US2141272A - Electric switch - Google Patents

Description

Dec. 27, 1938.

C. H. HILL ELECTRIC SWITCH Filed Nov. 21; 1935 2 Sheets-Sheet 1 Inventor. Charles H. Hill,

. 9 HIS Attorney Dec. 27, 1938. y c. H. HILL ELECTRIC SWITCH Filed Nov. 21, 1935 2 sheets-shut 2 Inventor- Char-les H. Hill, by 3 t3: othey.

Patented Dec. 27, 1938 UNITED STATES PATENT OFFICE ELECTRIC SWITCH Charles H. Hill, Drexel Hill, Pa., assignor to General Electric Company, a corporation of New York My invention relates to improvements in electric switches and more particularly to circuit breakers of the trip free type which operate automatically in response to abnormal circuit condi- 5 tions to interrupt a circuit. An object of my invention is to provide a circuit breaker which is light in weight, compact and easy to operate. Another object of my invention is to provide a circuit breaker which is adaptable with a mini- 10 mum number of parts to either single pole or multipole construction and in which-the precision requirements for the assembly of part assemblies are greatly reduced. A further object of my invention is to provide a circuit breaker 16 which will not be falsely tripped by shocks or vibrations. A still further object of my invention is to provide a circuit breaker construction which does not involve flying latches with their inherent necessity for guiding and special adjustment of co-operating parts. These and other objects of my invention will appear in more detail hereinafter.

Circuit breakers, whether power or manually operated; should not require such effort as to 5 necessitate large power-operated devices or long operating levers to gain the necessary mechanical advantage because such things increase space requirements and add to the cost and difficulties of operation. In accordance with my invention, I

30 provide ease of operation and to a certain extent, compactness of structure by combining in the operating mechanism the mechanical advantages of both the toggle and the inclined plane. Also, on ships, as well as in power stations where land 35 Values are high and space is limited, a compact circuit breaker construction is desirable. To this end, in accordance with my invention, I provide a compact operating mechanism and mount the operating and latching mechanisms in the same 40 frame. Inasmuch as circuit breakers must be providedin difierent numbers of poles, adaptability of parts is desirable from economical and service standpoints, so that any multipole circuit breaker can be assembled from the parts of a 45 single pole breaker with the addition 01 the fewest possible special parts. To this end and in accordance with my invention, I provide a circuit breaker-constructionembodying a, minimurn number of parts which can be assembled 50 to form circuit breakers with any desired number of poles. From the standpoint of economy in cost, as well as the expense of switchboard structure and also dead weight on ships or other moving devices requiring any considerable num- 55 ber of circuit breakers, reduction in weight is desirable. In accordance with my invention, I provide a circuit breaker construction which eliminates the necessity for the use of castings and the excess weight involved therein by the use of punched parts and the like and does not 5 depend on the mechanical strength of copper, as it is necessary to use only enough copper for the desired current carrying capacity. Where it becomes necessary to line up mechanisms with each other, as for example the operating and tripping mechanisms of a multipole breaker, accuracy in assembly is paramount and, consequently, the cost of assembly is high. In accordance with my invention, I provide a circuit breaker construction whereby the requirement for a high degree of precision in assembly between these two mechanisms is eliminated. Obviously on ships, and particularly war craft, circuit breakers must not open at crucial moments as a result of shock or vibrations caused by gun fire or otherwise. r

provide means whereby the circuit breaker can Q be locked in the circuit closing position regardless of any action of the tripping mechanism. Also in accordance with my invention, I provide a circuit breaker construction which does not embody any flying latch to bang around or require guiding and special adjustment of cooperating parts.

I My invention will be better understood from the following description when considered in connection with the accompanying two sheets of drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawings, Fig. 1 is a side elevation partly broken away and partly in section of a circuit breaker embodying my invention, the circuit breaker being shown in the closed position; Fig. 2 is a detail of a part of the embodiment of invention shown in Fig. 1; Fig. 3 is a partial side elevaton of the operating and tripping mechanisms of the circuit breaker shown in Fig. 1 with the parts in the tripped position; Fig.4 is a partial side elevation of the operating and tripping mechanisms of the circuit breaker-shown in Fig. 1 with the parts positioned in the reset condition preparatory to closll ing the circuit breaker; Fig. 5 is a detail of the mechanism for mechanically tripping the circuit breaker and also for locking the circuit breaker against tripping; Fig. 6 isan exploded view of a shockproof latch embodying my invention; and Figs. 7 and 8 are outline views illustrating the assembly of two and-three-pole circuit breakers embodying my invention.

