US3045083A

US3045083A - Spring closing mechanism for circuit breakers

Info

Publication number: US3045083A
Application number: US822900A
Authority: US
Inventors: Gayne D Gamel; Hauser Richard
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1959-06-25
Filing date: 1959-06-25
Publication date: 1962-07-17
Anticipated expiration: 1979-07-17
Also published as: DE1168538B

Description

y 17, 1962 G. D. GAMEL ETAL 3,045,083

SPRING CLOSING MECHANISM FOR CIRCUIT BREAKERS 5 Sheets-Sheet 1 Filed June 25, 1959 INVENTORS Goyne D. Gamel 8 Richard Houser.

WITNESSES July 17, 1962 s. D. GAMEL ETAL 3,045,033

SPRING CLOSING MECHANISM FOR CIRCUIT BREAKERS Filed June 25, 1959 5 Sheets-Sheet 2 Fig.2.

July 17, 1962 GAMEL ETAL 3,045,083

SPRING CLOSING MECHANISM FOR CIRCUIT BREAKERS Filed June 25, 1959 5 Sheets-Sheet 3 Fig. 3.

July 17, 1962 G. D. GAMEL ET AL 3,045,083

SPRING CLOSING MECHANISM FOR CIRCUIT BREAKERS Filed June 25, 1959 5 SheetsSheet 4 Fig. 4.

97 ?:::t I20? Y? I I00 I95 93 I23 I25 a G-us 1 I85 I83" Mm I75 I8I I39 I I |7| l 149 i 3 M J J C J 153 5 f J f July 17, 1962 Filed June 25, 1959 G. D. GAMEL ETAL SPRING CLOSING MECHANISM FOR CIRCUIT BREAKERS I 5 Sheets-Sheet 5 Fig. 5.

79 BI 83 89 L 88 I05 I95 75 I25 l 'r 69 m 3,045,083 Patented July 1 7, '1962 1 tie 3,045,083 SPRING CLOSING MECHANISM FQR CIRCUHT BREAKERS Gayne D. Game], Murrysville, and Richard Hansel, Forest Hills, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed June 25, 1959, Ser. No. 822,999 12 Claims. (Cl. 200-74) This invention relates to circuit breakers and more particularly to a spring closing mechanism for circuit breakers.

Frequently, during circuit breaker operation, it is necessary that the breaker be closed against an energized line. Because of the high magnetic forces which oppose such a closing operation, it is necessary that the contacts of the breaker be closed rapidly and forcefully. In a manually operated circuit breaker, the operators strength cannot be relied upon to produce the speed and force necessary for effective operation.

Accordingly, it is an object of this invention to provide a circuit breaker embodying a spring closing mechanism that is not dependent upon the strength of the operator for eifective operation.

Another object is to provide a circuit breaker embodying a spring closing mechanism that utilizes the expanding force of a compression spring during a closing operation.

Another object is to provide a circuit breaker embodying a spring closing mechanism wherein a closing spring is compressed and released by a continuous motion applied to an operating handle.

A further object is to provide a circuit breaker having a spring closing mechanism and a trip-free operating mechanism wherein the Weight of the spring closing mechanism assists in resetting the trip-free operating mechanism during an opening operation.

During the life of a circuit breaker, it is often necessary to operate the mechanism slowly to more easily observe the movement and relative positions of the parts for maintenance purposes.

Accordingly, it is afurther object of this invention to provide a circuit breaker embodying stored energy closing means for rapidly closing the circuit breaker, and means for slowly closing the circuit breaker contacts.

A further object is to provide a circuit breaker embodying a spring closing mechanism wherein the contacts of the circuit breaker can be closed slowly without utilizing the energy of the closing spring.

A further object is to provide a circuit breaker embodying a spring closing mechanism and an operating linkage latchable in a closed position wherein the contact means of the circuit breaker can be slowly closed without latching the operating linkage in a closed position.

