US3688228A

US3688228A - Actuating mechanism for operating handle of electrical switching device

Info

Publication number: US3688228A
Application number: US182328A
Authority: US
Inventors: Neil R Palmer; Joseph R Karge; Kenneth W Erickson
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1971-09-21
Filing date: 1971-09-21
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29
Also published as: IT975026B; GB1368365A; CA974280A

Abstract

A remote-control actuating mechanism for the handle of an electric circuit breaker. A single-pole double-throw switch selectively controls the direction of rotation of a gearmotor output shaft and of a crank arm resiliently connected thereto by a flat overtravel spring. The crank arm is provided with a cross member connected to the circuit breaker handle. A pair of alternately operated normally closed ON and OFF limit switches interrupt the flow of current through the motor of the gearmotor respectively in opposite directions. An operating member for the limit switches is disposed between their depressible operating buttons and is provided with a lost-motion connection either to the crank arm or to the flat overtravel spring, the lost-motion enabling the circuit breaker handle to move to tripped position without affecting the limit switches. Friction holds the limit switch operating member in position when the circuit breaker trips and also when the driving force thereon in either direction is released by the opening of the circuit through the motor. The frictional force on the limit switch operating member is greater than the restoring force on the depressible operating button of a limit switch, and hunting, i.e., repeated starting and stopping of the motor, is eliminated.

Description

United States Patent Palmer et al.

[1 1 3,688,228 [451 Aug. 29, 1972 [54] ACTUATING MECHANISM FOR OPERATING HANDLE OF ELECTRICAL SWITCHING DEVICE [7 2] Inventors: Neil R. Palmer, Cedar Rapids;

Joseph R. Karge, Anamosa; Kenneth W. Erickson, Cedar Rapids, all of Iowa [73] Assignee: Square D Company, Park Ridge, 111.

[22] Filed: Sept. 21, 1971 [21] Appl. No.:- 182,328

[52] U.S. Cl ..335/68 [51] Int. Cl. ..H01h 3/02 [58] Field of Search ..335/68, 69, 70, 71, 72, 73

[56] References Cited UNITED STATES PATENTS 2,959,649 11/1960 Powell ..335/71 2,870,288 1/ 1959 Schmidt ..335/69 3,211,955 10/1965 Soos, Jr. ..335/68 3,171,920 3/1965 Klein et a1. ..335/69 3,296,565 l/ 1967 Kiesel ..335/69 Primary ExaminerHarold Broome Att0rney-Harold J. Rathbun et a1.

[ ABSTRACT member connected to the circuit breaker handle. A

pair of alternately operated normally closed 0N and OFF limit switches interrupt the flow of current through the motor of the gearmotor respectively in opposite directions. An operating member for the limit switches is disposed between their depressible operating buttons and is provided with a lost-motion connection either to the crank arm or to the flat overtravel spring, the lost-motion enabling the circuit breaker handle to move to tripped position without affecting the limit switches. Friction holds the limit switch operating member in position when the circuit breaker trips and also when the driving force thereon in either direction is released by the opening of the circuit through the motor. The frictional force on the limit switch operating member is greater than the restoring force on the depressible operating button of a limit switch, and hunting, i.e., repeated starting and stopping of the motor, is eliminated.

10 Claims, 7 Drawing Figures ACTUATING MECHANISM FOR OPERATING HANDLE OF ELECTRICAL SWITCHING DEVICE This invention relates to a power actuating mechanism for the operating handle of an electric circuit breaker.

An object of the invention is to provide an improved electrically powered actuating mechanism for moving an operating handle of an electric circuit breaker selectively to ON and OFF positions.

Another object is to provide a power actuating mechanism which will permit tripping and manual operation of a circuit breaker handle while connected thereto.