In the illustrated embodiment of my invention, a base or switchboard panel I!) of suitable insulating material has'secured thereto fixed contacts, shown as pairs of strips or bars H and I2. These may be of copper, and the outer bars may be provided with silver inserts l3 to provide the actual contact engaging surfaces. The bars l2 in the lower fixed contact are preferably separated as shown for cooling purposes. The fixed contacts are arranged to be bridged by a movable contact shown as a block-type contact l4, which may be of copper and which may have silver inserts l5 to provide the contact engaging surfaces. Secondary and tertiary cooperating contacts i6 and I! may also be provided, as is customary in air circuit breakers. As shown, the movable contact I4 is connected to one of,the fixed contacts 12 by a fiexible lead l8 and also to the movable contacts of the secondary and tertiary pairs by a flexible lead IS in order to provide a suitable current conducting path whereby the arc or arcs will be interrupted at the contacts I6 and i1 provided for this purpose. As shown, the movable contact I4 is pivotally mounted at 20 on a contact carrying arm 2 l, which also serves to support the movable contacts of the secondary and tertiary pairs l6 and I1. This arm is pivotally supported at 22 on a frame 23, which is suitably supported on the base I0 and which, as shown, constitutes the support for the operating and latching mechanisms of the circuit breaker.

In order to provide a wiping contact action, the movable contact l4 has, in accordance with my invention, a lost-motion mounting, as shown. Thus, its pivot pin 29 may be set in a slot 20' which is inclined downwardly towards the fixed contacts as shown or is oblique to the face of the contact l4. Then as the circuit breaker opens, the resilient action of suitable means such as back-up springs 2i tends to force the pin 20 downward in the slot 20 so that, when the circuit breaker is closed the contact I4 is caused to rise upward and thus produce a wiping action on the silver insets l3 and I5 to clean them. These insets may be grooved or slotted diagonally to provide a place for foreign matter to go as the wiping action takes place on the closing of the circuit breaker.

In accordance with my invention, I provide means employing the principle of the toggle and the inclined plane for actuating the movable contact to and holding it in the circuit closed position. The toggle comprises a link 24, one end of which is pivotally connected to the circuit controlling member 2|, as at 25, and a link 26, one end of which is pivotally connected to a fixed support, such as a pivot 21, in the frame 23. Resilient means, such as a helical spring 23 may be connected between the pivots 25 and 2'! to expedite the circuit opening movement of the contact arm 2!.

For straightening the toggle 24-2G to move the contact i4 to the circuit closing position, I provide a wedging means, such as the cam-faced member 29, which is movable to engage the center joint of the toggle, preferably against a roller 30 mounted on the center pivot 3|. In order to obtain the desired inclined plane action and also the necessary trip-free action of the circuit breaker, the wedging member 29 is suitably supported or guided by a movable abutment 32 and is provided with suitable cam faces 33 and 34, which respectively engage the roller 30 on the toggle and a roller 35 on the abutment 32.

For actuating the cam member 29 between the toggle and the abutment in order to move the cam faces 33 and 34 along their respective rollers 30 and 35, the cam member may be pivotally mounted as at 36 on an arm of an operating member or crank 31, which may be pivotally supported at 21 co-axially with the toggle link 26. For connecting two or more poles together to form a multipole breaker, the toggle link 26 may be in the form of a crank having an arm 38 whereby the toggle mechanisms of the different poles can. be interconnected through a crossbar 39 for simultaneous operation by a single operating mechanism, the connecting bar 39 preferably being of suitable insulating material or so constructed that the different poles are insulated each from the other.

