arm. T he this stop is the zero position of the actuator arm 4d. rThe actuator arm is urged against stop 45, which is advantageously a metal post padded by a sheath. of nylon, by resilient means, in this case spring Spring iti does not directly contact arm 44 but works indirectly on arm 44 through the gear connections of the rotatable parts. The spring 46 does work on arm 2Q. The spring has one end 46a aliixed to supporting arm 20 and the other end 45b atiixed to supporting deck 42 and is coiled around s haft 39in such a manner. thatv arm` Zilis urged to rotate 15. Sup-` in the direction opposite its motor driven direction. The spring force is transmitted back through the gear train to arm `44 which it urges against stop 45.

Axial tubular shaft 54 is supported on the frame at deck 42. Shaft 54 provides a hollow conduit for electric leads, as will be described later, and likewise provides a support for the bushing of gear `43 and other rotatable parts of the structure. In addition to the gear 43 and the arm 44 member 54 supports a snugly iitting tubular ring 55 which is held in place on shaft 54 by a radially extending snap ring 56 near the end of said shaft remote lfrom deck 42. A tubular member 57 also coaxially surrounds shaft 54. Tubular member 57 has a portion which snugly engages the shaft 54. Over the greater part of its length, however, its inner diameter is larger than shait 54. The tubular ring 55 is snugly engaged by a larger inner diameter portion of this tubular member. The shoulder between the two inner diameters of tubular member 57 and an opposed shoulder formed by the end of ring 55 provide surfaces between which a spring 5S extends. This spring member 5 3 urges menibers 57 and 5S (hence member Sli) apart in an axial direction. Member 57 is iixed to knob 50 through a dielectric switch supporting block 59 of generally tubular form. Thus, the spring 58 has the effect of urging knob Sli axially toward the frame.

The frame, as previously described, supports one of the limiting means, the stop 45, in a iixed position. Block 59 supports the other limiting means, the switch, so that its position is adjustable relative to the frame. More specifically, the block 59 provides a rotatable support for the switch. The block is advantageously a solid of revolution which is arranged to rotate about its axis of revolution. It will be appreciated that the supporting structure for ythe switch and its supporting block are embellished over its most elementary form. However, this construction has advantages which will hereafter become apparent.

Block 59 also supports knob S0. Knob 5t) serves as a cover or enclosure for the movable parts, including gears 40 and 43 and actuator arm 44. It also has a portion adjacent the frame which may be provided with means for comparing the positions of the knob and the frame. The knob in this embodiment is composed of a generally cylindrical hollow member 51 and a shallow cup-like member 52, the inside walls of which are threadably engaged by one end of member S1.

The block Si@ is advantageously bonded to tubular member 57 using a means appropriate to the particular art involved with the specilic materials used. In general, block 59, which is advantageously composed of a molded dielectric material, is made to have dimensions which cooperate with shoulders in the enclosing knob portion Si. Accordingly, the block S9 has a great many outer diameters which provide shoulders. In particular metallic washer 1il3, which is held in place against block 59 by screws or otherA appropriate fasteners, abuts an opposed shoulder in the knob member 51 to hold the knob in place axially on the switch mounting block. Set screws 6b through knob Sti hold the block 59 against rotation relative to the knob.

