US3432787A

US3432787A - Manually operated switch

Info

Publication number: US3432787A
Application number: US659689A
Authority: US
Inventors: Jordan F Puetz
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1966-04-05
Filing date: 1967-08-10
Publication date: 1969-03-11
Anticipated expiration: 1986-03-11
Also published as: GB1131785A

Description

March 11, 1969 Filed Aug. 10, 1967 TORQ J. F. PUETZ MANUALLY OPERATED SWITCH ANGLE X INVEN TOR.

JORDAN F. PUETZ March 11, 1969 J. F. PUETZ 3,432,787

MANUALLY OPERATED SWITCH Filed Aug. 10, 1967 Sheet 3 of 5 INVENTOR.

JORDAN F. PUETZ United States Patent 3,432,787 MANUALLY OPERATED SWITCH Jordan F. Puetz, Milwaukee, Wis., assignor to Square D Company, Park Ridge, 11]., a corporation of Michigan Continuation-impart of application Ser. No. 540,406, Apr. 5, 1966. This application Aug. 10, 1967, Ser. No. 659,689 US. Cl. 337-153 Claims Int. Cl. H01h 71/20, 73/22, 3/20 ABSTRACT OF THE DISCLOSURE A fraction-a1 horsepower manually operable starter having movable contacts which are spring biased to a circuit closing position and moved to a circuit opening position against the spring bias by an overload responsive mechanism that has a pawl of rigid material which engages the teeth in a ratchet wheel of a solder pot type overload unit and a lever arrangement which will force the contacts open in event of a contact weld or a broken toggle spring and exert a maximum force to move the contacts to a circuit opening position upon release of the pawl by the ratchet wheel.

This invention relates to electric switches and more particularly, to electric switches which are manually operable at will to circuit opening and closing positions and automatically operated to a circuit opening position in response to overload currents such as are used for the control and protection of electric motors and is a continuation in part of Ser. No. 540,406, filed Apr. 5, 1966, now abandoned.

An object of the present invention is to provide an electric switch having a minimum number of parts with an improved overload release mechanism and a lever arrangement which will open the switch contacts in event of a contact weld or a broken toggle spring.

An additional object is to provide an overload release lever of an electric switch with a novel latching mechanism and an actuating spring arrangement, whereby the spring exerts a minimum force on the latching mechanism when the lever is in one position and a maximum force for opening the contacts of the switch when the lever is moved to another position.

A further object is to provide an electric switch with a novel pawl structure which is engageable with a releasable ratchet wheel of a fusible alloy type overload release mechanism which pawl is formed as a non-resilient member having a rounded position which engages the teeth of the ratchet wheel, and a portion which prevents engagement of the rounded portion during movement of the pawl to its engaging position and controls the relative positions between the rounded portion and the ratchet wheel when a the pawl is in its engaging position to minimize wear of the pawl and ratchet wheel and to assure proper positioning of the pawl on the ratchet wheel each time the pawl is moved to its engaging position and to carry the pawl on a lever which is spring biased so the rounded portion of the pawl engages the ratchet wheel with a minimum force to prevent injury to the wheel by the pawl and assure release of the rounded portion from the teeth of the wheel upon release of the wheel in response to an excess current flow through the contacts of the switch and to arrange the spring which biases the lever so the lever will open the switch contacts with a maximum obtainable force upon release of the wheel.

Further objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

3,432,781 Patented Mar. 11, 1961 FIG. 1 is a plan view of the electric switch according t the present invention with a portion thereof broken awaj to illustrate a latching pawl as used in the switch.

FIG. 2 is a view taken along line 22 in FIG. 1, show ing certain components in cross section with the operating mechanism in an ON and RESET condition.

FIG. 3 is a view taken along line 33 in FIG. 1 Witl a portion of a contact carrier removed to illustrate 2 stationary contact and with the operating mechanism it the OFF and TRIPPED condition.

FIG. 4 is a view of the switch parts as shown in FIG. 3 with the contact carrier shown in full and with the operating mechanism in the ON and RESET condition.

FIG. 5 is a view of the switch parts in FIG. 4 in the ON TRIPPED position.

FIG. 6 is a perspective view of one side of the pawl as used in the overload release mechanism as mounted on a broken-away portion of a lever.

FIG. 7 is an exploded view showing in perspective the operating parts of the switch in FIG. 1.

