US3009087A

US3009087A - Electrically operated automatic resetting circuit breaker mechanisms

Info

Publication number: US3009087A
Application number: US759718A
Authority: US
Inventors: Jr Wilson Ward Poulton
Original assignee: ITE Circuit Breaker Co
Current assignee: ITE Circuit Breaker Co
Priority date: 1958-09-08
Filing date: 1958-09-08
Publication date: 1961-11-14
Anticipated expiration: 1978-11-14

Description

Nov. 14, 1961 Filed Sept. 8, 1958 W. W. POULTON, JR ELECTRICALLY OPERATED AUTOMATIC RESETTING CIRCUIT BREAKER MECHANISMS 3 Sheets-Sheet 1 :==-=r 0, 5 420x50 INVENTOR.

Mayan/m flJdzra/y-M? Nov. 14, 1961 w. N, JR 3,009,087

ELECTRICALLY OPERATED AUTOMATIC RESETTING CIRCUIT BREAKER MECHANISMS Filed Sept. 8, 1958 5 Sheets-Sheet 2 1961 w. w. POULTON, JR 3,009,087

ELECTRICALLY OPERATED AUTOMATIC RESETTING CIRCUIT BREAKER MECHANISMS Filed Sept. 8, 1958 v 3 Sheets-Sheet 3 INV ENT OR. 50/1 JO/V 41 701A 70 4 MM M United States Patent 3 009,087 ELECTRICALLY OPER ATED AUTOMATIC RESET- TING CIRCUIT BREAKER MECHANISMS Wilson Ward Poulton, In, Broomall, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a

corporation of Pennsylvania Filed Sept. 8, 1958, Ser. No. 759,718 10 Claims. (Cl. 318-2) The instant invention relates generally to electrically powered mechanisms for the operation of circuit breakers and more particularly to a mechanism of this type which includes provisions for automatic resetting of the circuit breaker after it has been tripped open. Many circuit breakers, as exemplified by the molded case breaker described in the copending application of August Bodenschatz entitled Hold-Open and Anti-Rebound Latches, Serial No. 734,785, filed May 12, 1958, now US. Patent No. 2,932,706, and assigned to the assignee of the instant invention, include an operating mechanism which must be reset to effect a closing which follows the automatic tripping of the circuit breaker.

Prior art devices which include electrically operated automatic resetting mechanisms require the removal and replacement of the circuit breaker handle and the addition of an auxiliary switch mounted in the interior of the circuit breaker in order to achieve automatic reset. These prior art mechanisms usually require critical adjustments since they utilize a unidirectional motor and a rotary switch to limit motor travel. Further, operation of these devices is awkward, time consuming and dangerous.

When the circuit breaker is operated by hand to the open position, the automatic reset switch closes, which automatically energizes the motor thereby operating the lever to the OE position and in so doing jeopardizes the safety of the operation. In addition, the mechanism, utilizing a unidirectional motor in conjunction with a rotary switch for limiting motor travel, can continuously run when operated by hand.

The device of the instant invention provide a torque sensitive device in which power is transmitted from the motor through a clutching mechanism to a breaker cam which operates the breaker handle. In a first embodiment of my invention the clutching mechanism comprises a pair of shoes engageable with a drum with the shoes being spring loaded to slip at a torque slightly above that required to operate the breaker handle to the Reset and On positions. This permits the mechanism to be non-critical to handle position.

As the circuit breaker handle reaches the end of its stroke, the rotational force of the motor exceeds the break-away torque of the shoes thereby causing the shoes to slip with respect to the drum. When the mechanism reaches the end of its travel either in the On or Reset positions of the circuit breaker, the shoes absorb the inertia of the brake drum without damage to the circuit breaker handle or contact operating mechanism.