Other objects of the invention will be explained hereinafter or will be apparent to those skilled in the art.

The invention both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of a preferred embodiment thereof when read in conjunction with the accompanying drawings.

In said drawings:

FIGURE 1 is a side elevational view, partly in section, of a circuit breaker embodying the principles of the invention;

FIG. 2 is a sectional view of the operating mechanism when the circuit breaker is in the open circuit position;

FIG. 3 is a sectional view taken on line III-III of FIG. 2;

FIG. 4 is a sectional view, similar to that of FIG. 2, showing the position of the operating mechanism at the moment when the closing spring, which has been compressed, is about to be released; and,

FIG. 5 is a sectional view, similar to that of FIG. 2, showing the operating mechanism in the closed circuit position.

Referrin to FIG. 1 of the drawings, the circuit breaker is of the multipole type, each pole unit including a separable contact structure, indicated generally at 11, and an overcurrent trip device indicated generally at 13. Since the poles are similar, only the center pole of the circuit breaker is shown and described. The contact structure and the trip device for each pole are mounted on separate insulating bases 15 which are rigidly secured to a metal panel 17. The bases 15 of the several pole units are secured to the panel 17 by means of screws 19.

The contact structure 11 comprises stationary main contacts 23, a stationary intermediate contact 24 and a stationary arcing contact 25, all supported on the inner end of a terminal conductor 27 which extends through suitable clearance openings in the base 15 and panel 17. Cooperating with the stationary main, intermediate and arcing contacts '23, 24 and 25, respectively, are movable main contacts 29, a movable intermediate contact 30 and a movable arcing contact 31. The stationary main contacts 23 are pivotally supported and are biased into engagement with the movable main contacts in the closed position of the breaker. The stationary arcing contact is mounted for limited movement in a well known-manner and is biased into engagement with the moving arcing contact in the closed position. The movable main contact 29, the movable intermediate contact 30 and the movable arcing contact 31 are supported on a movable switch member 35 pivotally mounted by means of a pivot pin 37 on a bracket 39. The bracket 39 is secured by means of a screw dito the inner end or a lower terminal member 43. Spring-biased contact members 45 provide a wiping contact with the movable switch member 35 adjacent the pivoted end thereof. A spring 47, which is compresssed between a spring seat 49 on the base 15 and the movable switch member 35, biases the latter in opening direction.

The movable contact structure is normally maintained in the closed position by an operating mechanism, indicated generally at 61 (FIG. I), mounted in a U-shaped frame comprising spaced side members '65 and a connecting cross member 67, and is supported on a platform 69, which forms a cross member of a main bracket comprising a pair of spaced side members 71 (FIG. I) joined at their outer ends by the platform 69. The platform extends across the width of the breaker and the side members 71 are rigidly secured to the panel 17 on the outsides of the two outer pole units.

The operating mechanism includes an operating lever 73 pivotally mounted on a pivot pin 75 supponted in the side members of the frame. The lever 73 comprises a pair of spaced members joined by a cross member 77. A rod 79 which extends across all of the poles of the breaker, is supported between the spaced members of the lever 73. The rod 79 is operatively connected to the movable switch member 35 by means of an insulating connesting member 81 and pivot pin 82 in the switch member.

There is a connecting member 81 for each pole of the breaker connecting the rod 7910 the moving contact structure for each pole unit so that upon operation of the rod 79, the movable contact structures for all three poles move in umson.

An operating linkage comprising

toggle links

83, 85 and 87 is provided to hold the lever 73 and consequently the movable contacts in the closed position and to operate the movable contacts to open and closed positions. Each of these links has two identical legs integral with a cross portion, the cross portion of the link 87 being shown in FIG. 3 at 88. The toggle link 83 is pivotally connected to the lever 73 by a pivot pin 89 and the toggle link 85 is connected by a knee pivot pin 91 to the toggle link 83 and by a knee pivot pin 93 to the toggle link 87. The toggle link 87 is pivotally mounted on a fixed pivot 97 in the frame members 65.

