GB2054966A

GB2054966A - Improved manual and motor operated circuit breaker

Info

Publication number: GB2054966A
Application number: GB8020090A
Authority: GB
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1979-06-25
Filing date: 1980-06-19
Publication date: 1981-02-18
Also published as: FR2460034A1; IT8022927A0; IT1131546B; DE3022971A1; BR8004003A

Abstract

In a circuit breaker a handle operable slide 50 and a motor operable slide 56 are individually coupled with a charging mechanism 68 to independently charge springs 78 thereof. The charging mechanism is operative to charge the springs (100) of a contact operating mechanism as the charging mechanism springs 78 discharge. The charging mechanism includes a prop 122 controlled by the condition of the operating mechanism to releasably retain the charging mechanism springs 78 in a fully charged condition, while the operating mechanism includes a hook 110 to releasably retain the breaker contacts 40a, 41 open against the force of fully charged operating mechanism springs 100. Consequently, the circuit breaker is capable of executing multiple contact opening and closing operations without recharging the springs by either the handle or the motor via their respective slides. <IMAGE>

Description

SPECIFICATION Manual and motor operated circuit breaker having multiple spring actuating mechanism The present invention relates to circuit breakers of the industrial type which are equipped with both a manual operating handle and a motor operator mechanism to afford the capability of either local manual circuit breaker operation or typically remotely initiated motorized circuit breaker operation. Such remotely initiated operation may be effected manually (by control switch actuation) or automatically in coordination with the operations of other equipment. Thus, motor operated industrial circuit breakers have particular application as, for example, process control switches having the added benefit of affording overcurrent protection.

Heretofore, circuit breakers designed for both manual and motorized operation have typically required electrical and/or mechanical interlocking such that upon initiation of manual circuit breaker operation, motorized circuit breaker operation is locked out or defeated, and vice versa. This is done to prevent damage to the circuit breaker and possible injury to operating personnel since the circuit breaker mechanisms simply cannot tolerate concurrent manual and motorized operations.

Examples of such interlocking can be found in commonly assigned U.S. patents, Nos. 3,559,121 and 4,042,896.

Obviously, the inclusion of such interlocking adds complexity and expense to the circuit breaker design, in addition to constituting a potential source of field problems. A related problem that may be posed by this interlocking involves the possible loss of power or a malfunction in the motor operator mechanism while motorized circuit breaker operation is in process. In this event, it is highly desirable to be able to remove or defeat the interlocking such as to permit manual completion of the interrupted motorized circuit breaker operation. Defeatable interlocking, if accommodatable by the circuit breaker mechanisms, contributes further to design complexity and expense. The alternative is to await restoration of power or to remedy the source of the motor operator malfunction in order to complete the circuit breaker operation, which typically is totally unacceptable.

FIGURE 1 is an isometric view of a molded case industrial circuit breaker embodying the present invention; FIGURE 2 is a perspective view of the overall operating mechanism utilized in the circuit breaker of FIGURE 1; FIGURE 3 is an exploded perspective view of a portion of the charging mechanism utilized in the circuit breaker of FIGURE 1; FIGURE 4 is a side elevational view of the contact operating mechanism utilized in the circuit breaker of FIGURE 1; FIGURE 5 is a simplified, side elevational view of the charging mechanism and the contact operating mechanism as the former is about to be charged; FIGURE 6 is a simplified, side elevational view of the charging and contact operating mechanisms with charges stored in both mechanisms;; FIGURE 7 is a simplified, side elevational view of the charging and contact operating mechanisms wherein the former is discharged and the latter is charged; FIGURE 8 is a perspective view of the motor operator mechanism utilized in the circuit breaker of FIGURE 1; FIGURE 9 is a perspective assembly view of a variable drive coupling link assembly utilized in drivingly coupling the motor operator mechanism of FIGURE 8 to the circuit breaker charging mechanism; FIGURE 10 is a sectional view of a hub assembly utilized in the circuit breaker of FIGURE 1 to accommodate both manual and motor operator mechanism charging of the charging mechanism; FIGURE 11 is a simplified plan view of the link assembly of FIGURE 9 at the conclusion of motor operator mechanism charging of the charging mechanism;; FIGURE 12 is a simplified plan view of the link assembly of FIGURE 9 at the beginning of a charging mechanism charging cycle; and FIGURE 13 is a simplified plan view of the link assembly of FIGURE 9 as the charging mechanism is about to be charged.

Like reference numerals refer to like parts throughout the several views of the drawings.

Referring to FIGURE 1, the circuit breaker of the present invention, generally indicated at 20, consists of, in one version, three basic assemblies, namely, a circuit breaker assembly 22, a power unit assembly 24, and a cover assembly 26, all secured together in stacked relation. In this version, the circuit breaker is capable of both manual and motor powered operations. To provide a strictly manually operated circuit breaker, power unit assembly 24 is simply omitted, ieaving the cover assembly 26 stacked directly atop the circuit breaker assembly 22. As will be seen from the description to follow, circuit breaker assembly 22 includes a contact operating mechanism having basically the same construction as that disclosed in commonly assigned U.S. Patent No.

4,001,742. It will also be noted from the description to follow that power unit assembly 24 has many of the structural features disclosed in commonly assigned U.S. Patent No. 4,042,896.

The disclosures of both of these patents are specifically incorporated herein by reference.

Still referring to FIGURE 1, cover assembly 26 includes a manual operating handle 28 which may be cranked to manually charge circuit breaker 20.

The cover assembly also includes windows 30 and 32 through which indicators are visible to identify the existing condition of the circuit breaker.

Manual controls for conditioning the circuit breaker include an OFF button 34 and an ON pushbutton 36. The OFF pushbutton is depressed to trip the circuit breaker assembly 22, causing the circuit breaker contacts to spring from their closed circuit position to their open circuit positions. The ON pushbutton is depressed to cause the breaker contacts to spring from their open circuit position to their closed circuit positions once the breaker contact operating mechanism has been charged either via the power unit assembly 24 or the manual handle 28.

Circuit breaker assembly 22, seen in perspective in FIGURE 2, includes a molded insulated base 38 in which three sets of movable contact assemblies 40 are mounted for pivotal movement between their open and closed circuit positions, preferably in the manner disclosed in the above noted patent No. 4,001,742. Base 38 also mounts a charging mechanism, generally indicated at 42, in the region generally above the center pole of circuit breaker 20. The various components of this mechanism are mounted by a frame consisting of a pair of parallel, spaced sideplates 44 spanned by a stringer plate 45 and a block 46. Block 46 serves to rotatably mount an upright stub shaft 48 which is drivingly coupled via a hub assembly seen in FIGURE 10 to manual operating handle 28 of FIGURE 1 and a motor operator mechanism seen in FIGURE 8 and included in power unit assembly 24 of FIGURE 1.

