US2872542A

US2872542A - Combination momentary maintained switch

Info

Publication number: US2872542A
Application number: US731834A
Authority: US
Inventors: Clayton H Thompson
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-04-29
Filing date: 1958-04-29
Publication date: 1959-02-03
Anticipated expiration: 1976-02-03

Description

Feb, 3, 1959 c. H. THOMPSON 2,872,542

COMBINATION MOMENTARY MAINTAINED SWITCH Filed April 29, 1958 Tg3 El.; 57 45 6292 936s .v 40 36 7G E- INVENTOR.

CLAYTON H. THOMPSON .I BY

ATTORNEYS COMBINATIDN MMENTARY MAIN TAINED SWITCH Clayton H. Thompson, Elgin, lll. Application April 29, 1958, Serial No. 731,834 Claims. (Cl. 20G-86.5)

This invention relates to foot switches, and more particularly to an improved foot switch with a control means integrally embodied therewith.

Certain situations are frequently found by doctors, nurses and assistants in hospitals, as well as other operators in industry, that it is desirable to control a plurality of electrical circuits in predetermined arrangement by the use of foot switches. ln some such instances it is necessary to employ a separate foot switch for the operation of each circuit. This practice creates a problem of fatigue and error as well as time delay.

It is therefore an object of this invention to provide a single combination momentary maintained foot switch of improved and novel design having a multi-position treadle and latching bars by which a plurality of electrical circuits may be controlled in a predetermined manner.

It is a further object of this invention to provide in a foot switch and control means permitting the operator to place the switch upon the floor adjacent a device to be electrically controlled, arranging it in the desired operative position whereby the foot of the operator may be placed thereon in a simple and easy manner and oscillated without visually observing the switch.

It is another object of this invention to provide in a foot switch with control means to allow the foot of an operator to remain upon the'treadle and be freely oscillated between a plurality cf positions for effecting the control of a plurality of electrical circuits, or allow thetreadle to be moved by the foot in one direction to operate one electrical circuit, the treadle remaining in locked position even with the foot removed, until the treadle is again actuated by the foot and moved to another location.

Another object of this invention is to provide a foot switch and control therewith of the above type referred to which can be easily, quietly, and quickly converted from oscillating non-latching operation by downward pressure of the operators foot, or converted into latching position eifecting control of an electrical circuit by side movement of the operators foot before removal from the switch.

Another object of this invention is to provide a foot switch and manual control which lends itself to assembly and use in hazardous locations which require explosionproof equipment due to use of explosive vapors and explosive gases thereabout.

Other objects, and objects relating to details of construction and economies of manufacture will appear as in the following description of the embodiments ofthe invention which, for the purposes of the present applica` tion, is illustrated in the accompanying drawings, in which:

Figure 1 is a top plan view of an electrical switch and control embodied therewith embodying the features of this invention;

Figure 2 is a plan View of the electrical switch and ited States Patent 0 control means shown by Fig. l with the top cover, or treadle removed;

Figure 3 is a transverse sectional view taken along line III- Ill of Figure 2 showing the switch mechanism;

Figure 4 is a transverse sectional view taken along line IV-IV of Figure 2 showing the control mechanism;

Figure 5 is an end elevational view of the device shown in Fig. l, the actuator being shown in section and the treadle in vits initial inactive location;

Figure 6 is a view of the device shown in Figure 5 but having the treadle shown in one of its active locationsand latched in said location.

Figure 7 is an enlarged partial transverse sectional view of the parts shown in Figure 4, the control parts being shown in the location as shown by Figure 6, the treadle shown by dotted lines;

Figure 8 is a fragmentary sectional view of the actuator and a portion of the treadle taken substantially on line VIII- VIII of Figure l; and

Figure 9 is a fragmentary sectional view taken substantially on line X-IX of Figure l.

The features of the invention, although not necessarily so limited, lend themselves particularly to control means and to a switch of the foot pedal type and are, therefore, illustrated by way of example in connection with such a device.

The switch and control means 10 as illustrated in the figures, includes a housing 11 open at the top and having closed bottom and side walls. The cover, or treadle 25 is pivotally assembled upon the housing 11 for oscillation and eifecting actuation of the switch.