The

linkage

83, 85, 87 comprises two toggles one of which 83, 85 functions as a tripping toggle and the other 85, 87 as a closing toggle. The slightly underset above a line drawn through the

pivot pins

89, 93 and the

closing toggle

85, 87 is normally slightly underset below a line drawn through the

pivots

91, 97.

The

tripping toggle

83, 85 is normally biased in a direction to cause its collapse by the springs 4-7 which bias the moving contact structures for the several poles of the breaker in opening direction and bias the connecting members 81 toward the left. The tripping

toggle

83, 85 is normally prevented from collapsing by means of a main latch member 99 pivoted on a pin 100 and connected by a link 101 to the knee pin 91 of the tripping toggle, the link 101 being connected to the latch member 99 by a pivot pin 103.

The main latch 99 is held in latching position by an intermediate latch lever 105 pivoted on a pin 107 supported in the frame members 65. The latch lever 105 carries a latch roller 111 which normally engages the main latch 99 to releasably hold the latter in holding position. The latch lever 105 at its lower end carries a latch portion 113 which normally engages a latch roller 115 on a latch member 117 pivoted on a pin 119 in the frame members 65. The latch lever 105 and the member 117 are biased, by spring means (not shown), to their latching positions. Rigidly mounted on the right hand end of the channel-shaped member 117 is a trip bar 123 which extends across all of the poles of the breaker and has secured thereto an insulating bracket 125 for each pole of the breaker. Each of the brackets 125 has a headed screw 127 adjustably mounted therein for cooperating with the trip device 13 for the corresponding pole unit.

As long as the main latch 99 is held in latching position by the latching mechanism just described, the tripping

toggle

83, 85 will, through the link 101, be held in the position shown in which the breaker contacts are held in the closed position. The

closing toggle

85, 87 is normally prevented from collapsing by a shouldered support member 131 pivoted on the pin 107 and biased by a spring 133 into supporting engagement with the knee pin 93 of the closing toggle.

Referring to FIG. 1, the circuit breaker is in the closed and latched position with the support member 131 supporting the

closing toggle

85, 87 in its extended thrust transmitting position. The circuit breaker is automatically tripped open by operation of a tripping electromagnet indicated generally at 13. The tripping electromagnet 13 may be of any suitable type, and it is arranged to trip the breaker after a time delay and also instantaneously in response to overload currents of predetermined values.

tripping toggle is normally Upon the occurrence of an overload current, the tripping electromagnet produces an upward thrust of a rod 135 which strikes the screw 127 of the latch member 117. This moves the member 117 counterclockwise disengaging the latch roller 115 from the latch portion 113 of the latch lever 105. The latching engagement of the main latch 99 with the latch roller 111 is of the slip-off type, and as soon as the latch lever 105 is released, it is moved to unlatching position by the upward force applied to the main latch 99 through the link 101. The tripping

toggle

83, 35 immediately collapses upwardly permitting counterclockwise movement of the operating lever 73 and opening movement of the movable contact structure. During the collapse of the tripping

toggle

83, 85, a portion of the toggle link 85 engages and actuates the support member 131 against the bias of the spring 133 to a non-supporting position, thereby freeing the

closing toggle

85, 87. The closing toggle thereupon collapses downwardly under the weight of the

toggle linkage

83, 85 and 87, and the weight of a spring closing mechanism (to be described later), and during its collapse resets and relatches the tripping toggle 83, S5.

The

linkages

83, 85 and 85, 87 are trip free. During an opening operation, the contacts cannot be closed until after the closing toggle collapses resetting the linkages for a closing operation.

The opening operation, as described, was initiated by energization of the tripping electromagnet 13 rotating the latch member 117 counterclockwise. The opening operation can also be initiated manually by a trip lever (not shown) that also rotates the latch member 117.

A spring closing mechanism, indicated generally at 137, is provided for manual closing of the circuit breaker.

