US3495059A

US3495059A - Torque tube connected pantograph operating mechanism for electrical contact assemblies

Info

Publication number: US3495059A
Application number: US713907A
Authority: US
Inventors: Dorsey L Hardman; Philip G Hughes
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1968-03-18
Filing date: 1968-03-18
Publication date: 1970-02-10
Anticipated expiration: 1987-02-10

Description

3,495,059 ATING MECHANISM FOR ELECTRICAL CONTACT ASSEMBLIES Feb. 10, 1970 D. L. HARDMAN ETAL TORQUE TUBECONNECTED PANTOGRAPH OPER Filed March 18, 1968 3 Sheets-Sheet l NVVENTORS DORSEY L. f/mwmu PHIL/P 6T Haw/as /M M M ATTORNEY D. L. HARDMAN E TORQUE TUBE CONNECTED PANTOGRAPH OPERATING MECHANISM Feb. 10, 1970 FOR ELECTRICAL CONTACT ASSEMBLIES I5 Sheets-Sheet 2 Filed March 18, 1968 FIG.Z

START CONTACTOR RUN CONTACTOR FIG/i 3 INVENTORS DORSEY Z. HMoM/w I PHIL/P G. Huauss BY W WM Feb. 10, 1970 D. L. HARDMAN T 3,495,059

TORQUE TUBECONNECTED PANTOGRAPH OPERATING MECHANISM FOR ELECTRICAL CONTACT ASSEMBLIES Filed March 18, 1968 v 5 Sheets-Sheet 3 INVENTORS Dokssv L. HARP/mu PHIL/P G Hus BY% W M ATTORNEY United States Patent O 3,495,059 TORQUE TUBE CONNECTED PANTOGRAPH OPERATING MECHANISM FOR ELECTRI- CAL CONTACT ASSEMBLIES Dorsey L. Hardman, Lexington, and Philip G. Hughes,

Bloomingtorl, Ill., assignors to General Electric Company, a corporation of New York Filed Mar. 18, 1968, Ser. No. 713,907 Int. Cl. Hillh 3/06 U.S. Cl. 200-153 18 Claims ABSTRACT OF THE DISCLOSURE An operating mechanism for manually actuating a first contact assembly by rotation of a handle to a first position in a first direction from a rest position and for manually actuating a second contact assembly by rotation of the hand from the first position in the opposite direction through the rest position to a second position. The manual actuating force applied to the handle is transmitted through the operating mechanism which includes a pair of pantographs to the reciprocating actuators of the contact assemblies. The operating mechanism includes overcenter lever arrangements such that the manual actuating force required to rotate the handle decreases as the handle is rotated from its normal rest position to either of its fully rotated positions, thus favoring full actuation of the contact assemblies.

BACKGROUND OF THE INVENTION It is frequently desirable to start an alternating current motor at a reduced voltage, which is less than the motors normal operating voltage, before energizing the motor at its normal operating voltage. The reduced voltage may be provided by an autotransformer which is energized at the normal operating voltage of the motor. In order to avoid undesirable circuit conditions it is necessary that the motor be momentarily deenergized after it is energized at the reduced voltage, and before it is reenergized at its normal operating voltage. To bring about this sequence of energization of a motor by manual means, it is desirable to provide an operating mechanism wherein a first movement of an operating handle will cause the motor to be energized through the contacts of a first contact assembly at the reduced voltage and a second movement of the operating handle will first deenergize the motor and will then cause the motor to be energized through the contacts of a second contact assembly at its normal operating voltage. The operating mechanism should be constructed so as to encourage an operator to move the handle to the end of its travel in the first direction and to hold it in this position without relaxations such as would allow the contacts of the first contact assembly to lose their contact force, whereby arcing between the contacts and burning of the contacts might occur. In providing such an operating mechanism, it is desirable that it be of compact design and that it does not interfere with servicing and making electrical connections to the contact assemblies.

OBJECTS OF THE INVENTION It is therefore an object of this invention to provide a novel and improved operating mechanism for actuating a contact assembly wherein the operating force required decreases as the operating mechanism is moved from a normal rest position to a position wherein the contact assembly has been actuated.