On the supporting block 59, as may be seen in Figs. 3 and 5, are mounted various switch contacts which may be taken together to compose a single pole, double throw switch. This switch is so arranged that the actuator 65 which is merely a tab on actuator arm 44, will contact a knob 66 which is, in fact, one lever arm of a bell crank having another arm 67 (see Fig. 6). Arm 67 is supported by a supporting tabv 68 which, in turn, is mounted on block 59. Tab 68 provides a pair of parallel upright portions 68a and a shorter back portion 68b. Arm 67 provides a pair of tabs 67a which parallel tabs 68a of the support member, and all of these tabs are rotatably fixed together by a pin 69. The lever 67 is also extended to a point wherethe top edge ofbackI member 68711` provides a stop for it.A A spring 7i) is employed around the pin to apply pressure between back member 68h and the remote part of lever 67, as shown, in order to urge the adjacent part of lever 67 against stop 68h. Lever 67, which is conductively connected to base tab 68 through the metallic structure previously described, bears a contact 71. Other contacts are supported by conductive base tabs 74 and 75. Base tab 7S supports a spring-like 4 strip 77 which is normally urged away from the support block. Strip 77 is -the common conductor for two contacts. One of its contacts 78- will contact contact 79 on bracket 80 which overlies strip 77 and which is contacted to tab 74. The fact that the resilience of common support conductor 77 urges it upward will tend to keep contacts 78 and 79, which may be termed the first pair, normally closed. The other contact 81 on conductor '77 lies opposite contact 71 on arm 67. This contact is so arranged that when actuator 65 urges lever 66 forward, by the bell-crank effect, contact 71 will be urged against contact 81 thus completing the circuit between these two contacts, which may be called the second pair. Almost immediately strip 77 will be urged further downward so that contact is broken between the rst pair of contacts 78 and 79. Since the switch members are fixed relative to one another on supporting block 59, movement of block 59 will change the position of the switch. In moving the switch with respect to the frame it is also being moved with respect to stop member 45. Since block 59 provides a rotatable support member having the same axis of rotation as the actuator arm, movement of the switch by turning the knob changes the angle of revolution between the switch and the stop through which the actuator must move during the ltiming period.

1n order to give the position selected for the switch supporting member stability so that the switch will remain in the selected position, it is desirable to have some sort of cooperation between said' switch supporting member and the deck to prevent relative rotation after the timing device has been set. Such cooperation may be aforded, for example, by a pair of friction rings on the opposed surfaces of members to be held against rotation, acting to produce a clutching effect when urged axially together. However, in the preferred embodiment of the present invention such cooperation between the knob and the frame is accomplished by use of crown gears 85 and 86 xed respectively to the support frame and the knob 50. When axially urged together the teeth of these crown gears mesh. Since all of the teeth on both gears are triangular and of the same dimensions, the crown gears will be able to mesh in a plurality of positions. ln fact, they will mesh in as many positions as there are teeth. As a practical matter in designing the crown gears, the number of teeth in each gear is selected in accordance with the number of discrete switch positions desired. For example, if a complete revolution of the actuator represents sixty seconds and it is desired to time periods to a tenth of a second, each of the gears must have 60() teeth. The axial pressure driving the crown gears together is, of course supplied by spring 58, and this spring pressure should be suiiiciently strong to hold the crown gears in mesh against vibrations, accidental bumps and other random mechanical forces tending to produce rotation which it will experience in normal use.

A flange 8S is provided on the cylindrical portion 51 of the knob to extend radially inwardly a short distance so that it will contact stop member 45 at its radial ends. The flange 8S is preferably a planar arcuate piece of sheet metal terminated at its opposite ends in radial shoulders which cooperate with stop 45 to prevent more than one complete revolution of knob 50. It may limit rotation of the knob to much less than one complete revolution. How much less is determined by the size of the arc that tiange 88 occupies. The practical function of Aange 88 is to prevent twistingv of leads and to permit the'use of'the type of spring selected to accomplish zero positioning. y

The ared base portion of cylindrical body 51 of the knob is provided with a scale which is intended to be compared with some reference mark 91 on the supporting frame. This method of calibration has been found most convenient in actual use. The numbers could, of course, be on the frame member 42 -with the reference mark on the knob. The calibrations, of course, indicate the position of the switch, which is supported within the knob, relative to the frame and lthe stop it supports. Accordingly, the calibrations represent the timing periods in seconds (or in certain timers perhaps minutes or hours).