Other objects and advantages will become apparent when the following specification is considered along with the accompanying drawings in which:

FIG. 1 is a plan view of a circuit breaker handle actuating mechanism constructed in accordance with the invention, portions being broken away and a circuit breaker being shown fragmentarily in phantom;

FIG. 2 is an enlarged front elevational view of the mechanism of FIG. 1;

FIG. 3 is an enlarged view of a portion of FIG. 2 illustrating a pair of limit switches, but with an actuating member therefor in an opposite position from that of FIG. 2;

FIG. 4 is a fragmentary sectional view taken along the line 4-4 of FIG. 3;

FIG. 5 is a schematic wiring diagram for the mechanisms of FIGS. 1, 6, and 7;

FIG. 6 is a view similar to FIG. 2, but illustrating a different embodiment of the invention; and

FIG. 7 is a view similar to FIGS. 2 and 6, but illustrating still another embodiment of the invention.

With reference to the drawings, FIGS. 1 and 2 show a circuit breaker handle operating mechanism 10 constructed in accordance with the invention. A circuit breaker 11 having a handle 12 operable by the mechanism 10 is shown fragmentarily in phantom in FIG. 1. The circuit breaker l 1 may be like those of U.S. Pat. Nos. 3,341,791, issued Sept. 12, 1967, and 3,345,591, issued Oct. 3, 1967.

, The mechanism 10 includes a generally U-shaped housing member 14 having a top wall 14a, a pair of opposite side walls 14b and 140, and a pair of outwardly turned mounting flanges 14d and 14e respectively at the bottom of the side walls. Folded fiberboard sheet material (not shown) may be secured in place to provide front, back, and bottom walls and form a complete enclosure with the housing member 14.

A flanged mounting plate 16' is secured within the housing member 14 by a plurality of screws 18. A gearmotor 20 having an output shaft 21 is secured to the rear of the plate 16. The output shaft 21 extends through a suitable opening in the plate 16 to the front thereof. A generally U-shaped crank arm 22 is loosely mounted on the shaft 21 on the front side of the plate 16 and resiliently keyed thereto by a flat spring 2 The shaft 21 extends through suitable openings in

opposite leg portions

22a and 22b of the crank arm 22, and the spring 24 is disposed between the

leg portions

22a and 22b and extends through a suitable slot in the shaft 21 and also through a suitable slot in a bight portion 220 of the crank arm 22. The width of the spring 24 is several times its illustrated thickness, as would be apparent in FIG. 1 were it not for a covering tongue 16c is secured between two pins 25 each having opposite end portions frictionally held respectively in the

leg portions

22a and 22b. One of the pins may be provided with a washer (not shown) projecting into a suitable longitudinal slot in the spring 24 to prevent longitudinal shifting thereof.

The free ends of the

leg portions

22a and 22b are staked to a cross plate 26 in which a screw 28 is threadedly received to secure a channel shaped handle actuating member 30 to the crank arm 22. The actuating member 30 is provided with a pair of

prongs

30a and 30b between which the handle 12 of the circuit breaker 11 may be received. Two tubular members 31, formed preferably of hard plastic, are mounted respectively on the

prongs

30a and 30b for protection of the circuit breaker handle 12.

The top wall 14a of the housing member 14 is provided with an open-sided slot 14f through which the crank arm 22 extends. The plate 16 is provided with an upwardly extending tongue portion 16a adjacent the right-hand end as viewed in FIG. 2. The tongue portion 16a is bent forwardly to provide a partial flange 16b from which the tongue 160 extends toward the left through the crank arm 22 between the

leg portions

22a and 22b and under the top wall adjacent the left end of the slot 14f.