The interior of the housing 11 provides a bottom 24 with a forward area 12 and a rearward area 13, the rearward area 13 embodying two snap over

toggle switch mechanisms

14 and 15. arranged parallel with each other and in longitudinal alignment of the housing, the mechanism duly shown by Patent 2,521,015. Each switch embodies a body portion, a contact pin, an upper metal cover plate and an angular actuating arm pivotally mounted therewith. Said switch 14 embodies a body portion 17, an actuating pin 18, a pivoting plate 19 and an angularly formed actuating arm 2G, said arm 20 having an angular and elevating member 21 and a depending member 22, said member 21 extending outwardly and upwardly with regard to the longitudinal center line of the housing. Said switch 15 embodies a body portion 27, an actuating pin 28, a pivoting plate 29 and an angularly formed actuating arm 3i?, said arm 30 having an angular and elevating member 31 and a depending member 32, said member 31 extending outwardly and upwardly with regard to the longitudinal center line of the housing. A compression serpentine snap-over spring 33 is assembled with and interposed between depending

members

22 and 32, said spring 33 normally biasing the depending

arms

22 and 32 towards the

bodies

17 and 27 effecting the actuating

pins

18 and 28 to move inwardly into said body portions 17 andt27 thereby opening the electrical circuits associated therewith.

The iioor of the bottom 24 has an upwardly extending leg 35 with a circular bore 36 centrally located and adjacent the upper end thereof as shown by Figure 9. The treadle 25 has assembled therewith a rigid angular supporting member with a horizontal portion 38 and depending leg 39. A pin 40 is mounted in the lower end portion o-f said leg 39, a free end of the pin 4) extending horizontally and rearwardly beneath the treadle 25. The diameter of the pin is slightly smaller than the bore 36 in the leg 35. When the ltreadle 25 is assembled with the housing 11 the pin 4@ geraete in a threaded bore centrally located in the forward end Wall of the treadle, the screw 42 is provided with a threadless end which enters a threadless bore in the forward'end wall of the housing. The'treadle when mounted upon the housing as described is rockable and capable of oscillating from one side to the other upon pin di) and the end portion of the screw 42. s

The forward area 12 of the housing 11 embodies the control mechanism for operating the switch related to above. Supporting blocks 43 are arranged in said area 12. A C shaped plate is assembled upon the'supportingrblocks 43 with the rearward free ends bent downwardly and forming depending edge portions 51 and 52 spaced to the rear of said blocks and forming a transverse channel 4d therebetween. A pair of sliding bars l and d6 are transversely arranged in said transverse channel 44, thev lower edges thereof in sliding contact with the upper floor of the bottom 24; the upper edges thereof being in sliding contact with the undersides of the free ends 5l and 52vof the C plate. The bars 45 and y46 have outwardly extending ends 47 and i3 with notched portions 53 and 54, said notched end, portions normally extending a slight distance through

openings

55 and 56 in the

side walls

57 and 58 of the housing l. The notched end portions normally allow the treadle 25 to assume a horizontal position, the side walls 59 and 6@ of the treadle substantially contacting` the upper sides of said notched portions53 and 54. A pair of triangular-shaped operating cams 62 and 6d are pivotally mounted with the supporting blocks d3 adjacent the

bars

45 and 46. Each of the

cams

62 and 68 are arranged with one lower corner and two elevated corners, a pin 63 being rigidly secured in the lower corner of said cam 62 and a pin 69 being rigidly secured in the lower corner'of said cam 68. rThe free ends of said pins 63 and 69 are assembled in horizontal bores formed in the supporting blocks 43. Sub-V stantially above the pins 63 and 69 are provided

pins

72 and 73, said pins extending rearwardly from the cams 62 and 63 and iit into cross grooves 74 and 75 in the upper surfaces of said

bars

45 and 46. A serpentine type spring 76 is assembled with and interposed between the inner ends 0f the

bars

45 and 46, said spring 76 biasing each

bar

45 and 46 outwardly. The outward movement of the bars is limited by the travel distance of

pins

72 and 73 about the pins 63 and 69 and is further controlled by an actuator S6 arranged. above said