FIG. 8 schematically illustrates the lever arrangement of the overload release mechanism of the switch in FIG. 1.

FIG. 9 graphically illustrates the torque characteristics of the lever arrangement in FIG. 8.

FIG. 10 is a view of a modified form of the movable contact carrier and the relative position of the operating lever of the switch as may be used in the switch in FIG. 1.

An electric switch 10, shown in the drawings, comprises a housing 11 formed of molded insulating material to have two

mating housing parts

12 and 13 which provide an internal cavity 15 when the

parts

12 and 13 are assembled. A metal mounting plate 16 is mounted on the housing 11 by a book 17 and an car 18 which are held in position by the assembled

parts

12 and 13. The hook 17 and the ear 18 each extend downwardly from the plate 16 so the hook 17 will embrace a suitably located lug 19, formed on the housing part 12, while the car 18 engages a boss 20 The car 18 and the boss 20 each are provided with openings 21 which are aligned with openings formed in the

parts

12 and 13 to receive securing rivets or screws, not shown, for securing the

parts

12 and 13 together. Additionally, the ear 18 has a downwardly inclined portion 22 which engages a complementary surface on the boss 20. The plate 16 is provided with a central opening, generally rectangular in shape, which provides a passage for an operating lever 24 of the switch 10.

The operating lever 24, as shown in FIGS. 1-3 and 7, has a pair of oppositely extending pivot bearings 25 received in suitable openings in the

parts

12 and 13 for the purpose of pivotedly mounting the lever 24 in the housing 11. Surrounding the pivot bearings 25 are circular bosses 26 each presenting a flat surface 27 that is positioned adjacent a similar flat surface on the

parts

12 and 13 for the purpose of guiding the lever 24 in its rotation in the housing 11. The lever 24 is also provided with outer curved surfaces 28 shaped to close the opening in the plate 16 while permitting the lever 24 to rotate in the housing 11. As most clearly shown in FIG. 2, outwardly extending from a bottom edge 29 of the lever 24 and projecting from the outer surface 28 is a stop 30, the top surface of which is engageable with the bottom surface of the metal mounting plate 16 for the purpose of limiting the rotation of the lever 24 in a clockwise direction in FIG. 2. The lever 24 has an internal cavity 31 extending from the bottom edge 29 shaped to provide a securement for a member 32. The member 32, as most clearly shown in FIG. 7, has a portion 33 having projections thereon which are received in complementary grooves in the lever 24 to anchor the member 32 relative to the lever 24. The member 32 also has a downwardly curved portion 34 extending below the bottom surface 29 Ihich presents a downwardly facing notch 35 in general lignment with a center line extending through the pivots t5 and a handle portion 36 of the lever 24 which extends |utwardly from surface 28 above the plate 16. The notch 5 provides a seat for one end of a spring 37 which has ts other end positioned on a hook 38 extending from an nclined lever arm 39 on a contact actuator lever 40.

The contact actuating lever 40, as shown in FIGS. 2 1nd 7, has a pair of parallel arms 41 extending in the ;ame direction at an angle to the arm 39 to present free ends from which pivots 42 extend. The pivots 42 are re :eived in suitable bores in the

housing parts

12 and 13 to guide the rotation of the lever 40 in the housing 11. The arms 41 are spaced to provide a notch 43 wherein the spring 37 may move with clearance during the movement of the lever 24 and the lever 40. Similarly, the cavity 31 in the lever 24 provides clearance to accommodate the movement of the arm 39. Protruding from a junction of the

arms

39 and 41 is an arm 44 having a knob 45 at its free end. The knob 45 has an upper surface which engages a bottom surface of a stop 46 formed on the

housing parts

12 and 13 when the lever 40 is in the position as shown in FIG. 2 and a bottom surface which engages a surface 47 on a carrier 48 for the movable contacts of the switch when the lever 40 is positioned as in FIG. 3. The carrier 48, most clearly shown in FIGS. 5 and 7, is preferably formed of a molded insulating material and is guided for vertical movement in the cavity by a rib 49 which is received between suitably sized oppositely extending ribs 50, formed on the

housing parts

12 and 13,

and by spaced bulges 51 which are received in a groove 52 formed between the

housing parts

12 and 13. The carrier 48 also has raised surfaces 53 which are engageable with the inner walls of cavity 15 to further guide the carrier in its vertical movement in the cavity 15. The