A link 33 is disposed between the leg portion 22b and the flat spring 24 and is provided adjacent its left end as viewed in FIG. 2 with suitable apertures in which a pair of

pins

34 and 35 are tightly held. The

pins

34 and 35 are disposed on opposite sides of the flat spring 24, are spaced apart somewhat more than the thickness thereof, and project into a rectangular aperture 22d in the leg portion 22b. The link 33 is pivotally connected adjacent its right end as viewed in FIG. 2 to an actuating lever 37 by a pin 38. The lever 37 is pivotally mounted in spaced relationship to the mounting plate 16 by a pin 40 secured in the plate 16 and extending through a suitable aperture in the lever 37 after first passing through a spacer (not shown). The lever 37 is provided with a lost-motion connection to a reciprocally mounted limit switch actuator 42 driven thereby and disposed between an ON limit switch 44 and an OFF limit switch 46 each mounted on the plate 16 by a screw 48 having a slotted head on the front side of the plate and a screw 49 having a slotted head on the rear side of the plate. The actuator 42 is generally U- shaped, as best shown in FIG. 4, with outwardly turned flange portions 420 and 42b. Besides aiding in securing the

switches

44 and 46 in place, the screws 49,

threaded respectively into a pair of nuts 50, hold a friction plate 51 against the

flange portions

42a and 42b on the rear side of the plate 16. The U-shaped portion of the actuator 42 extends from the

flange portions

42a and 42b through a slot 16d in the plate 16 and, when moved by the actuating lever 37, selectively depresses operating buttons 44a and 46a of the

limit switches

44 and 46.

The gearmotor 20 includes a forward winding 20F (FIG. 5) connected to the ON limit switch 44 and-a reverse winding 20R connected to theOFF limit switch 46. A remote-control single-pole double-throw switch 52 has an ON contact 52a connected to the ON limit switch 44, an OFF contact 52b connected to the OFF limit switch 46, and a switch blade 52c connected to a power line Ll. A second power line L2 is connected to the junction of the forward winding 20F and the reverse winding 20R.

With respect to the ON contact 52a and the ON limit switch 44, the term ON designates that an electrical circuit is completed through these items when it is desired to move the handle 12 of the circuit breaker 1 l to ON position. Similarly, with respect to the OFF contact 52b and the OFF limit switch 46, the term OFF designates that an electrical circuit is completed through these items when it is desired to move the handle 12 of the circuit breaker 11 to OFF position. The OFF position of the handle 12 substantially corresponds with a RESET position for resetting the circuit breaker 11 after tripping thereof.

Assuming that the crank arm 22 is in the position corresponding to the OFF position of the circuit breaker handle 12, the actuating lever 37 and the actuator 42 are then positioned as shown in FIGS. 3 and 4, the OFF limit switch operating button 46a being held in open position and the ON limit switch operating button 44a being in its normally'closed position. To move the circuit breaker handle 12 to ON position, the switch blade 520 is moved into engagement with the ON contact 52a as shown in FIG 5. An electrical circuit is thus completed from line Ll through the switch blade 52c and contact 52a, the ON limit switch 44 (which is initially closed), and the forward winding 20F to line L2. The gearmotor 20 then rotates the shaft 21, flat spring 24, and crank arm 22 clockwise as viewed in FIG. 2 to the position shown, moving the circuit breaker handle 12 to ON position and also moving the link 33 to pivot the actuating lever 37 clockwise and move the actuator 42 to the right, allowing the OFF limit switch 46 to close. After the'circuit breaker handle 12 is in ON position and the crank arm 22 is stopped thereby, the shaft 21 continues to rotate, flexing the flat spring 24 and moving the actuator 42 sufficiently to open the ON limit switch 44 as shown in FIG.

and thereby interrupt the circuit through the forward winding F. The flat spring 24 then relaxes, but the actuator 42 remains in position, holding the ON limit switch 44 open, because the frictional force on the

flanges

42a and 42b is greater than the restoring force on the depressible operating button 44a.

To move the circuit breaker handle 12 back to OFF position, the switch blade 520 is moved into engagement with the OFF contact 52b. An electrical circuit is thus completed from line Ll through the switch blade 52c and contact 52b, the OFF limit switch 46, and the reverse winding 20R to line L2. The gearmotor 20 then rotates the shaft 21, flat spring 24, and crank arm 22 counterclockwise as viewed in FIG. 2, moving the circuit breaker handle 12 to OFF position and also moving the link 33 to pivot the actuating lever 37 counterclockwise and move the actuator 42 to the left to the position shown in FIG. 3, allowing the ON limit switchholding the OFF limit switch 46 open, because the frictional force on the

flanges

42a and 42b is greater than the restoring force on the depressible operating button 46a.

