US3066765A

US3066765A - Friction couples

Info

Publication number: US3066765A
Application number: US832192A
Authority: US
Inventors: Howard B Huntress
Original assignee: American Brake Shoe Co
Current assignee: American Brake Shoe Co
Priority date: 1959-08-07
Filing date: 1959-08-07
Publication date: 1962-12-04
Anticipated expiration: 1979-12-04

Description

H. B. HUNTRESS FRICTION COUPLES Dec. 4, 1962 Filed Aug. 7, 1959 4 Sheets-Sheet l LIN\NG ANCHOR INVENTOR. HOWARD B. HUNTRESS 1a Filed Aug. '7, 1959 Dec. 4, 1962 H. B. HUNTRESS 3,066,765

FRICTION COUPLES 4 Sheets-Sheet 2 LIN\N BACK\N ACTUAT\NG\ 42 49 r 47 '48 f g: 4

mmvnm HOWARD B. Hun-mass H E/J55- Dec. 4, 1962 H. B. HUNTRESS 3,066,765 I FRICTION COUPLES Filed Aug. 7, 1959 4 Sheets-Sheet 3 ACTUATlN uvwzwroza Hog/mm B. HUNTRESS Dec. 4, 1962 H. B. HUNTRESS 3,066,

FRICTION COUPLES Filed Aug. 7, 1959 4 Sheeos-Sheet 4 INVENTOR. HOWARD B. HUNTRESS i I i United States Patent Oflflce 3,065,765 Patented Dec. 4, 1962 of Delaware Filed Aug. 7, 1959, Ser. No. 832,192 2 Claims. (Cl. 188-78) This invention relates to friction couples such as brakes or clutches which incorporate a rotatable drum and one or more torque shoes engageable with a cylindrical surface of the drum to transmit a torque between the drum and the shoe. More specifically, this invention relates to novel arrangements for exerting pressure forces on such torque shoes to engage the torque shoes in frictional contact with a cylindrical surface of the rotating drum.

Heretofore it has been conventional practice in brake and clutch constructions to utilize relatively inflexible torque shoes which have generally been reinforced against flexing by stiffening webs, and to press such torque shoes against a rotating drum by applying a force to an end of one shoe by means of a hydraulic cylinder and to provide an anchor at an opposite end of the shoe for anchoring the shoe against the circumferential move- 25 ment with the drum. It has also been conventional practice in such constructions to link together a pair of torque shoes at-adjacent ends whereby a single cylinder may be utilized for applying an actuating force at a free or opposite end of a first shoe in the pair 30 and whereby a single anchor may be located at the adjacent free end of a second shoe in the pair to receive friction forces developed along the surfaces of both of the shoes of the pair. In the latter arrangement, the frictional force developed along the surface of the first shoe is transmitted to an end of the second shoe as an actuating force.

Under the present invention, a highly flexible shoe is used to construct a friction couple for reasons to be explained, and the shoe may be engaged with the drum by a flexible element disposed in adjacent relation to the non-drum engaging surface of the shoe to transmit a continuous actuating force along the length of the shoe upon flexing of the element. The present invention also comprehends friction couples which utilize a flexible shoe or shoes and multiple flexible elements acting on a single shoe in a manner such that at least one of the flexible elements is flexed by a transmission of a torque through the friction couple to add to or 50 subtract from the actuating force applied to the shoe by another of the flexible elements. The foregoing will be more completely described with reference to the drawings hereinafter.

One of the primary objects of this invention is to engage at least one flexible torque shoe in frictional contact with a rotating circumferential surface of a drum member by applying in a novel manner a continuous pressure force along the entire length of such a torque shoe; and another object of this invention is to utilize in the construction of a friction couple a novel, flexible band actuator disposed either radially outwardly of torque shoes which are disposed along an outer circumferential surface of a rotatable drum, or radiallly inwardly of torque shoes which are disposed along an inner circumferential surface of a rotatable drum, and to contact or expand such a band to engage the torque shoes and move the same into frictional contact with the drum.

It is another object of this invention to construct a friction couple with adjacent torque shoes arrayed around a cylindrical surface of a rotatable drum and having flexible tails, or extensions, each of which extends from an end of one shoe along the length of an adjacent shoe and terminates in a fixed anchor whereby the force developed at the anchor by frictional contact of a torque shoe with the rotatable drum acts to flex the extension either radially inwardly in tension or radially outwardly in compression to correspondingly vary a pressure force transmitted along the length of the adjacent shoe through the flexible extension.

It is another object of this invention to incorporate in a friction couple of the type which includes at least one flexible torque shoe disposed adjacent a cylindrical surface of a rotatable drum, a flexible member which. is connected at opposite ends to an end of the torque shoe d a fixed anchor respectively in a manner such that .e intermediate portion of the member extends along the length of the torque shoe in a folded-back relation whereby frictional contact of the shoe with the rotating drum develops either a tension or compression force in 20 the flexible member to move the flexible member into or out of pressure engagement with the shoe.

