US2525501A

US2525501A - Mechanical interlock

Info

Publication number: US2525501A
Application number: US34036A
Authority: US
Inventors: Owen L Taylor
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1948-06-19
Filing date: 1948-06-19
Publication date: 1950-10-10
Anticipated expiration: 1967-10-10

Description

Oct. 10, 1950 3 Sheets-Sheet 2 Filed June 19, 1948 Fig.4.

3 0 5 1- 5 A. 1 R z J 3 U 3 .7 k l Z A Mfl M 3 1 L #1 6 z I lNVENTOR OWEN L.TAYLQR.

BY M 6. M &

ATTORNEY Oct. 10, 1950 Filed June 19, 1948 WITNESSES A famio. 1.. TAYLOR MECHANICAL m mawgix 3 Sheets-Sheet 3 H 7 llllllllllllmllllllllll l'l Eli mmuuuumn KNVENTOR OWEN L. TAYLOR.

BY v

ATTORNEY Patented Oct. 10, 1950 UNITED STATES PATENT OFFICE MECHANICAL INTERLOCK Application June 19, 1948, SerialNo. 34,036

((11. Tie-483) 10 Claims.

This invention relates, as indicated, to a mechanical interlock for interlocking the operation of two relatively movable members and, more particularly, to an improved arrangement of in terlocking mechanism for a pair of electromagnetically operated switches controlling reversing or multiple speed electrical connections to a, motor.

The switches on reversing or multiple speed contactors must be interlocked in order to prevent the completion of a circuit through, more than one switch at any given instant. This requires that an operating circuit through the contacts on one of the switches must be open before a circuit can be established through the contacts on another switch. The interlock must not only be capable of preventing simultaneous physical contact engagement in more than one switch, but in addition must be effective to prevent contact engagement by a second switch prior to extinguishment of the are drawn by the contacts of the switch being opened. Premature contact engagement of the switch being closed before extinguishment of the arc drawn by the switch being opened would otherwise result in a short circuit. The problem of prevent ing such premature contact engagement is rendered difficult by relays of modern design due to their design tendencies toward small moving parts having low inertia, the use of high-speed magnets with small magnet travel, and a smaller open gap distance between the stationary and movable contacts.

Generally stated, the problem of arc extinguishment may be taken care of by an interlock which will operate to effect movement of one set of switch contacts to their full open position as determined by their open gap distance before allowing the other set of switch contacts to move substantially out of full open position Such interlocks have approached this problem by causing the difierent sets of contacts to move .at unequal rates of travel whereby those opening are moved initially at a high rate of speed into substantially full open position while those closing move at a relatively slow rate of speed only a small distance of their total travel from full open position. However, interlocks designed along this line have run into a condition known as jamming which is caused by the interlock op- ,eratin to hold a first switch in its closed position in response to force applied thereto upon energization of a magnet operating coil for a second switch. This condition will cause the operating coil for the second switch to fail in 2 a short period of time if it is maintained energized.

One of the principal objects of this invention is to, provide an improved arrangement of interlocking mechanism for a pair of electromagnetically operated switches which is efi'ective to prevent completion of a circuit through both of the switches under any condition, and which will accomplish its function without jamming the op: eration of either of the switches.

A further object of this invention is to provide interlocking mechanism for a pair of electromagnetically operated switches which is effective-to maintain one of the switches sub stantially in its full open position until such time as the other of the switches moves to its substantially full open position.

A still further object of the invention is to provide interlocking mechanism for a pair of electromagnetically operated switches which will operate to lock one of the switches in its full open position immediately upon movement of the other of the switches out of its full open position.

Another object of the invention is to provide a simplified arrangement of interlocking mechanism which may be produced at a minimum of cost and which will operate indefinitely without failure.

Another object of this invention is to provide an improved arrangement of interlocking mechanism in which the interlocking action is provided by a pair of locking links connected together for angular movement relative to each other and having operating connections respectively with the moving parts which they operate to interlock.

Another object .of this invention is to provide interlocking mechanism of the character just referred to in which the common connection for the locking links is provided by a fiat leaf spring having knife edge ,engageable in V-shaped notches formed in the locking Gther objects and advantages of this invention will become apparent from the following description.