Automatic reset is accomplished by utilizing a normally closed switch which is engaged by the circuit breaker handle when the circuit breaker is closed and when so engaged, the switch is opened. A second switch, operated by the circuit breaker cam as it nears the end of its travel toward either the Closed or Reset positions, is utilized to condition the operating motor for rotation in forward or reverse directions in which the cam will operate the circuit breaker handle toward the Reset and Closed positions respectively. That is, when the circuit breaker handle nears the Reset position, the second switch conditions the motor for rotation in the reverse direction and when the operating handle approaches the On position, the second switch conditions the motor for forward operation.

ice

When the motor is conditioned for forward operation and the first switch is closed, the motor will automatically operate the circuit breaker handle to the reset position when the circuit breaker is tripped.

The circuit breaker cam includes a pair of spaced rollers which engage the circuit breaker handle. With the circuit breaker closed, the handle is positioned toward the roller which was not utilized to move the handle to the closed position by the action of the circuit breaker toggle mechanism. If the circuit breaker is tripped the toggle mechanism tends to move the circuit breaker handle to a tripped position which is at a point between the On and Olf positions. This movement is suflicient to cause disengagement of the circuit breaker handle from the first switch thereby energizing the motor in a forward direction to operate the circuit breaker handle to the Reset position.

Prior to the arrival of the circuit breaker at the Reset position, the second switch will be operated to condition the motor for rotation in the reverse direction. However, the inertia of the mechanism is sufiicient to drive the circuit breaker handle to the Reset position.

With the motor conditioned for reverse rotation, depressing an On control button will energize the motor for rotation in the reverse direction which will cause the circuit breaker cam to move the handle toward the On position. Prior to the arrival of the handle at the On position the contacts of the circuit breaker will have become engaged and the toggle mechanism will cause the handle to move faster than the cam which is driving the handle toward the On position. Thereafter, the cam will operate the second switch so that the motor is conditioned for rotation in the forward direction. After the second switch is operated, the inertia of the mechanism will cause continued rotation of the circuit breaker cam until it strikes a positive stop which usually comprises the housing of the mechanism where the torque on the mechanism will exceed the break-away torque of the shoes and the mechanism will come to a halt. The fact that the second switch is thrown before the ends of the closing and reset strokes eliminates the problem of critical switch positioning.

Hand operation is accomplished by disengaging the motor from the brake drum. This is readily accomplished by utilizing a polygonal nut to transmit power from the motor to the brake drum with the nut being biased upwardly toward the motor. The polygonal nut is depressible into the brake drum by means of a sleeve and, when so depressed, the drum is disconnected from the motor thereby allowing hand operation. A' noncircular member or a splined circular member may be utilized as the equivalent of the polygonal nut.

The second embodiment of my invention utilizes a plurality of rollers in conjunction with a groove drum as the slip coupling means. With the rollers disposed within the grooves, there is a positive driving connection between the drum and the circuit breaker cam. However, the rollers are all biased toward the center of the drum so that when the circuit breaker operating handle reaches the Reset and On positions the biasing force is overcome and the rollers are driven from the grooves to ride on the periphery of the drum thereby severing the driving connection.

Since the mechanism of the instant invention includes a torque limiting device, it has the advantage of permitting infinite over travel of the driving means. Thus an extremely high speed motor, with its accompanying high inertia, may be utilized to achieve short time switching.

The construction of the mechanism is such that it may be mounted to a circuit breaker as a complete unit by merely utilizing two or more mounting studs secured to 3 the breaker and securing electrical leads to an enclosed terminal block. There is no need to modify the circuit breaker handle or secure any attachments thereto. Further, the mechanism does not require any critical adjustment when the mechanism is transferred from one breaker to another.

Accordingly, a primary object of the instant invention is to provide a novel electrically powered mechanism for the operation of a circuit breaker.

Another object is to provide a novel electrically powered mechanism which utilizes a torque limiting device comprising a coupling means which slips whenever the torque required to operate the mechanism exceeds a predetermined value.

A further object is to provide a novel electrically powered mechanism having means for the selective manual operation thereof.

A still further object is to provide an electrically powered mechanism, for the operation of circuit breakers, which may be secured to the circuit breaker as a unitary structure.

These as well as other objects of the instant invention shall become readily apparent after reading the following description of the accompanying drawings in which:

FIGURE 1 is a side elevation of a first embodiment of my novel mechanism shown mounted to a molded case circuit breaker.