In order to prevent the opening of the circuit breaker bya counterclockwise movement of the operating member 31, whether done intentionally or by jars or vibration, a latching member 40 .pivoted on the frame 23 at 4| may be biased by suitable means, such as a spring 42, to engage a projection 43 on the cam member 29 whereby to prevent movement of the cam member in such a way as to permit the collapse of the toggle In order to secure the desired trip-free action and at the same time provide a shockproof mechanism, I support the movable abutment 32 by a collapsible mechanism. As shown this comprises an underset toggle including links 44 and 45 which are respectively pivoted to the abutment 32 at 46 and to the frame 23 at 47. Since the toggle 4445 is underset and the pressure opening tendency of the circuit breaker against the wedging member 29 is in a direction to turn the abutment 32 clockwise about its pivotal support 49, I provide a shockproof latching mechanism for preventing this collapse of the abutment support. As shown, this latching mechanism includes a latch 49 mounted on a trip shaft 50 and provided with a toggle supporting face 5| which is engaged by an extension of the toggle link 45 to the left of its pivot 46. The latch 49 is biased to latching position against a stop 52 by suitable means, such as a spring 53. Since the duties of a latch are severe, particularly where the latch is subject to the corrosive action of a salt-water atmosphere, stainless steel is sometimes used for such devices. It is not mechanically simple or economical to provide holes of other than circular cross-section in material of this type when used for circuit breaker latches. I may, therefore, employ the construction shown more in detail in the exploded view of Fig. 6. Thus, instead of trying to provide a hole in the latch which would permit sliding it onto the trip shaft in such a way that it would have to turn with the shaft, I may employ an auxiliary member 54 which is not of stainless steel and may therefore readily have a hole of any suitable cross-section, such as a fiat-sided circular opening 55 made therein to match the shape of the shaft. The member 54 is then suitably secured to the latch 49 by a pin 56 engageable in holes 51 and 58 on the members 49 and 54 so as to line up the circular parts of the opening 55 in the member 54 and the opening 59 in the member 49 for passage of the trip shaft 50 therethrough. As shown in Fig. 6, the latching face may have a concave portion better to set a roller III on the toggle link 44.

In order to insure the shockproof ability of the latch 49, it is pivoted substantially on its center of gravity axis so that there is no tendency for it to rotate. overcoming friction also assists in the shockproof feature of the latch. In order to restore the abut-' ment 35 to its thrust transmitting position on the reset movement'of the circuit breaker, I provide suitable biasing means, such as a spring 60, which exerts on the abutment 32 a force tending to rotate it counterclockwise about its pivot'48.

For tripping the latch 49 in response to predetermined circuit conditions so as to effect the opening of the circuit breaker, any suitable means may be employed. The particular arrangement illustrated is electromagnetic with socalled sucker type time lag 9. As shown, this means includes an electromagnet 6| which is looped around the bars l2 of the lower fixed contact and which is provided with an armature 62.

In circuit breakers of small capacity a multiple turn series winding may be used as is well known to the art. The armature 62, upon attraction, is arranged to actuate a tripping member 63 which engages the tail 64 of the latch 49 and turns it counterclockwise to release the toggle link .44 from the latching face 5|. The time lag feature is provided by a movable disc 65 which rests in oil against a disc 66 so that the time of release is dependent on the time in which the oil film between the discs is broken. Suitable adjusting means are provided in the form of a screw and spring means 61-68 for controlling the pick-up of the armature 62.

Assuming the parts positioned as shown in Fig. 1 and that an abnormal circuit condition such as overcurrent through the circuit controlled by the circuit breaker causes the actuation of the tripping rod 63 and thereby the release of the tripping latch 49, the abutment 32 will be no longer maintained in its thrust transmitting position by the holding toggle 44-45 since the latch face 5| has been moved clear of the left-hand end of the link 44. Consequently, the opening action of the circuit breaker clue to the weight of the parts and the action of the springs 28 will act on the abutment 32 in a direction to turn it clockwise about its pivot 48 and the parts will move to the position shown in Fig. 3. In this position, the toggle 44-45 is collapsed, as shown, and the wedging member 29 is turned counterclockwise about its pivot 36 but is still engaging the rollers 30 and 35 of the toggle 24-46 and the abutment 32 respectively. 4

Before the breaker can be reclosed, the abutment must be restored to its thrust transmitting position. For this purpose, the operating handle or lever 31 is turned counterclockwise about its pivot 21, thereby effecting movement of the switching member in a direction to permit the restoration of the abutment 32 to its thrust transmitting position under the action of its biasing spring 60. This spring also lifts the free end of the switching member at the same time. During the resetting movement a roller on the extended portion of the toggle link 44 moves up along the edge of the latch 49 to engage the latch face 5| arm the latch is biased against the stop 52. The parts are now positioned as shown in The reset biasing spring 53 besides Fig. 4 with the abutment 32 in its thrust transmitting position. I

In order to close the circuit breaker, the operating handle 31 is turned clockwise thereby pulling the wedging member 23 to the right between the rollers 35 and 30 in such a way as to present an increasingly widening portion of the wedging member between these rollers so as to straighten the operating toggle 2426 and close the circuit breaker with the parts positioned as shown in Fig. 1. Just before the final closed position, the latch 40 engages the projection 43 on the wedging member 29 so that any attempt to move the operating lever 31 counterclockwise from its stop 69 while the circuit breaker is closed can not produce an opening of the circuit breaker. In other words, a slow opening of the breaker, intentional or otherwise, by manual operation of the operating handle or vibration causing the counterclockwise rotation thereof can not occur.

