US3388568A - Washing machine drive arrangement - Google Patents

Description

June 18, 1968 R. B. BEARE ETAL 3,388,568

WASHING MACHINE DRIVE ARRANGEMENT Filed July 1, 1966 4 Sheets-Sheet 1 HVVE/VIORS. CURT/S R. HARTLEY ROBERTS. BE ARE June 18, 1968 R. B. BEARE ETAL 3,388,568

WASHING MACHINE DRIVE ARRANGEMENT Filed July 1, 1966 4 Sheets-Sheet 2 INVENTORS CURTIS R. HARTLEY ROBERT E. BEARE June 18, 1968 R. B. BEARE ETAL 3,388,568

WASHING MACHINE DRIVE ARRANGEMENT 4 Sheets-Sheet 5 Filed July 1, 1966 INVENTORS. CURTIS R4 HARTLEY ROBERT 8. 85 ARE W Hi-F5 June 18, 1968 R. B. BEARE ETAL 3,388,568

WASHING MACHINE DRIVE ARRANGEMENT Filed July 1, 1966 4 Sheets-Sheet 4.

INVENTORS. CURTIS R. HARTLEY ROBERT B. 85405 BY Hi-Fl United States Patent 3,388,568 WASHING MACHINE DRIVE ARRANGEMENT Robert B. Beare, Her-tin, and Curtis R. Hartley, West Frankfort, Ill, assiguors to Borg-Warner Corporation, Qhicago, Ill., a corporation of Illinois Filed July 1, 1966, Ser. No. 566,449 17 Claims. ((11. 68-23) ABSTRACT OF THE DISCLOSURE A washing machine drive having a reversible motordriven shaft; an agitator-operating gear set including a drive gear, and a driven gear rotatable on a support connected to a clothes container; a motor-controlled latch rotatable with the drive gear and engageable with the driven gear to lock the gears together for unitary rotation of the support and clothes container; a helical spring clutch on the shaft and providing a positive drive to the gear set during shaft rotation and providing a slipping friction drive to operate the latch to lock the gears for container rotation during reversal of shaft rotation.

This invention relates to a washing machine drive arrangement and more particularly to drive arrangements for automatic washers having an oscillatable agitator in the clothes container for washing the clothes, and the container being rotatable to centrifugally extract water from the clothes.

An object of the invention is to provide an improved washing machine drive arrangement having an agitator drive gear set including a drive gear, and a driven gear connected to the agitator and rotatably mounted on a support connected to the clothes container, and means for locking the gears for unitary rotation to provide a reaction force on the support effective to rotate the container.

Another object of the invention is to provide an improved washing machine drive arrangement driven by a reversible motor and having an agitator-drive gear set incluuding relatively rotatable gears, one of the gears being rotatable on a support connected to the clothes container; and motor-controlled means for controlling the gear set to provide an agitator drive or to lock the gears to provide a reaction force effective to rotate the support and thereby the clothes container, dependent on the direction of rotation of the motor.

Another object of the invention is to provide an improved washing machine drive arrangement connected to a reversible motor-driven shaft and having a single helically'wound spring clutch connecting the shaft to drive means for the agitator and container and operative to provide a positive friction drive to the drive means for oscillating the agitator during rotation of the shaft in one direction, and to provide a slipping friction drive to the drive means for rotating the container during rotation of the shaft in a second direction.

Another object of the invention is to provide an improved drive arrangement as described in which the spring clutch is connected to a motor-driven shaft and is effective as a positive drive friction device to drive the agitator and is effective as a slipping clutch to gradually accelerate the speed of rotation of the clothes container from its state of rest to its maximum speed to prevent gyratory movement of the container due to unbalanced clothes loads and to prevent motor loading in combination with motor-controlled gear set latch means providing for locking the gear set to its support for unitary rotation and thereby provide a reaction force effective to drive the clothes container.

Further objects and advantages of the new invention 3,388,568 Patented June 18, 1968 will be apparent from the following description, reference being made to the accompanying drawings in which a preferred embodiment of the invention is disclosed.