OFF limit switch 46. The frictional force on the

flange portions

42a and 42b due to the

plates

16 and 51 maintains the actuator 42 in position to maintain the ON limit switch 44 open. Resetting of the circuit breaker 11 can then be accomplished by moving the switch blade 52c into engagement with the OFF contact 52b, whereupon the gearmotor 20 moves the handle 12 to OFF position as above explained, the OFF position essentially being a resetting position after the circuit breaker has tripped.

The circuit breaker 1 l and the gearmotor 20 can also be operated manually by pushing on the actuating member 30, although preferably the member 30 is removed and the circuit breaker handle 12 operated separately.

FIG. 6 partially shows a modification of the invention for use with a circuit breaker having a higher pivotal axis for its operating handle, such as the circuit breaker disclosed in US. Pat. No. 3,222,475, issued Dec. 7, 1965. A mounting plate 116 has a gearmotor (not shown) mounted on the rear side thereof and having an output shaft 121 extending therethrough to the front side shown. A generally U-shaped crank arm 122 similar to the crank arm 22 is loosely mounted on the shaft 121 and resiliently keyed thereto by a flat spring 124. The shaft 121 extends through suitable openings in opposite leg portions of the crank arm 122, one of the leg portions being broken away in FIG. 6, and the spring 124 is disposed'between the leg portions and extends through suitable slots in the shaft 121 and in the bight portion of the crank arm 122. An upper end portion of the spring 124 is secured between two pins 125 each having opposite end portions frictionally held respectively in opposite leg portions of the crank arm 122. One of the pins 125 may be provided with a washer (not shown) projecting into a suitable slot in the spring 124 to prevent longitudinal shifting thereof. A handle actuating member (not shown) similar to the member 30 is secured to the crank arm 122 for actuating a handle of a circuit breaker.

A limit switch actuator 142 in the form of a generally sector-shaped plate is pivotally mounted on the mounting plate 116 by a pin 143 and is provided with a pair of oppositely disposed flange portions 142a and l42b for selectively depressing operating buttons 144a and 146a of a pair of normally closed

limit switches

144 and 146 secured to the mounting plate 116 in spaced-apart relationship on opposite sides of the actuator 142 by pairs of screws 148. The switch 144 is an ON limit switch,

closed when the gearmotor is moving a circuit breakerhandle to ON position, and the switch 146 is an OFF limit switch, closed when the gearmotor is moving a circuit breaker handle to OFF position. The actuator 142 is provided with detent means in the form of a depression 142c on the front side of the actuator which results in a projection (not shown) on the rear side. The rear projection cooperates with suitable deformations (not shown) on the front of the mounting plate 116 to yieldably maintain the actuator I42 selectively in two extreme pivotal positions.

The operation of the device of FIG. 6 is substantially the same as the operation of the device of FIGS. 1-5. Assuming that the crank arm 122 is in the position corresponding to the OFF position of a circuit breaker handle, the actuator 142 is then in a pivotal position counterclockwise from that shown in FIG. 6, holding the button 146a depressed so that the OFF limit switch 146 is open, and the ON limit switch 144 is in its normally closed condition. To move the circuit breaker handle to ON position, a switch blade such as the switch blade 52c is moved into engagement with the ON contract 520 as shown in FIG. 5. The gearmotor then rotates the shaft 121, flat spring 124, and crank arm 122 clockwise as viewed in FIG. 6 to the position shown, moving the circuit breaker handle to ON position, and the actuator 142 is pivoted clockwise by the flat spring 124, releasing the button 146a and allowing the OFF limit switch 146 to close. After the circuit breaker handle is in ON position and the crank arm 122 is stopped thereby, the shaft 121 continues to rotate the flat spring 124, moving the actuator 142 sufficiently to open the ON limit switch 144 and thereby interrupt the circuit through the forward winding of the gearmotor. The flat spring 124 then relaxes, but the actuator 142 remains in position, holding the ON limit switch 144 open, because of the detent means at the depression l42c.