The structure of the present invention effectively provides an arm extending beyond the switch in the radial direction. It should be remembered that calibrations are effectively measurements of angle so that the further they are placed from the axis of rotation, the greater the distance between them. Accordingly, placing timing calibrations on the periphery of the knob beyond the switch radius, has the effect of separating adjacent marks and increasing the ease of adjustment of the timing period. It also makes possible very accurate positioning of the switch. Although the larger the radius of the knob, the easier its accurate setting, there must be practical limits to the size of the knob determined by other considerations.

Connected to the switch parts are leads 93, 94 and 95. Lead 93 is connected to tab 75 and hence to contact 79. Lead 94 is connected to tab 74, hence to strip 77 and to contacts 78 and 81. Lead 95 is connected to tab 72 and hence to contact 71. Tubular insulator members 96 surround the ends of leads 93, 94 and 95 and protect their soldered junctions with tabs, or other appropriate means iixed to the ends of rivets 97. Rivets 97 serve both as electrical connections to join the proper leads to their proper tabs and contacts and as mechanical supports holding the various switch parts in place on the switch supporting block. The actual form of apreferred type of connection may be seen in Fig. 1.

Throughout the drawings wiring has been omitted for Ithe most part in order to simplify the drawings and to prevent apparent further complication of an already cornpact mechanical structure. There are preferred ways of wiring the device of. the present invention but the preferred Ways are in `accordance with good electrical practices consistent with the amount of space available to make a particular connection. Since all of the electrical wiring is conventional except for leads 93, 94 and 95 and their location within the tubular member 54, it is deemed sufficient to show schematically in the diagram of Fig. 7 -the wiring of the structure previously described. In this circuit, in so far as possible, elements which have a. particular number designation in the previous drawings have that same designation in the circuit.` In some instances elements have been illustrated schematically for the sake of simplicity. Thus, for example, instead of showing an actuator 44, a cam 65 is illustrated to move a follower-switch contact 71', which represents our switch element 67 and contact 71, morder to open and close the contacts 79 and 77.

A dashed line is used to surround that portion of the circuitry which is enclosed within Ithe casing of the timing device. Circuitry external of these lines must be added by the user. It will be observed that there are four terminals marked H, R, -land C. Terminal H is connected to solenoid 30, the other side of which is connected to ground. Terminal R and terminal are connected together and, in turn, connected to switch contact 77. The motor 10 is connected between ground on one side and a contact 79' on the other side. This contact is the one which is normally closed (in contact with switch element 77'). Terminal C is connected to follower-contact 71 which may be driven against switch element 77 by actuator 65.

Three of the terminals which have been described are shown in Fig. l supported in an insulator 99 located at the end of the structure remote from the knob. The other terminal is also in this insulator but it cannot be seen in the sectional View. Leads from these terminals are not shown but lie inside the casing, each following a preferred path to the element to which it is to be connected. Thus, for example, lead 94 from `the -iterminal will be connected to switch element 77 and lead 95 from the C terminal will be connected to contact 71.

In operation, the drive shaft is driven by the motor 10 through the gear connections previously described. M otor 10 is energized by closure of a switch 101 (Fig. 7). Pinion 17 on drive shaft 15 in turn drives drum 23 through the train ofy gears 18, 21 and 22. Rotation of drum 23 will continue until energization of solenoid 30. At any desired time following closure of switch 101 and after motor 10 is operating up to speed, the solenoid :itl

may be energized by closing a switch 1.02 external to the circuit, thereby causing the brakeshoe 27 to engage the outer surface of the drum 23 and prevent further rotation. Since the drum 23 cannot rotate, gear 22 which is lixed to it cannot rotate. Nevertheless, pinion -17 which is driven by motor 10 must rotate and, in tum, cause rotation of gears 18 and 21. Since gear 21 still meshes with gear 22, the rotation of gears 18 and Z1 will cause radial arm to revolve about its supporting shaft as an axis. Since arm 20 is afiixed to shaft 39, this shaft will also rotate, thereby causing pinion to rotate.