cam members

62 and 68. I

The actuator Sil is clearly shown by Figures l, 4, 5, 6, 7 and 8 and particularly shown by Figure 8. Said actuator Si) consists of a metal member with a top surface $1, a forward depending leg 82, and an enlarged rear end portion S3. For assembly of the actuator to the treadle 25, the depending leg 32 is inserted downwardly through a transverse slot Sd, an angular pin 85 is inserted through an aperture 86 in the treadle 25 and into a vertical bore 37 in said actuator at the rear end thereof, said aperture S6 being arranged to the rear of said slot S4. The upwardly extending portion of said pin 85 is locked in said borevl by an Allen Set Screw S8 horizontally arranged in a threaded bore 89 extending from, the rear end of said actuator to the vertical bore 87 therein.A The horizontal portion 96 of said pin 85 allows rockable and oscillating movement of the actuator but prevents it from being accidentally removed from the treadle. ri'he depending leg 82 of the actuator remains within the slot 84 at all periods, however, it has free oscillation therein. The depending leg 82 has two corners 92 and 93, as shown by Figures 4 and 7. Said corner 92 is always in contact with the triangular cam member 62. Said corner 93 is always in contact with the triangular cam member 68. The oscillation ofsaid leg 32 raises one corner` and lowers the opposite corner, the raising and lowering of said corners 92 and 93 effecting the movement d ofY said

cams

62 and 68 as well as bars d5 and 46 biaser by the spring 76.

Vr[he treadle is pivotally mounted by pin d@ within bore 36 of leg 35 at its forward end and by the unthreaded end of screw d2 at its rearward end. The lower surface of the treadle rests upon the switch elevating members 2l and 3i of actuating arms Ztl and 3d. The lower corners of the leg 82 of the actuator Sti contact the

triangular cams

62 and 68. ln normal position of the treadle 2,5, the 'free ends 47 and 43 of bars d5 and preventV the depending sides 59 and 6l) of the treadle from being lowered or raised. By the application of foot pressure upon the actuator Sil, both cams are rocked downwardly and the bars d5 and d6 are biased inwardly, allowing free oscillation of the treadle if the foot is rocked to the right, bar d6 stays in its innermost position while bar is biased outwardly by the spring 76 since corner 92 of leg 82 is in an elevated position. if the foot pressure is withdrawn, as shown by Figure 7, the end 47 of bar d5 will hold the side wall 5g of treadle 25 in elevated position, while side wall 6i; thereof is free to pass over the end d8 of bar d6. Since the forward end of the treadle is pivoted, the member 3i of arm 3i) is depressed, the depending arm 32 is moved inwardly of the housing thereby allowing the pin 2% to snap outwardly from the body 27 of switch mechanism l5. The closing of the electrical circuit in said switch mechanism l5 will effect actuation of some movable object, such as the elevation of an operating table in a hospital. The switch will remain in set position until the actuator Si) is again depressed and the treadle 25 returned to a normal, substantially horizoital position. It will be noted that the operator was not required to hold the treadle in the active position by keeping his foot thereon, When a second electrical circuit is desired to be controlled, the treadle 25 is oscillated to the opposite side upon actuation of the actuator 8d by rocking of' the operators foot to the left. The bar d6 is then biased outwardly locking the side wall 6% of the treadle in an elevated position, which inturn forced the switch member 21 downwardly, the depending arm 22 allowing the pin 13 to snap outwardly from the body 25.7 of the switch mechanism i4. The treadle holding the switch in said set position until reset by actuation of the actuator 80. Y

From the above it will be understood that when the control and switch mechanism is attached to a table in a hospital, or the like, the operator can start the elevation of the table by depression ofthe actuator and treadle to one side, the table will continue its upward travel until automaticallyrstopped by a` safety switch or by further actuation of the treadle. lt is not necessary to retain a foot upon'the treadle after it is once depressed. Y It isohvious that the above invention provides a single foot Fcontrol and switch mechanism having a multil position treadle and latching means by which a plurality of electrical circuits may be controlled.

For simplicity of presentation and description, the switch embodying the invention has been described and shown in the drawings as a 1B-position switch. It will be apparent, however, that a foot switch constructedv in accordance with the invention may be designed to have more than two actuated positions by providing addi- Y tional bars and latching means. Y

It is believed that the operation of the` novel foot switch described herein is apparent from the foregoing description. itV can be seen that there has been provided a control for a footswitchV of novel construction in which will permit the control of a plurality of electrical circuits, the control and switch being of simple and rugged design assuring long and trouble-free service under adverse operating conditions.

As many changes could be made in the above construetion many apparently widely different embodiments asians-a of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in any limited sense.