It is another object of the invention to provide a novel and improved operating mechanism for actuating a contact assembly which is readily adjustable to provide proper actuation of the contact assembly.

ice

It is a further object of the invention to provide a novel and improved operating mechanism for a pair of contact assemblies wherein operation of the mechanism in a first direction will cause actuation of a first contact assembly, and subsequent operation of the mechanism in a second direction will first restore the first contact assembly to its unactuated condition, and will then cause actuation of a second contact assembly.

It is still another object of the invention to provide a novel and improved operating mechanism for a pair of contact assemblies which is of compact and efficient design and which incorporates a minimum number of inexpensive parts which are readily assembled with minimal effort and skill.

SUMMARY OF THE INVENTION The foregoing objects are accomplished in accordance with this invention in one form thereof by providing an operating mechanism for an electrical contact assembly which includes a pantograph. The pantograph comprises two pairs of spaced substantially parallel arms, each of which arms is pivotally secured at one point to one of the arms of the other pair and at a spaced point to the other arm of the other pair. One of the four pantograph pivot points is fixed relative to the housing on which the operating mechanism and the contact assembly are mounted. An actuating means is provided to apply an actuating force to a first of the two arms pivoted at the first fixed pivot point to rotate the arm about the first fixed pivot point. In order to transmit, with a variable mechanical advantage, the motion of this first arm to an operating means which is operably connected to the second arm pivoted at the first fixed pivot point, the movement of a second pivot point of the pantograph, which is diagonally opposite the fixed pivot point, is restricted to an arcuate path of nearly fixed radius relative to a second fixed point on the housing. This restriction of the motion of the second pivot point is effected by pivotally securing one end of a lever to the second pivot point and by pivotally securing the other end of the lever at a second point on the housing. Rotation of the first arm about the first fixed pivot point will cause rotation of the second arm which acts through an operating means to displace the actuator of the contact assembly. Rotation of the first arm from its normal position causes the axis of the lever, which extends between its pivot points to approach coincidence or parallelism with the axis of one of the arms pivoted at the second pivot point. Coincidence or parallelism of these axes is an overcenter position for the mechanism. As the overcenter position is approached, the actuating force needed to further displace the first arm and therefore the actuator of the contact assembly decreases, thus favoring full actuation of the contact assembly.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a front elevation view of a manual motor starter with a portion of the cover broken away to show the novel and improved operating mechanism for electical contact assemblies contemplated by this invention;

FIGURE 2 is an exploded perspective view of the righthand portion of the operating mechanism as Shown in FIGURE 1;

FIGURE 3 is a partial inside elevation view of the latching assembly mounted on the right wall as shown in FIGURE 1, with the latching assembly in the latched portion;

FIGURE 4 is a composite elevation view of portions of the operating mechanism and contact assemblies as shown in FIGURE 1;

FIGURE 5 is a sectional view taken substantially along the line 5-5 in FIGURE 1, showing the left-hand portion of the operating mechanism when the top contact assembly in FIGURE 1 is in the unactuated or open position and the bottom contact assembly is in the actuated or closed position; and

FIGURE 6 is a sectional view taken substantially along the line -5 in FIGURE 1, showing the left-hand portion of the operating mechanism when the top contact assembly in FIGURE 1 is in the actuated or closed position and the bottom contact assembly is in the unactuated or open position.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGURE 1, one embodiment of the operating mechanism as incorporated in a manual motor starter will be described. The manual motor starter, including the operating mechanism of this invention, is contained within a sheet metal mousing 10- which may be mounted upon the wall of a panel by screws or bolts (not shown passing through holes 12 provided in flanges 14 at the top and bottom of the housing. The housing 10 is provided with a cover 16, a portion of which is broken away to show the operating mechanism of this invention.

A pair of electrical contact assemblies are mounted within the housing 10* and are connected to an alternating current power supply, and autotransformer, and a motor in an arrangement whereby closing the contacts of one of the contact assemblies will energize the motor at a reduced voltage through the autotransformer, while closing the contacts of the other contact assembly will energize the motor at the power supply voltage. In FIGURE 1 rectangle 18 represents a three-pole contact assembly through which the motor is energized at line voltage for normal running, and rectangle 20, only a portion of which is shown, repersents a five-pole contact assembly through which the motor is energized at a reduced voltage from a three-phase autotransformer for starting. The three-phase autotransformer is enclosed within the housing 10 and is represented by the dashed lines 22. Details of the construction of the contact assemblies represented by the

rectangles

18 and 20 are shown in Patent No. 2,924,685 entitled Magnetic Switch by James R. Burch, which patent is assigned to the assignee of this application. The

contactors

18 and 20 differ from the magnetic switch shown in Patent 2,924,685 in that the coil and magnetic circuits are omitted. Bridging contacts in the run contact assembly 18 and the start contact assembly 20 are actuated by

actuators

24 and 26 respectively.