It will be obvious from the foregoing that only one operating mechanism is necessary for multipole breakers of the type usually met in the art since all that is necessary to do is to provide all but one of the poles with a simple toggle mechanism 24-2-6 and to connect the toggle mechanisms of all the poles to the single operating mechanism by the cross bar 39, as shown schematically in outline in Figs. 7 and 8. Thus, for example, Fig. '7 illustrates in outline a twopole breaker and as shown may be provided with a-toggle mechanism, but the complete operating a mechanism is only necessary for one of the poles, for example, either the right or left-hand pole. In Fig. 8, which representsa three-pole breaker in outline, the center pole is preferably provided with a complete operating mechanism while the other poles are provided only with toggles and all are connected by the crossbar 39. Similar combinations for breakers of four and five-poles will be obvious. Of course, wherever there are an odd number of poles, the load on the operating mechanism is balanced because there are the same number of poles each side of the center of the mechanism.

Since a multiple breaker must in most cases be responsive to abnormal circuit conditions in any one of the poles, a tripping mechanism responsive to an abnormal circuit condition in the respective pole is necesasry and the voperation of any one of the fault responsive means must effect the tripping of the circuit breaker. For this purpose the tripping shaft .50 may extend across all of the poles, each of which is provided with a trip latch 49 mounted on the trip shaft 50 so that the actuation of any latch will result in the actuation of the trip latch and thereby the collapse of the abutment supporting means. If the 'trip shaft runsthrough from pole to pole as a straight rigid member, then it is absolutely essential for smooth and correct operation of the circuit breaker that every tripping mechanism, the operating mechanism, and the toggles of each pole must be very carefully aligned each with respect to the other. Such alinement is a costly refinement and not always simple to maintain, especially where circuit breaker duties are severe.

In accordance with my invention, I provide means for eliminating this refinement of adjustment. As shown, this means comprises a universally jointed trip shaft which is shown more in detail in Fig. 2, and as shown, comprises the I trip shaft sections 50 which are interconnected to an insulation piece H by universal joints 12.

Thus, it is merely necessary with this arrangement to align the toggles of the difl'erent poles and connect them through their common crossbar 39, insert the trip shafts 50 into their respective tripping latches 4S and interconnect them by the universal joints 12 and the insulation tie members H.

Since there may be occasions, such as crucial periods during battles, when it may be absolutely necessary to maintain a circuit breaker closed even though the circuit which it controls is over loaded to the tripping point, I provide means under the control of the operator whereby a circuit breaker may be temporarily prevented from opening even though the tripping means functions to try to trip the circuit breaker. As shown in Fig. 5, this means is a manually-operateddevice which may also incorporate a manual tripping function. Referring now to Fig. 5, T3 is a trip control rod provided with a handle H and suitably supported in the frame at 15 and IS. The rod 13 is provided with a recessed portion 11 in which a trip pin I8 on the tripping shaft is normally free to turn enough to permit the tripping action. When the trip rod is pulled out, that is, from left to right, as viewed in Fig. 5, the inner shoulder 79 of the recess Tl engages the trip pin 18 and thereby turns the trip shaft 50 counterclockwise to trip the circuit breaker. The pull-out action of the trip rod is resisted by a biasing spring 80 which is positioned between the bearing 16 and a support 8i secured to the rod '13. This bias moves the shaft inwardly to the position shown in Fig. 5 after a pull-out operation. If it is desired to prevent a tripping action of the circuit breaker, the trip control rod 13 is pushed inwardly, that is, from right to left, as viewed in Fig. 5, until the shoulder 82 of the recess 11 engages the trip pin 18 on the front side. Then as long as the rod is held in this position, the trip shaft 50 cannot be turned counterclockwise to efi'ect tripping. Upon release of the trip shaft, the return spring 83, which was placed under compression on the inward movement of the trip rod 13 will return the trip rod to the position shown in Fig. 5. In order to prevent rotation of the trip rod and also to limit the outward and inward movements, a guide member, such as the bolt 84 secured to the support 16 may pass through the member 8| on the trip rod and also be provided with adjustable means, such as lock nuts 85 and 86, the position of which may be set to control the amount of movement of the trip rod in connection with the tripping and trip preventing actions.