As seen in FIGURES 3 and 10, the lower, reduced portion 48a of stub shaft 48 is received in a longitudinally elongated slot 50a formed in a manual operator slide 50. Fixed to shaft portion 48a is a crank arm 52 which carries at its free end an upstanding crank pin 54 operating in a transversely elongated slot 50b formed in slide 50. The rearward end of slide 50 carries a headed pin 50c which is received in an elongated slot 45a formed in stringer plate 45, thus completing the mounting of slide 50 to the mechanism frame.

As will be seen from the description to follow, counterclockwise rotation of shaft 48 by the handle swings crank arm 52 in the counterclockwise direction to propel slide 50, via pin 54 operating in slide slot 50b, through a rearward return stroke. Then, clockwise rotation of handle 28 back to its vertical position seen in FIGURE 1 swings arm 52 in the clockwise direction, forcing slide 50 to execute a forward charging stroke.

Still referring to FIGURES 2 and 3, the mechanism frame additionally serves to mount in side by side relation with slide 50, a second, motor operator slide 56. This slide carries at its rearend a headed pin 56a which is received in an elongated slot 45b formed in stringer plate 45. The forward portion of slide 56 is turned down into overlying relation with left frame sideplate 44 and is provided with an elongated slot 56b in which is received the shank of a screw 56c (FIGURE 2), completing the mounting of this slide to the mechanism frame. As will be seen, motivation of slide 56 to execute a rearward return stroke followed by a forward charging stroke is derived from the power unit assembly 24 via a pìn 58 (FIGURE 10) operating in a laterally extending slot 56d formed in this slide.

To couple the forward charging stroke of manual operator slide 50 to the circuit breaker operating mechanism, a transverse pin 60 serves to pivotally mount the rearward end of an elongated drive pawl 62 seen in FIGURE 3.

Similarly, motor operator slide 56 carries a transverse pin 64 pivotally mounting the rearward end of a second, identical drive pawl 66. A bell crank assembly, generally indicated at 68, includes a main shaft 68a rotationally mounted at its opposed ends by the frame slideplates 44.

Pinned to this shaft are a pair of crank arms 71 and 72. Keyed to the left end of shaft 68a is an arm 74 which carries adjacent to its free end a headed pin 74a operating in an elongated slot 76a formed in a spring anchor 76 secured to the forward ends of a pair of powerful tension springs 78 seen in FIGURE 2. Secured to the rearward ends of these tension springs is a spring anchor 80 which is affixed to the mechanism frame by a pin 81. Pinned to forward spring anchor 76 are a pair of elongated stop rods 82 which extend through the centers of tension springs 78 to abut against the rearward spring anchor 80. These stop rods are for the purpose of establishing a preloading of springs 78 of, for example, 100 pounds, and thus, when these springs discharge, the stop rods bottom out on the rearward spring anchor 80 before the spring convolutions can bottom out on themselves.This has the advantage of eliminating spring rebounding and also significantly reduces the potential for spring breakage.

Forward spring anchor 76, as seen in FIGURE 2, is also provided with a laterally turned tab 76b which serves to anchor the forward end of a small tension spring 84. The rearward end of this spring is anchored by a screw 85 carried by the left frame sideplate 44. As will be seen, spring 84 serves to return bell crank assembly 68 to an appropriate starting angular position after springs 78 have discharged.

Still referring to FIGURES 2 and 3, pawl 62, pivotally connected to manual operator slide 50, is undercut to provide a notch 62a adapted to engage a pin 72a carried by crank arm 72 of bell crank assembly 68. It is thus seen that when slide 50 is propelled forwardly by clockwise cranking movement of manual handle 28, pawl 62 picks up pin 72a, causing the bell crank assembly to rotate in the clockwise direction. As will be seen from FIGURES 5 through 7, this action charges springs 78. In corresponding fashion, pawl 66, pivotally connected to motor operator slide 56, is undercut to provide a notch 66a which is adapted to pick up a pin 71 a carried by bell crank arm 71 when this slide is motivated through a forward charging stroke by the motor operator assembly of FIGURE 8. The bell crank assembly is thus rotated also in the clockwise direction effective to charge springs 78.

As will be seen from the description to follow, charging springs 78, once charged, are sufficiently forceful to overpower a spring power breaker contact operating mechanism, such that the discharge of these springs is utilized to charge the contact operating mechanism springs which can then act to close and open the breaker contacts.

Thus, the operator slides 50 and 56 do not operate directly on the breaker contact operating mechanism, but rather indirectly via the bell crank assembly 68 and the powerful charging springs 78. Moreover, as will become clear from the following description, charging mechanism 42 accommodates essentially indiscriminate stroking movements of operator slides 50 and 56, thus eliminating the need for any mechanical and/or electrical interlocking between the manual operating handle and the motor operator mechanism. This is achieved by virtue of the independent mounting of these operator slides and the utilization of separate drive pawls to propel the bell crank assembly pursuant to charging springs 78.Thus, should the motor operator mechanism stall at some point during charging of the charging mechanism, possibly due to loss of power, the charge can be completed by the manual operating handle.

Contact operating mechanism of circuit breaker 20, seen in FIGURE 4, is constructed basically in the same fashion as disclosed in the above noted patent No. 4,001,742. Thus, a cradle 90 is pivotally mounted on a pin 91 supported by the frame sideplates 44. A toggle linkage consisting of an upper link 92 and a lower link 94 connects cradle 90 to center pole movable contact assembly 40. Specifically, the upper end of link 92 is pivotally connected to the cradle by a pin 95, while the lower end of link 94 is pivotally connected to the center pole movable contact assembly by a pin 96. The other ends of these toggle links are pivotally connected by a knee pin 98. Mechanism tension spring 100 acts between the toggle knee pin 98 and a pin 102 supported between the frame sideplates 44.In practice there are two mechanism springs 100, one to each side of the cradle 90 to thus balance the spring forces on the mechanism parts. The toggle links 92 and 94 are also preferably provided in pairs.