I claim as my invention:

l. In a foot switch, a bottom housing, a top treadle pivotally mounted upon said housing for oscillation from one side to the other of said housing, a pair of switches in said housing, pivotal arms mounted upon each switch and responsive to the movement of said treadle, spring means interposed between said arms for biasing the free ends thereof into contact with said treadle, and control means for retaining said treadle in one or more inclined oscillated positions, said control 'means including a pair of latch control bars arranged transversely of said housing, spring means interposed between adjacent inner ends of said bars, said bars normally extending beyond the opposite sides of said housing and having end portions formed to allow the treadle to assume there above 'a horizontal inactive switch position, cam means mounted in said housing adjacent the inner ends of said bars, means on said cam means for contacting and actuating said bars, and an actuator mounted upon said treadle and having a portion thereof in engagement with said cam means, said actuator being vertically and rockably mov- `able so that the depression of the actuator will cause both of said bars to be drawn inwardly whereby the treadle can be oscillated in either` direction ,and whereby oscillation of the treadle will cause one bar to be moved inwardly and the other bar to be moved outwardly thereby allowing one side of the treadle to be lowered and the opposite side to be raised and retained upwardly by said outwardly extending bar, and the inclined treadle retaining one of the switches'in active position and one in inactive position.

2. in a foot switch, a bottom housing, `a top treadle pivotally mounted upon said housing for oscillation from one side to the other of said housing, a pair of switches in said housing, pivotal arms with upper and lower free ends mounted upon each switch and responsive to the movement of said treadle, spring means interposed between the lower free ends of said arms for biasing the upper free ends thereof upwardly into contact with said treadle, and control means for retaining said treadle in one or more inclined oscillated positions, said control means including a pair of latch control bars arranged transversely in said housing, spring means interposed between the adjacent inner ends of said bars, said bars normally extending beyond the opposite sides of said housing and having reduced end portions to allow the treadle to assume a horizontal inactive switch position, cam means pivotally mounted in said housing adjacent the inner ends of said bars, means on said cam means for contacting and actuating said bars, and an actuator mounted upon said treadle and having a depending leg portion thereof in engagement with'said cam means, said actuator vertically and rockably movable so that the depression of the actuator will cause both of said bars to be drawn inwardly whereby the treadle can be oscillated in either direction, and whereby oscillation of the treadle will cause one bar to be moved inwardly and the other bar to be moved outwardly thereby allowing one side of the treadle to be lowered and the opposite side to be raised and retained upwardly by said outwardly extending bar, and the inclined treadle retaining one of the switches in active position and one in inactive position.

3. in a foot switch, a bottom housing, a top treadle pivotally mounted upon said housing for oscillation from one side to the other of said housing, a pair of switches in said housing, angular pivotal arms mounted between their ends with upper and lower free ends upon each switch an-d responsive to the movement of said treadle, spring means interposed between the lower free ends of said arms for biasing the upper free ends thereof up- A6 wardly into contact with said treadle, and control means for retaining said treadle in one or more inclined oscillated positions, said controi means including a pair of latch control bars arranged transversely of said housing, spring means interposed between the adjacent inner ends of said bars, said bars having reduced end portions to allow the treadle to assume a horizontal inactive switch position, a pair of generally triangular shaped cams pivotally mounted in the base of said housing adjacent the inner ends of said bars, means on each of said cams for contacting and actuating said bars, and an actuator mounted upon said treadle and having a portion thereof in engagement with said cams, said actuator vertically and rockahly movable so that the depression of the actuator will effect both of said bars to be drawn inwardly whereby the treadle can be oscillated in either direction, and whereby oscillation of the treadle will cause one bar to be moved inwardly and the other bar to be moved outwardly thereby allowing one side of the treadle to be lowered and the opposite side to be raised and retained upwardly by said outwardly extending bar, and the inclined treadle retaining one of the switches in active position and one in inactive position.