It is another object of this invention to incorporate the extension eithr in" tension 'or'eompressi'o'n 'to. 'vary' the actuating force transmitted to the torque shoe through the flexible member.

Other and further objects of the present invention will be apparent from the following description and 5 claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the 45 purview of the appended claims.

In the drawings:

FIG. 1 is a schematic, half-section, elevational view of a friction couple which incorporates flexible torque shoes actuated into pressure contact with a rotatable drum by a pressure force applied to an end of the torque shoes;

FIG. 2 is a schematic, half-section, elevational view of a friction couple which incorporates end actuatedtorque shoes but which additionally incorporates a flexible extension for actuating a torque shoe into pressure contact with the rotatable drum;

FIG. 3 is an elevation view in section of a friction couple which incorporates a flexible band actuator;

FIG. 4 is a perspective view of a band actuator utilized 60 in the arrangement illustrated in FIG. 3;

FIG. 5 is a schematic, half-section, elevation view of a friction couple which incorporates flexible torque shoeextensions and a band actuator;

FIG. 6 is a schematic, half-section, elevation view of 6 a friction couple which incorporates a torque shoe hav- FIG. 9 is an elevation view of a friction couple constructed in accordance with this invention which incorporates torque shoes having flexible members disposed in folded-back relation with the torque shoes and incorporatesalso a flexible band actuator; and

FIG. 10 is an elevation view of a friction couple of the external contracting type which incorporates torque shoes having flexible members and a flexible band actuator.

With reference to FIG. 1 of the drawings there is schematically illustrated a half-section view of a friction couple which is designated generally by the reference numeral 21. The friction couple comprises a rotatable drum 22 which has an inner cylindrical surface 23. First and second torque shoes 24-1 and 24-2, each of arcuate shape in section, are disposed in adjacent relation along the inner cylindrical surface 23 of the rotatable drum. Each torque shoe comprises a friction lining 24L and a.- backing plate 24B. The backing plate 24B. is of relatively thin sectional thickness so as to be easily bowed along the length of the shoe by a brake force applied thereto, such being analogous to exerting a compression force to the ends of a strip of spring steel.

Anchors 25-1 and 25-2 are disposed at the ends of the respective shoes 24-1 and 24-2 and are mounted on a torque receiving member such as the stator plate 26. Following the normal convention of designating the leading end of the torque shoe as that end which leads into the rotation of the drum, the anchors 25-1 and 25-2 are disposed adjacent the ends opposite the leading ends, that is, at the trailing ends, of the respective torque shoes 24-1 and 24-2 with the counterclockwise direction of rotation of the drum 22 as indicated by the arrow in FIG. 1. This conventional designation of the leading and trailing ends of the torque shoes will be followed throughout.

When forces F-l and F-2 are applied to the leading ends of the torque shoes 24-1 and 24-2 to move the shoes circumferentially into engagement with the anchors, the forces F-Iand F 2"are"develop'ed as'ciinipie'ssive forces in the torque shoes and act to bow the torque shoes radially outwardly and into frictional engagement with the inner circumferential surface 23 of the rotating drum. Such engagement of the torque shoes wtih the drum causes the tangential frictional force along the drum engaging surface of the shoes to build up exponentially along the length of the shoe as a function of the angle subtended by the arc of the shoe so that the forces received by the anchors 25-1 and 25-2 are considerably larger than the actuating forces F-1 and F-2. In this respect the action of the flexible torque shoes is analogous to a partial wrap of a line about a capstan.

For clarity of illustration in this and the subsequent figures of the drawings, the return means for biasing the shoes back to their non-actuated positions have not been illustrated. Such means can comprise springs as conventionally utilized for this purpose.

In FIG. 2 there is illustrated a friction couple 31 which incorporates a pair of adjacent flexible torque shoes 32-1 and 32-2 which are disposed along an inner circumferential surface 33 of a rotatable drum 34. Each of the torque shoes 32 comprises a lining 32L and a flexible back plate 32B as in the arrangement illustrated in FIG. 1. However, in the arrangement illustrated in FIG. 2, the first shoe 32-1 is additionally provided with a flexible extension or tail 32-E, which is connected, at the end opposite that joined to the backing of the first torque shoe, to the anchor 35-1, and which has a portion intermediate the two ends of the extension 32-E disposed in adjacent complementary relation with the radially inwardmost surface of the second. torque shoe throughout the complete length of the second torque shoe.