From the description thus far, it will be noted that the major distinction in the construction of the contact operating mechanism of FIGURE 4 herein and that disclosed in patent No. 4,001,742 is that the operating lever included in the latter to couple the operating slide to the cradle pursuant to charging the mechanism springs is omitted in the instant construction. In the absence of this operating lever, to which the upper ends of the mechanism spring were pinned in the patented construction, the upper end of mechanism springs 100 seen in FIGURE 4 are anchored to a stationary point, namely pin 102 carried by the mechanism sideplates 44. As will be seen, the function of the operating lever in the patented construction is assumed by the bell crank assembly 68 of FIGURES 2 and 3 in articulating the cradle 100 pursuant to charging mechanism springs 100.

Moreover, by virtue of the position of spring anchoring pin 102, the line of action of charged spring 100, while cradle 90 is in its latched reset position sustained by the engagement of a latch 106 with cradle latch shoulder 90a, is always situated to the right of the upper toggle link pivot pin 95. Thus, the mechanism springs continuously act to straighten the toggle. Since straightening of the toggle forces the movable contact assemblies 40, ganged together by crossbar 40b, to pivot downwardly to their phantom line, closed circuit positions with their movable contacts 40a engaging stationary contacts 41, circuit breaker 20 is biased toward contact closure while cradle 90 is reset.

To control the moment of contact closure, a hook 110 is provided to hold movable contact assemblies 40 in a hooked open circuit position as the cradle is being reset from a clockwise-most tripped position to charge mechanism spring 100, thereby maintaining the toggle collapsed to the left as seen in FIGURE 4. This hook is pivotally mounted on a pin 111 with its right hooked end 11 Oa configured to engage pin 96 carried by the center pole movable contact assembly 40. A spring 11 2 biases the hook into engaging relation with pin 96.The left end of hook 110 is provided with a laterally turned flange 11 Ob positioned to be engaged by the lower end of ON pushbutton 36 of FIGURE 1 to release the movable contact assemblies 40 for contact closure as spring 100 abruptly straightens toggle links 92, 94. While not shown in FIGURE 4, the center pole movable contact assembly carries a control surface to hold hook 110 in its phantom line release position so as not to interfer with pin 96 during counterclockwise opening movement of the contact assemblies. An example of such a hook control surface may be found in U.S. patent No.

4,128,750.

With the movable contact operating mechanism parts in their phantom line, closed circuit position seen in FIGURE 4, toggle knee pin 98, seen in phantom at 98, engages a shoulder 90b of cradle 90 while latched in its reset position by latch 1 06. This shoulder serves as a stop to prevent the toggle from snapping over center and in fact stops the toggle just short of its fully straightened position. It will also be noted that with the contacts in their closed circuit positions, a shoulder 92a formed in upper toggle link 92 is positioned, as indicated at 92a, in contiguous relation with a stationary pin 114.Thus, when cradle 90 is released by a latch 106, either in response to depression of OFF pushbutton 34 of FIGURE 1 or automatically in response to an overcurrent condition sensed by the circuit breaker's trip unit, clockwise pivotal movement of the cradle toward its tripped position under the urgence of mechanism spring 100 brings the upper toggle link shoulder 92a into engagement with pin 114, thereby accelerating the rate of collapse of the toggle. This action produces abrupt and accentuated separation of the circuit breaker contacts under the urgence of the discharging mechanism spring 1 00. Also contributing to the speed with which contact separation is achieved is the fact that the cradle shoulder 90b stops the toggle linkage short of its fully straightened condition while the breaker contacts are closed, as previously noted.Since the toggle does not have to snap through center to start the contact opening movement of the movable contact assemblies 40, contact separation is achieved that much more rapidly. That is, the initial movement of the toggle linkage upon unlatching of the cradle starts the collapse of the toggle which is further accentuated by the presence of pin 114. Contact separation is thus initiated without hesitation. In fact, under high fault conditions, contact separation may be initiated by the electromagnetic forces associated with the high fault currents prior to release of the cradle. It is seen that the toggle can accommodate this initial, forced contact separation by immediately beginning its collapse and the cradle, upon its release, catches up with the collapsing toggle linkage in completing the interruption without contact reclosure.

Reference is now had to FIGURES 5 through 7 for a description of the overall operation of the circuit breaker 20 of FIGURE 1 and specifically the operation of the charging mechanism in resetting the contact operating mechanism of FIGURE 4 pursuant to charging its spring 100. It will be recalled that the contact operating mechanism spring 100 is charged when cradle 90 is swung about its pivot pin 91 in the counterclockwise direction from a clockwise-most tripped position to bring its latching shoulder 90a into engagement with latch 1 06. To induce.this resetting pivotal movement of cradle 90, the bell crank assembly 68, best seen in FIGURES 2 and 3, is provided with a reset roller 1 20 eccentrically mounted between the bell crank arms 71 and 72.As will be seen, when charging springs 78 discharge, bell crank assembly 68 is rotated to swing the reset roller around to engage cradle 90 while in its tripped position, driving it in the counterclockwise direction to its reset position, in the process charging the contact operating mechanism spring 100.

Referring first to FIGURE 5, bell crank assembly 68 is seen in a start angular orientation achieved by the action of tension spring 84. Manual operator slide 50 is shown in its left-most return position with its pawl 62 retracted to a position where its notch 62a is in intercepting relation with pin 72a carried by crank arm 72 of bell crank assembly 68. At this point it should be pointed out that motor operation slide 56 and its drive pawl 66 act on bell crank assembly 68 in the same fashion as the manual operator slide and its drive pawl 62. Thus, the operation to be described in connection with FIGURES 5 through 7 applies whether it is initiated by reciprocation of manual operator slide 50 or motor operator slide 56.The only distinction is that the motor operator drive pawl 66 engages pin 71 a carried by crank arm 71, whereas the manual operator drive pawl 62 engages pin 72a carried by crank arm 72.

From FIGURE 6, it is seen that when slide 50 is driven to the right through a charging stroke by clockwise cranking movement of manual operating handle 28, drive pawl 62 is pushed to the right. Its notch 62a picks up pin 72a, causing bell crank assembly 68 to be rotated in the clockwise direction. When the bell crank assembly reaches its angular position of FIGURE 6, it is seen that charging springs 78 are stretched to a charged state. It is assumed, at this point in the description, that the movable contact operating mechanism of FIGURE 4 is tripped, and thus cradle 90 is in its clockwise-most tripped position seen in FIGURE 5. Under these circumstances, the essentially discharged contact operating mechanism spring 100 has lifted the movable contact assemblies 40, to a counterclockwisemost, tripped open position seen in FIGURE 5.In this position, the top surface of the center pole movable contact assembly engages and lifts the left lower end 1 22a of a prop 122 pivotally mounted intermediate its ends on a pin 123. The other, upper end 1 22b of this prop is moved downwardly out of an engaging relation with the arcuate surface portion of one of the bell crank arms against which it is normally engaged under the bias of a return spring 124. While in FIGURE 7, prop 1 22 is shown as being biased into engagement with the arcuate surface portion 72b of crank arm 72, in practice, prop 122 acts against crank arm 71 simply as a matter of structural convenience.