In the drawings:

FIG. 1 is a perspective view of a washing machine embodying the improved drive arrangement of the present invention;

FIG. 2 is a sectional elevational view taken on line 22 of FIG. 1;

FIG. 3 is a vertical sectional view of the drive mechanism of the washing machine;

FIG. 4 is an exploded view of portions of the drive mechanism;

FIG. 5 is a horizontal sectional view taken on line 5-5 of FIG. 3, illustrating the gearing of the drive mechanism, and control therefor;

FIG. 6 is an enlarged view of a portion of FIG. 5;

FIG. 7 is a horizontal sectional view taken on line 7-7 of FIG. 3 and illustrating a brake assembly of the drive mechanism.

Referring now to the drawings and more particularly to FIGS. 1 and 2, there is shown a washing machine 10 having an outer cabinet 11 with its top wall 12 defining an access opening closed by a cover 13 hinged to the wall and mounting a backguard 14 having controls for the washing machine.

As shown in FIG. 2, the cabinet contains a tub 15 having a cylindrical side wall 16 and a bottom wall 17, the upper end of the wall 16 having a clothes guard 18 mounted thereon and defining an opening for insertion of clothes into a container or basket 19. The basket 19 has a cylindrical perforate side wall 20, and a bottom wall 21 connected to a vertically disposed hollow center post 22.

The tub bottom wall is connected to a plurality of struts 23 extending radially inwardly and downwardly for connection to upstanding 'fianges of a bracket 25 mounted on an annular plate 26. The cabinet is provided with a base assembly 27. As seen in FIG. 3, the plate 26 has a cylindrical depending mounting flange 28 for a collar 29 receiving the outer race of a bearing assembly 39. The inner race of the bearing assembly is supported by one end of a cylindrical support tube 31, the tube 31 having a shaft 48 extending therethrough and being splined to the shaft for rotation by a pulley 35. The pulley is connected to the lower end of shaft 48 by a collar 52 splined to the shaft 48, and a flexible rubber coupling 33 compressed between the collar 32 and hub 34 of the pulley 35. The pulley 35 is rotatably supported on the base assembly 27 by a plate 36 fixed to the base assembly 27, and a bearing assembly 37 disposed between the plate 36 and hub 34 of the pulley 35.

To provide snubbing action for gyratory movement of the tub, four radially extending flexible leaf arms 40 (FIG. 2) are disposed between and connected to the plate 26 and bracket 25 and each arm has friction pads 41 contacting snubber plates 42, fixed to the cabinet base 27, and held in engagement therewith by springs 43 connected to the arms 40 and the cabinet base.

Referring to FIG. 3, the drive arrangement of the present invention is indicated at 44 and generally comprises a two-piece housing 45; an agitator drive assembly 46, and a helically-wound coil clutch spring 47 in the housing 45; the motor-driven shaft 48 and an agitator drive shaft 4? extending within the housing; a basket brake mechanism 50; and a motor-controlled latch mechanism 39.

A reversible drive motor 51 is mounted on the cabinet base 27 and has its shaft extending through an opening in the base to drive a pulley 52 connected by a belt 53 to the pulley 35. The shaft 48 extends through the support hub 31, a lower tubular portion 54 of the housing 45, a cylindrical drive hub 55, and a pinion gear 56 of the agitator drive arrangement 46. The drive hub 55 is fixed to the motor-driven shaft 48 by a connector pin 59, and the gear 56 is rotatable on the shaft 48. The gear 56 is formed to provide a cylindrical hub 57 adjacent drive hub 55, the coaxial hubs 57 and 55 have outer cylindrical surfaces surrounded by and engaged with the coils of the helical friction clutch spring 47. The cylindrical surface of hub 57 has its major portion 57a slightly increased in diameter relative to the diameter of the cylindrical surface of the hub 55 with a minor portion 57b of hub 57 having the same diameter as that of the cylindrical surface of hub 55. This relationship is for the purpose of insuring spring slippage on hub 55 during initial spin accelera tion. The relaxed internal uniform diameter of the spring 47, before assembly, is smaller than, the external cylindrical diameter of the hubs 55 and 57 so that, upon rotation of the shaft 48 by the reversible motor in a clockwise direction, viewed from the bottom of the shaft, friction from contact of the coils with the hubs 55 and 57 tends to contract the spring to tighten its engagement with the hubs 55 and 57 to provide a positive friction drive between. the hubs to rotate the gear 56.

