US3289790A - Spring charging mechanism for a circuit breaker - Google Patents

Description

Dec. 6, 1966 H. L. lVlNS 3 SFRING CHARGING MECHANISM FOR A CIRCUIT BREAKER Filed June 16, 1965 {5 sheetswSheet l H. L. IVIN5 Dec. 6, 1966 SPRING CHARGING MECHANISM FOR A CIRCUIT BREAKER Filed June 16, 1965 5 Sheets-5heet 0 Q 0 i EL ZIZZE" 50 1547a y. W

Dec. 6, 1966 H. 1 wms 3,289,79U

SPRING CHARGING MECHANISM FOR A CIRCUIT BREAKER Filed June 16, 1965 5 Sheets-Sheet 5 United States Patent 3,289,790 SPRING CHARGING MECHANISM FOR A CIRUUIT BREAKER Herbert L. Ivins, Cleveland, ()hio, assignor to Square 1) Company, Park Ridge, Ill., a corporation of Michigan Filed June 16, 1965, Ser. No. 464,338 Claims. (Cl. 18539) This invention relates to a mechanism for charging springs, and more particularly to a spring-charging mechanism for charging the closing springs of a power circuit breaker.

Because the current flowing upon the initial engagement of the contacts of a power circuit breaker during a closing operation can result in large forces tending to drive the circuit breaker to its open position, it is necessary to have considerable mechanical energy available if the closing operation is to be completed. When the force required to completely close a circuit breaker under all possible circuit conditions is in excess of that which can be imparted manually, or by a solenoid or motor of reasonable size, closure is often effected by releasing mechanical energy previously stored in closing springs which have been precharged by intermittent operation of a manually driven crank or by a motor.

In accordance with the present invention, there is provided an improved spring-charging mechanism in which a crank or lever is manually movable through an indefinite number of strokes of indefinite length to charge the closing springs of a circuit breaker in descrete steps. The mechanical advantage of the charging crank is augmented by a cam which also serves as a motion converter. An improved clutch, operatively interposed between the crank shaft and the cam, permits the charging of the springs by short repeated strokes of the crank with the crank being positionable by the operator for the most convenient and efficient application of manual force. The mechanism is such that rotation of the cam can be effected either automatically by an electric motor or manually by the crank.

It is an object of this invention to provide an improved spring-charging mechanism for charging the closing springs of a circuit breaker.

Another object is to provide a spring-charging mechanism for a circuit breaker which includes an improved clutch operatively interposed between a manually operable crank and a charging cam.

Another object is to provide an improved springcharging mechanism for charging the closing springs of a circuit breaker in which the springs are compressed by a cam rotated selectively through a one-way clutch either by manual force exerted on a crank or directly by an electric motor which may be controlled from a remote point.

Other objects and advantages will become apparent from the following description wherein reference is made to the drawings, in which:

FIG. 1 is a frontal perspective view of a spring-charging mechanism in accordance with this invention with the springs in the uncharged condition and showing a portion of a circuit breaker with which the mechanism may be used;

FIG. 2 is a front elevation view of the mechanism of FIG. 1;

FIG. 3 is a fragmentary side elevational view, partly in section, of the mechanism of FIG. 1;

FIG. 4 is a fragmentary sectional view taken as indicated at 4-4 in FIG. 3 showing a stop means of the mechanism;

FIG. 5 is a cross sectional view of an operating shaft and spring clutch assembly;

FIG. 6 through 8 are views of an operating mechanism 3,289,790 Patented Dec. 6, 1966 "ice of an exemplary circuit breaker with which the springcharging mechanism of FIGS. 1 through 5 may be used and wherein the uncharged, open-charged, and closed-uncharged positions are shown, respectively;

FIG. 9 shows another embodiment of the invention in which the spring-charging mechanism of FIGS. 1 through 5 is modified for operation either by an electric motor or manually; and

FIG. 10 is a view similar to FIG. 4 but showing a portion of the modification of FIG. 9.