As seen in FIGURE 6, the rightward charging stroke of operator slide 50 is sufficient to carry the line of action of charging springs 78 through the axis of the bell crank assembly shaft 68a.

Consequently, with prop 122 in its FIGURE 5 position, the charging springs immediately discharge and the bell crank assembly is thereby driven in the clockwise direction, swinging reset roller 1 20 into engagement with a nose 90c of cradle 90 in its tripped position of FIGURE 5. The cradle is thus swung in the counterclockwise direction to its reset position as the discharging springs 78 drive the bell crank assembly to its angular position seen in FIGURE 7. As cradle 90 is being reset, contact operating mechanism spring 100 is charged to exert a bias tending to drive the movable contact assemblies 40 to their closed circuit positions seen in phantom in FIGURE 7.

However, hook 110 is in position to intercept pin 96 and detain the movable contact assemblies in a hooked open position seen in FIGURES 6 and 7.

In this hooked open position, the center pole contact assembly releases the lower end 1 22a of prop 122, and its return spring 1 24 urges the other end 1 22b thereof into engagement with the arcuate surface portion 72b of bell crank arm 72 as seen in FIGURE 7. By virtue of the loss motion coupling between bell crank assembly 68 and charging spring 78 afforded by slot 76a in its anchor 76, spring 84 acts to continue the clockwise rotation of bell crank assembly 68 from its angular position of FIGURE 7 around to its start position of FIGURE 5 with pin 74a again bottomed against the right end of slot 76a in charging spring anchor 76.

From the description thus far, it is seen that the first charge-discharge cycle of charging springs 78 has been effective in resetting the contact operating mechanism cradle 90 and charging the spring 100 thereof, but the breaker contacts are sustained in their open circuit positions by hook 110. At this point, the operator slide 50 can be motivated by handle 28 through a second rightward charging stroke to again charge springs 78. Since movable contact assemblies 40, in their hooked open position, have released prop 122, its upper end 1 22b rides off arcuate surface portion 72b of bell crank arm 72 are the bell crank assembly is rotated in a clockwise direction.

Spring 124 serves to elevate end 1 22b of prop 1 22 into intercepting relation with the flattened surface 72c of bell crank arm 72 at the conclusion of the operator slide charging stroke just as the line of action of the charging springs 78 passes below the axis of bell crank assembly shaft 68a.

Thus, as seen in FIGURE 6, prop 122 serves to prevent-further clockwise rotation of the bell crank assembly 68, and the charging springs 78 are held in a fully charged condition. It is thus seen that while the breaker contacts are held in their hooked open circuit position by hook 110, both the charging springs 78 and contact operating mechanism spring 100 are poised in their fully charged conditions. At this point, ON pushbutton 36 may be depressed, causing hook 110 to release the movable contact assemblies 40, whereupon they pivot to their closed circuit position under the urgence of mechanism spring 100. It will be noted that closure of the movable contacts has no effect on prop 122, and thus charging springs 78 are sustained in their fully charged condition.

When the circuit breaker 20 is eventually tripped open, either by depression of OFF pushbutton 34 or operation of the circuit breaker trip unit in response to an overcurrent condition, the unlatched cradle 90 swings to its tripped position, and the movable contact assemblies 40 abruptly pivot upwardly to their tripped open position of FIGURE 5, ail under the urgence of the discharging contact operating mechanism spring 100. As the center pole movable contact assembly 40 moves to its tripped open position, it picks up the lower end of prop 122, ducking its upper end 1 2b out of engagement with the flat peripheral surface portion 72c of crank arm 72.

The clockwise rotational restraint on the bell crank assembly 68 is thus removed, and charging springs 78 abruptly discharge, swinging reset roller 120 around to drive cradle 90 from its tripped position of FIGURE 5 back to its reset position of FIGURE 7. The contact operating mechanism spring 100 is again charged, and the movable contact assemblies 40 moved to their hooked position seen in FIGURE 6. At this point, the charging springs 78 may again be charged, and the charge therein will be automatically stored by prop 122 until needed to recharge the contact operating mechanism spring 100. Alternatively, and more significantly, hook 110 may be articulated by ON pushbutton 36 to precipitate closure of breaker 20, and thereafter the breaker may be tripped open without charging the charging springs 78.

From the foregoing description, it is seen that with the breaker contacts open and its contact operating mechanism tripped, the charging springs can be put through a first chargedischarge cycle to charge to contact operating mechanism spring 100 and then a second charge which is stored by prop 122 until needed to recharge the mechanism spring 1 00. Thus, circuit breaker 20, starting in its tripped open condition and with two chargings of charging springs 78, can be closed, tripped open, reclosed and tripped open again without an intervening charging of the charging springs. It follows from this that the charging springs can be charged with the breaker contacts closed to achieve open, closed and open operations of the circuit breaker without an intervening charge.

The essential elements of power unit assembly 24 of FIGURE 1 operating to reciprocate motor operator 56 in FIGURES 2 and 3 are shown in detail in FIGURES 8 through 13. Thus, as seen in FIGURE 8, the power unit assembly 24 includes a molded insulative base 1 30 which, as seen in FIGURE 1, is sandwiched between circuit breaker base 38 and the cover assembly cover. Supported atop this base is an electric motor 1 32 whose output shaft is drivingly connected to the input shaft (not shown) of a gear box 134. The construction of this gear box may take the form disclosed in above-noted patent No. 4,042,896.

Keyed to the gear box output shaft, indicated at 135 in FIGURES, is a crank arm 136. Adjacent the free end of this crank arm is a hole 1 36a in which the head of a shouldered pin 1 38 is inserted and peened over to fixedly secure it in place. The shank of this pin extends through an elongated longitudinal slot 1 40a in a link 140. A circular cam 142 is keyed on the shank of pin 138 in position below link 140. Finally, a washer 1 43 is inserted on the lower end of pin 138 and a snap ring 144 clipped in the very end retains the pin captured in slot 1 40a in link 140. The other end of link 140 is pivotally connected to a crank arm 146 by a pin 148.Crank arm 146 is secured by screws 147 to a hub assembly, generally indicated at 150 and mounted by base 130 of power unit assembly 24.