top surface of the carrier adjacent the surface 47 includes indentations 54 extending inwardly from the raised surface 53. The indentations 54 are each arranged to be engaged by a free end 55 of an overload lever 56 to be later described. The top surface of the carrier 48 is also provided with an inclined portion 57 which in the embodiment shown in FIGS. 1-9 provides clearance for the movement of the portion 34 of the member 32. Extending upwardly from a bottom surface of the carrier 48 is a notch 58 which straddles a rib 59 formed on the

housing parts

12 and 13 to provide electrical clearance between a pair of spaced contacts 61 which are received in a pair of spaced transversely formed grooves 60 in the carrier 48. The movable contacts 61 are each formed of a conducting metal part 62 having a contact surface 63 on each of its free ends and a central portion 64 which is engaged by one end of a compression spring 65. The other end of the compression spring 65 is received in a spring seat 66 that rests in suitably formed notches in the

housing parts

12 and 13. The spring 65 constantly urges the carrier 48 in an upward direction within the cavity 15.

The switch 10, as shown in FIG. 1, is provided with four identical terminal and stationary contact members 67, each of which, as shown by the single member in FIG. 7, comprises a generally U-shaped section of conducting metal having a downwardly facing electrical contact portion 69 on its lower arm and a threaded hole in an upper arm in which a terminal screw 70 operates. The

parts

12 and 13 are provided with suitable recesses extending downwardly to ledges in the top surface of the

parts

12 and 13 whereon the terminal screw 70 portion is positioned. The side walls of the

parts

12 and 13 are provided with suitable passages or openings extending from the exterior of the

parts

12 and 13 into the cavity 15 so that the electric contact portion 69 is positioned within the cavity 15 above the movable contacts 61. The passages in the housing 11 are arranged so the contact portions 69 are spaced along the side walls of cavity 15 to provide two pairs of stationary contacts with each pair including a contact portion 69 which is carried by the part 12 and a contact portion 69 carried by the part 13. The respective pairs of contact portions 69 are bridged by the contacts 61 as the contacts 61 are moved upwardly by the compression spring 65 and are moved out of engagement when the lever 40 causes the contact carrier 48 to move downwardly.

The foregoing described components of the switch will provide the switch with a simple ON/ OFF function, as will now be described, reference being made to FIG. 2 of the drawings. When the switch parts are positioned as shown in FIG. 2, the switch will be in the ON or circuit making position, wherein the movable contacts 63 are in engagement with the pairs of stationary contact portions 69 and the lever 24 is in its furthest clockwise position of rotation which is limited by engagement of the stop with the plate 16. When the lever 24 is thus positioned, the line of centers passing through the notch and the hook 38 will be to the left of the pivots 42 so the spring 37 will cause the lever to rotate counterclockwise about its pivots 42 to a position wherein it is limited by the engagement of the knob with the stop 46. When the lever 40 is thus positioned, the springs will force the contact carrier 48 upwardly to cause engagement between the contacts 63 and 69.

The switch is actuated to an OFF position by rotating the lever 24 counterclockwise. The counterclockwise rotation of lever 24 will cause the portion 34 of the member 32 to pass below the pivots 42 so the line of centers passing through the notch 35 and the book 38 moves to the right of the pivots 42. As the line of centers thus passes through the pivots 42, the spring 37 provides a toggle force which causes the lever 40 to rotate in a clockwise direction and the knob 45 to engage the surface 47 to move the contact carrier 48 downwardly and thereby cause the separation of the contacts 63 from the Contact portions 69 to place the parts of the switch in the circuit opening position. The movement of the lever 24 in the counter-clockwise direction to the OFF position is limited when the bottom surface 29 on the stop 30 engages an upper surface of the overload lever 56 which will be described in connection with the overload mechanism which is incorporated in the switch 10 according to the present invention.

As illustrated by FIGS. 1 and 7, the overload mechanism includes a current responsive device comprising a rotatable ratchet wheel 73 secured on the end of a shaft 74 that is surrounded by a cup having a thermal connection with a heater element 76. Within the cup and disposed between its internal surface and the shaft 74 is a relatively low melting point alloy which in the conventional manner in the solidified condition prevents rotation of the ratchet wheel 73 and the shaft 74. The heater element 76, which is connected by a screw 77 to the terminal contact member 67, includes a number of turns of resistance wire. The other end of the heater element 76 is connected to a terminal member 78 by a screw 79. The terminal member 78, which is secured to the outer side wall of the switch 10, has an additional terminal screw to provide a connection for a conductor so current flowing between the

screws

75 and 77 will flow through the heater element 76 when the switch contacts are in a circuit closing position.