Referring to FIGURE 4, the operating mechanism of this invention is such that with an operating handle 28 in the off position as shown, the bridging contacts 30 in the start contact assembly 20 and the bridging contacts 32 and the run contact assembly 18 are both in their open position. Movement of the operating handle 28 in the clockwise direction as viewed in FIGURE 4 from its off or rest position to the start position, shown by dashed lines 34, is transmitted through the operating mechanism of this invention to actuator 26 of the start contact assembly 20 to close the bridging contacts 30 on fixed contacts 36. When the operator has observed that the motor has started and has gained sufficient speed to run at line voltage, the operator moves the operating handle 28 in a counter-clockwise direction from the start position through the off position wherein both

bridging contacts

30 and 32 are opened, to the run position, shown by dashed lines 38, wherein the bridging contacts 32 in the run contact assembly 18 close on fixed contacts 40.

The construction of the operating mechanism of this invention through which the start contact assembly 20 may be actuated by clockwise rotation of the operating handle 28 from the off position, and the run contact assembly 18 may be actuated by counter-clockwise rotation of the operating handle 28 from the start position through the off position may best be understood by referring to FIGURES l and 2. A shaft 42, which is provided with a pair of parallel flat sides, supports most of the elements of the operating mechanism and is itself supported from the side walls of the housing 10 by a pair of

bearings

44 and 46, one of which is secured to each side wall. The operating handle 28, along with a pair of

tripping levers

48 and 50, one of which is located at each side of the housing are provided with apertures which conform to the shaft cross-section and receive the shaft such that rotation of the handle also rotates the shaft and the tripping levers. The other elements of the operating mechanism which are also supported by the shaft 42, are not keyed to the shaft and may rotate or pivot independently of it.

The portion of the operating mechanism shown on the left in FIGURE 1 and as shown in further detail in FIG- URES 5 and 6 is effective upon rotation of the tripping lever 48 in the clockwise direction as viewed from the right-hand end of FIGURE 1 and as viewed in FIGURES 5 and 6 to displace the actuator 26 of the start contact assembly 20 to close its contacts. Similarly, the portion of the operating mechanism shown on the right in FIGURE 1 and as shown in further detail in FIGURE 2 is effective upon rotation of the tripping lever 50 in the counterclockwise direction as viewed from the right-hand end of FIGURES 1 and 2 to displace the actuator 24 of the run contactor 18 to close its contacts. The two portions of the operating mechanism, are substantially similar, such that by reference to FIGURE 2 the portion on the right will be described, and similar elements of the portion on the left will be identified by the same numeral, but with a prime thereafter. The tripping lever 50 is formed with a pair of spaced parallel connected members each having an aperture therein which conforms to the shaft cross-section so that the lever 50 is keyed to the shaft 42.

Tabs

52 and 54 extend at right angles from the spaced parallel members in overlapping relationship. Rotary motion of the shaft 42 and the tripping lever 50 is transmitted to a pair of

operating levers

56 and 58 each of which is provided with a circular aperture which loosely receives the shaft within the space between the parallel members of tripping lever 50. The rotary motion of the tripping lever 50 is transmitted to the

operating lever

56 and 58 by engagement of the

tabs

52 and 54 with

edge

60 or 62 respectively of the operating levers. The

operating levers

56 and 58 are each formed with a pair of

arms

64, 66, and 68, 70 respectively.

Arms

66 and 70 in cooperation with a coil spring 72 connected therebetween and a pair of stops formed as

right angle brackets

74 and 76 act to return the tripping lever 50, shaft 42 and handle 28 to the off position. The ends of coil spring 72 are secured in apertures in

arms

66 and 70, such that the tensile force of the spring tends to rotate the

levers

56 and 58 toward each other. In so rotating the

levers

56 and 58,

arms

64 and 68 will be drawn into engagement with

stops

74 and 76 respectively.