In the operation of the arrangement illustrated in FIG. 2, and with the counterclockwise direction of rotation of the drum '34, as indicated by the arrow, forces F-ll and transmitted through the friction 4 F-12 are applied to the leading ends of the respective first and second torque shoes 32-1 and 32-2. Such forces act in compression along the length of the torque shoes and cause the flexible shoes to bow outwardly into frictional contact with the inner cylindrical surface 33 of the rotating drum. As in the arrangement illustrated in FIG. 1, the flexible nature of the torque shoes causes a frictional force to wrap-up along the length of each shoe to cause a significantly larger force to be developed at each of the anchors 35-1 and 35-2 than initiated at the leading end of the shoes by the forces F-11 and F-12. The flexible extension 32-E of the first torque shoe serves as an intermediate member for transmitting the force developed at the trailing end of the first torque shoe to the anchor 35-1 to thereby anchor the first torque shoe against circumferential movement. However, the flexible extension 32-E serves an additional important function. The flexible nature of the extension 32-E permits the force at the trailing end of the first torque shoe to how the extension radially outwardly and into continuous pressure contact with the full length of the second torque shoe 32-2. Thus, the, second torque shoe is actuated into frictional torque transmitting contact at the inner surface 33 of the drum by two separate and independent forces. The first of these is the initiating force F-12 which bows the torque shoe outwardly and causes the frictional force along the surface of the shoe to wrap-up and increase from the leading to the trailing end of the shoe in the manner described hereinabove. The second actuating force is the continuous pressure force developed by the flexing of the extension '32-E which transmits a substantially uniformly distributed load along the radial inner surface of the second shoe. This actuating force from the extension 32-E causes a friction force to be developed along, and wrap-up along, the length of the second shoe and this force is additional to that caused by the force F-12. For this reason the force developed on the anchor 35-2 is considerably larger than that developed on the anchor 25-2 in the arrangement illustrate'din FlGTlfassiimin' I V the leading ends of the respective first and second torque shoes in both arrangements. Withthe counterclockwise direction of rotation of the rotating drum as indicated in FIG. 2, the compressive force developed within the flexlble extension 32-E acts in a positive manner on the second torque shoe to obtain a greater transmission of torque through the friction couple for any given initial actuating giie 1than is possible with the arrangement illustrated in The force at the anchor end of the first shoe in the arrangement illustrated in FIG. 2 is regenerative in its action on the second shoe inasmuch as a portion of the torque couple is reapplied to actuate the operative elements of the friction couple to generate a greater torque transmission.

In accordance with this invention one or more torque shoes may be moved radially into frictional contact with a cylindrical surface of a rotatable drum by a force which is applied substantially uniformly along the length of each torque shoe. In FIG. 3 there is illustrated an arrangement wherein a flexible band-type actuator is utilized for accomplishing such a result. In FIG. 3 a friction couple is designated generally by the reference numeral 41. The friction couple comprises an outer rotatable drum 42 having an inner cylindrical surface 43. A plurality of arcu'ate-shaped, flexible torque Shoes 44-1, 44-2, and 44-3 are arranged in an annular manner about the inner circumferential surface 43 and are movable in radial and circumferential directions. A plurality of anchors 45-1, 45-2, and 45-3 are stationarily mounted to some torque receiving structure such as the stator plate 50. The anchors 45 are disposed between adjacent ends of the torque shoes 44 to limit movement of the torque shoes in either clockwise or counterclockwise directions of circumferential movement. Each of the g equal forces are applied to torque shoes 44 comprises a lining 44-L and a thin-section, flexible backing plate 44-B. A flexible band 46 is disposed radially inwardly of the annular array of torque shoes and is bowed complementary to the arcuate shape of the torque shoes in a manner such that the band 46 presents a thin-walled cylindrical configuration, as best seen in FIG. 4. The band 46 has

end portions

47 and 48, which are spaced apart to form a gap 49 in the cylindrical surface of the band. The band 46 is provided with radially inwardly projecting pairs of lugs 51 and 52, and a pair of

levers

53 and 54 each has one end pivotally connected between the respective pairs of lugs 52 and 51. A hydraulic expansion cylinder 55 includes projecting

piston rods

56 and 57 which are pivotally connected to the ends of the

levers

53 and 54 opposite the ends connected to the lugs 52 and 51. The

levers

53 and 54 are pivotally pinned together at a point 58 intermediate the ends of the levers.

In the operation of the arrangement illustrated in FIG. 3, expansion of the

piston rods

56 and 57 axially outwardly of the cylinder 55 rotates the

levers

53 and 54 about the pivot point 58 to enlarge the size of the gap 49 formed between the ends of the band and thereby expand the band radially outwardly and into pressure contact with the torque shoes 44. The flexible nature of the band permits the band to bow freely but yet transmit a compressive force through the band. Thus, the band transmits a substantially uniform force to the rear, inward surface of each of the torqueshoes throughout the entire length of each shoe. Assuming a counterclockwise direction of rotation of the drum 42 as indicated by the arrow in FIG. 3, the actuating force of the band causes the first torque shoe "44 l'to move radially into frictional contact with the inner surface 43 and move circumferentially into engagement with the anchor 45-1. The frictional force on the drum engaging surface of the torque shoe wraps-up along the length of the torque shoe from the leading end to the trailing end engaged with the anchor 451 so that a relatively small radial force hxerted by the band 46 is effective to generate a large force at the fixed anchor. Each of the remaining torque shoes is actuated in like manner into frictional contact with the drum and anchoring relation with its respective anchor.