The overload lever 56, as most clearly seen in FIG. 7, includes a pair of parallel spaced arms 80 extending from a pair of oppositely extending pivots 81 which are received in suitable bores in the walls of the cavity 15 to permit rotation of the lever 56 in the cavity 15. The arms 88 are spaced to provide clearance for the movement of the lever 24 during its rotation. The free ends 55, formed on the ends of the arms 80 which are remote from the pivots 81, are received in the indentations 54 when the lever 56 is positioned as shown in FIG. 3. Extending from the pivots 81, in a direction opposite of the arms 80, is a lever 82 which, as shown in FIG. 3, has a notch 83 formed on its undersurface to position a spring seat 84 for a compression spring 85. The other end of the compression spring 85 is positioned on a spring seat 86 which rests in a notch 87 in the bottom wall of the cavity 15. Extending downwardly of the pivots 81 at an angle from a line of centers through the free ends 55 and the notch 83 is a lever 88 which provides a support for a latch member 89 which is formed of rigid metal. The latch member 89 is pivoted on the lever 88 by a pin 91 which extends through a pair of spaced ears 92 on the latch member and a bore 91a in the lever 88, shown in FIG. 7. The spaced ears 92 are formed to extend outwardly from opposite marginal edges of a main body portion 93 of the latch member 89. Extending along one of the marginal edges on the main body portion 93 in the opposite direction from the ears 92 is an ear 94 which has a rounded edge 95. The rounded edge 95 is engageable with the teeth 96 on the ratchet wheel when the lever 56 is in the position shown in FIG. 4 of the drawing. Additionally, the main bod portion 93 is indented to provide a raised portion 97 which extends from the body portion 93 in the same direction as the ear 94 and is arranged to ride upon the teeth 96 as the latch member is moved relative to the ratchet wheel 73 from the position shown in FIG. 3 to the position shown in FIG. 4. The raised portion 97, by being formed as an indentation in the main body portion 93, thereby provides a depression on the face opposite the main body portion 93 from which the raised portion 97 extends. The indentation is used to provide a seat for one end of a compression spring 98 which extends in a suitable groove 99 in the lever 88 to a spring seat 100 at the base of the groove 99. The spring 98 is arranged to constantly bias the ear 94 toward its latching position with the ratchet wheel 73. The extent of movement of the main body portion 93 by the spring 98 is limited by a stop 101, shown in FIG. 6, that is formed along the marginal edges of the main body portion 93 so the stop 101 will engage a ledge 102 formed on the lever 88.

The operation of the overload mechanism of the switch will now be explained. When the components of the switch 10 are positioned in the RESET position, as shown in FIG. 4, the ratchet wheel 73 is held against rotation and the rounded edge 95 is in engagement with the teeth 96 to maintain the lever 88 against a counterclockwise rotation. When the components of the switch 10 are thus positioned, the point of pivot of the spring seat 84, which is in the lines of centers through the spring seat 87 and the pivots 81, will be slightly to the right of a center line passing through the pivot 81 and the spring seat 87. Thus in spite of the fact that the spring 85 is fully compressed, because of the small displacement of the spring seat 84 from the center-line through the pivot 81 and the seat 87, the force of engagement between the rounded edge 95 and the teeth 96 will be minimal as the engaging force is the product of the spring force and the distance of displacement. Also, when the overload mechanism is in the reset position, the lever 56 will be positioned so the free ends 55 of the arms 80 are out of engagement with the indentations 54 on the carrier 48, permitting the switch 10 to be operated as an ON-OFF switch as previously described.

When the overload mechanism of the switch 10 responds to a current flow sutficient to liquify the solder connection between the ratchet wheel 73 and the shaft 74, the ratchet wheel 73 becomes rotatable and ceases to maintain the lever 56 against rotation. When the lever 56 is thus released, the spring 85 causes the lever 56 to rotate in a counterclockwise direction from the reset position shown in FIG. 4 to the tripped position illustrated in FIG. 5.