To move the circuit breaker handle back to OFF position, the switch blade such as the blade 520 is moved into engagement with the OFF contact 52b. The

. gearmotor then rotates the shaft 121, flat spring 124,

and crank arm' 122 counterclockwise as viewed in FIG. 6, moving the circuit breaker handle to OFF position, and the actuator 142 is pivoted counterclockwise by the flat spring 124, releasing the button 144a and allowing the ON limit switch 144 to close. After the circuit breaker handle is in OFF position and the crank arm 122 is stopped thereby, the shaft 121 continues to rotate the flat spring 124, moving the actuator 142 sufficiently to open the OFF limit switch 146 and thereby interrupt the circuit through the reverse winding of the gearmotor. The flat spring 124 then relaxes, but the actuator 142 remains in position, holding the OFF limit switch 146 open, because of the detent means at the depression 142c. The detent means and the lost-motion connection between the flat spring 124 and the actuator 142 enable a circuit breaker to trip without changing the condition of the

limit switches

144 and 146.

FIG. 7 partially shows a modification of the device of FIGS. 1-5 wherein the link 33, actuating lever 37, and actuator 42 have been replaced by an elongated cam 242. A mounting plate 216 has a gearmotor (not shown) mounted on the rear side thereof and having an output shaft 221 extending therethrough to the front side shown. A generally U-shaped crank arm 222 similar to the crank arm 22 is loosely mounted on the shaft 221 and resiliently keyed thereto by a flat spring 224. The shaft 221 extends through suitable openings in opposite legportions of the crank arm 222, one of the leg portions being broken away in FIG. 7, and the spring 224 is disposed between the leg portions and extends through suitable slots in the shaft 221 and in the bight portion of the crank arm 222. An upper end portion of the spring 224 is secured between two pins 225 each having opposite end portions frictionally held respectively in opposite leg portions of the crankarm 222. One of the pins 225 may be provided with a washer (not shown) projecting into a suitable slot in the spring 224 to prevent longitudinal shifting thereof. A

handle actuating member (not shown) similar to the 1 member 30 is secured to the crankarm 222 for actuating a handle of a circuit breaker.

The cam 242 is connected to the leg portion of the crank arm 222 nearer the plate 216 by a pin 243 mounted in the leg portion and extending through an elongated slot 242a in the cam 242. A pin 245 fixedly mounted in the cam 242 is movably secured to the mounting plate 216, extending through an elongated slot 216d in the mounting plate. An ON limit switch 244 and an OFF limit switch 246 are secured to the mounting plate 216 on opposite sides of the cam 242 by pairs of screws 248. The cam 242 is provided with appropriate cam surfaces for selectively depressing operating buttons 244a and 246a of the normally closed switches 244 and 246.

Assuming that the crank arm 222 is in the position corresponding to the OFF position of a circuit breaker handle, the cam 242 is then in a position leftward from that shown in FIG. 7, holding the button 246a depressed so that the OFF limit switch 246 is open, and the ON limit switch 244 is in its normally closed condition. To move the circuit breaker handle to ON position, a switch blade such as the switch blade 520 is moved into engagement with the ON contact 52a as shown in FIG. 5. The gearrnotor then rotates the shaft 221, flat spring 224, and crank arm 222 clockwise as viewed in FIG. 7 to the position shown, moving the circuit breaker handle to ON position, and the cam 242 is moved to the right, releasing the button 246:; and allowing the OFF limit switch 246 to close, and depressing the button 244a to open the ON limit switch 244 and thereby interrupt the circuit through the forward winding of the gearmotor.