While the band type of actuator has been illustrated in FIG. 3 as being applicable to a three shoe expanding-type of friction couple, it will be recognized that one or any number of torque shoes can be utilized and that the band type of actuator is equally applicable to an external contracting type of friction couple wherein the torque shoes may be annularly arrayed along an external circumferential surface of a revolving drum. The actuating band may be slotted or otherwise modified to extend around any fixed parts, such as stationary anchors or other structure, which may be interposed between the band and the torque shoes. Also, while the torque shoes have been illustrated as being circumferentially movable to engage or abut the fixed anchors so as to be leading with respect to the anchors, connecting linkages may be interposed between the torque shoes and selected anchors so that the torque shoes trail the anchors upon actuation of the band.

A flexible band-type actuator such as that illustrated in FIGS. 3 and 4 may conveniently be applied to actuate torque shoes having tails of extensions such as those illus trated in FIG. 2. In such an arrangement the force of the flexible band replaces the end actuating forces such as F-11 and F-12 as illustrated in FIG. 2. With such a flexible band actuator it is also possible to so connect the flexible shoe extensions to the anchors that the flexible shoe extension acts in a negative or degenerative manner to decrease the force exerted by the band on the torque shoe rather than acting in a positive, regenerative manner to increase the force causing engagement of the torque shoe with the rotating drum in the manner described above with relation to the arrangement illustrated in FIG. 2.

Thus, FIG. 5 illustrates an arrangement wherein a flexible band actuator is combined with a flexible shoe extension which acts in a positive or regenerative manner with one direction of rotation of the drum and which acts in a negative or degenerative manner with another, opposite direction of rotation of the drum. The manner in which these modes of operation are obtained will now be described with reference to the structural features of the arrangement illustrated in FIG. 5.

In FIG. 5 a friction couple is designated generally by the reference numeral 61. The friction couple comprises an outer drum 62 which has an inner cylindrical surface 63. In the half section illustrated in FIG. 5, a pair of arcuateshaped torque shoes 641 and 64-2 are disposed in adjacent relation along the inner cylindrical surface 63. The torque shoes each comprise a lining 64L and a relatively thin-section, flexible backing member 64B. A pair of anchors 651 and 652 are stationarily aflixed to a stator plate 60 adjacent one end of the torque shoe 64-2. The anchor 65--2 is positioned to abut an end of the torque shoe 642 to limit circumferential movement of the torque shoe in a counterclockwise direction. As illustrated in FIG. 5, the torque shoe 642 abuts torque shoe 641 upon rotation of the drum 62 in a clockwise direction. The backing plate of the torque shoe 64-1 is provided with a flexible extension, or tail 64-E, which extends from one end of the torque shoe along the length of the back plate for the torque shoe 6 1-2 and is connectedat its extremity to the anchor 65-1. A flexible band actuator'66 is disposed radially inwardly of the back plate 64B-1 for the first torque shoe and is also disposed radially inwardly of the flexible extension 64-E in a manner such that the flexible extension 64-E is intermediate the band 66-and-the-back plate 643-2 for the torque shoe 64-2.

In the operation of the friction couple illustrated in FIG. 5, a clockwise direction of rotation of the drum 62, as indicated by the arrow, will be considered first. Outward expansion of the band 66 by any suitable expansion means, not illustrated in the half section of FIG. 5, causes the band to engage the backing plate 643-1 and the flexible extension 64-E of the torque shoe 64'1 in continuous pressure contact. Such a pressure force acts directly on torque shoe 64-1 to move the torque shoe into frictional contact with the cylindical surface 63 and acts through the flexible extension 64-E on the torque shoe 64-2 to move that torque shoe into frictional contact with the surface 63. Such frictional contact of the torque shoes and the drum acts on the torque shoes to cause the torque shoes to move in a clockwise circumferential direc tion. The torque shoe 64-1 is restrained from movement in this direction by means of flexible extension 64-E which is connected to the fixed anchor 65-1 The torque shoe 642 can move circumferentially only to the extent determined by engagement with the torque shoe 64-1. Thus, both of the torque shoes develop a tension force in the flexible extension 64-E which tends to straighten the extension and move it out of engagement with the flexible back plate of the torque shoe 642. Such flexing of the extension is resisted by the flexible band 66 which maintains the flexible extension in pressure transmitting engagement with the back plate of the torque shoe 64-2. The effect of this tension that is developed in the extension 64-E is to decreasethe radial actuating force transmitted to the torque shoe 642 Thus, the clockwise direction of rotation of the drum 62 as illustrated in FIG. 5 causes the torque which is transmitted from the drum to the anchor 65-1 to act in a negative or degenerative manner as a tension force in the flexible extension 64-E to decrease the effect ofthe initial actuating force developed within the flexible band 66. This effect is beneficial in those applications where it is desirable to diminish the response of torque transmitting etfectiveness to increasing coeflicients of friction so that materials with larger coeflicients of friction have a less powerful effect on increasing the torque transmitting effectiveness of the friction couple.