During the counterclockwise rotation of the lever 56 from the RESET to the TRIPPED position, the spring seat 84 will move upwardly and to the right, while the free ends 55 on the lever arms 80 move downward and engage the indentations 54 in the carrier 48. The counterclockwise rotation of the lever 56 thus causes the carrie 48 to be moved downwardly against the force of th springs 65, to a position wherein the contact portions 6; are separated from the stationary contacts 69, thereb placing the components of the switch 10 in a circuit open ing position. As is most clearly shown in FIG. 5, wher the lever 56 is in the tripped position, the point of pivo of the spring seat 84 will be displaced upwardly and tc the right a greater distance from the center line through the pivots 81 and the spring seat 87 than when the mechanism was positioned as shown in FIG. 4. Thus in spite of the fact that the force exerted by the spring 85 is reduced as the spring 85 expands to move the lever 56 in a counterclockwise direction, the efiective force provided by the spring 85 which cause the separation of the contact portions 63 from the contacts 69 increases. This result occurs as the force exerted by the spring 85 is applied through a lever arm component which increases as the lever 56 rotates and is represented by the increased displacement of the pivot 84 from the center-line through the pivots 81 and the spring seat 87.

Under normal circumstances, the foregoing described operation of the overload mechanism to the TRIPPED position will occur while the components of the switch 10, which provide the ON/OFF switch operation, are in the ON position. As was previously stated, when the components of the switch which provide the ON/OFF switch operation are moved to the switch OFF condition, the movement of the lever 24 was limited when the surface 29 engaged an upper surface portion of the overload lever 56. The surface engaged by the surface 29 is designated by a numeral 103 and is formed, as shown in FIG. 3, as an inclined surface adjacent an inner wall of one of the levers and extends generally outwardly and downwardly from a center-line passing through the pivots 81. Thus when the overload lever 56 rotates from the RESET position to the TRIPPED position, the surface 103 will be moved upwardly. The restoration of the components of the overload mechanism to the RESET condition is accomplished by first moving the lever 24 from the switch ON position to the switch OFF position, which results in the movement of the member 32, the spring 37, and the lever 40, as previously described. Without a continued application of an external force, the lever 24 will not be moved by the force of the spring 37 to a full OFF position when the components of the overload mechanism are in the TRIPPED position. During the rotation of the lever 24 toward the OFF position and after the line of centers through the hook 38 and the notch 35 passes through the pivot 42, the spring 37 will supply a force to cause a continued movement of the lever 24 to a position wherein the surface 29 engages the surface 103. As the surface 103 is displaced upwardly when the overload mechanism is in the TRIPPED position, the movement of lever 24 will cease when the lever 24 reaches a position intermediate the OFF and the ON position.-

The components of the overload mechanism are moved to the reset position when the handle 24 is rotated clockwise by an external force, as in FIG. 3, from the intermediate position to the full OFF position. As the lever 24 rotates clockwise, the engagement between the

surface

29 and 103 will cause the lever 88 to also rotate clockwise. The clockwise rotation of the lever 88 causes the surface 55 to be disengaged from the indentations 54 so that the carrier 48 is free to be moved upwardly by the springs 65. However, the carrier 48 is prevented from moving to a circuit closing position by the lever 40 which moved to the circuit opening or OFF position when the lever 24 was moved from the ON to the OFF position. The clockwise rotation of lever 56 also causes the lever portion 88 to rotate clockwise, causing the latch member 89 to pass over the ratchet wheel 73. The movement of the latch member 89 is unhindered as the latch member pivots to an out-of-the-way position on the pivot pin 91 the handle 24 is moved from the OFF position to the ON position the rotation required of the handle 24 will cause the curved edge to be retracted to a position wherein a free edge 34b on the portion 34 is out of a line of movement of the carrier 48a before the contact operating lever 40 moves with a snap action against the stop 46 to permit engagement between the movable and stationary contacts. When the handle 24 is moved from the ON position to the OFF position, the curved edge 34a will move toward the inclined surface 57a. The parts of the switch 10, including the elevation of the surface 57a and the location of the edge 55a of the notch 35, are arranged so that when the edge 35a is adjacent the surface 57a, the operating lever 40 moves with a snap action and moves the carrier 48:: out of the path of movement of the surface 35a as the contacts 63 separate from the stationary contacts 69. Also when the switch handle 24 is in the ON position and the overload lever 56 is moved in response to an excess current condition, the operation of the switch will be as previously described and the edge 35a will be positioned out of the path of movement of the carrier 48a.