The spring closing mechanism 137 is partially enclosed Within a U-shaped housing 139 which is welded or otherwise attached to the underside of the platform 69. This housing has two vertically

elongated openings

141 and 143 on each side which receive

cross bolts

145 and 147 which move vertically in these openings. The cross bolt 145 extends through openings in the legs of a U-shaped top spring support 149 which spring support is enclosed within the housing 139. The cross bolt 147 extends through openings in the legs of a U-shaped bottom spring support 151 which is also enclosed within the housing 139. The

cross bolts

145 and 147 prevent horizontal rotating movement of the top and bottom spring supports. An operating compression spring 153 is disposed between the top and the bottom spring supports 149 and 151. Two

guide bolts

155 and 163 extend through openings in the bottom and top spring supports. They serve to keep the spring 153 in place; to prevent vertical wobbling movement of the bottom and the top spring supports, and to preset the amount of vertical rectilinear movement of the spring supports.

The guide bolt 155 is connected to the bottom spring support 151 by nuts 157 and 159 (FIG. 3) which are fastened to the guide bolt on each side of the bottom spring support. A stop nut 161 is fastened to the guide bolt 155 on the upper side of the top spring support 149. The guide bolt 163 is connected to the top spring support 149 by

nuts

165 and 167 which are fastened to the guide bolt on each side of the top spring support. A stop nut 169 is fastened to the guide bolt 163 on the lower side of the bottom spring support 151. The guide bolt 155 moves vertically with the bottom spring support, and the guide bolt 163 moves vertically with the top spring support.

A toggle link 171 is pivotally connected to the vertically movable cross bolt 145, and a toggle link 173 is pivotally connected to a stationary cross bolt 175 which 18 rotatably connected to the sides of the U-shaped housing 139. The toggle link 173 is also pivotally connected to the lower end of a vertically movable thrust rod 177 by a pivot pin 179. The thrust rod 177 has an opening in its upper end for receiving the pivot pin 93. The toggle links 171 and 173 are pivotally connected by a pivot pin 181.

A lift link 183 is provided for lifting the bottom spring support 151. The lift link 183 is a flat member that passes through an opening in the top spring support 149,

and has an angle shaped lower portion with a flat leg 185 projecting through an opening in the bottom spring support 151. The cross bolt 147 passes through an opening in the projecting fiat leg 185 of lift link 183. Upward movement of the lift link 183, therefore, lifts the bottom spring support 151.

A handle 185 (FIG. 2) having a horizontal tubular portion 186 is provided for operating the spring closing mechanism. The handle is removably mounted on an operating shaft 187 by a pivotal latch 189 biased to latching position by a spring 191. The handle has an opening for receiving a spring 193 and the outer end of the operating shaft 187. There are two slots 195 in the handle horizontal tube 186 (only one being shown in FIGS. 4 and for receiving the ends of a pin 197 which extends through the operating shaft 187. These slots are positioned to engage the pin 197 when the handle 185 is moved to a 2:00 oclock position and pressed in against the bias of the spring 193. There is no compression force on the spring 193 when the parts are in the position shown in FIG. 2 and, therefore, the handle 185 can rotate freely on the operating shaft 187.

The operating shaft 187 is rotatably mounted in a sleeve 199 which is attached to the inside base of the housing 65 by a bracket 201. A plate 203 (FIGS. 2 and 3) is secured to the inner end of the operating shaft 187. The plate 203 is pivotally connected to the upper end of the lift link 183 by a pivot pin 285 (FIG. 3). A contact roller 207 is rotatably mounted on the pivot pin 205.