Referring to FIGURE 10, hub assembly 1 50 includes an outer hub 1 52 which is received in an opening 1 30a provided in the power unit assembly base 130. An upper flange plate 1 54 is secured to the upper end of hub 1 52 by the screws 147 securing crank arm 146 to the hub assembly. A lower flange plate 1 56 is secured to the lower end of hub 1 52 by screws 1 57. It is thus seen that these flange plates serve to capture outer hub 1 52 for rotational movement in opening 1 30a of power unit assembly base 130. Pin 58, operating in slot 56d of motor operator slide 56, is eccentrically mounted to lower flange 156.As will be seen, the unidirectional rotation of the gear box output shaft 135 (FIGURE 9) results in oscillatory rotation movement of outer hub 1 52 pursuant to reciprocating motor operator slide 56.

Still referring to FIGURE 10, outer hub 152 and flange 1 54 are provided with respective central openings 1 52a and 1 54a in which is received a female square drive member 1 58. Integrally formed with this female drive member for upward extension through a reduced diameter opening 1 46a in crank arm 146 is a stub shaft 1 60 which terminates in a male square drive member 1 60a seen in FIGURE 8. A snap ring 161 cooperates with the shoulder 162 between member 1 58 and stub shaft 1 60 to capture these elements in hub assembly 1 50 for rotational movement as an inner hub independently of outer hub 1 52.The upper, male square drive member end 1 60a of stub shaft 1 60 accommodates rotational drive coupling engagement with handle 28 when cover assembly 26 is assembled in place. Stub shaft 48, previously mentioned in connection with FIGURE 2, is clearly shown in FIGURE 10 with its reduced diameter lower end portion 48a journalled in a bore 46a provided in block 46. Crank arm 52 is affixed to this reduced stub shaft portion as is a flange 1 64 which cooperates with a snap ring 1 65 in capturing stub shaft 48 in mounting block bore 46a for rotational movement. As previously described, crank arm 52 mounts pin 54 which operates in slot 50b of manual operator slide 50.

The upper end of stub shaft 48 is in the form of a male square drive member 48b which is received in the square sided central hole 1 58a provided in female square drive member 1 58 pursuant to drivingly coupling stub shaft 1 60 with stub shaft 48 and thus handle 28 with manual operator slide 50.

As will be seen in the following description in conjunction with FIGURES 11 through 13, a motor operator mechanism charging cycle is executed by swinging crank arm 136 through a full 3600 revolution. During the initial portion of each crank arm 3600 revolution, motor operator slide 56 is propelled from a home position through a return stroke, retract its pawl 66 into position where it can pick up pin 71 a carried by a crank arm 71 of the bell crank assembly 68 (FIGURE 3). During the concluding portion of each 3600 revolution, slide 56 is driven forwardly through a charging stroke back to its home position, whereupon bell crank assembly 68 is rotated in the clockwise direction (FIGURES 5 through 7), pursuant to charging charging springs 78.As will be seen, link 140 is jointly acted upon by pin 138 and circular cam 142 so as to provide a lost motion coupling between the link and crank arm 1 36 effectuated at the conclusion of the motor operator slide charging stroke to decouple link 140 from crank arm 136. This lost motion coupling provides a coasting zone during which the de-energized motor 132 of FIGURE 8 is permitted to coast to a stop without disturbing the motor operator slide home position achieved at the conclusion of its charging stroke. By virtue of this coasting zone, the necessity for special braking provisions to abruptly stop rotation of the motor output shaft at the conclusion of a charging cycle are rendered unnecessary. This constitutes a distinct advantage in terms of design efficiency and field reliability.

Paradoxically, it will be seen that this coasting zone is achieved while maintaining equal clockwise and counterclockwise throws of crank 146, and thus equal length return and charging strokes of motor operator slide 56.

The motor operator mechanism drive parts are shown in FIGURE 11 with the axes of gear box output shaft 135, pin 138 and pin 148 in alignment along a center line 170. Since pin 138 is aligned on the opposite side of output shaft 1 35 from pin 148, crank arm 1 46 has arrived at the end of its counterclockwise throw, and motor operator slide 56 has reached the end of its forward charging stroke, which is directed downwardly in FIGURE 11. It will be noted that pin 138 is bottomed against the outer end of slot 1 40a in link 140, while the periphery of eccentrically mounted circular cam 142 is spaced from the inner end of this slot constituted by a downward turned tab 1 40b best seen in FIGURE 9.As crank arm 136 is rotated in the counterclockwise direction by gear box output shaft 135 away from centerline 170, pin 138 moves away from the outer end of slot 1 40a, and link 1 40 is simply swung in the counterclockwise direction about pin 1 48. It is not until the periphery of circular cam 142 moves into engagement with tab 1 40b at the inner end of slot 1 40a that any effective driving force is exerted on link 140 to swing crank 146 in the clockwise direction to begin a return stroke of motor operator slide 56 away from its home position.

There is thus provided a lost motion connection between crank arm 136 and link 140 which creates a coasting zone through which crank arm 136 may revolve without exerting any driving force on crank arm 146 tending to move slide 56 from its home position. Thus, when pin 138 is revolved to its position in FIGURE 11, motor 132 in FIGURE 8 may be de-energized and simply allowed to coast to a stop without disturbing the home position of slide 56. Under these circumstances, special provisions to abruptly brake the motor at the conclusion of a slide charging stroke and thereby preserve the slide home position is rendered unnecessary.

To this end, crank arm 146 is provided with an upwardly turned flange 1 46a through which is adjustably threaded a set screw 1 70. When the parts are in their position shown in FIGURE 11, screw 170 engages and pivots a lever 172 into actuating engagement with a normally closed switch 1 74. Upon actuation of this switch, the energization circuit for motor 1 32 is interrupted, and it is simply permitted to coast to a stop.

In FIGURE 12, the parts in FIGURE 11 are seen in their positions assumed at the end of the coasting zone when the periphery of cam 1 42 has just moved into engagement with tab 1 40b at the inner end of slot 140a. In the illustrated embodiment, the configuration and dimensions of cam 142 is such as to provide a coasting zone of approximately 450 through which crank arm 136 can swing from centerline 1 70 to centerline 1 76 without exerting any driving force on crank arm 146. It is apparent that when cam 142 engages tab 140b, only then is driving force exerted on link 140, propelling crank arm 146 through its clockwise throw pursuant to initiating motor operator slide 1 56 return stroke away from its home position. It is noted that initially this driving force is exerted through a shortened effective driving length in link 140.