In the drawings there are shown several embod-iments of the invention. In this showing:

Figure 1 is a plan view, with parts thereof being shown in section, of a pair of electromagnetically operated switches illustrating the application thereto of a preferred embodiment of interlockin mechanism constructed in accordance with the principles of this invention;

Fig. 2 is a partial plan view, similar to Fig. 1,

showing the position of the interlocking mechanism when one of the switches is in its closed position;

Fig. 3 is a view similar to Fig. 2, showing the position of the interlocking mechanism when the other of the switches is in its closed position;

Fig. 4 is a bottom plan view of the interlocking mechanism shown in Figs. 1, 2 and 3;

Fig. 5 is a side elevational view looking from the right of the interlocking mechanism shown in Fig. 4;

Fig. 6 is a plan view of a modified form of interlocking mechanism;

Fig. '7 is a plan view of a pair of verticallyspaced electromagnetically-operated switches illustrating the application thereto of interlocking mechanism constructed in accordance with the principles of this invention;

Fig. 8 is a broken away side elevational view of the interlocking mechanism shown in Fig. 7 looking from the right;

Fig. 9 is a view similar to Fig. 8 looking from the left of the interlocking mechanism; and

' Fig. 10 is a view similar to Fig. 8 illustrating a difierent position of the interlocking mechanism.

The preferred embodiment of the invention is shown in Figs. 1 through 5. Referring to Fig, 1, the numeral 1 designates a support on which is mounted in horizontally spaced relation a pair of electromagnetically operated switches indi- 1*:

cated as a whole by the numerals 2 and 3. Each of the switches 2 and 3 is provided with an insulated housing or arcing chamber 4 containing a set of stationary contacts 5 and a set of movable contacts 6. mounted in a conventional manner on a movable contact carrying member I for movement from the full open position shown in Fig. l to a closed position in which the stationary contacts 5 are electrically engaged with the movable Contact ii. The movable contact carrying parts I of the switches 2 and 3 are provided respectively with operating parts 8 and 9 which are movable in parallel paths for effecting movement of the respective switches to circuit completing positions. Operation of each of the operating parts 8 and 9 is efiectedby an armature l8 constituting part of an electromagnet l i having an energizing coil l2. Upon energization of a selected one of the coils [2, its armature It] will operate to move the operating part 8 or 9 to which it is connected in an upward direction, as viewed in Fig. move one of the switches 2 or 3 to its closed position.

Operation of the operating parts 8 and 9, and thereby the operation of the switches 2 and 3, is controlled by interlocking mechanism indicated as a. whole by the numeral l3. As best shown in Figs. 4 and 5, the interlocking mechanism l3 comprises a supporting bracket l4 having a back portion l5 by which it may be secured to the support I as by screws 16. Projecting outwardly from the bracket portion I5 are a pair of legs I"! and 18 of unequal length. Bell crank levers l9-and 20 are connected to the outer ends of the legs I! and 18 by pivots 2| and 22. The bell crank 29 is provided with an outwardly projecting arm 23 having its end operatively connected to the operating part 8 of a switch 2 so that operation of the switch 2 will be effective to impart pivotal movement to the bell crank 29. The bell crank I9 is similarly provided with an outwardly projecting arm 24 which is operatively connected to the operating part 9 of the switch 3 so that operation of the switch 3 Wi Each set of movable contacts 6 is impart pivotal movement to the bell crank 19. The bell cranks l9 and 29 are provided respectively with

arms

25 and 26 projecting inwardly toward each other and in overlapping relation so that their respective ends 2! and 28 are positioned on opposite sides of a center line between the pivots 2| and 22. Looking

links

29 and 39 are connected respectively to

ends

21 and 28 by pivots 3| and 32. The lower ends of the

locking links

29 and 39 are connected together for angular movement relative to each other by a flat leaf spring 33. As best shown in Fig. 5, the leaf spring 33 is L-shaped and has a back portion 34 thereof anchored to the bracket 14 by means of a slot 35 formed in the bracket part l5 in which the one edge of the leaf spring portion 34 is receivable. An end of the leaf spring portion 34 is secured to the bracket 14 by threaded fastening members 36. A flexible portion 3'! of the spring 33 projects outwardly from its back portion 34 to a position between the pivots 2i and 22 as best shown in Figs. 1 through 3. A slot is formed in the upper edge of the flexible spring 31 to provide a knife edge 38 which projects upwardly into the apex of V-shaped notches 39 formed in the lower ends of the

locking links

29 and 30. The knife edge 38 on the flexible portion 31 of the spring 33 thus provides a common connection for the

links

29 and 30 at their lower ends about which the

links

29 and 39 may move relative to each other in a manner and for a purpose to be described.