To move the circuit breaker handle back to OFF position, the switch blade such as the blade 520 is moved into engagement with the OFF contact 52b. The gearmotor then rotates the shaft 221, flat spring 224, and crank arm 222 counterclockwise as viewed in FIG. 7, moving the circuit breaker handle to OFF position, and the cam 242 is moved to the left, releasing the button 244a and allowing the ON limit switch 244 to close, and depressing the button 246a to open the OFF limit switch 246 and thereby interrupt the circuit through the reverse winding of the gearmotor.

The frictional force resulting from the pressure of the buttons 244a and 246a on the cam 242 and the lostmotion connection between the crank arm 222 and the cam 242 enable the circuit breaker to trip without changing the condition of the limit switches 244 and t We claim:

1. An actuating mechanism for moving an operating handle of an electrical switching device selectively to ON and OFF positions, the mechanism comprising a reversible motor having an output shaft, a crank arm resiliently connected adjacent one end to the output shaft, a handle actuating member secured to the other end portion of the crankarm and connectible to a handle of an electrical switching device, a normally closed ON limit switch electrically connected to the motor for completing a circuit through the motor to cause rotation of the output shaft in one direction and effect movement of a handle of an electrical switching device to an ON position, a normally closed OFF limit switch electrically connected to the motor for completing a circuit through the motor to cause rotation of the output shaft in an opposite direction and effect movement of a handle of an electrical switching device to an OFF position, each of the limit switches having an outwardly biased operating button inwardly depressible to effect opening of the limit switch, the limit switches being disposed in spaced relationship, a limit switch actuator movably mounted in operative relationship with the operating buttons of the limit switches and movable between two operative positions in a first of which it allows the OFF limit switch to close and holds the operating button of the ON limit switch depressed to maintain the ON limit switch in an open condition and in a second of which it allows the ON limit switch to close and holds the operating button of the OFF limit switch depressed to maintain the OFF limit switch in an open condition, and lost-motion connecting means operatively connecting the limit switch actuator to the crank arm for moving the limit switch actuator to the first position upon final movement of the crank arm to a position corresponding to an ON position of a handle of an electrical switching device and moving the limit switch actuator to the second position upon final movement of the crank arm to a position corresponding to an OFF position of a handle of an electrical switching device.

2. An assembly as claimed in claim 1 including a control switch having an ON contact electrically connected to the ON limit switch, an OFF contact electrically connected to the OFF limit switch, and means for completing an electrical circuit selectively through the contacts.

3. An assembly as claimed in claim 1 wherein the operating buttons of the limit switches face in opposite directions.

4. An assembly as claimed in claim 3 wherein the operating buttons of the limit switches face each other.

5. An assembly as claimed in claim 1 including a flat spring resiliently connecting the crank arm and output shaft, the flat spring extending through the shaft and having an end portion secured to the crank arm.

6. An assembly as claimed in claim 5 wherein the crank arm is generally U-shaped and has opposite leg portions and a bight portion, the output shaft extends through openings in the opposite leg portions of the crank arm, the flat spring extends through the bight portion of the crank arm on one side of the output shaft, and an end portion of the flat spring is secured to the opposite leg portions of the crank arm on the opposite side of the output shaft.

tons of the limit switches, and the flat spring extends between the flange portions to provide the lost-motion connecting means operatively connecting the limit switch actuator to the crank arm.

8. An assembly as claimed in claim 1 including a mounting plate on a front side of which the limit switches are mounted, the limit switch actuator being generally U-shaped and having outwardly turned flanges confined on a rear side of the mounting plate and a U-shaped portion disposed substantially on the front side of the mounting plate and extending through an elongated slot therein with clearance lengthwise of the slot, an elongated link having an end portion pivotally connected to the crank arm, and an elongated actuating lever having an end portion pivotally connected to the mounting plate on the front side thereof, the actuating lever extending through the limit switch actuator and the other end portions of link and actuating lever being pivotally connected.

9. An assembly'as claimed in claim 1 including a mounting plate on which the limit switches are mounted, the limit switch actuator being an elongated cam slidably mounted adjacent one end on the mounting plate and connected to the crank arm adjacent the other end.