Referring to FIGS. 2 and 3, the parts of the circuit breaker are shown in the open circuit position. In order to close the breaker, the handle 185 is rotated counterclockwise to a 2:00 oclock position. This positions the slots 195 (FIGS. 4 and 5) to receive the pin 197 on the operating shaft 187 as the handle is pressed in against the bias 'of the spring 193 (FIG. 2). The handle 185 is then rotated clockwise, thereby rotating the operating shaft 187 and the plate 203 in a clockwise (FIG. 3) direction. As the plate 203 rotates, it lifts the lift link 183 and the bottom spring support 151. Upward movement of the top spring support 149 is prevented because the toggle links 171 and 173 are on dead center. The upward movement of the lift link 183, therefore, compresses the spring 153 between the bottom-spring support 151 and top spring support 149 (FIG. 4).

In the position shown in FIG. 4, the contact roller 207 of the lift link 183 is positioned between .the legs of the toggle link 87, and is just making contact with the underside of the cross portion 88 which is integral with the legs of the toggle link 87. Upon further clockwise rotation of the operating handle 185, the contact roller 207 is raised with the lift link 183, and it pivots the toggle link 87 counterclockwise about the pivot pin 97 raising the thrust rod 177 which rotates the toggle link 173 clockwise about its pivot 175. This moves the

toggle

171, 173 01f of dead center permitting it to collapse which, in turn, permits upward movement of the top spring support 149 under the expanding force of the compression spring 153.

As the top spring support 149 is forced up, it rapidly collapses the

toggle

171, 173 and forces the thrust rod 177 upwards. As shown in FIGS. 2 and 4, the

closing toggle

85, 87 is collapsed and the tripping

toggle

83, 85 is held in thrust transmitting position. Therefore, as the thrust rod 177 is forced upwardly, it straightens the

closing toggle

85, 87 moving the operating lever 73 clockwise to close the breaker '(FIG. 5). The operator then releases hold on the handle 185, and the spring 193 moves the handle axially out of engagement with the pin 197 permitting the handle to fall to its normal vertical position by gravity.

The closing operation under the expanding force of the compression spring 153 is rapid and forceful. For maintenance purposes, it is desirable to be able to close the breaker contacts 23, 29; 24, 3t}; and 25, 31 slowly so that the interaction and relative positions of these contacts may be observed. The circuit breaker contacts of this invention may be closed slowly by first breaking the

toggle

171, 173 off of dead. center by slightly pushing rod 79 towards the closed position. This permits upward movement of the top spring support 149 and prevents complete compression of the spring 153. The toggle .171, 173, therefore, slowly collapses and forcesthe thrust rod 177 upwards as the bottom spring support 151 is raised. The only closing force, therefore, is that applied to the handle 185 in order to raise the bottom spring support 151. In this manner, the speed of closing the contacts is determined by the speed at which the operator rotates the handle 185.

During this slow closing operation the spring 153 compresses to some extent under the restraining forces of the operating mechanism and movable contact structure. This compression is such that the operating

linkage

83, and 87 will not be latched in a closed position by the support member 131 when the lift link 183 has reached its uppermost position. The contacts, however, close before the operating

linkage

83, 85 and 87 reaches a latched position. For maintenance purposes, therefore, an operator .can. slowly and continually open and closethe contacts without latching the operating linkage in a closed position. This permits observation of the wiping action and relative positions of the contacts during a closing operation.

It is important to note that the operating

linkage

83, 85 and 87 is trip free. During the opening operation as previously described, the tripping

toggle

83, 85 first collapses, and until the

closing toggle

85, 87 collapses downwar-dly to reset the tripping

toggle

83, 85 into a thrust transmitting position, the circuit breaker cannot be closed. During the opening operation, it is the weight of the spring closing mechanism 137 and of the operating

linkage

83, 85 and 87 that pulls the thrust rod 177 and hence the

closing toggle

85, 87 down to reset the linkages.

From the foregoing description, it will be apparent that a spring closing mechanism has been provided which so utilizes the energy of a compression spring that an operator may forcefully and rapidly close the contacts of a circuit breaker. The spring closing mechanism also assists in resetting the trip-free linkages of the circuit breaker during an opening operation. Moreover, the circuit breaker contacts can be closed slowly without utilizing the energy of the compression spring when a careful observationof the interaction and relative positions of parts is desired for maintenance purposes.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made wihout depart. ing from the spirit and scope of the invention.