Attention is particularly invited to the fact that the parts of the interlocking mechanism l3 are symmetrically arranged with respect to the flexible spring 31 when both switches 2 and 3 are in the open position as shown in Fig. 1. It will be noted in particular that the pivots 2| and 22, which form the fulcrums for the bell cranks I 9 and 20, are spaced equal distances from and on opposite sides of the flexible spring 31 which can flex in a direction toward and away from such pivots. It will also be noted that the

arms

23 and 24 extend in opposite directions'to their points of engagement with the operating parts 8 and 9 of the switches 2 and 3. It will also be noted that the unequal length of the parts I1 and I8 of the support M, as shown in Fig. 4, together with the offset construction of the bell cranks enables the inwardly projecting

arms

25 and 26 to overlap each other with their

end points

21 and 28 on opposite sides of the spring 33. The symmetrical arrangement is completed by the common connection provided by the knife edge 38 at the lower ends of the locking

links

29 and 30 which have their upper ends pivoted at 3| and 32 to the

ends

21 and 28 of the bell cranks I9 and 28.

With both switches 2 and 3 in their full open position as shown in Fig. 1, closure of either switch 2 or 3 may be readily effected by energization of the appropriate magnet H. Assuming that the switch 2 is closed by energization by its operating magnet H, the first action that will take place will be upward movement of the operating part 8 for the switch 2. As the operating part 8 moves upwardly, the bell crank 20 will be pivoted in a clockwise direction, and the end point 28 of its arm 26 will move downwardly. As the endpoint 28 moves downwardly, the locking link 39 will operate t flex the spring 31 to the left, and such action will cause the locking link 29 to rotate in a clockwise direction. When the switch 2 moves into its fully closed position, its operating part 8 and the parts of the interlockin mechanism l3 will occupy the position shown. in Fig. 2. In this position it will be noted that the locking link 29 is effective to prevent rotational movement of the bell crank [-9 in a counterclockwise direction and thus upward movement of the operating part 9 for the switch 3. This locking action is due to the movement of the knife edge 38 to a position substantially underneath the pivot 3| as shown in Fig. 2. While this movement is taking place, the link 29 is pivoting in a clockwise direction about its pivot 3|, and such pivotal movement takes place without any perceptible movement being imparted to the bell crank $9. In addition, substantiall all of the flexing of the spring .31 and movement of the knife 38 to the left takes place during the initial portion of the. closing movement of the switch 2; At the moment the closing action begins to take place, it will be noted that pivot 32 will move downwardly toward the spring 3'! and its knife edge 38, thus tending to shorten the distance between the pivot 32 and the knife edge 33. This results in a rapid movement of the knife edge 38 to the left from the position shown in Fig. 1, and the switch 2 will have barely moved out of its open position when the locking link 29 Will become operable to prevent movement of the bell crank l9 and consequent movement of the switch 3 out of its full open position. During the final closing action of the switch 2 to the positioifihown in Fig. 2, it will be noted that the pivot 32 is moving substantially tangentially with respect to a circle having as its center the knife edge 38. As a result there will be very little movement of the spring 3'! during the final movement of the switch 2 to its closed position.

The above-described movements of the interlocking mechanism l3 must be reversed to return the parts to the position shown in Fig. 1 before the operating part 9 may move upwardl to effect closing of the switch 3. This means that the operating part 8 for the switch 2 must be lowered from the position shown in Fig. 2, and during its initial movement very little movement of the knife edge 38 is permitted. Most of the flexing movement of the spring 31 during the return of the knife edge 38 to its center position, as shown in Fig. 1, takes place during the final mov ment of the switch 2 to its full open position. It will thus be seen that as the switch 2 moves into its full open position, the switch 3 will still be in its full open position.

When the operating part 9 moves upwardly to effect a closing of the switch 3, the parts of the interlocking mechanism I3 will move to the posi tion shown in Fig. 3. In this position the link 39 is operative to prevent clockwise movement of the bell crank 25 and upward movement of the operating part 8 to close the switch 2. The movement of the parts into the position shown in. Fig. 3 is acomplished in the same manner and at the same rates of travel as described in connection with Fig. 2.

From the foregoing, it will be apparent that a small movement of either switch toward its closed position will be effective to lock the other of the switches againstmovement to its closed position. It will also be noted that the switch which has moved toward or into its closed posi tion must be returned to substantially its full open position before the other switch can move toward or into its closed position.