FIGURE 2 is a plan view of the mechanism of FIG- URE 1.

FIGURE 3 is a cross-section taken through line 33 of FIGURE 2 looking in the direction of the arrows 33.

FIGURES 4 and 5 are cross-sections taken through line 4-4 of FIGURE 3 looking in the direction of the arrows 4- 4. In FIGURE 4 the circuit breaker handle is illustrated in the On position and in FIGURE 5 the circuit breaker handle is illustrated as being in the Reset position.

FIGURE 6 is a schematic diagram illustrating the electrical connections necessary to achieve automatic resetting.

FIGURE 7 is a cross-sectioned figure similar to FIG- URES 4 and 5 illustrating a second embodiment of my invention.

Now referring more particularly to FIGURES 1-6, mechanism 10 is secured to circuit breaker 11 by means of studs 12 which extend from circuit breaker 11 through openings in the bottom surface 14 of housing 15 and are engaged by nuts 13. The bottom surface 14 is bowed in the region 16 thereby creating a pressure at the opposite end 17 of surface 14 against the top of the circuit breaker housing to achieve a firm seating of mechanism 10 upon circuit breaker 11.

Mechanism 10 comprises a motor 20 which drives gear train 21 whose output shaft 22 drives pinion 23. The teeth of pinion 23 are in mesh with the teeth of drive gear 24 which is rotatably mounted about sleeve 25. Shaft 26 is mounted within sleeve with one end 27 thereof being positioned within bearing opening 28 of block 29. An extension 30, the outer edge of which is impinged, extends from block 29 through an opening in bottom surface 14 thereby securing block 29 to housing '15.

End 27 of shaft 26 is provided with a pair of flat opposed surfaces entered into complementary shaped opening 31 of cam 32. Spring retainer 33 engages shaft end 27 thereby securing shaft 26 to cam 32 for rotation in unison therewith.

Drum 34 is positioned adjacent to the top surface of cam 32 and is arranged coaxially with shaft 26. Coil spring 35 is disposed about shaft 26 in the region of brake drum '34. Drum 34 is provided with a square shaft opening 37 at the center thereof. Polygonal nut 36, in the shape of a square, is disposed within opening 37 and is biased upwardly by coil spring 35 toward engagement with drive gear 24 which is also provided with a square opening 38. The bottom surface 39 of sleeve 25 is positioned adjacent to the top of nut 36. A pointer 40 is rigidly secured to shaft 26 by means of screw 41 and provides an external indication of the angular position of cam 32. Spacer 42 is disposed within sleeve opening 43 to provide clearance between pointer 40 and sleeve 25 as shaft 26 rotates.

Arms 50 and 51, formed of structural sections, are pivotally mounted at 52, 53, respectively, to cam 32. Shoes 5-4, 55, including

friction linings

56, 57, respectively, are pivotally mounted at 58, 59 near one of the ends of the arms 50, 5 1, respectively. The other ends of

arms

56, 51 are interconnected by

members

60, 61, respectively, which are pivoted at 62, 63, respectively. Member 60 engages a pin 64 which is disposed within a central opening 65 of member 61. A compression spring 66 is disposed about member 61 and is positioned to urge

members

60 and 61 away from each other. Thus, spring 66 urges linings 56, 57 against the peripheral surface of drum 34.

Rollers 67, 68 are pivotally mounted to cam 32 in spaced apart relationship forming gap 69 therebetween. Circuit breaker operating handle 70 extends through opening 70a in the bottom surface 14 of housing 15 to be disposed within gap 69 and when operated to its On position (FIGURE 4) will engage switch 71 secured to housing 15 by means of bracket 72. Another switch 73 is secured to the bottom surface 14 of housing 15 and is positioned for operation by means of pins 74 and 75 which project downwardly from cam 32.