While I have shown and described by invention in considerable detail, I do not desire to be limited to the exact arrangement shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in one of its circuit controlling positions including a support, a toggle connecting said member and said support, a movable abutment, means for holding said abutment in one position, a wedging member between said abutment and said toggle engageable therewith to straighten the toggle when moved in one direction while the abutment is held in said position, and means for moving said wedging member in said direction.

2. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in the circuit closing position, including a fixed support, a toggle having one end connected to said member and the other end connected to said support, a movable abutment and means for holding said abutment in one position, a wedging member between said abutment and the center joint of said toggle engageable therewith to straighten the toggle when moved in one direction while the abutment is held in said position, and an operating member mounted on said support and con nected to said wedging member movable in one direction to efiect the toggle straightening movement of said wedging member.

3- An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in the circuit closing position including a fixed support, a toggle having one end connected to said member and the other end connected to said support, a movable abutment and means for holding said abutment in one position, a wedging member between said abutment and the center joint of said toggle engagement therewith to straighten the toggle when moved in one direction while the abutment is held in said position, an operating member mounted on said support and connected to said wedging member movable in one direction to effect the toggle straightening movement of said wedging member, and means for preventing the reverse movement of said operating member while the circuit controlling member is in the circuit closing position.

4. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in the circuit closing position including a fixed support, a toggle having one end pivotally connected to said member and the other end pivotally connected to said support, a movable abutment, collapsible means for holding said abutment in one position, a wedging member between said abutment and the center joint of said toggle engageable therewith to straighten the toggle when moved in one direction while the abutment is held in said position, and an operating member pivotally mounted on said support and pivotally connected to said wedging member rotatable in one direction to effect the toggle straightening movement of said wedging member.

5. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in the circuit closing position including a fixed support, a toggle having one end pivotally connected to said member and the other end pivotally connected to said support, a movable abutment, collapsible means for holding said abutment in one position, a wedging member between said abutment and the center joint of said toggle engageable therewith to straighten the toggle when moved in one direction while the abutment is held in one position, an operating member pivotally' mounted on said support and pivotally connected to said wedging member rotatablein one direction to eflect the toggle straightening movement of said wedging member, and latching means for preventing the reverse rotation of said operating member while the circuit controlling member is in the circuit closing position.

6. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in the circuit closing position including a fixed support, a toggle having one endpivotally connected to said member and the other end pivotally connected to said support, a movable abutment, collapsible means for holding said abutment in one position, a wedging member between said abutment and the center joint of said toggle engageable therewith to straighten the toggle when moved in one direction while the abutment is held in said position, an operating member pivotally mounted on said support and pivotally connected to said wedging member rotatable in one direction to effect the toggle straightening movement of said wedging member, and means for tripping said collapsible means to effect movement of said wedging member in a direction to cause the collapse of said toggle whereby the circuit controlling member is free to move to the circuit opening position.

7. An electric switch comprising relatively movable co-operating contacts, means for effecting and maintaining the engagement of said contacts including a fixed support, a toggle having one end pivotally connected to one of said contacts and the other end pivotally connected to said support, a movable abutment, means for holding said abutment in a predetermined position, a cam member having opposed divergent cam faces between said member and the center joint of said toggle engageable therewith to straighten the toggle when moved in one direction while said abutment is held .in said predetermined position and a crank pivotally mounted coaxially with the end of the toggle connected to said support and having an arm pivotally connected to said cam member rotatable in one direction to effect the toggle straightening movement of the cam member.

8. An electric switch comprising relatively movable co-operating contacts, means for effecting and maintaining the engagement of said contacts including a fixed support, a toggle having one end pivotally connected 'to one of said contacts and the other end pivotally connected to said support, a movable abutment, means for holding said abutment in a predetermined position, a cam member having opposed divergent cam faces between said member and the ,center joint of said toggle engageable therewith to straighten the toggle when moved in one direction while said abutment is held in said predetermined position and a crank pivotally mounted coaxially with the end of the toggle connected to said support and having an arm pivotally connected to said cam member rotatable in one direction to eflect the toggle straightening movement of the cam member, and means for preventing the reverse rotation of said crank while said contacts are engaged.