In addition to the action of the spring 3'! in cooperation with the locking

links

29 and 39 to insure movement of both switches to a full open position before either can be closed, it will be noted that the tension imparted to. the spring 31 by closure of one of the switches is effective to produce a biasing force for returning a switch to its open position upon deenergization. of its operating magnet l I. In the event that the operating magnet for a switch in open position is energized prior to movement of the other position to its full open position, the closing force applied by the magnet.v energized will. bev transmitted in a direction assisting the spring 31 in the return of the other switch to its full open position.

Referring to Fig. 2, it will be noted that the knife: edge 38. is positioned slightly to the right of a position directly underneath the pivot 31. Referring to Fig. 3, it will be noted that the knife edge 38 is positioned slightly to the left ofa positiondirectly underneath the pivot 32. The positions of the knife edge 38- illustrated respectively in Figs. 2 and 3 represent the extreme end portions of. the path of movement of the knife edge 38. By constructing the parts in such manner that the end points of the path of movement of the knife edge 38 are maintained within the outer limits of the pivots 3i and 32, jamming action by reason of energization of one of the operating magnets prior to deenergization of the other operatin magnet is effectively prevented. This action will be best understood by referring to Fig. 2 and assuming that the magnet l I to the right of Fig. 2 is energized prior to deenergization of the magnet ll. Since. the knife edge 38 is positioned to the right of the pivot 3|, the force applied to the bell crank arm 24 upon energization of the magnet to the right is applied to the bell crank 20 through the interlocking mechanism 13 in a direction tending to move the operating part 8 for the switch 2 down wardly and to its open position. Consequently, upon deenergization of the magnet II, this force will be effective immediately to' open the switch 2 without any jamming action tending to hold the switch in its closed position.

The modified form of interlocking mechanism illustrated in Fig. 6 is essentially the same as the interlocking mechanism shown in Figs. 1 through 5, and like parts have been designated by like numerals. In this construction, the common connection at the base of the links 29 and 3i! is provided by a, pivot pin 40 about which the links 29 and may move angularly relative to.

each other. A roller M is carried by the pivot and is engageable with a surface 42 during the back and forth movement of the common connection or pivot 40 between the pivots 2| and 22. The operation of this structure during opening and closing movements of a pair of switches is substantially the same as that described in connection with Figs. 1 through 3.

The modification, illustrated in Figs. 7 through 10, illustrates the application of interlocking mechanism, designated as a whole by the numeral 50, and constructed in accordance with the principles of this invention, to a pair of switches 5| and 52 mounted in vertically spaced relation and respectively having electromagnetically actuated operating

parts

53 and 54. The interlocking mechanism comprises a support 55 on which a pair of arcuately-shaped

levers

58 and 57 are pivotally mounted respectively by

pivots

58 and 59. The arrangement of the

pivots

58 and 59 will be best understood by referring to Figs. 8 and 9 which show the interlockin mech anism 50 from opposite sides thereof. As best shown in Figs. 7 and 8, the lever 56 is pivotally connected to an actuating member 60, which in turn is connected to a, vertically movable actuating part 6! of the switch 52. As best shown in Figs. 7 and 9, the link 51 is pivotally connected to a vertically movable operating part 62 of the switch A locking link 63 is pivotally connected to the lever 58 and a locking link 64 is pivotally connected to the lever 51. l he links 63 and 54 are provided with V-shaped notches 65 at their lower ends, and a knife edge 56 provided on a fiat leaf spring 51 extending transversely of the

levers

56 and 57 projects upwardly into the notches 65 to provide a common connection at the lower ends of the locking

links

63 and 64.

When both of the switches 5i and 52 are in their full open position, the locking

links

63 and 64 will be symmetrically arranged with respect to the spring 61. Figs. '1, 8 and 9 show the relative positions of the parts with the lower switch 5| in a closed position. When the switch 5! moves to a closed position, the lever 51 moves upwardly about its pivot and causes the locking link 54 to move the spring 61 to the left as viewed in Fig. 8. With the locking link 63 in the position shown in Fig. 8, the spring 81 will function to prevent upward movement of the link 63 and pivotal movement of the lever 55 in a clockwise direction, as viewed in Fig. 8. Upward movement or the operating part 6| and consequent movement of switch 52 to a closed position will thus be prevented.