4. In a foot switch, a bottom housing, a top treadle pivotally mounted upon said housing for oscillation from one side to the other of said housing, a pair of switches in said housing, pivotal angular arms mounted between its ends upon each switch and responsive to the movement of said treadle, a spring interposed between the lower free ends of said arms for biasing the upper free ends thereof upwardly into contact with said treadle, and control means for retaining said treadle in one or more inclined oscillated positions, said control means including a pair of latch control bars in longitudinal alignment and arranged transversely of said housing, a spring interposed between the adjacent inner ends of said bars, said bars having notched end portions, a pair of generally triangular shaped cams pivotally mounted at one of its corners by a pin inserted in a bore in the base of said housing adjacent the inner ends of said bars, a pin extending from one of the upper corners of each of said cams for contacting and actuating said bars, and an actuator mounted upon said treadle and having a depending portion thereof in engagement with said cams, said actuator vertically and rockably movable so that the depression of the actuator will cause both of said bars to be drawn inwardly whereby the treadle can be 4oscillated in either direction, and whereby oscillation of the treadle will cause one bar to be moved inwardly and the yother bar to be moved outwardly thereby allowing one side of the treadle to be lo-wered and the opposite side to be raised and retained upwardly by said outwardly extending bar, and the inclined treadle retaining one of the switches in active position and one in inactive position.

5. In a foot switch and control therefore, a housing, a top treadle pivotally mounted upon said housing for rocking from one side to the other of said housing, a pair of switches in said housing, substantially angular pivotal arms mounted upon each switch responsive to the movement of said treadle, said arms pivoted between their ends providing free lower and upper ends, a spring interposed between the lower free ends of said arms for biasing the upper free ends thereof upwardly into contact with said treadle, and control means for retaining said treadle in one or more positions, said control means including a pair of latch control bars in longitudinal alignment and arranged transversely of said housing, a spring interposed between the inner ends of said bars, said bars having notched end portions extending beyond the sides of the housing and allowing the treadle to assume a horizontal inactive switch position, a pair of triangular shaped cams pivotally mounted in the base lof said housing adjacent the inner ends of said bars, said cams mounted with one corner at the bottom with a flat surface and two corners thereabove, means projecting from each of the inner upper corners of said cams for fitting into grooves in the top surfaces of said bars for actuating said bars, an actuator mounted upon said treadle and having a depending portion thereof in engagement with said cams, said actuator verticaliy and rockably movable so that4 the depression of the actuator willY cause both 4of said bars to be drawn inwardly whereby the treadle can be oscillate-d in either direction, and whereby oscillation of the treadle will cause one bar to be moved inwardly and the other bar to be moved outwardly'thereby allowing one side of the treadle to be lowered and the opposite side to be raised and retained upwardly by said outwardly extending bar, and the inclined treadle retaining one of the switches in active position and Vone in inactive position.

6; A control means integrally assembled with a toot switch, comprising a b ottom housing, a pair of switches in said housing, a top treadle pivotally mounted upon said housing for oscillation from one side to the other of said housing, pivotal angular arms mounted upon each switch responsive to the movement of said treadle, said arms being pivoted between their ends providing free upper and lower ends, a spring means interposed between the lower free ends of said arms for biasing the upper free ends thereof upwardly into contact with said treadle, and controlV means for retaining said treadle in one or more oscillated positions, said control means including latch control bars arranged transversely of said housing, spring means interposed between adjacent ends of said bars, said bars being constructed to permit the treadle to assume a horizontal inactive switch position on said bottom housing, cam means mounted in said housing adjacent said inner ends of said bars for contacting and actuating said bars when actuated, an actuator associated with said treadle and having a portion engageable by said cam means, said actuator being vertically and rockably movable so that the depression of the actuator causes both of said bars to be drawn inwardly whereby the treadle can be oscillated in either direction, and whereby oscillation of the treadle will cause one bar to be moved inwardly and the other bar to be moved outwardly thereby allowing one side of the treadle to be lowered and the opposite side to be raised and retained upwardly by said outwardly extending bar, and the treadle thus retaining one of the switches in active position and one in inactive position.

7. In a foot switch, an open upper end housing, a pair.

of switches in said housing, a top treadle pivotally mounted upon said housing for covering said housing and -f for oscillation from one side to the other of said housing, substantially right angie pivotal arms mounted between their ends upon each switch responsive to the movement of said treadle, said arms having free upper and lower ends, a spring interposed between the lower free ends of said arms for biasing the upper free ends thereof upwardly into contact with said treadle, and control means for retaining said treadle in one or more inclined oscillated positions, said control means including a pair of latch control bars in alignment and arranged transversely of said housing, a spring interposed between the adjacent inner ends of said bars, each of said bars having a groove in its top surface and a notched end portion to allow the treadle to assume a horizontal inactive switch position, a pair of cams pivotally mounted upon supporting means in tr e base of said housing adjacent the inner ends of said bars, means extending rearwardly from each of said cams for iitting into the grooves in said bars for actuating same, an angular shaped actuator mounted upon said treadle having a depending end portion in engagement with said cams, said actuator being vertically and rockably movable so that the depression of the actuator will cause both of said bars to be drawn inwardly whereby the treadle can be oscillated in either direction, and whereby oscillation of theV treadle will d cause one bar to be moved inwardly and the other bar to be moved outwardly thereby allowing one side of the treadle to be lowered and the opposite Yside to be raised and retained upwardly by said outwardly extending bar,

Vand the inclined treadle retainingone `of the switches in active position and one in inactive position.