Stops

74 and 76 are so positioned on the side walls that when arms 64 and '68 engage the

stops

74 and 76 respectively, the

edges

60 and 62 of the levers are spaced apart by approximately the width of

tabs

52 and 54 on tripping lever 50, thus positioning the tripping lever 50 in its off position.

Having described the manner in which the tripping lever 50 and the operating handle 28 are biased to the off position, the portion of the operating mechanism shown on the right in FIGURE 1 and as shown in FIGURE 2 which transmits motion from the operating lever 56 to the actuator 24 of run contact assembly 18 will be described. This portion of the operating mechanism includes what will hereinafter be called a pantograph, that is, a four member linkage with the opposite sides substantially parallel and substantially forming a parallelogram. One of the four arms of the pantograph is operating lever 56. Operating lever 56 is the first arm of a set of parallel arms of the pantograph which also includes a second arm or link 78. A second set of parallel arms of the pantograph includes a first arm 80 and a second arm or link 82. A first pivot point for the pantograph is formed by the shaft 42, on which is pivotally mounted a first end of arm 80 and operating lever 56 as previously set forth. A second pivot point of the pantograph which is diagonally spaced from the first pivot point is formed by a pivot pin 84 which pivotally secures first ends of

links

78 and 82 to each other and to one end of a link 86. The other end of link 86 is provided with a sleeve 88 which is pivotally received over a pin 90 secured on a plate 92. The plate is fastened to the side wall of the housing 10 by bolts (not shown) which pass through holes 94 in the plate and slots (shown in FIGURES and 6) in the side wall. The slots are provided so that the position of the plate 92 on the side wall may be adjusted. The other pivot points of the pantograph are formed by a pivot point 93 which pivotally secures arm 64 of operating lever 56 and the second end of link 82, and by a pivot pin 95 which pivotally secures the second ends of link 78 and arm 80.

Rotation of the first arm 80 resulting from clockwise actuation of handle 28 is transmitted to the actuator 24 of run contact assembly 18 through an operating means which includes a torque tube 96 loosely received over the shaft 42. The first arm 80 is secured to the outer end of the torque tube and an operating arm 98 is secured to the inner end. An additional operating arm 100, substantially similar to operating arm 98, is spaced from operating arm 98 with a channel member 102 placed between and secured to the operating arms. To the base of this channel member is secured a bar 104 which engages the actuator 24 of run contact assembly 18.

As shown in FIGURES 1 and 2, by forming the levers, arms and links of sheet material, such as sheet metal, the right and left portion of the operating mechanism are assembled very compactly adjacent the side walls of the housing 10. Thus, by merely removing the cover 16, easy access is gained to the contact assemblies 18 and 20-.

The operation of the operating mechanism will now be described. As previously set forth, similar elements in the right and left portions of the operating mechanism are identified by the same numeral, a prime identifying the elements of the left portion as viewed in FIGURE 1. Assuming that the handle 28 is in the oif position, the operating levers 56 and 56' are in engagement with the stops 74 and 74' respectively as shown in FIGURE 5 for operating lever 56'. Similarly, the operating levers 58 and 58 will "be in engagement with the stops 76 and 76' as shown in FIGURE 5 for operating lever 58 by dashed lines. Rotation of the operating handle 28 toward the start position (clockwise as viewed in FIGURES 5 and 6) will cause the tabs 52, 54' on the tripping lever 48 to engage edge 60' of operating lever 56', rotating it clockwise about the shaft 42 as viewed in FIGURE 5. Rotation of the operating lever 56' will be resisted by the tensioning of'spring 72'. As the tripping lever 48 is rotated toward the position shown in FIG- URE 6, link 82' is moved upward, rotating link 86 in the clockwise direction as viewed in FIGURES 5 and 6. This moves pivot pin 84 and link 78 to the left, thereby moving the lower end of arm 80 to the left. This clockwise movement of the arm 80 is transmitted to arm 98' by torque tube 96', thus moving the upper end of operating arm 98' to the right, and thereby depressing the actuator 26 to close the contacts in start contact assembly 20. The extent to-which actuator 26 is depressed for a given position of the operating handle 28 is adjusted by repositioning plate 92 on the side wall of the housing. Moving plate 92 to the left as viewed in FIGURES 5 and 6 will cause a greater depression of actuator 26 for a given position of operating handle 28.