Fig. illustrates the positions of the parts of the interlocking mechanism 55 when the operating part 6| has moved upwardly to close the switch 52. When the operating part El moves upwardly to close the switch 52, the lever 56 is pivoted in a clockwise direction, as viewed in Fig. 10, and the locking link 63 moves the spring 6'! to the right as viewed in Fig. 10. In this position upward movement of the link 64 is prevented by reason of its engagement with the spring 61. Consequently, upward movement of the lever 51 and downward movement of the operating part 62 connected to the magnet for the switch 5| is prevented, and closure of the switch 5! is likewise prevented.

In the arrangement shown in Figs. '7 through 10, the

levers

55 and 51, together with the locking

links

63 and 54, and the common connection provided by the spring 61 is effective to prevent movement of one of the switches out of its full open position upon movement of the other switches toward or into its closed position. In addition, the interlocking mechanism 5!) is effective to insure that the switch in closed position is returned to its full open position before the other switch can be moved to its closed position.

Since certain changes may be made in the above-described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the above description and shown in the accompanying drawings shall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. An interlocking mechanism comprising a pair of bell cranks respectively having a fulcrum and a, pair of arms disposed in fixed relative angular positions, said fulcrums being located at spaced points, one arm on each of said bell cranks projecting outwardly and each being constructed and arranged to have a force applied thereto to move the associated one of said bell cranks, the remaining arm of each of said bell cranks extending inwardly toward the remaining arm of the other bell crank, the end points of the remaining arms lying in overlapping relation to provide end points on opposite sides of a center-line between said spaced fulcrums, a pair of locking links, each of said end points on said remaining arms having a pivot to which one of said links is connected, and a common connection interconnecting said links for angular movement relative to each, said common connection having a position located substantially centrally with respect to said fulcrums prior to movement of either of said bell cranks.

2. An interlocking mechanism comprising a pair of bell cranks respectively having a fulcrum and a pair ofarms, said fulcrums being located at spaced points, one arm on each of said bell cranks projecting outwardly and being constructed and arranged to have a force applied thereto to move the associated one of said bell cranks, the remaining arm of each of said bell cranks extending inwardly toward the remaining arm of the other bell crank, the end points of the remaining arms lying in overlapping relation to provide end points on opposite sides of a centerline between said spaced fulcrums, a pair of locking links, each of said end points on said remaining arms having a pivot to which one of said links is connected, and a flat leaf spring positioned centrally of said bell cranks and mounted for flexing movement toward and away from said fulcrums, each of said locking links having V- shaped notches provided therein, said spring having a knife edge projecting into said notches to provide a common connection about which said links may move angularly relative to each other.

3. An interlocking mechanism comprising a pair of hell cranks respectively having a fulcrum and a pair of arms, said fulcrums being located at spaced points, one arm on each of said bell cranks projecting outwardly and being constructed and arranged to have a force applied thereto to move the associated one of said bell cranks, the remaining arm of each of said bell cranks extending inwardly toward the remaining arm of the other bell crank, the end points of the remaining arms lying in overlapping relation to provide end points on opposite sides of a center-line between said spaced fulcrums, a pair of locking links, each of said end points on said remaining arms having a pivot to which one of said links is connected, a common pivot interconnecting said links for angular movement relative to each other, said pivot being located an equal distance from each of said end points, a roller carried by said pivot, and a support having a surface extending between said fulcrums with which said roller is engageable.

4. An interlocking mechanism for a pair of levers for locking one lever upon movement of the other which comprises a pair of pivotally mounted levers, a pair of locking links, each of said links having a separate pivotal connection to one of said levers, and a flat leaf spring positioned between said levers, each of said locking links having V-shaped notches provided therein, said spring having a knife edge projectin into said notches to provide a common connection about which said links may move angularly relative to each other.

5. An interlocking mechanism for a pair of levers for locking one lever upon movement of the other which comprises a pair of levers respectively having a pivot mounting, said pivot greater 9 mountings being located at spaced points, said levers extending toward each other and in overlapping relation from their respective pivot mountings and having end points positioned on opposite sides of a center-line between said mountings, a pair of locking links, each of said end points having one of said links pivotally connected thereto, and a common connection connecting said locking links for angular movement relative to each other, said common connection being located substantially centrally of said pivot mountings priorto movement of either'of said levers, pivotal movement of one of said levers being effective through the locking link connected thereto and said common connection to move the other of said locking links into a locking position with respect to the other of said levers to prevent movement of the other of said levers.