Referring to the drawings, a spring-charging mechanism 10 in accordance with this invention is shown as arranged to charge a pair of springs 11 for effecting closure of a circuit breaker. Although it may be used with circuit breaker operating mechanism of different types, the springcharging mechanism 10 is illustrated in connection with a circuit breaker operating mechanism 12 shown in FIGS. 6 through 8 for which it is particularly suited,

Referring to FIGS. 6 through 8, the circuit breaker operating mechanism 12 comprises, among other components, a plurality of fixed pivot shafts 14 through 20, appropriately marked with the symbol F to indicate that they are fixed, and which are suitably supported at opposite ends in sides plates 21 (FIGS. 1 and 2), a plurality of displaceable pivot shafts 24 through 2 8, a closing crank link 34, a contact closing crank 35, a main trip latch 36, a secondary closing latch 38, a main closing latch 39, a drive crank 40, a pair of spaced drive links 41, a secondary trip latch 42, a gauging crank 45, and a ganging crank link 46, all of which are arranged to move pairs of contacts 48a and 48b on respective movable contact structures 49 into and out of engagement with respective pairs of stationary contacts Stla and Stlb. Although only one contact structure 49 is shown in FIGS. 6, 7, and 8, it is to be understood that there are three contact structures 49 driven by the operating mechanism 12 and interconnected by an interconnecting portion 45a of the ganging crank 45.

The drive crank 4t) which is in the form of a bell crank is pivoted on the fixed shaft 17 and has an arm portion 40a pivoted on the displaceable shaft 25 on which the drive links 41 are also pivoted. While the closing springs 11 are being compressed, the displaceable shaft 25 moves downwardly from the position of FIG. 6 representing the uncharged, open-contact position, to the position of FIG. 7 wherein the springs 11 are fully charged. The downward movement of the shaft 25 pivots the drive crank 40 counterclockwise about its pivot shaft 17. When the drive crank 40 reaches the position of FIG. 7, the main closing latch 39, which is biased in a counterclockwise direction by a spring 39a positioned about the fixed pivot shaft 16, turns counterclockwise so that a shoulder portion 39b thereon captivates a roller 40b on an arm portion 400 of the crank 40. The main closing latch 39 is releasably held in this latching position by the action of the secondary closing latch 38. The secondary closing latch 38 is springbiased in a clockwise direction by a spring (not shown) about its fixed pivot shaft 15 so that an arm 38a thereof, upon the spring 11 becoming fully charged, abuts a roller on the main closing latch 39 thereby to hold the springs 11 in the charged condition preparatory to a contact-closing operation.

Concurrently, the downward movement of the displaceable shaft 25 draws the spaced drive links 41 downwardly and in turn causes clockwise rotation of the closing cam 44 around its fixed pivot shaft 19 to disengage the forward portion of the closing cam 44 from the movable pivot shaft 28. This permits the collapse of the toggle linkage comprising the links 34 and 46 from the position of FIG. 6 to the position shown in FIG. 7. The consequent downward movement of the movable shaft 28 causes counterclockwise rotation of the contact-closing crank 35 around its fixed pivot shaft 14. The crank 35 rotates until the position of FIG. 7 is reached where an arm portino 36a of the main trip latch 36 abuts a roller 35a on the closing crank 35 and latches the closing crank 35 in a substantially horizontal position. The secondary trip latch 42 is biased counterclockwise by a spring (not shown) and turns counterclockwise to the position of FIG. 7 where a forward portion 42a abuts a roller 36b on the main latch 36,