It should be observed that the operating mechanism is such that an incremental rotation of the handle 28 from the position shown in FIGURE 5 toward that shown in FIGURE 6 causes a greater rotation of the arm 80' at the beginning of such a rotation, than it does when the position shown in FIGURE 6 is approached, thus providing an increasing mechanical advantage which favors full actuation of the start contact assembly 20.

Referring to FIGURE 2, during clockwise rotation of the operating handle 28 to the start position as viewed from the right hand end of FIGURE 2, the

tabs

52 and 54 of the tripping lever 50 will engage the edge 62 of operating lever 58 to rotate it in the clockwise direction. Since clockwise rotation of operating lever 56 is prevented by stop 74, this rotation of operating lever 58 will cause the tensioning of spring 72, thus developing a force to return the operating lever 58 and the shaft to the off position.

After the operator has moved the operating handle 28 to the start position, and has maintained it in that position for a suflicient length of time such that through the closing of

contacts

30 and 36 of the start contact assembly the motor has been brought up to a predetermined speed through energization at a reduced voltage, the operator will move the operating handle 28 from the start position through the off position toward the run position. With particular reference to FIGURE 2, the actuation of the run contactor 18 by rotation of the operating handle 28 in the counter-clockwise direction as viewed from the right hand end of FIGURE 2 will be described. Counter-clockwise rotation of the operating handle is transmitted through the shaft 42 to the tripping lever 50.

Tabs

52 and 54 on the tripping lever engage edge 60 of the operating lever 56 to rotate it in the counter-clockwise direction. This rotation of operating lever 56 is transmitted through link 82 to the pivot pin 84 which pivotally secures link 82 and link 78 to the free end of link 86. Link 86 is rotated in the counter-clockwise direction as viewed from the right hand end of FIG- URE 2, thereby moving the link 78 to the right and rotating arm in the counter-clockwise direction as viewed from the right hand end of FIGURE 2. The counterclockwise rotation of the arm 80 is transmitted through the torque tube 96 to the operating arm 98. Counterclockwise rotation of the operating arm 98 results in movement of the bar 104 to depress the actuator 24 to thereby close the contacts in the run contact assembly 18.

When the run contacts have been closed through counter-clockwise rotation of the operating handle as viewed in FIGURE 4, they are maintained in this position by a latch assembly shown in FIGURE 3. The latch assembly is arranged to cooperate with an extension 106 of the tripping lever 50 as shown in FIGURE 2. An L- shaped member 108, which is pivoted at its apex, is spring biased to rotate in a counter-clockwise direction about its apex to the position shown in FIGURE 3 by a spring 110. Attached to an arm of the L-shaped member by a pin 112 is a link 114 which is pivotally connected to a latch arm 116 having a cam surface which engages the end of extension 106 of the tripping lever. With the handle 28 moved to the run position, the extension 106 of the tripping lever engages the cam surface of latch arm 116 as shown in FIGURE 3. Upon closing of the contacts of run contact assembly 18, a solenoid 118 in the latch assembly is energized, such that its armature 120 is moved upward against the bias of a coil spring 122 to the position shown in FIGURE 3. With the solenoid energized to raise the armature 120 to the position shown, the L-shaped member 108, which is engaged by armature 120 when solenoid 118 is deenergized, is rotated under the force of spring in the counter-clockwise direction as viewed in FIGURE 3 such that a spacer 124 mounted on the pin 112 engages the end of an adjustment screw 126 as shown. With respect to the pivot point of L-shaped member 108, this is an overcenter position, such that the force of extension 106 on latch arm 116 will not be effective to lift the latch arm 116 and thereby release itself. This overcenter position is determined by the setting of adjustment screw 126.