However, should the toggle spring 37 be broken, the switch 10, which includes the carrier 48a, may be operated from either the ON position to the OFF position, or from the OFF position to the ON position. Also, should the contacts 63 and 69 become welded together with a weld requiring a force greater than the force exerted by the spring 37 to break the weld, the switch 10 may be operated to move the carrier 48a to a circuit opening position by breaking the weld between the contacts 63 and '69. Additionally, should the switch 10 be subjected to an overload current condition which releases the overload lever 56 when the force exerted by the spring 85 through the lever 56 on the carrier 48a is insufiicient to break a weld between the contacts 63 and 69 and should the strength of the weld be of such magnitude that the additional force supplied by the spring 37 through the lever 40 when the handle 24 is operated to the OFF position when combined with the force exerted by the spring 85 is insufiicient to break the weld between the contacts 63 and 69, the presence of the

surfaces

34a and 57a will cause the weld between the contacts 63 and 69 to be broken as follows. When the force exerted by the spring 37 or the force exerted by the spring 85 or the combined force exerted by the

springs

37 and 85 as above described is insufficient to break a weld between the contacts 63 and 69 or the spring 37 is broken, the contact carrier 48a will be held by the weld between the

contacts

63 and 67 or the springs 65, depending upon the type of switch 10 failure, in a position to complete a circuit between the contacts 63 and 69. Under any of these failure conditions operation of the lever 24 will move the edge 34a to a position wherein the edge 34a engages the inclined surface 57a. As the surface 34a follows an arcuate path during movement of the lever 24 and the surface 57a is inclined, the movement of the surface 34a on the inclined surface 5711 provides a camming action and causes the carrier to be positively moved by the manual force on the lever 24 to break the weld between the contacts 63 and 69. If the malfunction of the switch 10 is caused by a broken toggle spring 37, the switch 10, because of the surfaces 37a and 57a, may be operated as an ON-OFF switch without a toggle feel during the operation of the handle 24 in a manner previously described.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

-1. In an electric switch having:

(a) an insulating housing,

(b) a set of cooperating fixed and movable contact within the housing,

(c) a movable carrier supporting the movable contacts said carrier being movable in the housing for mov ing the movable contacts from a first position where at the movable contacts are separated from tht stationary contacts to a second position whereat the movable contacts and the stationary contacts are engaged,

(d) biasing means engaging the carrier, said biasing means providing a force having a direction for urging the carrier to the second position for causing the movable contacts to engage the stationary contacts,

(e) a melting alloy type current responsive means for moving the carrier to the first position in response to an excess current flow in a circuit comprising:

('1) a lever pivoted on the housing for rotation, said lever having a portion movable upon rotatation of the lever from a first position wherein said portion is spaced from the carrier to a second position wherein the portion engages the carrier and positions the carrier in the second position whereas the movable contacts are separated from the stationary contacts (2) a spring operating between the lever and the housing to constantly provide force which exceeds the force provided by the biasing means to move the lever portion toward the second position (3) a rotatable ratchet wheel (4) means responsive to current flow in the circuit for holding the ratchet wheel stationary when current flow through the circuit is less than a predetermined value and for releasing the ratchet wheel when the current flow is in excess of the predetermined value (5) a pawl formed of non-resilient material having a first portion pivotally mounting the pawl on the lever, a second portion positionable on a portion of the periphery of the ratchet wheel to provide a latching engagement with the ratchet wheel for maintaining the lever against the force of the spring in its first position when the ratchet wheel is held stationary, and a third portion engageable with the ratchet wheel for directing the second portion to the same position relative to the periphery of the ratchet wheel when the lever is moved [from the second position to the first position to provide the latching engagement (6) and a resilient means positioned between the pawl and the lever for urging the second portion into its latching engagement with the ratchet wheel.

2. The combination as recited in claim 1 wherein the resilient means is a coil spring and the third portion on the pawl provides a seat for one end of the coil spring.

3. The combination as recited in claim 2 wherein the pawl also includes a stop portion which engages a portion of the lever to limit the movement of the pawl by the spring.

4. The combination as recited in claim 1 wherein the ratchet wheel has a plurality of teeth along its periphery and the latching engagement with the teeth on the ratchet Wheel is provided by a rounded edge on the second portion of the pawl.

5. The combination as recited in claim 1 wherein the third portion prevents engagement of the second portion with the periphery of the ratchet wheel during the movement of the lever from its second position to its first position.