The operating mechanism 12 is now in the position of FIG. 7 with the springs 11 charged preparatory to closing the contacts 4858. To effect such closure, the secondary closing latch 38 is, by means hereinafter described, rotated about its fixed pivot shaft in a counterclockwise direction thereby releasing the main closing latch 39 which, in turn, releases the drive crank 41 The drive crank 40 is then free to rotate in a clockwise direction around the fixed pivot shaft 17. The closing springs 11 expand and the movable shaft moves upward sharply. Since the contact-closing crank has been rotated and latched by the main trip latch 36 in a substantially horizontal position, the thrust of the springs 11 is directed along the longitudinal axis of the drive links 41 and is translated into a lateral force directed to the left as viewed in FIGS. 6, 7, and 8 by the closing cam 44 and the toggle linkage comprising the links 34 and 46. This turns the ganging crank 45 counterclockwise around its fixed pivot shaft 19 thereby to effect closure of the contacts 48-50. At the same time, a pair of parallel-spaced opening springs 51 connected between the gauging crank 45 and respective fixed points on the side plates 21 are extended by the rotation of the ganging crank 45.

To effect opening of the contacts 48-50, the secondary trip latch 42 is rotated, by means not shown, in a clockwise direction out of engagement with the main trip latch 36. The bias of the opening springs 51 acting through the links 34 and 46 and the closing crank 35 forces the main trip latch 36 to rotate in a clockwise direction permitting the closing crank 35 to rotate clockwise to the position of FIG. 6. The contacts 48-50 are then forced vigorously apart by the contraction of the opening springs 51 which turn the ganginng crank 45 clockwise to the position of FIG. 6.

Referring now to FIG. 1, the means for operating the secondary closing latch 38 comprises a closing operator 54 on the front of the circuit breaker having a protruding button portion 54a secured to an angle bracket 54b slidably mounted at the upper end portion of one of the side plates 21. To effect a closing operation, the operator 54 is moved rearwardly against the bias of a spring (not shown) to cause a shoulder portion 58 on the bracket 54b to engage a crank 59 thereby to effect rotation of a shaft 60 secured to the crank 59 and rotatably supported at opposite ends by the respective side plates 21. Upon rotation of the shaft 60, a crank 61 thereon lifts a rod 62 secured at its lower end to one arm of the closing latch 38 causing the latch 38 to rotate in a counterclockwise direction as viewed in FIGS. 6, 7, and 8. As previously described, counterclockwise rotation of the secondary closing latch 38 unlatches the main closing latch 39, and the stored energy in the springs 11 is then transmitted to the drive links 41 whereby the movable contacts 48 are moved rapidly and with adequate force into engagement with the stationary contacts 50.

It is thus seen that, during charging of the springs 11, the shaft 25 moves downwardly from the position of FIG. 6 to the position of FIG. 7 to condition the operating mechanism 12 for a subsequent closing operation. The closing latches 38 and 39 maintain the operating mechanism 12 in this position until operation of the operator 54 releases the latch 38. Upon such release, the springs 11 move the shaft 25 upwardly to eflect the closing operation of the contacts 48-50.

Referring now to FIGS. 1 through 4, spaced side walls 64 of the circuit breaker support an angle bracket 65 therebetween which carries the charging mechanism 10 of this invention. A pair of bolts 66 passing through openings in a vertical wall of the bracket 65 hold a rear support plate 68 against the vertical wall of the bracket 65. Spaced forwardly from the rear support plate 68 by spacers 78 (FIG. 3) and supported by the bolts 56 is a front support plate '71. A pair of bolts 72 passing through openings in the plates 68 and 71 support a control plate 74 forwardly of the front support plate 71 and a rear plate 75 rearwardly of the rear support plate 68.