The latching mechanism is designed to require quick movement of the operating handle 28 from the start through the off to the run" position. If the operating handle 28 should be moved too slowly from the start, through the oif toward the run position, the latch mechanism will prevent movement of the operating handle to the run position. With the operating handle 28 in the off position the solenoid 118 is not energized, and therefore under the force of coil spring 122 armature 120 is drawn downward against the arm of L-shaped member 108 to rotate it in the clockwise direction to a position wherein pin 112 is to the left of the pivot point of the L shaped member 108. Movement of the operating handle 28 to the start position causes extension 106 of the tripping lever to engage cam surface 128 of the latch arm 116, rotating both it and the L-shaped member clockwise. Movement of the operating handle 28 from the start position through the off position to the run position must be quick enough so that extension 106 of the tripping lever moves from engagement with cam surface 128 to engagement with cam surface 130, and then become latched 'With cam surface 132. If the movement is not quick enough, the L-shaped member 108 under its own weight and that of link 114 and latch arm 116 will rotate counter-clockwise, thereby lowering latch arm 116 and causing extension 106 of the tripping lever to be caught in hook portion 134 of the cam surface of latch arm 116, thus preventing its movement to the run position.

Should the solenoid 118 be deenergized, or an undervoltage condition occur, armature 120 of the solenoid will be moved downward by the force of spring 122, thereby pivoting the L-shaped member 108 clockwise and lifting the link 114 and the latch arm 116 to permit the extension 106 of the tripping lever to move free of the cam surface 132, thereby opening the contacts of the contact assembly through rotation of the shaft and actuation of the operating mechanism under the bias force of

springs

72 and 72.

The motor may be manually stopped by depressing a knob 136 (FIGURE 3) which is attached to an arm 138 slidably supported by a guide 140. The arm 138 is positioned such that its end is engageable with the edge of the link 114. Movement of the arm 138 to the left as viewed in FIGURE 3 will cause the upper end of the link 114 to be moved to the left, thereby causing the lower end of the link to be lifted to raise the latch arm 116 whereby the extension 106 of the tripping lever 50 is released from the cam surface 132.

While a particular embodiment of this invention has been shown and described it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the invention in its broader aspects, and therefore, it is intended that the appended claims cover all such changes and modifications that fall within the true spirit and scope of this invention.

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

1. An operating mechanism for actuating at least one contact assembly having contacts which are actuated by displacement of an actuator, comprising:

(a) a pantograph including first and second sets of substantially parallel arms, a first pivot point for first ends of first arms of said first and second sets of arms fixed relative to said contact assembly, a second pivot point diagonally opposite said first pivot point for first ends of second arms of said first and second sets of arms,

(b) a link having one end pivoted at a point fixed relative to said contact assembly and having its other end pivotally connected to said pantograph proximate to said second pivot point,

(c) actuating means for applying an actuating force to one of said first arms to cause its rotation about the first pivot point, and

(d) operating means for operably connecting the other one of said first arms to the actuator of said contact assembly, whereby the application of an actuating force to said one of said first arms through said actuation means, causes rotation of the other one of said first arms to displace the actuator of the contact assembly through said operating means, said pantograph and link approaching an overcenter relationship wherein the longitudinal axis of said link is parallel with the longitudinal axis of one of said second arms when the contacts of the contact assembly reach their actuated position, such that the neces sary actuating force decreases as the contacts approach their actuated positions.

2. An operating mechanism as defined in claim 1 wherein the position of said fixed pivot point of said one end of said link is adjustable relative to said first pivot point, such that the displacement of the actuator of the contact assembly by said operating means may be adjusted for proper operation of the contact assembly contacts.

3. An operating mechanism as defined in claim 1 wherein said actuating means includes resilient means biasing said one of said first arms to a position wherein the contacts of the contact assembly are maintained in their unactuated positions.

4. An operating mechanism as defined in claim 1 wherein the contact assembly and said pantograph, link and operating means are enclosed in a housing having a wall including a substantially fiat portion, said pantograph and said link being formed of sheet material and being positioned adjacent said flat portion of said wall so as to provide a compact operating mechanism.

5. An operating mechanism as defined in claim 4 wherein said first pivot point is a shaft journaled in said fiat portion of said wall with a first portion of said shaft extending through said wall, said actuating means including said shaft, an operating handle secured to said first portion of said shaft, and a lever keyed to said shaft within said housing, whereby rotation of said handle applies an actuating force through said shaft and lever to said first arm to cause its rotation.