The drive arrangement 46 for the agitator 58 will now be described. Referring to FIGS. 3 and 5, the agitator shaft 49 has secured thereto an oscillatable driven member 60 which is in axial alignment with the agitator shaft 49. A stub shaft 61, mounted in a boss 62 of the housing 45, has an arcuate rocking link 63 mounted thereon, this link 63 being provided at one end with a bifurcated bearing 64 and having a rocking arm portion 65. A stub shaft 66 is disposed on the arcuate rocking link 63 intermediate the stub shaft 61 mounting and the bifurcated bearing 64. Integrally formed with and extending from the oscillatable driven member 60 is a rocking arm 67 with a bearing 68 at its end. A curved link 69 is connected for pivotal movement at its end in the bearings 64 and 63 by pins 70 and 71.

A drive gear 72 is mounted on a stub shaft 73 and forms one member of a speed reduction gear train comprising a pinion 74, mounted on a stub shaft 75, in engagement with the drive gear 72, the stub shaft 75 also carries a drive gear 76 in engagement with the pinion gear 56 on the motor-driven shaft 48.

A pitman rod 78 is connected at one end, eccentrically, as at 79, with the drive gear 72 and at the other end thereof, it is journaled in the stub shaft 66 on the rocking link 63. The described gear train, comprising the pinion gear 56, drive gear 76, pinion 74 and drive gear 72, will impart continuous rotation to the drive gear 72 to turn the same in one direction. The pitman rod 78, through its eccentric mounting on the drive gear 72, will cause rocking arm 65 to oscillate about stub shaft 61 which will impart a similar rocking or oscillatory movement to link 63. The rocking end of the link 63, connected by curved link 69 with the outer end of arm 67, will cause the oscillatable member 60 to rock about its axis which is defined by the agitator drive shaft 49, and the parts will be continuously swung backward and forward thereby to impart the desired oscillatory motion to the agitator. The agitator drive assembly is disclosed more fully in US. Patent 2,807,951.

For the purpose of extracting water from the fabrics in the basket, subsequent to the washing operation by the described agitator-oscillating drive assembly 46, the basket is drivingly connected to the housing 45 of the drive assembly 46. Referring to FIGS. 1 and 2, the tub bottom wall 17 has a frusto-conical portion 17a defining a central opening at its top in which is located a bearing and seal housing 80 connected to the peripheral edge of the wall portion 17a by bolts, as shown. Located withto the top of the housing 45, the hub 82 extending within the housing and being rotatably supported on a bearing 84 mounted on the housing 80. The basket bottom wall 21 is also formed with a frusto-conical portion 21a defining a central opening through which the hollow post 22 extends. The post 22 has a base flange 85 engaging the inner opening-defining peripheral edge of the basket wall portion 21a and is secured thereto by bolts 86, as shown. These bolts 86 are in threaded engagement with an annular plate 87 snugly engaging the hub 82 and retained in assembly therewith by a nut 88 threaded on the hub 82 and bearing against the top of the plate 87. It is believed apparent from this description, rotation of the transmission housing 45 will effect rotation of the basket.

As shown in FIG. 2, the agitator drive shaft 49 extends through the hub and tube assembly 81 and the center post 22 and is drivingly connected to the top of the agitator by a conventional spline arrangement.

The brake mechanism 50 is provided for restraining rotation of the housing 45 and thereby the basket during operation of the agitator during the washing operation. More particularly and referring to FIGS. 3 and 7, the brake mechanism comprises a brake drum 90 formed as a bottom portion of the housing 45, an annular brake band 91 having suitably secured thereto on the inside surfaces thereof conventional frictional brake band material 92 disposed in frictional engagement with the peripheral surface of the brake drum, said brake band having at one end thereof a lip 93 adapted to become engaged, under certain conditions hereinafter to be described in a slot 94 disposed in a latch 95 mounted, by pivot 96, for pivotal movement on plate 26. The latch has a spring 97 having one end engaged with the latch 95 and the other end thereof being suitably secured to the bracket 26 as at 98, said spring being effective to urge the latch in one direction of pivotal movement, and said latch has fixedly secured thereto an arm 99 of a solenoid 1% adapted, under certain conditions, to overcome the forces of the spring and cause pivotal movement of the latch in the opposite direction of pivotal movement.

When the motor is operating in a direction to cause the agitator shaft to rotate, the spring 97 is operative to position the latch to engage the brake band to effect gripping engagement of the band with the brake drum to prevent the housing 45 and thereby the basket from rotating.