The friction couple illustrated in FIG. may also be adapted for operation in a regenerative manner similar to that described in relation to the arrangement illustrated in FIG. 2. To achieve this effect it is necessary only to provide for rotation of the drum 62 in a counterclockwise direction with the disposition of the structural parts as illustrated in FIG. 5. With such clockwise rotation ofthe drum 62, expansion of the band 66 radially outwardly actuates the torque shoes 64-1 and 64-2 into frictional contact with the inner cylindrical surface 63 whereby the frictional forces engendered on the friction or drum-engaging surfaces of the torque shoes tend to move the shoes circumferentially in a counterclockwise direction as viewed in FIG. 5. The anchor 65-2 limits the circumferential movement of the torque shoe 64-2 and. causes the forces on the radial outer surface of. the. shoe-to wrap-up. along the length of the shoe from the leading end to the trailing end as described fully hereinabove with reference to FIGS. 1 and 2. The force which is developed at the trailing end of the shoe 64-1 flexes the extension '64-.-E radially outwardly to add to the actuating force transmitted to the torque shoe 64-2 by-the actuating band 66.

In the foregoing arrangements the flexible extension or tail has. been connected to a torque shoe and an anchor in a manner such that like forces are developed within the shoe and the extension, That is, the flexible extension has been connected in a manner such that a compressive force, is developed in the shoe at the same time that a compressive force is developed in the extension, and a tension force is developed in the shoe at the same time that a tension forceis developed in the extension. Itis possible to have the extension or tail in tension when the shoe is in compression by flexibly connecting the tail to an end of the shoe and a fixed anchor in a manner such.that.the tail is disposed in folded-back relation with the shoe. throughout the full length of the shoe. This is the arrangement that is illustrated 'in-FIG:6;

-In FIG- 6 afriction couple is designated generally by the reference .numeraljl. The friction couple comprises anrouter rotatable drum .72} having an.inner cylindrical surface 73'. An arcuate-shaped torque shoe. 74 is disposed in-adjacent spaced relation with a portion of. the cylindricallsurface73. The torque shoe includes a lining 74L and a flexible,.thi n-section backing plate 743. An anchor 75'is stationarily affixed to suitable structure and a flexible tail 74T is flexibly connected at one end by means of a hinge 76 to one end of the torque shoe and is connected at an opposite end to the anchor 75. The portion intermediate the ends of the tail is bowed and extends along the radially inner surface of the torque shoe. The hinge connection 76 permits some relative movement in a radial direction between the torque shoe and the tail but substantially prevents any tangential movement therebetween. A flexible actuating band 77 is disposed radially inwardly of the flexible tail 741, and may preferably be of a cylindrical configuration like that illustrated in FIG. 4. Thus, the disposition of the flexible tail is such-that an actuating force initiated by the band 77 must be transmitted through the tail 74T before being received by the shoe 74.

Inthe operation of the friction couple illustrated in FIG. 6, the. band 77 is expanded and flexed radially outwardly into a continuous pressure transmitting engagement with the flexible tail 74T. The band 77 moves the tail 74T radially outwardly and into continuous pressure transmitting engagement with the flexible backing 74B of the torque shoe to engage the lining surface of the torque shoe .with the cylindrical surface 73 of the rotating drum. Assuming a clockwise direction of rotation of the drum as indicated by the arrow in FIG. 6, a frictional force is developed on the lining surface of the shoe which tends to shift the shoe circumferentially in a clockwise 5 tail 74T and this tension force acts throughout the length of the tail to straighten the tail by flexing the tail radially inwardly. However, the actuating force of the band 77 resists such inward flexing of the tail. Thus, the frictional force developed on the shoe 74 acts as a tension 1 force in the tail 74T in a negative or degenerative manner to decrease the magnitude of the actuating force transmitted from the band 77 to the shoe 74.

This arrangement of the flexible tail 74T and the negative action of the tail with the clockwise direction of rotation of the drum as indicated in FIG. 6 has a beneficial effect in that increasing friction has a less powerful effect on increasing the torque transmitting effectiveness of the friction couple than in arrangements which do not provide such negative or degenerative action. Thus, ma-

terials having relatively high coeflicients of friction may be utilized in applications where it is desirable to adapt the arrangement illustrated in FIG. 6 for operation as a brake. Thatis, materials which have a coefficient of friction likely to cause lock-up in conventional braking ar- 5 rangements can be employed to provide a well-controlled braking action in the arrangement illustrated in FIG. 6 due to the negative. action of the tail.