6. An operating mechanism as defined in claim 3 wherein said actuating means includes a lever pivoted at one end at said first pivot point, and a pair of stops fixed relative to said contactor, said resilient means cooperating with said one of said first arms and said lever, whereby without an actuating force applied to said actuating means, said resilient means causes said one of said first arms to engage one of said stops and said lever to engage the other one of said stops, wherein the contacts of the contact assembly are maintained in their unactuated position, with the application of an actuating force to said one of said first arms, said resilient means being stressed with said lever engaging the other one of said stops and said one of said first arms being rotated against the force of said resilient means to cause rotation of the other one of said first arms to displace the actuator of the contact assembly to actuate the contacts.

7. An operating mechanism as defined in claim 5, wherein said operating means includes a torque tube having a bore, said shaft being received within said bore such that said tube may rotate independently of said shaft, said other one of said first arms secured at said first end to said torque tube, and an operating arm secured at one end to said torque tube, whereby the application of an actuating force to said one of said first arms through said actuating means, causes rotating of the other one of said first arms, said torque tube, and said operating arm to displace the actuator of the contact assembly.

8. An operating mechanism as defined in claim 1 for actuating a pair of contact assemblies, each having contact which are actuated by displacement of an actuator, wherein a first pantograph, a first link, and a first operating means are provided to actuate the first contact assembly, and a second pantograph, a second link, and a second operating means are provided to actuate the second contact assembly, and

(a) an actuating means is provided for applying an actuating force to one of said first arms of said first pantograph to cause its rotation about the first pivot point when a force in a first direction is applied to said actuating means, and for applying an actuating force to one of said first arms of said second pantograph to cause its rotation about the first pivot point when a force in a direction opposite said first direction is applied to said actuating means.

9. An operating mechanism as defined in claim 8 wherein said actuating means includes at least one resilient means biasing said ones of said first arms of said first and second pantographs to positions wherein the contacts of the first and second contact assemblies are maintained in their unactuated positions.

10. An operating mechanism as defined in claim 8 wherein the contact assemblies and said first and second pantographs, first links, and operating means are enclosed in a housing having a pair of walls each of which include a substantially flat portion, which flat portions are substantially parallel to each other, said first pantograph and said first link being formed of sheet material and being positioned adjacent said flat portion of one of said walls, and said second pantograph and said second link being formed of sheet material and being positioned adjacent said flat portion of the other of said walls, so as to provide a compact operating mechanism for said contact assemblies.

11. An operating mechanism as defined in claim wherein said first pivot point of said first and second pantographs is a shaft journaled in said flat portions of said walls, with a first portion of said shaft extending through one of said walls, said actuating means including said shaft, and operating handle secured to said first portion of said shaft, and a pair of levers keyed to said shaft within said housing, whereby rotation of said handle in a first direction applies an actuating force through said shaft and first lever to said first arm of said first pantograph to cause its rotation about the shaft to displace the actuator of the first contact assembly to close its contacts, and rotation of said handle in a second direction, opposite said first direction, applies an actuating force through said shaft and second lever to said first arm of said second pantograph to cause its rotation about the shaft, to displace the actuator of the second contact assembly to close its contacts.

12. An operating mechanism as defined in claim 9 wherein said actuating means includes a first lever pivoted at one end at said first pivot point of said first pantograph, a second lever pivoted at one end at said first pivot point of said second pantograph, first and second pairs of stops fixed relative to said contact assemblies, a first resilient means cooperating with said one of said first arms of said first pantograph and with said first lever, a second resilient means cooperating with said one of said first arms of said second pantograph and with said second lever, whereby without an actuating force applied to said actuating means, said first and second resilient means cause said ones of said first arms to each engage a first stop of said first and second pairs of stops, and said first and second levers to each engage the other stop of said first and second pairs of stops, wherein the contacts of the contact assemblies are maintained in their unactuated position, with the applications of an actuating force to said one of said first arms of said first pantograph, said first resilient means being stresses with said first lever engaging the other one of said first pair of stops and said one of said first arms of said first pantograph being rotated against the force of said first resilient means to cause rotation of the other one of said first arms of said first pantograph to displace the actuator of the first contact assembly to actuate its contacts, with the application of an actuating force to said one of said first arms of said second pantograph, said second resilient means being stressed with said second lever engaging the other one of said second pair of stops and said one of said first arms of said second pantograph being rotated against the force of said second resilient means to cause rotation of the other one of said first arms of said second pantograph to :displace the 10 actuator of the second contact assembly to actuate its contacts.