It is to be noted that when the circuit breaker handle 70 is in the On position of FIGURE 4 there is a substantial gap between handle 70 and roller 67. Thus, when circuit breaker 11 is automatically tripped due to the occurrence of a fault current, the spring loaded toggle mechanism of circuit breaker 11 will move handle 70 against roller 67, as indicated in phantom in FIGURE 4. In this position, handle 70 is disengaged from switch 71 so that the switch 71 is now in the closed position.

Motor 20 is of a universal type having a field winding 77 for rotation of the motor 20 in a reverse direction. By depressing On control 78 with switch 73 thrown to the dotted line position of FIGURE 6, motor 20 will rotate in a forward direction so as to rotate drive gear 24 counterclockwise with respect to FIGURE 5.

At this time, nut 36 is disposed within opening 38 so as to form a driving connection between drive gear 24 and drum 34.

Linings

56, 57 in engagement with drum 34 form a driving connection which, acting through

pins

52 and 53, transmits a counterclockwise rotation to cam 32 thereby moving rollers 67, 68 counterclockwise about shaft 26. Thus, roller 67 engages handle 70 to move handle 70 from the Reset position of FIGURE 5 toward the On position of FIGURE 4.

At the point where the toggle mechanism of circuit breaker 11 crosses over center to rapidly move the cooperating contacts (not shown) of circuit breaker 11 into engagement, handle 70 moves away from roller 67 to- Ward roller 68. Cam 32 will continue to move counterclockwise until the inertia energy, of motor 20 and the elements of gear box 21, has been spent or until such time as surface 79 of cam 32 strikes the wall 80 of housing 15. Under the latter circumstances the force required to rotate cam 32 in the clockwise direction exceeds the break-away torque of the coupling mechanism, comprising drum 34 and

shoes

54, 55, thereby causing the coupling mechanism to slide without damage to the closing mechanism 10 or circuit breaker 11.

In moving from the Reset position of FIGURE 5 to the On position of FIGURE 4 pin 74, carried by cam 32, has engaged arm 82 of switch 73 thereby throwing switch 73 to the solid line position illustrated in FIG- URE 6. In this position of switch 73, motor 20 is conditioned for rotation in the reverse direction and cannot be operated in the forward direction by depressing the On control 78. That is, upon the closing of automatic reset switch 71 or the closing of Off control 83, winding 76 will be energized so as to cause rotation of motor 20 in a direction such that drive gear 24 will rotate clockwise with respect to FIGURE 4. If the mechanism is in the On position of FIGURE 4, depressing switch 83 will cause motor 20 to operate cam 32 clockwise about shaft 26 with roller 68 engaging handle 70 to operate the circuit breaker to the Reset position of FIGURE 5.

Since contacts 84 of automatic reset switch 71 are connected in parallel with Off switch 83, as soon as handle 70 has become disengaged from switch 71, mechanism will continue to move handle 70 to the Reset position even though Off switch 83 is released before handle 70 has reached the Reset position. Before handle 70 has reached the Reset position, pin 75 will have engaged arm 82 of switch 73 thereby throwing switch 73 to the dotted line position of FIGURE 6 to deenergize winding 77 and condition motor for the rotation in the forward direction. This operation of switch 73 usually takes place before handle 70 has been driven to the reset position by roller 68. However, the inertia energy of motor 20 and the elements of gear box 21 is sufiicient to cause continued rotation of drive gear 24 so as tomove handle 70 completely to the Reset position, with the torque limiting features of the clutching

mechanism

34, 54, 55 preventing any damage to handle 70 as well as other elements of the circuit breaker mechanism 11. Automatic resetting takes place in a similar manner. That is, when circuit breaker 11 is opened due to an overload condition, the toggle mechanism thereof will cause handle 70 to move from the solid line position of FIGURE 4 to the phantom position of FIGURE 4 thereby perrnitting the contacts 84 of automatic reset switch 71 to move to the closed position. Since switch 73 is in the solid line position of FIGURE 6, motor 20 is conditioned for operation in the reverse direction. Thus, when contacts 84 are closed, winding 76 is energized and mechanism 10 will operate handle 70 to the reset position of FIGURE 5.