After agitation has been completed and prior to rotation of the basket for performing the water-extracting operation, solenoid 100 is energized to overcome the force of the spring 97 and move the latch to disengage lip 93 from the slot 94 and permit the brake band to rotate with the brake drum so that the basket is now free to rotate. A purpose of this brake mechanism is to prevent relative rotation of the basket in either direction Whenever the agitator 58 is in operation.

When the solenoid 100 becomes deenergized and the motor is conditioned for reverse operation, the forces of the spring will become effective to urge the latch toward its latch position whereupon the brake band, rotating with the brake drum. will cause engagement of the lip 93 with the surface 101 of the latch which will be effective to guide the lip home to its position in the slot 94 where it will be maintained until the solenoid 100 is again energized. After lip 93 has been effectively positioned in the slot 94, the brake elements are again in their applied position effective to hold the brake drum from relative rotation in either direction.

As the agitator drive assembly 46- has been described, attention is directed to the structure and operation of the drive arrangement for rotation of the basket for centrifugal extraction of the water in the clothes at the termination of the washing operation. For this purpose, the motor 51 is energized to reverse the direction of rotation of the drive shaft 43; the agitator drive assembly 46 is controlled, to prevent rotation of the gears to induce a reaction torque on the housing 45 to rotate the basket, by the novel motor-controlled latch mechanism 39; and the brake mechanism 59 is released by energization of solenoid 190 to permit rotation of the basket.

More particularly, and referring to FIGS. 3, 4, 5, and 6, the latch mechanism 39 comprises a locking dog or latch 102 having an opening receiving the upper stub shaft extension 104 on the gear 56, the latch being seated on a shoulder 195 of the gear 56. The latch is frictionally engaged with the shoulder 105 and a spring-like wave washer 106 positioned on the latch, by a drive washer 167 having a tongue 1G8 extending radiall inwardly thereof into a slot 169 in the gear stub shaft 104, a snap ring 110 located in a circular groove 103 in the shaft extension IE4 and operative to urge the ring 110' and washer 107 toward the spring washer 106 to compress the washer 106 between the locking dog or latch 1G2 and the drive washer 167. A spacer washer 111, and a snap ring 112 surround the projecting end of shaft 48, and snap ring 112 is located in a groove in shaft 48 to restrain gear 56 from axial movement on shaft 48. As a result, rotative movement of the latch is accomplished by the frictional engagement of the latch with the shoulder 105 and the spring washer 166, induced by snap ring 110. The latch or dog 102 is formed of sheet metal and has a flat locking portion 102:: perpendicular to its pivot portion 102b, provided with a straight edge 1020 at one end thereof for reception between the teeth of gear 76 during rotation of the motordriven shaft, in a clockwise direction as viewed in FIGS. 5 and 6, by the friction drive engagement of the spring clutch 47 with the hubs 55 and 57. As the latch is engaged with the teeth of gear 76, the latch is effective to prevent rotation of the gear 76 and thereby relative movement of the components of the agitator drive mechanism. Upon rotation of the shaft 48 in the counterclockwise direction by the motor (FIGS. 5 and 6), the spring clutch 47 again becomes effective to transmit drive from the hub 55 to the hub 57 thereby rotating the latch from the full line position to the dotted line position in FIG. 6, to disengage the latch from the teeth of gear 76 and permit rotation of gear 76 by the gear 56 for oscillating the agitator. It will be apparent that the latch movement is controlled in accordance with the direction of rotation of the shaft 4.8 by the motor 51. The counterclockwise movement of the latch is limited by a stop 114 on the Wall of the transmission housing to restrict arcuate movement of the latch.

When the latch is effective to prevent relative rotation of the gears 56 and 76 and locking up the gear set, a resultant reaction torque is induced effective to rotate the agitator drive assembly 56 and housing 45 as a unit and thereby to effect rotation of the basket to provide the water-extraction operation.

An important feature of the novel spring clutch arrangement is that a single helically-wound spring is effective to provide drive to the agitator and container drive mechanisms, and is operative, during rotation of the reversible motor-driven shaft in one direction, to be tightly wound to increase the radial pressure of the coils on the driving member of the mechanism to provide a direct and positive friction drive to oscillate the agitator, the spring further being effective to obtain the desired slipping friction drive, during rotation of the shaft in a second direction, by decrease of the radial pressure of its coils on the driving member, to slowly accelerate the speed of rotation of the basket until a predetermined maximum speed has been attained when the spring is effective to provide substantially a 1:1 ratio drive of the shaft and container.