Rotation of pinion 40 produces rotation of gear 43 to which actuator arm 44 is aiixed. This causes movement of the actuator member away from its zero position as the actuator arm is driven away from stop 45. In the course of its rotation, actuator 65 will contact knob 66 of the switch. When knob 66 is contacted arm 67 will rotate about pin 69 causing contact 71 to engage contact 81 on strip 77. The arm 67 will continue to rotate driving contact 78 away from contact 79. The effect of actuation may be seen by reference to Fig. 7. Fig. 7 schematically represents the actuator and switch as a cam and follower with associated contacts. Rotation of the cam 65 is equivalent to rotation ofthe actuator arm. In the case of the cam, however, the follower is always in Contact with the cam. Accordingly it takes a discontinuity in the cam to drive Contact member 71 into Contact 77 and the latter away from contact 79. cle-energize the motor 10. The contact made with member 77 (contact 81) will close the circuit from terminal -lto terminal C. The exact nature of this connection will depend on its particular use, but for example, it may energize a. solenoid which will close a switch which will remain closed thereafter. After subsequent opening of switch 102 spring 46 will act to urge arm 2G back to its rest or Zero position with actuator arm 44 against stop 45.

The timing period may be varied simply by adjustment of the knob. This is done preferably by pulling the knob 50 axially outward away from the frame. When spring 53 has been suiiciently compressed to permit disengagement of crown gears and 86, knob S0 may be rotated so that its time scale may be compared against indicator member 91. As previously mentioned, the switch mounting member 59 is held against rotation relative to the knob 50 by set screws 60` or other convenient means. If desired, the knob 50 may be turned without withdrawal by the operator against spring 58. The meshing teeth of the crown gears will cam over each other.

The leads 93, 94 and 95 are approximately axially located in passing through tubular shaft and arranged in parallel relation when knob 50 is at Icenter of its range ofmovement. This axial location and parallel arrangement-preventstheirbeing twistedsubstantially in turning Breaking the contact 79 (or 79') will when the. knob isturned; Actually they will bel twisted slightly in adjusting the switch position, but the twisting will be4 a maximum of one-half turn for thelength of the tubular shaft which willY not be harmful to theleads. Location of the leads in any other manner with a movable switch would make it necessary for them tobe bent or twisted` much more severely so that in time they would undoubtedly work harden and become brittle and their insulation would `crack 0E. Moreover, in another arrangement it is likely that the leads would tend toniove into the path of movement of some of the relatively movable parts, which movement cannot occur here. Accordingly, parallel location of switch leads on the axis of rotation of the switch provides an important advantage in the present invention.

it will be apparent to those skilled in the art that many changes may be made in the device described within the scope and spirit of the present invention. Such a possible modiiication is adjustment of` the position of the support member it bears, by a remote adjustment means such as a knob, at a distance from the support member, as through a gear chain.

As previously suggested, it is within the scope and `spirit of the present invention to employ merely a radially extending arm to rncvably support the switch rather than the relatively complex support and enclosure described. It is also possible within the scope of the present invention to employ a cam actuator structure of the sort described in connection with the circuitry instead oi' an actuator arm, in which case the cam will be understood to be for all practical purposes the equivalent of an actuator arm. All sorts of modifications in the shape and arrangement of the actuator arm and the rotatable support member are intended to be within the scope o-f the present invention.

Other changes will occur to those skilled in the art. All such changes within the scope ofy the claims are intended to be within the scope and spirit ofthe present invention.