We claim as our invention:

1. A circuit breaker having relatively stationary contact means and movable contact means cooperating with said relatively stationary contact means to open and close the circuit breaker,a closing spring, means for compressing the closing spring, means for releasing the compressed closing spring to rapidly close the circuit breaker, and means for slowly closing thecircuit breaker contact means without utilizing the expanding force of the closing spring.

2. A circuit breaker having relatively stationary contact means and movable contact means cooperating with said relatively stationary contact means to open and close said circuit breaker, stored energy closing means, means for operating said stored energy closing means to rapidly close said circuit breaker, and means for slowly closing said circuit breaker contact means without utilizing the energy of said stored energy closing means.

3. A circuit breaker comprising, in combination, relatively stationary contact means, movable contact means cooperating with said relatively stationary contact means to open and close said circuit breaker, an operatinglinkported between said age for moving said movable contact structure, means for latching said operating linkage in a closed position, a closing spring, means for compressing said closing spring, means for releasing said compressed closing spring to rapidly close said circuit breaker, and means for slowly closing said circuit breaker contact means without latching said operating linkage in a closed position.

4. In a circuit breaker having relatively stationary contact means and movable contact means cooperating therewith to open and close said circuit breaker, a bottom spring support, a top spring support, a closing spring supbottom and top spring supports, restraining means for preventing vertical movement of said top spring support, lifting means for raising said bottom spring support to compress said closing spring between said top and bottom spring supports, releasing means for releasing said restraining means after said closing spring has been compressed permitting expansion of said compressed closing spring to rapidly close said circuit breaker, an operating handle, said lifting means and said releasing means being operated by said operating handle, and means for releasing said restraining means before said closing spring is compressed permitting a slow closing of said circuit breaker contact means.

5. In a circuit breaker having relatively stationary contact means and movable contact means cooperating therewith to open and close said circuit breaker, a bottom spring support, a top spring support, a closing spring supported between said bottom and top spring supports, restraining means for preventing vertical movement of said top spring support, lifting means for raising said bottom spring support to compress said closing spring between said top and bottom spring supports, means for releasing said restraining means after said closing spring has been compressed permitting expansion of said compressed closing spring to rapidly close said circuit breaker, and means for releasing said restraining means before said closing spring is compressed permitting a slow closing of said circuit breaker contact means.

6. In a circuit breaker having relatively stationary contact means and movable contact means cooperating therewith to open and close said circuit breaker, a bottom spring support, a top spring support, a closing spring supported between said bottom and top spring supports, restraining means for preventing vertical movement of said top spring support, lifting means for raising said bottom spring support to compress said closing spring between said top and bottom spring supports, releasing means for releasing said restraining means after said closing spring has been compressed permitting expansion of said compressed closing spring to rapidly close said circuit breaker, an operating handle, said lifting means and said releasing means being operated by a continuous movement of said operating handle, and means for releasing said restraining means before said closing spring is compressed permitting a slow closing of said circuit breaker contact means.

7. A circuit breaker including, in combination, relatively stationary contact means, a movable contact structure cooperating with said stationary contact means to open and close said circuit breaker, a trip free operating linkage in thrust transmitting position to move said movable contact structure to close said circuit breaker, spring closing means cooperating with said operating linkage to close said circuit breaker, said operating linkage collapsing and being reset to a thrust transmitting position during an opening operation, and the weight of said spring closing means contributing to reset said operating linkage during an opening operation.

8. A circuit breaker having relatively stationary contact means and a movable contact structure cooperating therewith to open and close said circuit breaker, a trip free operating linkage for moving said movable contact structure, a spring closing mechanism including a closing spring for operating said trip-free operating linkage to 8 close said circuit breaker, an operating handle movable to compress said closing spring, releasing means operated by said handle for releasing said compressed closing spring, the expanding force of said released closing spring moving said movable contact structure to close said circuit breaker, and the Weight of said spring closing mechanism contributing to reset said trip-free operating linkage during an opening operation.