The plates as, 71, 74, and 75 serve as hearing supports for an operating shaft assembly (best seen in FIG. 5) comprising three coaxial shafts 7 8, 7 9, and of uniform outside diameter. Keyed to the intermediate shaft 79 is an operating cam 81 which engages a cam follower 82 rotatably mounted between a pair of horizontally-disposed, spaced bars 8-4 supported at opposite ends by a pair of spring-drive rods Each of the rods '85 comprises a rectangular upper portion 86 and a cylindrical lower portion 88. The portions 86 and 88 may be joined by a keyed connection as shown. The lower end faces of the rectangular portions 86 bear against respective upper spring holders 89 positioned at the top of the respective springs 11 which surround the respective rod portions 88 and which, at their lower ends, are held by spring seats 98 secured to the respective side plates 21 as by screws 90a. The lower end portions of the rod portions 88 pass through respective openings in the spring seats 91 and are threaded into respective openings near opposite ends of the shaft 25 of the operating mechanism 12 thus to secure the shaft 25 to the rods 85.

Surrounding adjacent portions of the shafts 79 and 80 is a helical spring 91 and surrounding adjacent portions of the shafts 78 and 79 is a helical spring 92. One end of the spring 91 is secured to the shaft 79 as by a pin 91a (FIG. 3) and one end of the spring 92 is secured to the shaft 79 as by a pin 92a. The other end of the spring 92 is free, and the other end of the spring 91 is in driving engagement with a stop means to be described.

The shafts 79 and 80 are maintained in coaxial relationship by reception of an axially projecting portion 79a of the shaft 79 in a complementary axial recess 80a in the shaft 80. In the absence of the spring 91, the shafts 79 and 80 would be free to rotate relative to each other in either direction. In like manner, the shafts 78 and 79 are maintained in a coaxial relationship by reception of an axially projecting portion 78a of the shaft 78 in an axial complementary recess 7% of the shaft 79. In the absence of the spring 92, the shaft 79 would be free to rotate relative to the shaft 78 in either direction. The shaft 78 has a serrated end portion 78b inserted in a like serrated opening in the rear plate 75 to firmly fix the shaft 78 against rotation.

The spring 91 is so wound that clockwise rotation of the shaft 80 (as viewed in FIGS. 1 and 2) causes the spring 91 to be radially contracted thereby to tighten the con- Volutions thereof firmly about the shafts 79 and 80 to cause the shafts to rotate as a unit. Upon counterclockwise rotation of the shaft 80, the spring 91 expands and permits relative rotation between the shafts 79 and 80. The spring 92 is so wound that clockwise rotation of the shaft 79 (as viewed in FIGS. 1 and 2) causes radial expansion or unwrapping of the spring 92, thereby permitting the shaft 79 and the cam 81 to rotate freely in a clockwise direction to charge the springs 11. The shaft 79 cannot rotate in the counterclockwise direction because any tendency to do so causes contraction of the spring 92 about the shafts 78 and 79.

When the spring 91 secures the shafts 79 and 80 together in order to cause them to rotate together, the spring 92 is released to permit the shaft 79 to rotate relative to the fixed shaft 78. Conversely, when it is desired to rotate the shaft 80 relative to the shaft 79 preparatory to a subsequent charging stroke, the spring 92 prevents movement of the shaft 79 in a counterclockwise direction relative to the shaft 78. In this manner, any number of clockwise charging strokes of any length of a crank or lever 94 releasably mounted on the forward end portion of the shaft 80 convenient to the operator may be used to charge the springs 11, and each stroke may be started, without lost motion, at any turned position of the shaft 80. At the completion of a charging stroke, the crank 94 may be moved counterclockwise freely because the spring 91 expands to permit rotation of the shaft 80 relative to the shaft 79. This enables the crank 94 to be re-positioned for convenient application of manual force.

While the shaft 79 turns by force exerted on the crank 94, the cam 81 turns to drive the bars 84 downward to charge the springs 11.