In FIGURE 13, the motor operator drive parts are shown in their positions assumed at the end of the clockwise throw of crank arm 146 to conclude the return stroke of slide 56. The axes of pin 148, gear box output shaft 135 and pin 138 are now aligned along a center line 180, with pin 138 between pin 148 and shaft 135. It is significant to note that circular cam 142 is now angularly oriented with its peripheral surface of maximum radius in engagement with tab 140b. This maximum radius is selected such as to return pin 1 38 into engagement with the outer end of slot 1 40a in link 140, thereby reestablishing this link to its full effective driving length.Consequently, the abrupt reduction in effective length of link 140 utilized during the coasting zone is progressively restored to its full driving length by the conclusion of the return stroke of the slide 66. Since the return stroke is very lightly loaded, the loss of mechanical advantage occasioned by the reduction in effective driving length is of no concern.

With continued counterclockwise position of crank arm 136 from its position seen in FIGURE 13, it is seen that pin 138 is bottomed against the outer end of slot 1 40a in link 140, and crank arm 146 is pulled through its counterclockwise throw pursuant to propelling slide 56 through its forward charging stroke. When crank arm 136 swings back around to its position seen in FIGURE 11, bringing the axis of pin 138 back into alignment with center line 170, the charging stroke is concluded. Slide 56 is thus returned to its home position, and, switch 1 74 is actuated. Motor 132 coasts to a stop, again without exerting the driving force of the crank arm 1 36 on motor operator slide 56 to disturb its home position.

Since by the conclusion of the operator slide return stroke (FIGURE 13), link 140 has been restored to its full effective driving length (pin 138 bottomed against the outer end of link slot 140a), and this full effective driving length is sustained during the slide charging stroke, clockwise and counterclockwise throws of crank arm 146 are equal, as are the lengths of the operator slide return and charging strokes.

It will be appreciated that the operational effect of the pin 138-cam 142 with link slot 1 40a can be provided in other ways to achieve the desired coasting zone. For example, link 140 may be constituted by a toggle which is controlled such as to partially collapse at the end of the slide charging stroke. Return stroke drive is initially effected through the partially collapsed toggle.

The toggle is then progressively calmed back to its straightened condition by the end of the return stroke. The toggle remains in its fully straightened condition as the operator slide is pulled through its forward charging stroke by crank arm 136.

Moreover, the pin-cam means may be carried by the link to function with a slot in the crank arm pursuant to effecting the requisite coasting zone accommodating lost motion coupling.

Claims

1. A circuit breaker comprising, in combination: A. a manual operating handle; B. a motor operator mechanism; C. a manual operator member drivingly coupled with said handle for motivation thereby through a first operating cycle; D. a motor operator member drivingly coupled with said motor operator mechanism for motivation thereby through a second operating cycle independent of said first operating cycle; E. a contact operating mechanism including a mechanism spring capable of effecting breaker contact closure when charged and discharging to effect breaker contact opening; and F. a charging member drivingly coupling said manual operator member and said motor operator member with said contact operating mechanism such that execution of an operating cycle by either of said members effectuates charging of said mechanism spring.

2. The circuit breaker defined in claim 1, wherein said charging member is mounted for rotary motion in execution of a charging cycle effective in charging said mechanism spring, said charging member eccentrically mounting first and second driven elements, a first drive element connected with said manual operator member and engaging said first driven element during said first operating cycle to drive said charging member into its charging cycle, and a second drive element connected with said motor operator member and engaging said second driven element during said second operating cycle to also drive said charging member into its charging cycle.

3. The circuit breaker defined in claim 2, wherein said first and second driven elements are in the form of pins, and said first and second drive elements are in the form of pawls respectively pivotally connected with said manual operator member and said motor operator member.

4. The circuit breaker defined in claim 3, wherein said manual and motor operator members are independently slideably mounted for reciprocating movement pursuant to executing their respective operating cycles.

5. The circuit breaker defined in claim 2, which further includes a charging spring connected with said charging member such as to be charged via either of said manual and motor operator members during a first portion of said charging member charging cycle, said charging spring discharging during the concluding portion of said charging member charging cycle to power the charging of said mechanism spring.

6. The circuit breaker defined in claim 5, wherein said first and second driven elements are in the form of pins, and said first and second drive elements are in the form of pawls respectively pivotally connected with said manual operator member and said motor operator member.

7. The circuit breaker defined in claim 6, wherein said manual and motor operator members are independently slideably mounted for reciprocating movement pursuant to executing their respective operating cycles.

8. The circuit breaker defined in claim 5, which further includes means conditioned by said contact operating mechanism to prevent rotary motion of said charging member through the concluding portion of its charging cycle only when said mechanism spring is charged, thereby to releaseably sustain said charging spring in its charged condition.

9. The circuit breaker defined in claim 8, wherein said contact operating mechanism includes means selectively operable to prevent contact closure against the bias of said charged mechanism spring.

10. The circuit breaker defined in claim 7, which further includes a hub assembly comprising first and second hubs concentrically mounted for independent rotary movement, said first hub driving interconnecting said manual operating handle with said manual operator member and said second hub drivingly interconnecting said motor operator mechanism with said motor operator member

11. The circuit breaker defined in claim 10, wherein the driving connection of said first hub with said manual operator member is in the form of an eccentric first pin driven by said first hub and received in a transverse slot formed in said manual operator member, whereby cranking motion of said handle in opposite directions reciprocates said manual operator member through a return stroke and a charging stroke during said first operating cycle.

12. The circuit breaker defined in claim 11, wherein the driving connection of said second hub with said motor operator member is in the form of an eccentric second pin driven by said second hub and received in a transverse slot formed in said motor operator member, whereby rotary motion of said second hub in opposition directions by said motor operator mechanism reciprocates said motor operator slide through a return stroke and charging stroke during said second operating cycle.