6. An interlock for a pair of relatively movable members operable to lock one of said members against movement in response to movement of the other of said members which comprises pair of levers respectively having a pivot mounting and a connection operable to effect pivotal movement thereof in response to movement of one of said members, a pair of locking links, each of said levers having one of said locking links pivotally connected thereto, and a fiat leaf spring mounted for flexing movement between said levers, each of said links being provided with a V-shaped Y notch, said spring having a knife edge projecting into both of said notches to provide a common connection between said links about which they may move angularly relative to each other, pivotal movement of one of said levers in response to movement of one of said members being effective through the locking link connected thereto and said common connection to move the other said links into a locking position with respect to the other of said levers for preventing movement of the other of said levers.

'7. An interlock for a pair of relatively movable members operable to lock one of said members against movement in response to movement of the other of said members which comprises a pair of levers respectively having a pivot mounting and a connection with one of said members so that movement of either of said members will impart pivotal movement to one of said levers, said pivot mountings being located at spaced points, said levers extending toward each other and in overlapping relation from their respective pivot mountings and having end points positioned on opposite sides of a center-line between said pivot mountings, a pair of locking links, each of said end points having one of said locking links pivotally connected thereto, and a common connection connecting said links for angular movement relative to each other, said common connection being located'substantially centrally of said pivot mountings prior to movement of either of said members, pivotal movement of one of said levers in response to movement of one of said members being effective through the locking link connected thereto and said common connection to move the other of said locking links into a locking position with respect to the other of said levers to prevent movement of the other of said members.

8. An interlock for a pair of relatively movable members operable to lock one of said members against movement in response to movement of the other of said members which comprises apair of levers respectively having a pivot mounting and a connection with one of said members so that 10 movement of either of said members will impart pivotal movement toone of said levers, said pivot mountings being located at spaced points, .said levers extending toward each other and in overlapping relation I from their respective pivot mountings and having end points positioned on opposite sides of a center-line between said pivot mountings, a pair of locking links, each of said end points having one of said locking links pivotally connected thereto, and a flat leaf spring positioned between and mounted for flexing movement toward and away from said pivot mountings, each of said links being provided with a V-shaped notch, said spring having knife edge projecting into both of said notches to provide a common connection for said links about which they may move angularly relative to each other, said common connection being located substantially centrally of said pivot mountings prior to movement of either of said members, pivotal movement of one of said levers in response to movement of one of said members being effective through the locking link connected thereto and said common connection to move the other of said locking links into a locking position with respect to the other of said levers to prevent movement of the other of said members.

9. An interlocking mechanism for a pair of levers for locking one lever upon movement of the other which comprises a pair of levers respectively having a pivot mounting, said pivot mountings being spaced from each other, said levers extending toward each other and in overlapping relation from their respective pivot mountings and having end points positioned on opposite sides of a center-line between said pivotmountings, a pair of locking links, each of said end points having one of said links pivotally connected thereto, and a flat leaf spring mounted between said pivot mountings for flexing movement toward and away from said pivot mountings, each of said locking links having a V-shaped notch formed therein, said spring having a knifeedge projecting into said notches to provide a common connection between said links about which said links may move angularly relative to each other, said common connection being normally located substantially centrally of said pivot mountings prior to pivotal movement of either of said switches, pivotal movement of one of said levers being effective through the locking link connected thereto and said common connection to move the other of said locking links into a locking position with respect to the other of said levers to prevent operation of the other of said levers.

10. An interlocking mechanism for a pair of levers for locking one lever upon movement of the other which comprises a pair of levers respectively having a pivot mounting, said levers being positioned side-by-side and having their pivot mountings spaced from eachother, a flat leaf springextending transversely of said levers and mounted for flexing movement toward and away iromsaid pivot mountings, each of said levers having a locking link pivotally connected thereto, each of said locking links having a V-.

shaped notch formed therein, said flat leaf spring having a knife edge extending into said notches to provide a, common connection about which said locking links may move relatively to each other, movement of one of said levers being effective through the link connected thereto to flex said leaf spring, flexing movement of said spring being effective to pivot the other of said links into 11 a locking position with respect to the other of said levers to prevent operation of the other of said levers.

OWEN L. TAYLOR.

REFERENCES CITED The following references are of record in the file of this patent:

Number 12 UNITED STATES PATENTS Name Date Langley Nov. 17, 1914 Albers Oct. 10, 1916 Lull Dec. 26, 1922 Wilms Feb. 15, 1938 Ellis May 23, 1944 Bellon Oct. 3, 1944