8. A door switch and control device of the character described including a bottom housing having spaced apart side walls, a front walls, and a rear wall, a slotted top treadle pivotally mounted with and longitudinally of therhousing, said treadle having spaced-apart side walls for overlapping the side walls of said housing, a pair of switches mounted in the rear portion of said housing, a pivotal angular shaped arm mounted upon each switch, arms having upper'and lower free end portions, the app r tree end arm portions in contact with said treadle, a spring interposed between said lower free end portions of said arms, land control means for retaining the treadle in one or more predetermined locations located in the forward portion of said housing, said control means including a pair of latclied control bars in general alignment, a spring interposed between` the inner ends of said bars, said bars having their outer ends normally extending beyond the sides of said housing, a pair of cams pivotally mounted in said housing adjacent the inner ends of said bars, the upper surface of each bar having a groove at the inner end thereof, means on each cam and extending rearwardly into said groove in a bar, and an actuator mounted upon the upper surface of the Vtreadle and having a depending leg portion thereof extending through the slot in said treadle and in engagement with said cams, said actuator movable vertically and sideways, the depression of said actuator causing movement of said bars edecting latching ot Athe treadle and switches in contact therewith.

9. An enclosed iioor switch and control device of the character described including a bottom housing having spaced apart side walls, a front wall, and a rear wail, a top treadle pivotally mounted with and longitudinally of the housing, said treadle having spaced-apart side walls for overlapping the side walls of said housing, a pair of switches mounted in the rear portion of said housing, a pivotal arm mounted upon each switch, said arms having upper and lower free end portions, the upper free end arm in contact with said treadle, a spring interposed between said lower free end portions, and manual control means for retaining the treadle in one or more predetermined locations located in the forward portion of said housing, said control means including two control bars arranged in general alignment slidably mounted upon the base or the housing, a spring interposed between the inner ends of said bars, said bars having their outer ends normally extending beyond the sides of said housing, a pair of cams pivotally mounted in said housing adjacent the inner ends of said bars, the upper surface of each bar having a depression at the inner ends thereof, means on each cam and extending rearwardly into said depression in a bar, and an actuator mounted upon the upper surface of the treadle and having a depending leg portion thereof extending through said treadle and in engagement with said cams, said actuator being movable vertically and sideways, the depression of said actuator eiecting movement of said bars causing latching of the treadle and switches in contact therewith.

li). An enclosed floor switch and control device of the character described including a bottom housing having spaced apartV side weils, aifront wall, and a rear wall, a top treadle, a support member extending upwardly from the base of said housing, said treadle being pivotally mounted to said support member longitudinally ofthe housing, said treadle also being pivotally mounted to the front wall of said housing, said treadle having spaced-apart side walls for overlapping the side walls of said housing, a pair of switches including actuating pins mounted in said housing, pivotal arms mounted upon each switch, Said arms having upper and lower free end portions, the upper free end portions in contact with the said treadle, the downwardly extending free arm portions in contact with said switch actuating pins, and manual control means for retaining the treadle in one or more predetermined locations located in the forward portion of said housing, said control means including two control bars arranged in longitudinal alignment slidaby mounted upon the base ofthe housing, a spring interposed between the inner ends of said bars, said bars having their outer ends normally extending beyond the sides of said housing, a pair of cams pivotally mounted in said housing adjacent the inner ends of said bars, a piu on each cam and extending into engagement with one of said bars, and an actuator mounted upon the upper surface of the treadle and having a depending portion thereof extending through said treadle and in engagement with said cams, said actuator movable vertically and sideways, the depression of said actuator effecting movement of said bars thus causing latching of the treadle and switches in contact therewith.

Schneider Apr. 21, 1953 Heidman Oct. 9, 1956