1 3. A circuit breaker comprising, in combination: A. a manual operating handle; B. a motor operator mechanism; C. a first slide drivingly coupled with said handle and mounted for reciprocating movement thereby through a return stroke and a charging stroke; D. a second slide drivingly coupled with said motor operator mechanism and mounted for reciprocating movement through a return stroke and a charging stroke independently of said first slide;; E. a contact operating mechanism capable of assuming reset and trip conditions, 1) at least one movable contact arm, and 2) a mechanism spring capable of being charged incident with conversion of said operating mechanism from its tripped condition to its reset condition, said charged mechanism spring powering contact closure movement of said arm with said operating mechanism in its reset condition and contact opening movement of said arm upon conversion of said operating mechanism from its reset condition to its tripped condition;; F. a charging member coupled with said contact operating mechanism and operative to convert same from its tripped to its reset condition during an operating cycle thereof, said charging member being independently drivingly coupled with said first and second slides such as to execute an operating cycle initiated by a charging stroke of either of said slides, as said charging member is propelled into its operating cycle by one of said slides, the other of said slides being drivingly decoupled from said charging member.

14. The circuit breaker defined in claim 13, wherein said charging member is mounted for rotary motion and in turn eccentrically mounts first and second driven elements, a first drive element connected with said first slide and drivingly engaging said first driven element to propel said charging member into its operating cycle as said first slide is driven through its charging stroke, and a second drive elements connected with said second slide and drivingly engaging said second driven element to propel said charging member into its operating cycle as said second slide is driven through its charging stroke.

15. The circuit breaker defined in claim 14, wherein said first and second elements are in the form of pins, and said first and second drive elements are in the form of pawls respectively pivotally connected with said first and second slides.

1 6. The circuit breaker defined in claim 14, which further includes a hub assembly comprising first and second hubs concentrically mounted for independent rotary motion, said first hub drivingly interconnecting said handle with said first slide and said second hub drivingly interconnecting said motor operator mechanism with said second slide.

17. The circuit breaker defined in claim 14, which further includes a charging spring connected at one end to said charging member, said charging member, while rotated in one direction in response to a charging stroke by either of said slides, acting during the initial portion of its operating cycle to charge said charging spring, at the conclusion of a slide charging stroke said charging spring discharging to propel said charging member in the same rotational direction through the concluding portion of its operating cycle and to incidentally power the conversion of said contact operating mechanism from its tripped to its reset condition.

18. The circuit breaker defined in claim 17, which further includes prop means operative while said contact operating mechanism is in its reset condition to releaseably engage said charging member such as to prevent the rotation thereof through the concluding portion of its operating cycle, thereby to store the charge in said charging spring until said contact operating mechanism is converted from its reset condition to its tripped condition.

19. The circuit breaker defined in claim 18, wherein said contact operating mechanism further includes hook means selectively releaseably engaging said contact arm to restrain contact closure thereof while said contact operating mechanism is in its reset condition and its mechanism 'spring charged.

20. The circuit breaker defined in claim 1 7, which further includes a hub assembly comprising first and second hubs concentrically mounted for independent rotary motion, said first hub drivingly interconnecting said handle with said first slide and said second hub drivingly interconnecting said motor operator mechanism with said second slide.

21. The circuit breaker defined in claim 20, wherein the driving connection of said first hub with said first slide is in the form of an eccentric first pin driven by said first hub and received in a transverse slot in said first slide, whereby cranking motion of said handle in opposite directions drives said first slide through said return stroke to bring said first drive element into drive engaging relation with said first driven element and then through said charging stroke during which said first drive element engages said first driven element to propel said charging member into its operating cycle.

22. The circuit breaker defined in claim 21, wherein the driving connection of said second hub with said second slide is in the form of a second pin driven by said second hub and received in a transverse slot formed in said second slide, whereby rotary motion of said second hub in opposite directions by said motor operator mechanism drives said second slide through said return stroke to bring said second drive element into drive engaging relation with said second driven element and then through a charging stroke during which said second drive element engages said second driven element to propel said charge member into its charging cycle.

23. A circuit breaker comprising, in combination: A. a manual operating handle; B. a motor operator mechanism; C. a manual operator member drivingly coupled with said handle for motivation thereby through a first operating cycle; D. a motor operator member drivingly coupled with said motor operator mechanism for motivation thereby through a second operating cycle independent of said first operating cycle; E. a movable contact operating mechanism; and F. a member independently drivingly coupling said manual operator member and said motor operator member with said movable contact operating mechanism such that execution of an operating cycle by either of said members conditions said movable contact operating mechanism for breaker closure.

24. A circuit breaker comprising, in combination: A. a contact operating mechanism including 1) at least one movable contact arm, 2) a mechanism spring coupled with said contact arm and operative when charged to drive said contact arm to a closed position, said mechanism spring, upon discharging, driving said contact arm to an open position;; B. a charging mechanism including 1) means coupling said charging mechanism with said contact operating mechanism, 2) a charging spring connected with said coupling means and capable of being charged, upon subsequent discharge thereof, said coupling means being driven through a contact operating mechanism charging cycle pursuant to charging said mechanism spring, and 3) prop means controllably positioned by said contact operating mechanism to permit discharge of said charging spring when said contact arm assumes its open position and to prevent discharge of said charging spring when said contact arm is in its closed position; and C. circuit breaker operator means coupled with said charging mechanism to charge said charging spring.

25. The circuit breaker defined in claim 24 wherein said contact operating mechanism further includes hook means releaseably holding said contact arm in a hooked open position intermediate said open and closed positions against the bias of said charged mechanism spring, while said contact arm is in said hooked open position, said prop means being positioned to prevent discharge of said charging spring.

26. The circuit breaker defined in claim 25 wherein said contact operating mechanism further includes a cradle mounted for movement between a tripped position assumed in reponse to discharge of said mechanism spring and a reset position, said coupling means acting on said cradle during each contact operating mechanism charging cycle to drive said cradle from its tripped position to its reset position pursuant to charging said mechanism spring.

27. The circuit breaker defined in claim 26 which further includes a latch releaseably holding said cradle in its reset position pursuant to sustaining the charged condition of said mechanism spring, the line of action of said charged mechanism spring being continuously oriented to bias said contact arm toward said closed position while said cradle is in its reset position, said hook means arresting movement of said arm toward its closed position such as to hold said contact arm in its hooked open position.

28. A circuit breaker comprising, in combination: A. a contact operating mechanism capable of assuming reset and tripped conditions, 1) at least one movable contact arm, 2) a mechanism spring capable of being charged incident with conversion of said operating mechanism from its tripped condition to its reset condition, said charged mechanism spring powering contact closure movement of said arm with said operating mechanism in its reset condition and contact opening movement of said arm upon conversion of said operating mechanism from its reset condition to its tripped condition, and 3) means selectively releaseably engaging said contact arm to restrain contact closure movement thereof under the urgence of said charged mechanism spring;; B. a charging mechanism capable of assuming charged and discharged conditions, said charging mechanism including 1) a charging spring capable of being charged incident with said charging mechanism assuming its charged condition and then capable of discharging to drive said charging mechanism to its discharged condition, 2) means coupling said charging mechanism with said operating mechanism such that the discharge of said charging spring converts said operating mechanism from its tripped condition to said reset condition, in the process charging said mechanism spring, and 3) means automatically responsive to the condition of said operating mechanism for selectively, releaseably detaining said charging mechanism in its charged condition; and C. motivating means drivingly coupled with said charging mechanism for powering the conversion thereof from its discharged to its charged conditions.