10. An assembly comprising an electrical switching device having an operating handle movable selectively to ON and OFF positions, and an actuating mechanism for moving the handle of the switching device, the mechanism including a mounting plate, a reversible motor secured to the mounting plate on a rear side thereof and having an output shaft extending through a suitable hole in the mounting plate to the front side thereof, a crank arm resiliently connected adjacent one end to an outer end portion of the output shaft on the front side of the mounting plate, a handle actuating member secured adjacent one end to the other end portion of the crank arm and connected adjacent the other end to the handle of the switching device, a normally closed ON limit switch mounted on the front side of the mounting plate and electrically connected to the motor for completing a circuit through the motor to cause rotation of the output shaft in one direction and effect movement of the handle of the switching device to ON position, a normally closed OFF limit switch mounted on the front side of the mounting plate and electrically connected to the motor for completing a circuit through the motor to cause rotation of the output shaft in an opposite direction and effect movement of the handle of the switching device to OFF position, each of the limit switches having an outwardly biased operating button inwardly depressible to effect opening of the limit switch, the limit switches being disposed in spaced relationship on the mounting plate, a limit switch actuator movably mounted on the front side of the mounting plate in operative relationship with the operating buttons of the limit switches and movable between two operative positions in a'first of which it allows the OFF limit switch to close and holds the operating button of the ON limit switch depressed to maintain the ON limit switch in an open condition and in a 1.07 position corresponding to the ON position of thehandle of the switching device and moving the limit switch actuator to the second position upon final movement of the crank arm to a position corresponding to the OFF position of the handle of the switching device.

Claims

7. An assembly as claimed in claim 5 wherein the limit switch actuator is a pivotally mounted plate member having a pair of oppositely disposed flange portions for selectively depressing the operating buttons of the limit switches, and the flat spring extends between the flange portions to provide the lost-motion connecting means operatively connecting the limit switch actuator to the crank arm.

9. An assembly as claimed in claim 1 including a mounting plate on which the limit switches are mounted, the limit switch actuator being an elongated cam slidably mounted adjacent one end on the mounting plate and connected to the crank arm adjacent the other end.

10. An assembly comprising an electrical switching device having an operating handle movable selectively to ON and OFF positions, and an actuating mechanism for moving the handle of the switching device, the mechanism including a mounting plate, a reversible motor secured to the mounting plate on a rear side thereof and having an output shaft extending through a suitable hole in the mounting plate to the front side thereof, a crank arm resiliently connected adjacent one end to an outer end portion of the output shaft on the front side of the Mounting plate, a handle actuating member secured adjacent one end to the other end portion of the crank arm and connected adjacent the other end to the handle of the switching device, a normally closed ON limit switch mounted on the front side of the mounting plate and electrically connected to the motor for completing a circuit through the motor to cause rotation of the output shaft in one direction and effect movement of the handle of the switching device to ON position, a normally closed OFF limit switch mounted on the front side of the mounting plate and electrically connected to the motor for completing a circuit through the motor to cause rotation of the output shaft in an opposite direction and effect movement of the handle of the switching device to OFF position, each of the limit switches having an outwardly biased operating button inwardly depressible to effect opening of the limit switch, the limit switches being disposed in spaced relationship on the mounting plate, a limit switch actuator movably mounted on the front side of the mounting plate in operative relationship with the operating buttons of the limit switches and movable between two operative positions in a first of which it allows the OFF limit switch to close and holds the operating button of the ON limit switch depressed to maintain the ON limit switch in an open condition and in a second of which it allows the ON limit switch to close and holds the operating button of the OFF limit switch depressed to maintain the OFF limit switch in an open condition, and lost-motion connecting means operatively connecting the limit switch actuator to the crank arm for moving the limit switch actuator to the first position upon final movement of the crank arm to a position corresponding to the ON position of the handle of the switching device and moving the limit switch actuator to the second position upon final movement of the crank arm to a position corresponding to the OFF position of the handle of the switching device.