The shaft 80 is effectively disconnected from the main drive shaft 79 when the springs 11 are fully charged, so that further rotation of the shaft 80 by the crank 94 has no effect. This is accomplished by a stop means comprising a disc 100, rotatably mounted on the shaft 80, and an L-shaped trip lever 101 having a vertical arm 101a and a horizontal arm 101k. The lever 101 is pivotably mounted intermediate its ends on a pin 102 carried by the front support plate 74 as shown in FIGS. 1, 2, and 4. A spring 104 is connected between a post 105 located on an upper portion of the plate 74 and a like post 106 aflixed to the outer end portion of the vertical arm 101a of the lever 101 so as to normally bias the same inwardly about the pin 102. As best seen in FIG. 4, a pair of spaced ears 107 is provided on the disc 100 which receive therebetween an outwardly turned portion 91b of the otherwise free-end portion of the helical spring 91. The disc 100 is free to rotate on the drive shaft 80 and is essentially circular in configuration with an indentation 100a therein forming a shoulder stop 10012.

When the springs 11 are uncharged, a post 108 extending forwardly from the front one of the support bars 84 (FIG. 1) engages an end portion of the horizontal arm 101b of the trip lever 101 to pivot the vertical arm 101a about the pin 102 against the bias of the spring 104 in a clockwise direction as viewed in FIGS. 1 and 2 to a position where the post 106 is beyond the outermost limits of the peripheral edge of the disc 100. Under these conditions, when the crank 94 drives the shaft 80, the helical spring 91 is radially contracted as previously describedwhereby the convolutions thereof are securely tightened around the shafts 79 and 80 and cause them to rotate in unison. The spring 91thus turns with the shafts 79v and 80 and the end portion 91b positioned between the ears 107 and bearing against the uppermost one as viewed in FIG. 4 causes the rotation of the disc 100. The disc 100 thus rotates clockwise as viewed in FIG. 2 in unison with the shafts 79 and 80 until, the indentation 100a is opposite the pin 106. The spring 104 then pivots the vertical arm 101a of the lever 101 inwardly about the pin 102 to the position of FIGS. 2 and 4. The disc 100 is now prevented from further rotation by the post 106 abutting the shoulder stop When the disc 100 is held in this position, the spring end portion 91b is also held in fixed position by the ears 107, and further rotation of the shaft 80 causes the convolutions of the spring 91 to open thereby to disconnect the shaft 80 from the main drive shaft 79. Thus it is seen that further rotation of shaft 80 has no effect. The cam 81 has now been turned to the position of FIG. 2 and has charged the springs 11 by effecting downward movement of the bars 84.

The disc 100 is maintained in this nonrotatable position until the springs 11 are discharged whereupon the post 108 moves in the upward direction and, by engagement with the end portion of the horizontal arm 1011: of the lever 101, causes the vertical arm 101a to move to a position where the post 106 again clears the edge of the disc 100 to permit the disc to rotate as previously described.

The foregoing description with reference to FIGS. 1 through 5 pertains to the operation of the spring-charging mechanism 10 by manual means, i.e., by rotating the shaft 80 by use of the crank 94. In this embodiment, the

shaft portion 78 is fixed to the rear support plate 74 and is non-rotatable.

In the embodiment of the invention shown in FIGS. 9 and 10, which permits operation of the spring-charging mechanism 10 either manually or by an electric motor 110 mounted on the horizontal support bracket 65, the motor 110 includes a worm drive section 110a positioned to operatively engage a portion of a shaft 78, which is substituted for the shaft 78 of the principal embodiment. The shaft 78 is rotatable relative to the shaft 79 in the same manner as the shaft 80. Further, a second rotatable disc 111 like the rotatable disc is provided on the shaft 78' and has a pair of cars 112 for receiving therebetween an outwardly turned end portion 92b of the spring 92. A trip lever 113 is provided which is like the lever 101 and the pin 108 is made longer so as to engage the horizontal portion of the lever 113. Further the rear plate 75 is replaced by a plate 75' shaped like the front plate 74.