6. The combination as recited in claim 4 wherein the rounded edge engages the teeth substantially at the same angle each time the latching engagement is accomplished by moving the lever to its first position.

1 l 7. In an electric switch the combination comprising: pair of pivot spaced on a centerline, a lever including hub rotatable about a first of said pair of pivots, a first rm extending from the hub to provide a free end on a irst side of the centerline and a second arm extending rom the hub to provide an end on a second side of the :enterline, a latch means including a releasable member lisposed on the second side of the centerline engaging he end of the second arm for maintaining the free end )f the first arm in a position adjacent the centerline on .he first Side of the centerline when the latch means is n one condition of operation and means including a spring having portions disposed on the first side of the centerline reacting between the second of the said pair of pivots and the free end of the first arm for moving the first arm from the position adjacent the centerline to a position on the first side of the center line remote from the centerline when the latch means is in another condition of operation.

8. The combination as recited in claim 7 wherein the lever has a third arm extending from the hub on the second side of centerline engageable with a contact carrier of the switch for moving a pair of contacts carried by the carrier to a circuit opening condition when the first arm of the lever is moved to the position remote from the centerline.

9. The combination as recited in claim 7 wherein the latch means includes: a rotatable ratchet wheel positioned on the second side of the centerline, means responsive to current flow for holding the ratchet wheel stationary and thereby placing the latch means in said one condition of operation when current fiow through a circuit is less than a predetermined value and for releasing the ratchet wheel and placing the latch means in the said another condition of operation when the fiow of current is in excess of the predetermined value, a pawl formed of non-resilient material having a first portion pivotally mounted on the end of the second lever, a second portion positionable on a portion of the periphery of the ratchet wheel with a latching engagement with the ratchet wheel for maintaining the first arm in its adjacent position relative to the centerline when the ratchet wheel is held stationary, and a third portion engageable with the ratchet wheel for directing the second portion to the same position relative to the periphery of the ratchet wheel when the second portion is moved into its latching engagement, and a resilient means positioned between the second arm and pawl for urging the second portion into its latching engagement with the ratchet wheel.

10. An electric switch having:

(a) an insulating housing (b) a set of cooperating fixed and movable contacts within the housing (c) an insulating carrier supporting the movable contacts, said carrier being linearly movable along an axis with respect to the fixed contacts for moving the movable contacts from a first position in the housing wherein the movable contacts are separated from the fixed contacts to a second position Within the housing wherein the movable contacts and the fixed contacts are in engagement,

((1) resilient biasing means reacting between the housing and the carrier providing a force for constantly urging the carrier to the second position wherein the contacts are in engagement,

(e) a rotatable handle pivoted on the housing (f) a rotatable toggle lever pivoted on the housing and having a portion engageable with the housing limiting rotation of the toggle lever from a stopped position in one direction and engageable with the carrier for moving the carrier from the second position to the first position when the toggle is rotated from the stopped position in a direction opposite the said one direction to an actuated position,

(g) means including a spring connected between the handle and the toggle lever for imparting rotation of the handle to the toggle lever for causing the handle to move with a snap action when the lever is rotated from a first position past a central position toward a second position and for causing the toggle lever to rotate from the stopped position to the actuated position with a force exceeding the force provided by the biasing means for causing separation of the movable contacts from the stationary contacts,

(h) current responsive means including a lever pivoted on the housing for rotation between two positions, said lever having a portion engageable with the carrier for moving the carrier to the second position when the lever is rotated from a first position to a second position, a spring operatively positioned between the housing and the lever for constantly urging the lever toward the second position with a force exceeding the force provided by the biasing means for causing separation of the movable contacts from the stationary contacts upon rotation of the lever from the first to the second position, and means responsive to current flow in a circuit for maintaining the lever in the first position when current flow in the circuit is less than a predetermined value, and for releasing the lever for rotation to the second position when the fiow of current is in excess of the predetermined value,

(i) and means including a surface on the handle and a cam surface on the carrier which is engaged by the surface on the handle when the carrier is in the second position and the handle is rotated from the first to the second position for moving the carrier from the second position and causing separation of the movable contacts from the stationary contacts when the forces supplied by the spring on the toggle lever or the lever of the current responsive means are insuflicient to cause the separation of the movable contacts from the stationary contacts.

References Cited UNITED STATES PATENTS BERNARD A. GILHEANY, Primary Examiner. HIRAM B. GILSON, Assistant Examiner.

US. Cl. X.R.