29. The circuit breaker defined in claim 28 wherein said charging mechanism further includes an operator member drivingly coupled with said motivating means for movement thereby through a charging stroke and a return stroke, and a drive element carried by said operator member for drivingly engaging said coupling means to convert said charging mechanism from its discharged condition to its charged condition in response to a charging stroke by said operator member, said drive element being drivingly decoupled from said coupling means during conversion of said charging mechanism from its charged to its discharged condition upon discharge of said charging spring.

30. The circuit breaker defined in claim 29 wherein said motivating means is in the form of a manual operating handle.

31. The circuit breaker defined in claim 29 wherein said coupling means is in the form of a bell crank assembly carried on a shaft for rotation in one direction from a start position to a charged position, a discharged position and back to said start position, said assembly including a crank arm connected at its free end to one end of said charging spring and an eccentric drive pin, said drive element being in the form of a pawl engaging said drive pin to rotate said assembly during an operator member charging stroke from its start position to its charged position where the line of action of said charged charging springs is swung through the axis of said shaft, whereby the discharge of said charging spring rotates said assembly to its discharged position.

32. The circuit breaker defined in claim 31 wherein said crank arm is connected to said charging spring via a lost motion connection to chargingly decouple said crank arm from said charging spring during rotation of said assembly from its discharged position to its start position, said charging mechanism further including separate spring means acting to rotate said assembly from its discharged position to its start position.

33. The circuit breaker defined in claim 32 wherein said detaining means selectively engages said bell crank assembly in its charged position to detain said charging mechanism in its charge condition.

34. The circuit breaker defined in claim 33 wherein said bell crank assembly eccentrically mounts a reset element to drivingly engage said contact operating mechanism pursuant to converting same from its tripped condition to its reset condition incident with movement of said assembly from its charged position to its discharged position.

35. A circuit breaker comprising, in combination: A. a contact operating mechanism including 1) at least one contact arm mounted for movement between open and closed tripped positions, 2) a cradle mounted for movement between reset and tripped positions, 3) a toggle interconnecting said contact arm and said cradle and including a pair of links pivotally interconnected by a knee pin, said toggle maintaining said contact arm in its open position while collapsed and forcing said contact arm to its closed position when straightened, 4) a mechanism spring, connected between a fixed point and said knee pin and adapted to be charged as said cradle moves from its tripped position to its reset position, said charged mechanism spring acting to straighten said toggle while said cradle is in its reset position and discharging to collapse said toggle when said cradle is released from its reset position, incidentally with collapsing said toggle, said mechanism spring driving said cradle to its tripped position; B. breaker opening means operable to release said cradle from its reset position; ; C. a charging mechanism including 1) an operator member, 2) charging means mounted for movement between a charged position and a discharged position, said charging means drivingly coupled with said operator member, 3) means carried by said charging means for engageably moving said cradle from its tripped to its reset position incident with movement of said charging means from its charged to its discharged position, 4) a charging spring connected with said charging means such as to be charged incident with operator member driven movement of said charging means from its discharged to its charged position, whereupon said charging spring discharges to drive said charging means from its charged to its discharged position and thereby propel said cradle from its tripped to its reset position, thus charging said mechanism spring to enpower straightening of said toggle, and 5) a prop selectively operable to releaseably detain said charging means in its charged position and thereby store the charge in said charging spring; and D. circuit breaker operating means drivingly coupled with said operator member.

36. The circuit breaker defined in claim 35, wherein said prop is controlled by said contact operating mechanism to detain said charging means in its charged position while said contact arm is in its closed position and to release said charging means from its charged position when said contact arm is in its open position and said cradle is in its tripped position.

37. The circuit breaker defined in claim 36, wherein said contact operating mechanism further includes a hook operable with said cradle in its reset position to releaseably engageably detain said contact arm in a hooked open position intermediate said open and closed positions against the bias of said charged mechanism spring, whereby said hook and prop function to respectively store charges in said mechanism and charging springs.

38. The circuit breaker defined in claim 37, which further includes breaker closing means acting on said hook to release said contact arm for movement from its hooked open position to its closed position.

39. The circuit breaker defined in claim 38 wherein said prop is controlled by said contact operating mechanism to also detain said charging means in its charged position while said contact arm is in its hooked open position, thereby enabling charges to be concurrently stored in said mechanism and charging springs.

40. The circuit breaker defined in claim 39, wherein said operator member is drivingly coupled with said circuit breaker operating means for movement thereby through a charging stroke and a return stroke, said charging mechanism further including a drive element connected with said operator member for drivingly engaging said charging means to drive same from its discharged position to its charged position in response to a charging stroke by said operator member, said drive element being drivingly decoupled from said charging means during movement of the latter from its charged to its discharged position as propelled by the discharge of said charging spring.

41. The circuit breaker defined in claim 40, wherein said charging means is in the form of a bell crank assembly carried on a shaft for rotation in one direction from a start position successively to said charged position, said discharged position and back to said start position, said assembly including a crank arm connected at its free end to one end of said charging spring and an eccentric drive pin, said drive element being in the form of a pawl engaging said drive pin to rotate said assembly during an operator member charging stroke from its start position to its charged position where the line of action of said charged charging spring is swung through the axis of said shaft whereby the discharge of said charging spring drivingly rotates said assembly to its discharged position.

42. The circuit breaker defined in claim 41, wherein said crank arm is connected to said charging spring via a lost motion connection to chargingly decouple said crank arm from said charging spring during rotation of said assembly from its discharged position to its start position, said charging mechanism further including separate spring means acting to rotate said assembly from its discharged position to its start position.

43. The circuit breaker defined in claim 41, wherein said prop selectively engages said bell crank assembly in its charged position to store a charge in said charging spring.

44. The circuit breaker defined in claim 43, wherein said bell crank assembly eccentrically mounts a reset element to drivingly engage said cradle and drive same from its tripped position to its reset position incident with movement of said assembly from its charged position to its discharged position.