We claim:

l. In a timing device, a single pole double throw switch Y comprising an insulating support, a fixed contact supported on said insulating support, two contacts on a common conductor supported on said insulating support, one of said contacts being arranged to cooperate with said xed contact, said `cooperating contacts constituting a first pair, a bell crank rotatably mounted on the insulating support, a movable contact mounted on one arm of the bell crank, the other arm of said bell crank providing an actuating lever, said movable contact being arranged to cooperate with the other of said two contacts on the `common conductor, said cooperating `contacts constituting a second pair, resilient means acting on the common conductor and urging one pair of contacts closed in such a way that rotation of the bell crank will exert an opposing pressure `on the common conductor in contacting the second pair of contacts in order to close the normally open pair `of contacts and to open the normally closed pair of contacts, and a rotatable actuator movable in timed relation into contact with said actuating lever, said actuating lever lying substantially directly in the path of movement of said rotatable actuator.

2. In a timing device, a switch as described in claim l wherein the common conductor supporting two contac' is a resilient spring-like metallic strip which normally urges closed the first pair of contacts and wherein the contact on the bell crank is arranged to oppose the resilient conductor in such a manner as to drive apart the first contacts.

3. In a timing device adapted to be driven by a motor, the combination of a frame including a deck plate, a hollow shaft mounted by said plate and extending outward from one side of the plate, an actuator varrn mounted for rotation on said shaft, spring means urging said arm to rotate in a rst. direction, iixed stop means on the frame for limiting rotation `of the arm in said iirst direction, said arm being adapted to be motor driven in a second direction, a cup-like control member mounted for limited rotation on said shaft and having its open end facing said deck plate, a switch mounted within said control member and movable therewith, said switch having a portion lying in the path of movement of said arm and adapted for actuation thereby, and conductor means extending through said hollow shaft and connected to said switch.

4. The device of claim 3, in which opposed means are provided on said deck plate and control member forming cooperat'vely engageable serrated surfaces, and spring means act between said shaft and control member to urge said control member axially in a direction to engage -said serrated surfaces.

5. The device of claim 3, in which a sleeve-like mem ber of insulating material is mounted in said control member and surrounds said hollow' shaft, and said switch is mounted on said sleeve-like member.

6. The device o-f claim 3, in which a bearing sleeve is mounted in said control member and has a portion bearing on said shaft, the outer end portion of said bearing sleeve has an inside diameter greater than the diameter of the shaft to form with the shaft an annular recess and to form with the bearing portion a shoulder at the inner end of the recess, a spring is received in the recess in surrounding relation to the shaft and bears at its inner end against said shoulder, a ring is secured to said shaft near the outer end of said bearing sleeve and forms a shoulder against which the outer end of said spring bears, said ring also providing a bearing surface `for supporting the outer end of said bearing sleeve.

7. rPhe device of claim 3, in which said switch is a single pole double throw switch, having a rst set of contacts opened by said arm and a second set of contacts closed by said arm.

8. The device of claim 7, in which the switch includes an insulating support, a fixed contact mounted on said support, two contacts on a common conductor mounted on said support, one of said contacts being arranged to cooperate with said xed Contact, said cooperating contacts constituting a first pair, a movable contact arranged to cooperate with the other of said two contacts on the common conductor and constituting therewith a second pair, resilient means acting on the common conductor in a iirst direction to urge the iirst pair of contacts closed, said movable contact being movable by said actuator arm in a second direction to close said second pair of contacts and open said rst pair of contacts in sequence.

References Cited in the tile of this patent UNITED STATES PATENTS 1,789,057 Vickery Jan. 13, 1931 2,163,419 Warren June 20, 1939 2,195,642 DeLarm Apr. 2, 1940 2,312,077 Cowles Peb. 23, 1943 2,388,686 Habig Nov. 13, 1945 2,506,784 Haydon May 9, 1950 2,559,910 White July 10, 1951 2,573,130 Moore et a1. Oct. 30, 1951 2,605,367 Cochran July 29, 1952 2,631,664 Poole Mar. 17, 1953 2,647,962 Batcheller Aug. 4, 1953 2,777,027 Tesh Jan. 8, 1957 2,842,626 Gallagher et al. July 8, 1958

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