In.FIG. 7' there is illustrated in full elevation an embodiment of a friction couple constructed in accordance go with this invention which incorporates a flexible bandtype actuator and torque shoes provided with flexible tails of extensions. In FIG. 7 a friction couple is designated generally by the reference numeral 81. The friction couple 81 comprises an outer rotatable drum 82 which hasan inner cylindrical surface 83. A plurality of torque shoes 84-1, 84-2, 84-3 are annularly arrayed along and in spaced relation with the cylindrical surface 83. Each of the torque shoes 84 is accurately shaped and includes a lining. 84L and a flexible backing plate 843.

'-- y-Each of the shoes 84-1, 84-2, and 84-3 is provided with flexible tails 84T-1, 84T-2 and 84T3 respectively which are formed by extensions of the flexible backing plates 84B projecting beyond one end of the lining 84L. Thefriction couple 81 also includes anchors 85-1,

85-2, and 85-3 which are mounted on a torque receiving stator plate 86. The stator plate 86 is provided with a central, circular aperture 87 for mounting the stator plate on an axle or other structure. Each of the tails 84T extends along the entire length of an adjacent 5Q torque shoe and have their free ends bent radially inwardly and attached to the anchors 85 which are disposed in alignment with the spacing between the ends of adjacent torque shoes but mounted radially inwardly there- -from. A flexible, cylindrically shaped band 88 is disposed radially inwardly of the flexible tails 84T and extends substantially around the entire inner circumference of the friction couple.

As best viewed in FIG. 8, the band is provided with a rectangular shaped slot 89 in each of the portions adjacent the anchors 85-1 and 85-3. The tails 84T-3 and 84T-1 are slightly tapered at their free ends to provide a portion of reduced width that is passed radially through the slot 89 to the point of attachment to the respective anchors 85-3 and 85-1. The band 88 is 5 provided with ends 91 and 92 which are spaced apart to provide a gap 93 in the cylindrical surface of the band. The free end of the tail 85T-2 is passed through the gap 93 to the anchor 85-2. The respective end portions 91 and 92 are provided with radially inwardly directed lugs 94 and 95.

A double piston hydraulic cylinder 96 is mounted on the back-up plate 86-by a plurality of screws 97.

Piston rods

98 and 99 project axially outwardly from opposite ends of the cylinder 96'. A lever 101 is pivotally connected to the free endof the piston rod 98 and is pivotally connected at its opposite end to the lug 95. In. like manner a second lever 102 is pivotally connected at its opposite end to the piston rod 99 and the lug 94. The

levers

101 and 102 are thus disposed in crossed relation as viewed in FIG. 7 and are pinned together for pivoting action about a point 103. The cylinder 96, piston rods, and levers 101 and 102 comprise means for, actuating the band 88 radially outwardly by increasing the size of the gap 93.

With the clockwise direction of rotation of the outer drum 82 as indicated by the arrow in FIG. 7, the operation of the friction couple illustrated in FIG. 7 is basically that described with relation to the arrangement illustrated in FIG. 5. Thus, expansion of the

piston rods

98 and 99 axially outwardly of the cylinder 96 flexes the band 88 radially outwardly to engage the tails 84T with the flexible backing plates 84B of the individual torque shoes and move the shoes into frictional contact with the cylindrical surface 83. The frictional force developed on the surface of the lining of the shoes tends to move the shoes circumferentially in a clockwise direction with the rotating drum so that tension forces are developed in the tails 84T. The tension forces in the tails counteract the actuating force transmitted from the band 88 to decrease the actuating effect of the band. Thus, the, torque transmitted by the friction couple acts in a negative manner to decrease the torque generating effective-t ness of the initiating force.

The torque transmitted by the friction couple 81 is much greater with a counterclockwise direction of rotation of the outer drum than with the above described clockwise direction of rotation of the outer drum. Assuming such 'acounterclockwise direction of rotation, the frictional force developed by contact of the lining surfaces with the cylindrical surface 83 tends to move the respective torque shoes in a counterclockwise circumferential direction to compress the flexible tails 84T radially outwardly to add to the initial actuating force in a positive, regenerative manner as described in detaiL hereinabove with reference to FIG. 2.