It is important to note that the spring clutch tends to expand and slips to effect a frictional drive of the gear hub 57 during initiation of clockwise rotation of shaft 48 (FIG. 6) due to the inertia of the basket and its clothes load resisting rotation of the basket. This slipping frictional drive is effective to provide sufficient driving torque to rotate the basket slowly at the start of the water-extraction operation and to gradually accelerate the basket from zero to substantially the maximum rotational speed of the motor-driven shaft 48. Even though the speed of rotation of the motor is constant, the drive torque, to effect rotation of the basket, provided through the spring clutch friction, tends to cause the spring clutch to couple the drive hubs 55 and 57 from an initial low acceleration speed to substantially a direct drive ratio.

Upon termination of the water-extraction operation, the brake solenoid 50 and motor 51 are deenergized. At this time, the basket rotation is stopped by the brake mechanism and rotation of shaft 48 is resisted by the motor, the resultant reaction, conveyed by the housing 45 and drive shaft 43 to the spring clutch causes the clutch to expand to its maximum slipping capacity to pievent damage to the components of the drive arrangement. Upon initiation of a subsequent agitate-rinse period, rotation of shaft 48 in a counterclockwise direction (FIGS. 5 and 6) causes the friction drive between the gear 56 and locking dog 102 to rotate the dog from its engagement with the teeth of gear 75 to the dotted line position of FIG. 6.

An important feature of the drive arrangement of the present invention is that the spring clutch drive for the basket is effective to permit slippage or friction torque during initiation of basket rotation to overcome the inertia of the agitator drive assembly 46 and housing 45, and the basket and its clothes load and the drag resistance to rotation thereof by the water in the tub, to prevent overloading and stalling of the electric motor. In the present case, the clutch operates to provide a slipping friction drive initially to gradually accelerate the speed of rotation of the basket from zero to substantially the maximum motor-driven shaft speed, when a constant torque friction drive is accomplished.

A further important feature is that the spring clutch of the drive arrangement has proven particularly effective in the control of the gyratory movement of the tub under conditions of the clothes being located in the basket to provide an unbalanced load. An unbalanced load will prevent attainment of the maximum speed of rotation of the basket because of the slipping of the clutch and the basket rotation will be held at a safe speed preventing uncontrolled gyrations of the tub. In this regard, it has been found that the conventional out-of-balance electrical control to deenergize the motor can be eliminated as the tub gyrations are reduced to an extent that the tub does not strike the cabinet.

it is also important to note that the housing 45 is filled with oil and, although heating of the oil occurs by friction slippage of the clutch, the oil heat finally reaches stabilization at a temperature where no overheating of the oil occurs, despite slipping of the clutch in the case of an unbalanced load, or other factors, causing rotation of the basket at low speed.

While the present preferred embodiment of the invention has been disclosed, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the invention as defined in the appended claims.

What is claimed is:

1. In a clothes-cleaning machine; a clothes container; means supporting said container for rotation; an agitator in said container; agitator drive means comprising relatively rotatable gears including a first drive gear and a second driven gear; a drive shaft for said first gear; means supporting said second gear and connected to said container for rotation of said container; and means rotatable with one of said gears and engageable with the other gear for connecting said gears for unitary rotation to provide a reaction force on said supporting means to rotate said container.

2. In a clothes-cleaning machine as defined in claim 1 in which the supporting means is a housing for the agitator drive means.

3. In a clothes-cleaning machine as defined in claim 1 in which brake means are provided to hold the supporting means against rotation during relative rotation of said gears to drive said agitator and releasable to permit rotation of said supporting means during operation of said rotatable means.

4. In a clothes-cleaning machine as defined in claim 1 in which the rotatable means includes a latch rotatable by said one gear to engage the teeth of the other gear to prevent relative rotation of said gears.

5. In a clothes-cleaning machine as defined in claim 1 in which said first gear is supported on and rotatable by said drive shaft, and said second gear meshes with said first gear and is rotatably mounted on said supporting means in spaced relation to the-rotational axis of said first gear and drive shaft, and said rotatable means includes a latch operable by said first gear for engaging the teeth of said second gear.