When the springs 11 are in the uncharged condition, operation of the motor 110 rotates the drive shaft 78 causing the convolutions of the spring 92 to tighten about the shafts 78' and 79 thereby causing the shafts 78 and 79 to rotate in unison. The spring portion 92!) located between the ears 112 effects rotation of the disc 111 until a shoulder stop 1111) therein is reached and the trip lever 113 holds the disc 111 stationary. The shaft 78' is now free to rotate with respect to the main drive shaft 79. The disc 111 is held in the non-rotatable position until the springs 11 are discharged and the trip lever 113 is pivoted by the pin 108 to a position to free the disc 111 and allow it to rotate.

When the crank 94 is used to turn the shaft 84 of the embodiment of FIGS. 9 and 10, the worm 110a locks the shaft 78' so that operation is as in the principal embodiment.

It will be noted that the spring closing mechanism 10 is operative to charge the springs 11 when the circuit breaker operating mechanism 12 is in the position of FIG. 8 with the contacts 48-50 closed. This is because the shaft 25 is free to move downwardly without disturbing the toggle-linkage comprising the links 34 and 46 so long as the main trip latch 36 is in the position of FIG. 8.

While only the specific embodiments of the invention shown in the drawings have been described, it will be understood that various modifications and variations therefrom may be effected without materially departing from the true scope of the invention.

What is claimed is:

1. In a charging mechanism for a closing spring of a circuit breaker, means movable to compress the spring by engagement with an end thereof, a rotatable cam for moving said movable means, a first shaft fixed to said cam for rotating said cam, second and third shafts coaxial with said first shaft and extending respectively from opposite ends thereof, a first helical spring means surrounding at least a portion of each of said first and second shafts and a second helical spring means surrounding at least a portion of each of said first and third shafts, said first spring means being operative to permit rotation of said second shaft with respect to said first shaft in one direction and to prevent relative rotation therebetween for the opposite direction of rotation, said third shaft being fixed against rotation, and said second spring means being operative to permit relative rotation between said first and third shafts in one direction only.

2. In a charging mechanism for a closing spring of a circuit breaker, the closing spring having a fixed end and an end movable to effect compression of the spring, a pair of support plates carried by the circuit breaker, a first shaft rotatably positioned between said support plates and supported thereby, a rotatable cam fixed to said first shaft and positioned between said support plates, means interposed between said rotatable cam and the movable end of the closing spring operable to compress the spring when the cam is rotated, second and third shafts coaxial with said first shaft and extending respectively from opposite ends thereof, said second shaft being rotatable and said third shaft being fixed, a first helical spring surrounding at least a portion of said first and second shafts, a second helical spring surrounding at least a portion of said first and third shafts, said first helical spring having convolutions which contract about said first and second shaft portions when said second shaft is rotated in one direction, whereby said first and second shafts rotate in unison, said convolutions of said first helical spring loosening when said second shaft is rotated in the opposite direction, said second helical spring having convolutions which loosen when said second shaft is rotated in said one direction to permit said first and second shafts to rotate in unison relative to said third fixed shaft, said convolutions of said second helical spring contracting about said portions of said first and third shafts to hold the same in a fixed position when said second shaft is rotated in said opposite direction.

3. In a charging mechanism for a closing spring of a circuit breaker, the closing spring having a fixed end and an end movable to effect compression of the spring, a pair of support plates carried by the circuit breaker, a first shaft rotatably positioned between said support plates and supported thereby, a rotatable cam fixed to said first shaft and positioned between said support plates, means interposed between said rotatable cam and the movable end of the closing spring operable to compress the spring when the cam is rotated, second and third shafts coaxial with said first shaft and extending respectively from opposite ends thereof, said second shaft being rotatable and said third shaft being fixed, a first helical spring surrounding at least a portion of said first and second shafts, a second helical spring surrounding at least a portion of said first and third shafts, rotatable disc means carried on said second shaft and positioned between said first helical spring and said first support plate, said disc means being rotatable relative to said second shaft, said first helical spring having one end secured to said first shaft and the other end secured to said rotatable disc means, said second helical spring having one end secured to said first shaft and the other end free, said first helical spring having convolutions which contract about said portions of said first and second shafts when said second shaft is rotated in one direction whereby said first and second shafts and said rotatable disc means rotate in unison, said convolutions of said first helical spring loosening when said second shaft is rotated in the opposite direction, said second helical spring having convolutions which loosen when said second shaft is rotated in said one direction to permit said first and second shafts and said rotatable disc means to rotate in unison relative to said third fixed shaft, said convolutions of said second helical spring contracting about said portions of said first and third shafts to hold the same in a fixed position when said second shaft is rotated in said opposite direction, and stop means engaging said rotatable disc means to hold the disc against further rotation at a predetermined turned position thereof, whereby further rotation of said second shaft in said one direction causes loosening of said convolutions of said first helical spring from said second shaft, whereby said second shaft is free to rotate relative to said first shaft.