In FIG. 9 there is illustrated in full elevation an embodiment of this invention wherein the flexible tails are utilized in a manner to produce more uniform torque transmitting effectiveness for both directions of rotation of the drum. Referring to FIG. 9, a friction couple is indicated by the reference numeral 111 and comprises an outer rotatable drum 112 having an inner cylindrical surface 113. A plurality of torque shoes, in this case three in number, are denoted by the reference numbers 114-1, 114-2, and 1143, and are annularly arrayed along the cylindrical surface 113. Each torque shoe includes a lining 114L and a flexible backing plate 114B. Each torque shoe is further provided with a flexible tail 114T which has one end connected by means of a hinge 114H to an end of the torque shoe and is disposed in foldedback relation with the torque shoe and is attached at its opposite end to an anchor 115. A flexible band 116 extends circumferentially along the inner surfaces of the flexible tails 114T and is slotted in the manner illw trated in FIG. 8 in the areas adjacent the first and second anchors 115-1 and 115--2 to permit the ends of the flexible tails 114T-2 to be passed therethrough. End portions 117 and 118 of the band 116 are spaced apart toprovide a gap 119 therebetween. The end portions 117 and 118 are provided with radially inwardly directed

lugs

121 and 122. An expansion cylinder 123 is mounted by means of screws 124 to a non-rotatable back plate 125 and includes

piston rods

126 and 127 which extend axially outwardly from opposite ends of the cylinder 123. A pair of

levers

128 and 129 are connected at opposite ends to one of the lugs and one of the piston rods so as to be disposed in overlying crossed relation as viewed in FIG. 9. The levers are pivotally pinned together at point 131.

The operation of the embodiment of the invention il- 75 lustrated in FIG. 9 is basically the same as that described in relation to the arrangement illustrated in FIG. 6. Upon actuation of the

piston rods

126 and 127 outwardly of the cylinder 123 the band 116 is fixed into engagement with the tails 114T which, in turn, engage the flexible backing plates 114B to move the torque shoes into frictional contact with the cylindrical surface 123. Assuming a clockwise direction of rotation of the drum as viewed in FIG. 9, the tails 114T are placed in tension to counter- 10 act the compressive force developed in the band 116.

With rotation of the drum 112 in an opposite, counterclockwise direction the frictional forces developed on the lining surface of the torque shoes are transmitted through the flexible tails 114T to the anchors 115 as a compressive force which adds to the actuating force supplied by the flexible band 116. Thus, the friction couple 111 acts in a positive or regenerative manner with a counterclockwise direction of the rotation of the drum.

1 With the arrangement illustrated in FIG. 9, wherein each torque shoe and tail assembly is substantially independent of an adjacent torque shoe and tail assembly, the hinge and anchor connections of various ones of the flexi-v ble tails can conveniently be reversed from that illustrated in FIG. 9, so that selected flexible tails 114T will act in a negative manner while others act in a positive manner.

Thus, by suitable selection of the number of flexible tails that are to act in one sense as compared to the number that are to act in an opposite sense, a friction couple can be provided which provides a desired ratio of effectiveness in one direction of rotation to the effectiveness in type friction couple.

opposite direction of rotation.

While the friction couples so far described have been of the internal expanding type, the principles of this in vention are equally applicable to an external, contracting FIG. 10 illustrates an arrangement wherein a flexible band actuator and flexible folded-back tails are incorporated in a friction couple having torque shoes movable radially inwardly into engagement with a cylindrical surface of an inner rotating drum.

In FIG. 10 a friction couple of the external contracting type is designated generally by the reference numeral 141 and includes an inner rotatable drum 142 having an external cylindrical surface 143. A plurality of torque shoes 1441, 1442, and 1443 are annularly arrayed along the cylindrical surface 143. Each of the torque shoes 144 includes a lining 144-L and an outer backing plate 144B. Each of the torque shoes is provided with a flexible tail 144T which has one end connected by a hinge 144H to an end of the torque shoe. The opposite end of each tail 144T is connected to an anchor 145 which is fixed to some torque receiving structure. Each of the tails 144T has a portion intermediate the ends disposed in closely adjacent relation with the backing plates 1443. The anchors 145 are aligned with the spacing between adjacent shoes and disposed radially outwardly thereof.

A flexible band 146 encircles the torque shoes 144 and is spaced radially outwardly of the tails 144T. The band 146 is provided with slots similar to those illustrated in FIG. 8 in the areas adjacent anchors 1451 and 145-2 and tapered down portions of the flexible tails 144T-1 and 144T2 are passed therethrough. The band has spaced apart end portions 147 and 148 which provide a gap 149 in the cylindrical surface formed by the band. The free end of the tail 144T-3 is passed through this gap and attached to the anchor 3. Radially outwardly projecting lugs 151 and 152 are provided at the respective end portions 147 and 148. An expansion cylinder 153 is mounted on some suitable non-rotatable struc- 70 ture radially outwardly of the gap 149. The cylinder 153 includes

piston rods

154 and 155 which project axially outwardly of the opposite ends of the cylinder. A first lever 156 is pivotally connected at opposite ends to the piston rod 154 and the lug 151. A second lever is pivotally connected at its opposite ends to the piston rod 155 1 1 and the lug 152. A tie member 158 extends between and is pinned at its opposite ends to

levers

156 and 157 so that the levers are pivotal about the pinned connections to the tie member 158 whereby expansion of the

piston rods

154 and 155 axially outwardly of the piston 153 reduces the size of the gap 149 by pulling the ends 147 and 148 of the band toward one another.