The upper end 44 of sleeve 25 is usually positioned above the upper end 45 of shaft 26, which is of a square cross-section and reduced in size from the central portion of shaft 26. Manual operating crank 46 includes a transverse head 47 at one end thereof which is provided with a recess having a circular portion 48 of approximately the same diameter as sleeve 25 and a square portion 49 of approximately the same size as the end portion 45 of shaft 26. By mounting head 47 on sleeve 25, sleeve 25 may be depressed to move nut 36 downward against the force of spring 35 thereby disengaging nut 36 from drive gear 24.

The upper portion 85 of nut 36 is tapered as is the bottom portion of opening 38 thereby facilitating the disengagement of nut 36 from drive gear 24. Simultaneously, the square end portion 45 of shaft 26- will nest in recess 49 so that a rotation of crank 46 will cause a corresponding rotation of cam 32. Thus, when sleeve 25 is depressed a manual rotation of shaft 26 by crank 46 will cause the rotation of cam 32 about shaft 26 as a center to effectuate the operation of a circuit breaker handle 70. Even though motor 20 should be energized at this time, the rotation drive gear 24 will not be transmitted to drum 34 since nut 36 is-disengaged from drive gear 24. Thus, the operator will not be injured by an accidental energization of motor 20 while he is attempting a manual operation of the mechanism.

Whenhandle 46 is removed from the remainder of the mechanism 10, spring 35 will force nut 36 upwardly toward drive gear--24.- At this time, opening 38 of drive gear 24 may not be in the correct angular position to receive nut 36. However, upon energization of motor 20 and rotation of drive gear 24, spring 35 will force nut 36 to enter opening 38 when opening 38 and nut 36 are in corresponding angular positions thereby once again establishing the driving connection between motor 20 and drum 34.

Lamps 91-93 (FIGURE 6) provide an indication of the condition of circuit breaker 11, that is, if lamp 91 is lighted circuit breaker 11 is On, if lamp 92 is lighted circuit breaker 11 has been tripped, and if lamp 93 is lighted circuit breaker 11 has been operated to the Off position.

The mechanism of FIGURE 7 is identical to that of mechanism 10 except for the clutching means. Accordingly, for the sake of brevity and clarity the same reference numbers have been utilized to identify identical elements.

The clutching means of mechanism 100 comprises drum 101 having equally spaced depressions 102105 in the periphery thereof. Rollers 106-107 pivotally secured to shoe 54 and

rollers

108, 109 pivotally secured to shoe 55 are adapted to nest in depressions 102105.

With rollers 106109 nested in depressions 102105 a driving connection exists between drum 101 and cam 32. When the torque required to drive cam 32 exceeds the torque supplied by spring rollers 106109 will be forced out of depressions 106 to ride on the periphery 110 of drum 101. In this position the driving connection between drum 101 and cam 32 is broken without damage to mechanism 100 of circuit breaker 11.

Since a definite outward radial movement of

shoes

54 and 55 is required to effect disengagement of the driving connection between drum 101 and cam 32 this movement may be utilized to actuate switches (not shown) for conditioning the motor for halting motor rotation in one direction and conditioning the motor for rotation in the opposite direction. This type of arrangement may be utilized in place of the long stroke toggle switch 73 and is especially useful for slow speed operation wherein the inertia energy of the driving means is at a low level.

Accordingly, I prefer to be bound not by the specific disclosure herewith but only by the appending claims.

I claim:

1. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a coupling means; said coupling means forming a first driving connection between said cam and said driving means; said cam being operatively positioned to engage a circuit breaker operating handle; said coupling means being constructed to slip when the torque required to drive said cam exceeds a predetermined value; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker with the operating handle of the circuit breaker being positioned within said gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving means when disengaged preventing said driving means from operating the circuit breaker; said circuit breaker handle being movable between a first and a second position; said mechanism also including a normally closed first switch operatively positioned for engagement by said handle when said handle is in said first position; said switch being open when engaged by said handle.

2. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a coup-ling means; said coupling means forming a first driving connection between said cam and said driving means; said cam being operatively positioned to engage a circuit breaker operating handle; said coupling means being constructed to slip when the torque required to drive said cam exceeds a predetermined value; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker with the operating handle of the circuit breaker being positioned within said gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving means when disengaged preventing said driving means from operating the circuit breaker; said circuit breaker handle being movable between a first and a second position; said mechanism also including a normally closed first switch operatively positioned for engagement by said handle when said handle is in said first position; said switch being open when engaged by said handle; a second switch having a third and a fourth position; said driving means being conditioned for operation in a forward direction to move said handle to said first position when said second switch is in said third position and being conditioned for operation in a reverse direction to move said handle to said second position when said second switch is in said fourth position.

3. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a coupling means; said coupling means forming a first driving connection between said cam and said driving means; said cam being operatively positioned to engage a circuit breaker operating handle; said coupling means being constructed to slip when the torque required to drive said cam exceeds a predetermined value; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker with the operating handle of the circuit breaker being positioned within said gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving means when disengaged preventing said driving means from operating the circuit breaker; said circuit breaker handle being movable between a first and a second position; said mechanism also including a normally closed first switch operatively positioned for engagement by said handle when said handle is in said first position; said switch being open when engaged by said handle; a second switch having a third and a fourth position; said driving means being conditioned for operation in a forward direction to move said handle to said first position when said second switch is in said third position and being conditioned for operation in a reverse direction to move said handle to said second position when said second switch is in said fourth position; a first control efiective to actuate said driving means when said second switch is in said third position; a second control effective to actuate said driving means when said second switch is in said fourth position.

4. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a coupling means; said coupling means forming a first driving connection between said cam and said driving means; said cam being operatively positioned to engage a circuit breaker operating handle; said coupling means being constructed to slip when the torque required to drive said cam exceeds a predetermined value; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker with the operating handle of the circuit breaker being positioned within said gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when dis engaged permitting manual operation of the circuit breaker; said second driving means when disengaged preventing said driving means from operating the circuit breaker;

said circuit breaker handle being movable between a first and a second position; said mechanism also including a normally closed first switch operatively positioned for engagement by said handle when said handle is in said first position; said switch being open when engaged by said handle; a second switch having a third and a fourth position; said driving means being conditioned for operation in a forward direction to move said handle to said first position when said second switch is in said third position and being conditioned for operation in a reverse direction to move said handle to said second position when said second switch is in said fourth position; a first control effective to actuate said driving means when said second switch is in said third position; a second control effective to actuate said driving means when said second switch is in said fourth position; said first switch being connected in parallel with said second control.

5. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a coupling means; said coupling means forming a first driving connection between said cam and said driving means; said cam being operatively positioned to engage a circuit breaker operating handle; said coupling means being constructed to slip when the torque required to drive said cam exceeds a predetermined value; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker with the operating handie of the circuit breaker being positioned Within said gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving connection comprising a polygonal nut biased toward engagement with said driving means to be received by a complementary opening therein.

6. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a coupling means; said coupling means forming a first driving connection between said cam and said driving means; said cam being operatively positioned to engage a circuit breaker operating handle; said coupling means being constructed to slip when the torque required to drive said cam exceeds a predetermined value; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker being positioned within said gap; a second driving connection interposed be tween said driving means and said driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving connection comprising a polygonal nut biased toward engagement with said driving means to be received by a complementary opening therein; selective means extending externally of said mechanism and operable to move said nut against the force of its bias away from said driving means to disengage said second driving connection.

7. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a coupling means; said coupling means forming a first driving connection between said cam and said driving means; said cam being operatively positioned to engage a circuit breaker operating handle; said coupling means being constructed to slip when the torque required to drive said cam exceeds a predetermined value; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker being positioned within said gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving connection comprising a polygonal nut biased toward engagement with said driving means to be received by a complementary opening therein; selective means extending externally of said mechanism and operable to move said nut against the force of its bias away from said driving means to disengage said second driving connection; a shaft coaxial with' said drum and keyed to said cam; said selective means comprising a depressible sleeve coaxial with said shaft; said sleeve having a first end thereof in engagement with said nut and a second end adapted for engagement by an external operating crank.

8. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a coupling means; said coupling means forming a first driving connection between said cam and said driving means; said cam being operatively positioned to engage a circuit breaker operating handle; said coupling means being constructed to slip when the torque required to drive said cam exceeds a predetermined value; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker with the operating handle of the circuit breaker being positioned within said gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving connection comprising a polygonal nut biased toward engagement with said driving means to be received by a complementary opening therein; selective means extending externally of said mechanism and operable to move said nut against the force of its bias away from said driving means to disengage said second driving connection; a shaft coaxial with said drum and keyed to said cam; said selective means comprising a depressible sleeve coaxial with said shaft; said sleeve having a first end thereof in engagement with said nut and a second end adapted for engagement by an external operating crank; said shaft having a formation at an end thereof engageable by a complementary formation of said crank when said sleeve is depressed thereby providing a driving connection between crank and said cam.

9. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a slip coupling; forming a first driving connection between said cam and said driving means; said cam including a first portion and a second portion spaced from said first portion to form a gap therebetween; said mechanism being adapted for mounting to a circuit breaker with its operating handle being positioned within said gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving connection comprising a polygonal nut biased toward engagement with said driving means to be re ceived by a complementary opening therein, selective means extending externally of said mechanism and operable to move said nut against the force of its bias away from said driving means to disengage said second driving connection; a shaft coaxial with said drum and keyed to said cam; said selective means comprising a depressible sleeve coaxial with said shaft; said sleeve having a first end thereof in engagement with said nut and a second end adapted for engagement by an external operating crank; said shaft having a formation at an end thereof engageable by a complementary formation of said crank when said sleeve is depressed thereby providing a driving connection between crank and said cam; indicator means carried by said shaft and positioned externally of said mechanism whereby the position of said cam may be determined.

10. A mechanism for the operation of a circuit breaker manual operating handle; said mechanism comprising a driving means, a cam, and a slip coupling; forming a first driving connection between said cam and said driving means; said cam including a first portion and a second portion spaced from said first portion to form a gap there between; said mechanism being adapted for mounting to a circuit breaker with the operating handle of the circuit breaker being positioned within the gap; a second driving connection interposed between said driving means and said first driving connection; said second driving means being selectively disengageable and when disengaged permitting manual operation of the circuit breaker; said second driving means when disengaged preventing said driving means from operating the circuit breaker; said circuit breaker handle being movable between a first and a second position; said mechanism also including a normally closed first switch operatively positioned for engagement by said handle when said handle is in said first position; said switch being open when engaged by said handle; a second switch having a third and a fourth position; said driving means being conditioned for operation in a forward direction to move said handle to said first position when said second switch is in said third position and being conditioned for operation in a reverse direction to move said handle to said second position when said second switch is in said fourth position; a first control effective to actuate said driving means when said second switch is in said third position; a second control effective to actuate said driving means when said second switch is in said fourth position; said first switch being connected in parallel with said second con trol; said clutch means comprising a rotatable drum'and engaging means in contact with the peripheral surface of said drum and biased toward the center of said drum; said engaging means being carried by said cam; said second driving connection comprising a polygonal nut biased toward engagement with said driving means to be received by a complementary opening therein; selective means extending externally of said mechanism and operable to move said nut against the force of its bias away from said driving means to disengage said second driving connection; a shaft coaxial with said drum and keyed to said cam; said selective means comprising a depressible sleeve coaxial with said shaft; said sleeve having a first end thereof in engagement with said nut and a second end adapted for engagement by an external operating crank; said shaft having a formation at an end thereof engageable by a complementary formation of said crank when said sleeve is depressed thereby providing a driving connection between crank and said cam.

References Cited in the file of this patent UNITED STATES PATENTS 620,839 Bernadini et a1. Mar. 7, 1899 2,050,613 Kellogg Aug. 11, 1936 2,675,835 Kiekhaefer Apr. 20, 1954 2,761,331 Buescher Sept. 4, 1956