13. An operating mechanism as defined in claim 11, wherein said first operating means includes a first torque tube having a bore which received said shaft such that first tube may rotate independently of said shaft, said other one of said first arms of said first pantograph secured at said first end to said first torque tube, and a first operating arm secured at one end to said first torque tube, and said second operating means includes a second torque tube having a bore which receives said shaft such that said second tube may rotate independently of said shaft, said other one of said first arms of said second pantograph secured at said first end to said second torque tube, and a second operating arm secured at one end of said second torque tube, whereby the rotation of said handle in a first direction applies an actuating force to said first arms of said first pantograph through said actuating means, to cause rotation of the other one of said first arms of said first pantograph, said first torque tube, and said first operating arm to displace the actuator of the first contact assembly, and the rotation of said handle in a second direction opposite said first direction applies an actuating force to said first arm of said second pantograph through said actuating means, to cause rotation of the other one of said first arms of said second pantograph, said second torque tube, and said second operating arm to displace the actuator of the second contact assembly.

14. An operating mechanism for actuating a pair of contact assemblies, each of which has contacts which are actuated by displacement of an actuator, comprising:

(a) a housing inluding a base and a pair of spaced substantially parallel side walls,

(b) a shaft extending between and supported for rotation by said side walls,

(c) a pair of torque tubes loosely supported on said sha'ft, a first one of said torque tubes extending from near a first one of said side walls about 'half the distance between said side walls, the other one of said torque tube extending from near the other one of said side Walls about half the distance between said side walls such that the inner ends of said torque tubes are closely spaced at the center of said housing,

((1) a first portion of the operating mechanism, positioned adjacent the first one of said side walls, cooperating with said shaft and said first torque tube to transmit rotation of said shaft in a first direction said first torque tube,

(e) a first operating means adjacent the center of the housing operatively connecting said first torque tube and the actuator of a first one of the contact assemblies such that rotation of the shaft in the first direcgiian actuates the actuator of the first contact assem- (f) a second portion of the operating mechanism, po-

sitioned adjacent the second one of said side walls, cooperating with said shaft and said second torque tube to transmit rotation of said shaft in a second direction to said second torque tube, and

(g) a second operating means adjacent the center of the housing operatively connecting said second torque tube and the actuator of a second one of the contact assemblies such that rotation of the shaft in the second direction actuates the actuator of the second contact assembly.

15. An operating mechanism as defined in claim 14 wherein said first and second portions of the operating mechanism each comprises:

(a) a pantograph including first and second sets of substantially parallel arms, said shaft is a first pivot point for first ends of each arms of said first and second sets of arms, and a second pivot point is diagonally opposite said first pivot point for first ends of second arms of said first and second sets of arms, and

(b) a link having one end pivoted at a point fixed relative to said contact assemblies, and having its other end pivotally connected to said pantograph proximate to said second pivot point, said pantograph and link approaching an overcenter relationship wherein the longitudinal axis of said link is parallel with the longitudinal axis of one of said second arms when the contacts of the contact assembly reach their actuated position, such that the necessary actuating force decreases as the contacts approach their actuated positions.

16. An operating mechanism as defined in claim 15 wherein in said first and second portions of the operating mechanism the portion of said fixed pivot point of said one end of said link is adjustable relative to said first pivot point, such that the displacement of the actuators of the contact assemblies by said first and second operating means may be adjusted for proper operation of the contact assemblies contacts.

17. An operating mechanism as defined in claim 15 wherein one of said first arms in said first portion of the operating mechanism is secured at its first end to the outer end of said first torque tube, and said first operating means includes an operating arm secured at one end to the inner end of said first torque tube, and one of said first arms in said second portion of the operating mechanism is secured at its first end to the outer end of said second torque tube, and said second operating means includes an operating arm secured at one end to the inner end of said second torque tube.

18. An operating mechanism as defined in claim 14 wherein a portion of said shaft extends through one of said side walls and an operating handle is secured to said portion of said shaft.

v References Cited UNITED STATES PATENTS 2,929,288 3/ 1960 Harvey et a1. 15 3,158,724 11/1964 Emerick et a1.

FOREIGN PATENTS 600,989 7/ 1934 Germany. 755,361 8/1956 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner ROBERT A. VANDERHYE, Assistant Examiner US. Cl. X.R.