9. A circuit breaker having relatively stationary contact means and a movable contact structure cooperating therewith to open and close said circuit breaker, a tripfree operating linkage for moving said movable contact structure, a spring closing mechanism including a closing spring for operating said trip-free operating linkage to close said circuit breaker, an operating handle movable to compress said closing spring, releasing means operated by said handle for releasing said compressed closing spring, the expanding force of said released closing spring moving said movable contact structure to close said circuit breaker, said closing spring being compressed and released by a continuous movement of said operating handle, and the weight of said spring closing mechanism contributing to reset said trip-free operating linkage during an opening operation.

10. A circuit breaker comprising, in combination, relatively stationary contact means, a movable contact structure cooperating with said stationary contact means to open and close said circuit breaker, an operating linkage for moving said movable contact structure to close said circuit breaker, a thrust rod having one end connected to said operating linkage, a toggle connected to the other end of said thrust rod, a top spring support connected to said toggle, said toggle being positioned substantially on dead center preventing upward movement of said thrust rod and said top spring support, a bottom spring support, a closing spring supported between said top and bottom spring supports, an operating handle, means operated by said operating handle to break said toggle off spring support compressing said closing spring, and means operating by said operating handle to break said toggle ofi of dead center allowing upward movement of said top spring support and said thrust rod under the expanding force of said compressed closing spring to close said circuit breaker.

11. A circuit breaker comprising, in combination, relatively stationary contact means, movable contact means cooperating with said stationary contact means to open and close said circuit breaker, an operating linkage for moving said movable contact means to close said circuit breaker, a thrust rod having one end connected to said operating linkage, a toggle connected to the other end of said thrust rod, a top spring support connected to said toggle, said toggle being positioned substantially on dead center preventing upward movement of said thrust rod and said top spring support, a bottom spring support, a closing spring supported between said top and bottom spring supports, an operating handle for lifting said bottom spring support to compress said closing spring, means operated by said operating handle to break said toggle off of dead center allowing upward movement of said top spring support and said thrust rod under the expanding force of said compressed closing spring, and means for breaking said toggle prior to the initiation of a closing operation allowing the circuit breaker contact means to be closed slowly by operation of the operating handle.

12. A circuit breaker comprising a pair of contacts cooperable to open and close an electric circuit, a spring closing mechanism comprising a first spring support and a second spring support, a compression-type spring sup ported between said first and second spring supports, an operating handle rotatable to move said first spring support toward said second spring support, an operating linkage comprising a toggle in a latching position to prevent movement of said second spring support while said operating handle is being rotated whereby said spring I 3,045,083 n 9 -1@ becomes compressed between said first and second spring References Cited in the tile of this patent supports, means operable by continued rotational move ment of said operating hand-le after said spring is eom- UNITED STATES PATENTS pressed a certain amount to unlatch said'toggle whereupon 1,799,099 Johnson Mar. 31, 1931 said compressed spring expands to move said second 5 2,769,374 OOggeshall etal NOV-6, 1954 spring support away from said first spring support, and 2,848,575 Hahn Aug. 19, 1958 said movement of said second spring support effecting 2,914,635 Lester et a1 Nov. 24, 1959 closing of said contacts. 2,943,163 Hay June 28, 1960 UNITED STATES CERTIFICATE 0 PATENT OFFICE F CORRECTION July 17, 1962 Patent No.

numbered pata said Letters Patent should read as olumn 8, llne 38 for "break sa1d toggle off" read lift sald bottom llne 40, for "operating", first occurrence, read operated Signed and sealed this 19th day of February 1963.

(SEAL) Attest:

ESTON G. JOHNSON DAVID L. LADD Attesting Officer Commissioner of Patents