4. In a charging device for a closing spring of a circuit breaker, an improved multi-section shaft and clutch mechanism comprising a first shaft portion having a recess at one end and a reduced neck at the other end, a second shaft portion having a recess at one end for rotatably receiving said reduced neck of said first shaft portion therein, said recess of said first shaft portion rotatably receiving a reduced neck portion of a third shaft portion, said shaft portions being aligned substantially coaxially, a first helical spring surrounding each of said first and second shaft portions, a second helical spring surrounding each of said first and third shaft portions, said first helical spring having convolutions which contract about said first and second shaft portions when said second shaft portion is rotated in one direction, whereby said first and second shaft portions rotate in unison, said convolutions of said first helical spring loosening when said second shaft portion is rotated in the opposite direction, said second helical spring having convolutions which loosen when said second shaft portion is rotated in said one direction to permit said first and second shaft portions to rotate in unison relative to said third shaft portion, said convolutions of said second helical spring contracting about said first and third shaft portions to hold the same in fixed relation to each other when said second shaft rotates in said opposite direction.

5. In a charging mechanism for a closing spring of a circuit breaker, means movable to compress the spring by engagement with an end thereof, a rotatable cam for moving said movable means, a first shaft fixed to said cam for rotating said cam, second and third shafts coaxial with said first shaft and extending respectively from opposite ends thereof, a first helical spring means surrounding at least a portion of each of said first and second shafts and a second helical spring means surrounding at least a portion of each of said first and third shafts, said first spring means being operative to permit rotation of said second shaft with respect to said first shaft in one direction and to prevent relative rotation therebetween for the opposite direction of rotation, an electric motor, gearing interposed between said motor and said third shaft permitting said motor to drive said third shaft and preventing rotation of said third shaft except when driven by said motor, and said second spring means being operative to permit relative rotation between said first and third shafts in one direction only.

No references cited.

EDGAR W. GEOGHEGAN, Primary Examiner.

Claims (1)

1. IN A CHANGING MECHANISM FOR A CLOSING SPRING OF A CIRCUIT BREAKER, MEANS MOVABLE TO COMPRESS THE SPRING BY ENGAGEMENT WITH AN END THEREOF, A ROTATABLE CAM FOR MOVING SAID MOVABLE MEANS, A FIRST SHAFT FIXED TO SAID CAM FOR ROTATING SAID CAM, SECOND AND THIRD SHAFTS COAXIAL WITH SAID FIRST SHAFT, AND EXTENDING RESPECTIVELY FROM OPPOSITE ENDS THEREOF; A FIRST HELICAL SPRING MEANS SURROUNDING AT LEAST A PORTION OF EACH OF SAID FIRST AND SECOND SHAFTS AND A SECOND HELICAL SPRING MEANS SURROUNDING AT LEAST A PORTION OF EACH OF SAID FIRST AND THIRD SHAFTS, SAID FIRST SPRING MEANS BEING OPERATIVE TO PERMIT ROTATION OF SAID SECOND SHAFT WITH RESPECT TO SAID FIRST SHAFT IN ONE DIRECTION AND TO PREVENT RELATIVE ROTATION

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