6. In a clothes-cleaning machine as defined in claim 5 in which said stop means are provided on said supporting means to limit rotation of said latch on disengagement with the teeth of the second gear.

7. In a clothes-cleaning machine as defined in claim 5 in which means are provided for frictionally engaging said latch for rotating said latch.

8. In a clothes'cleaning machine as defined in claim 5 in which means are provided for supporting said latch. in frictional engagement with said first gear for rotation to and from engagement with the teeth of said second gear.

9. In a clothes-cleaning machine as defined in claim 5 in which said drive shaft rotation is reversible to move said latch into and out of engagement with said second gear.

10. In a clothes-cleaning machine, a clothes container; an agitator in said container; agitator drive gear means and including relatively rotatable gears; means supporting said drive means and connected to said container for rotation of said container; a reversible motor driven shaft; and control means operable by said driven shaft during rotation in one direction to lock said gears for unitary rotation to provide a reaction force on said supporting means to rotate said container, said control means including a control member rotatable with one of said gears and frictionally movable by said driven shaft to engage and disengage the other of said gears, dependent on the direction of rotation of said driven shaft.

11. In a clothes-cleaning machine, a rotatable con tainer; an oscillatable agitator in said container; a reversible motor-driven shaft; drive means for said agitator and including first and second relatively rotatable members; means connecting said first rotatable member and said shaft, including a friction drive coaxially disposed about said driven shaft and said first rotatable member and operable to drive said first member in either direction of rotation of said shaft, rotation of said shaft in one direction providing for relative rotation of said members for oscillating said agitator; means supporting said second rotatable member and connected to said container; and means controlled by one of said members, during shaft rotation in a second direction, to connect said members for unitary rotation by said friction drive to provide a reaction force on said supporting means to rotate said supporting means and thereby said container.

12. In a clothes-cleaning machine as defined in claim 11 in which the friction drive is a helically-wound clutch 8 spring operative to provide a positive drive between said shaft and said first rotatable member during rotation of said shaft in said one direction, and operative to provide a slipping friction drive between said shaft and said first rotatable member during rotation of said shaft in said second direction.

13. In a clothes cleaning machine as defined in claim 11 in which the friction drive includes a helically-wound clutch spring coaxial around said driven shaft and having coils drivingly engaged with said shaft, and said first rotatable member includes a cylindrical friction surface embraced frictionally under radial pressure by coils surrounding said first member, said spring being driven, during rotation of said shaft in said first direction, to increase the radial pressure of said coils on said first rotatable member to provide a positive friction drive of said first rotatable member, and said spring being driven, during rotation of said shaft in said second direction, to decrease the radial pressure of said coils on said first member to provide a slipping friction drive of said first member.

14. In a clothes cleaning machine as defined in claim 11 in which the controlled means includes a latch frictionally connected to and movable by said first rotatable member and said shaft to and from connecting engagement with said second member, dependent on the direction of rotation of said shaft.

'15. In a clothes-cleaning machine as defined in claim 12 in which the first and second relatively rotatable members are first and second gears, and the controlled means includes a latch frictionally connected to and movable by said first gear and said shaft to engage and disengage the teeth on said second gear, dependent on the direction of rotation of said shaft.

16. In a clothes-cleaning machine as defined in claim 12 in which brake means are provided to prevent rotation of said container during oscillation of said agitator.

17. In a clothes-cleaning machine, a rotatable container; an agitator in said container; a reversible motor-driven shaft; drive means for said agitator and said container, said drive means being operative to drive said agitator during rotation of said shaft in a first direction, and said drrve means being operative to drive said container during rotation of said shaft in a second direction; and means connecting said driven shaft to said drive means including a helically wound clutch spring coaxial with said shaft and having coils in surrounding driven engagement with said shaft, and a cylindrical friction member for driving said drive means and disposed coaxially with said shaft and embraced frictionally under radial pressure by coils of said spring, said spring being driven in a direction, during rotation of said shaft in said first direction, to tighten engagement of its coils with said member to provide a positive friction drive, and said spring being driven in a second direction, during rotatron of said shaft in said second direction, tending to reduce the radial pressure of the coils upon said friction member to provide frictional slippage between the frictron member and coils engaged therewith.

WILLIAM I. PRICE, Primary Examiner.

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