9. An electric switch comprising relatively movable co-operating contacts, means for effecting and maintaining the engagement of said contacts including a fixed suport, a toggle having one end pivotally connected to one of said contacts and the other end pivotally connected to said support, a movable abutment, collapsible means for holding said abutment in one position, a cam member having opposed divergent cam faces between said member and the center joint of said toggle engageable therewith to straighten the toggle when moved in one direction while said abutment is held in said predetermined position and a crank pivotally mounted coaxially with the end of the toggle connected to said support and having an arm pivotally connected to said wedging member rotatable in one direction to effect the toggle straightening movement of said cam 7 member, and shockproof latching means for retainlng said collapsible means in a rigid position.

10. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in one of its circuit controlling positions including a support,

' a toggle connected to said member and said suping said member to and holding it in one of its circuit controlling positions including a support, a toggle connected to said member and said support, a movable abutment, means for holding said abutment in one position, a member having opposed divergent cam faces between said abutment and said toggle engageable therewith to straighten the toggle when moved in one direction while the abutment is held in said position, means for moving said cam-faced member in said direction, and means for preventing movement of the cam-faced member in the opposite direction while said circuit controlling member is in said one of said circuit controlling positions. I

12. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in the cirsuit closing position including a support and a toggle connecting said member and said support, a movable abutment, collapsible means for hold ing said abutment in one position, a member having opposed divergent cam faces between said abutment and said toggle engageable therewith to straighten the toggle when moved in one direction while the abutment is held in said position, means for moving said cam-faced member in said direction, means for preventing movement of the cam-faced member in the opposite direction while the circuit controlling member is in the circuit closing position, and means for effecting the collapse of said collapsible mechanism whereby to effect the movement of the circuit controlling member to the circuit opening position.

13. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in one of its circuit controlling positions including a support,

. a toggle connected to said member and said support, a movable abutment, means for holding said abutment in one position, a member having opposed divergent cam faces between said abutment and said toggle engageable therewith to straighten the toggle when moved inone direction while the abutment is held in said position, means for'moving said cam-faced member in said direction, means for releasing said holding1 means to effect movement of the circuit conport, an abutment, means engaging said abutment and the center joint of said toggle for providing a mechanical advantage to straighten the toggle, and means for actuating said mechanical advantage means whereby to straighten the toggle.

15. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in the circuit closing position including a fixed support, a toggle having one end connected to said support and the other end connected to said mem ber, an abutment, means engaging said abutment and the center joint of said toggle for providing a mechanical advantage to straighten the toggle, and an operating member mounted on said support and connected to said mechanical advantage means movable in one direction toefiect the toggle straightening movement of said mechanical advantage means.

16. An electric switch comprising a movable circuit controlling member and means for moving said member to and holding it in the circuit closing position including a fixed support, a toggle having one end pivotally connected to said member and the other end pivotally connected to said support, a movable abutment, collapsible means for holding said abutment in one position, means between said abutment and the center joint of said toggle for providing a me chanical advantage to straighten the toggle when actuated While the abutment is held in said position and an operating member pivotally mounted on said support and pivotally connected to said mechanical advantage means rotatable in one direction to effect the toggle straightening movement of the mechanical advantage means.

17. An electric switch comprising a movable circuit controlling member and means or moving said member to and holding it in the circuit closing position including a fixed support, a toggle having one end connected to said member and the other end connected to said support, an abutment, means between said abutment and the center joint of said toggle for providing a mechanical advantage to straighten the toggle, an operating member mounted on said support and connected to said mechanical advantage means movable in one direction to efiect the toggle straightening movement of said mechanical advantage means, and means for preventing the reverse movement of said operating member while the circuit controlling member is in the circuit closing position. I

18. An electric switch comprising relatively movable cooperating contacts, means for efiecting a circuit closing movement of said contacts, means for holding said contacts in circuit closing position, means comprising a member rotatable in one direction to release said holding means, and means adapted to be operated to prevent the rotation of said member in said one direction.

19. An electric switch comprising relatively movable cooperating contacts, means for efiecting a circuit closing movement of said contacts, means for holding said contacts in circuit closing position, means for releasing said holding means, and means comprising a member movable in one direction to prevent the release of said holding means by said releasing means and in the opposite direction to eflect the release of said holding means independently of said releasing means.

CHARLES H. HILL.

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