In the operation of the external contracting friction couple illustrated in FIG. 10, the torque shoes are actuated into torque transmitting contact with the drum by a force initiated in the exansion cylinder 153. Expansion of the piston rods outwardly of the cylinder contracts band 146 in tension to transmit a continuous radially inwardly directed pressure force through the tails 144T to the backing of the respective torque shoes. The frictional force developed on the surface of the linings of the torque shoes acts on the tails in a circumferential direction which is dependent upon the direction of rotation of the drum to develop either a compressive or a tension force in the flexible tails. With the external contracting arrangement illustrated in FIG. 10, clockwise direction of rotation of the drum 142 develops a tension force in the tails which adds to the actuating force supplied by the band 46. With a counterclockwise direction of rotation of the drum 142 the torque transmitted to the torque shoe develops a compressive force in the tail which acts in opposition to the tension force in the band 146 to lessen the actuating force applied to the shoe.

As in the embodiment illustrated in FIG. 9, the arrangement of the hinge and anchor means on various ones of the shoes may be reversed so that the torque transmitting effectiveness for opposite directions of rotation of the drum may be more nearly equalized.

It will be apparent that torque shoes incorporating extensions like those illustrated in FIG. 7 can equally well be applied to an external contracting friction couple of the type illustrated in FIG. 10. And while the arrangements illustrated in F165. 7-10 incorporate three torque shoes, the principles of this invention can equally Well be applied to friction couples having a greater or lesser number of torque shoes. For example, the flexible band actuator can be utilized to actuate a friction couple having a single torque shoe extending substantially around the entire circumference of the rotatable drum and such a torque shoe could also be provided with an extending tail of the type illustrated in'FlGS. 2 and 5 or a foldedback tail of the type illustrated in P16. 6.

In the embodiments illustrated the length of the tails or extensions have been shown as being substantially the same length as the individual torque shoes, but the tails can be one or more times the length of a shoe so that a single tail can be effective on multiple shoes.

Hence, while I have illustrated and described the preferred embodiments of my invention, it is to be understood that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. In a friction couple including a rotor member and a stator member, arcuate torque shoe means including a plurality of individual shoe members each so disposed as to have the arcuate friction surface opposite the back thereof engaged in coupling relation with the rotor member upon moving said shoe members radially into contact with a surface of the rotor member whereupon said shoe members tend to move circumferentially with the rotor, anchor means fixed to said stator member to limit the circumferential movement of the shoe members, an arcuate flexible member having an end secured to one of said shoe members to be movable therewith and having the opposite end thereof immediately opposite and aligned with said anchor means so as to be subjected to a bending force when said one shoe member moves circumferentially, the portion of said flexible member between the ends thereof being immediately radially opposite and unsecured to the back of the next adjacent shoe member, and an expandable and contractable actuating band disposed radially opposite the backs of said shoe members and said flexible member and effective when actuated to exert a radial force on and uniformly along the back of the shoe members and said flexible member to engage the friction couple.

2. In a friction couple including a rotor member and a stator member, arcuate torque shoe means including a plurality of individual shoe members each so disposed as to have the arcuate friction surface opposite the back thereof engaged in coupling relation with the rotor member upon moving said shoe members radially into contact with a surface of the rotor member whereupon said shoe members tend to move circumferentially with the rotor, anchor means fixed to said stator member, an arcuate flexible member having a portion secured to one of said shoe members to be movable therewith and having another portion thereof disposed immediately opposite said anchor means as to react thereon and be subjected to a force that bends the flexible member radially when said one shoe member moves circumferentially, a third portion of said flexible member being immediately radially opposite and unsecured to the back of the next adjacent shoe member, an expandable and contractable actuating band disposed radially opposite the backs of said shoe members and said flexible member and effective when flexed radially to exert a radial force uniformly along the back of the shoe members and said flexible member, and means to flex the band radially to exert the radial force as aforesaid thereby engaging the friction couple.

References Cited in the file of this patent UNITED STATES PATENTS 1,629,407 Patus et al May 17, 1927 1,808,947 Edgerton June 9, 1931 1,818,920 Minturn Aug. 11, 1931 1,930,779 Snell Oct. 17, 1933 2,052,054 Patterson Aug. 25, 1936 2,182,386 Patterson Dec. 5, 1939 2,206,742 Dodge July 2, 1940 2,275,142 Hale Mar. 3, 1942 2,596,379 Dodge May 13, 1952 2,605,863 Talboys et al. Aug. 5, 1952 2,723,016 Goldberg Nov. 8, 1955 FORElGN PATENTS 686,613 France Apr. 15, 1930