US2417193A - Automatically adjusting brake - Google Patents

Description

March 1l, 1947.

R. A. GQEPRICH 2,417,193

AUTOMATICALLY ADJUSTING BRAKE original Filed Aug. 1, 1942 VIII? INVENTOR.

hatentefd Mar. 11, 1947 AUTOMATICALLY AnJJs'rmG BRAKE Rudolph A. Goepfrich, South Bend', Ind., assignm-v to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware i @riginal application This invention relates to automatically adjusting brakes, and is partichlarly intended for brakes of the type in which one or more `f rictionelements or shoes are forced outwardly into contact with a rotating drum. The present application is a division of applicationSerial No. 453,237, led August 1, 1942, now Patent'No. 2,389,618.

In general, the object of the present invention is to provide an improved construction of auto-` matic adjustment mechanism of thetype wherein a drum contact member is utilized to measure the amount ofadjustment required. The improved adjustment mechanism disclosed in the present application both improves the efliciency of operation of the automatic adjuster and reduces the cost of manufacturing the same.

Other objects and`advantages of the invention will become apparent during the following description. In the drawings:

Figure 1 isa, section taken through a brake assembly which includes a drum actuated automatic adjustmenand f Figures 2,3, and 4 are lines 2 2, 3 3, and ure 1.

The brake shown in the drawing includes a sections. taken on the 4 4, respectively,` of Figrotatable drum I2, a nonrotatable support mem` ber or backing plate I4, two brake shoes I6 and I8 pivoted on backing platel I4 by means of anchor pins 20 and 22, and a hydraulic actuator 24 located between the free ends of the shoes August 1, 1942, Serial No. 453,237, mow Patent No. vember 27, 1945. Divided August 27, i945, Serial No.

'i claims. (c1. iss-,795)

2,389,618, dated Noiand this application position,` and therefore the amount of pedal travel required to move the shoe vinto contact with the drum remains substantially the same,

except of course when the drum expands appreciably due to excessive heat.

If the drum I2 be assumed to rotate in the counter-clockwise direction when .the vehicle is moving'forwardly, then the shoe I6 will be the self-energizing shoe a large portion of the time. Therefore, because wearing away of the lining of shoe I 6 occurs much faster than wearing away of the lining of shoe` I8, the provision 'of an automatic adjuster for shoe I6 only willy usually be adequate.. 4 I

Lying against the web 32 of shoe I6 Iis a drum contact adjustment control member 36, the outer end of which extends through alignedshots 38 and 40 provided respectively in the rim 30 and lining 34 of the shoe. The outer surface 42,` of member 36 is ush with the face `44 of lining 34, and therefore contacts the inner surface of,l drum I'2whenever they lining is moved against the` drum. Themember 36 may be made of any suitable material, but I have found it particularly convenient to form it. of steel, because this is an inexpensive material, and lmay be readily shaped to 4the desired configuration.

and adapted to move the sameloutwardly into contactcwith y:the brake l. drum atohprovide a fric f Adjustment -control member 36 is prevented from. moving laterally by means of raised nibs 46 and 48 provided on web 32, said web normally being a sheet metalstamping whichflends itself, readily to the formation oifthe nibs 46 and `4l?.

Further guiding for theladjustment control memtional resistance tov-rotation ofthe Aux-1 f f iliary 'mechanical shoefr spreading :rmechanism comprising a vthrustflink 2li-and a 'lever 28 having f a pin-like element 21' integral therewith for engagement with said thrust-linkmay also be incorporated in the brake assembly. Members 29 and 3| areprovided to prevent-lateral displacement of the shoe I6, and the shoe I8 and lever 28, respectively. I j

The shoes. I6` and I8 are iT-section shoes,` each Ahaving arim 30 and a web 32 normal to the rim. Secured to the outer surface 4 of the rim of each usual frictionl lining As the brake is used, the lining mashoe is a layer 34of the material.

pose 0f the present invention to. provide improved means for automatically 'adjusting the released adjustmentv 'means results vin the maintenance of a substantially constant clearance'betweenthe drum'and theshoe when the latter is in released berj'ishprovided vby'an offset or raised portion liformedon said member 36 and extending into a slot 52 cut inthe radiallyinner edge oiweb Holding adjustment control lmember` 36v tightly against the side of web 32 is a resilient element or leaf spring 54, which islsecure'd by means of,N arivet 56 to'thel oiset portion` 56 of member-33, and which has an edge 58 in contact with the 'sideof web 32 .opposite the surface `which contacts member 36.

terial 34 graduallyv wears away, and it is the pur- An inclined camsurfac 60 is provided on one side* of adjustment control member 36, and this surface is in contact with theend ofzan arm 62 of bell fcrank'lever.64. Lever 64 is fulcrumed on the web of shoe I6by means of 'a pin 66. The other arm 68 of-thelever has a folded 'over end portion 10 which is located on the opposite side of the shoe web from the main partof the lever,

vand Whichthereby assistsin holding the lever in position. Thesurface 'I21'of the lever `contactsu. stop member I4 which maybe an eccentric supported on pin 16, which is carried by v moving radially inward l surface 12 of the from the shoe. Therefore, after a bralrev applireleased position,

` is to retain substantially backing plate it. The purpose of the eccentric "is to provide an brake shoe.

initial manual adjustment for the (Zvperation of the automatic adjustment mechanism is as follows. As the lining of shoe IG wears down with successive brake applications, the' substantially non-wearing outer surface d2 of adjustment control member 36 is pushed in by contact with the brake drum, said member with respect-to the rim shoe. As this movement of member 36 occurs. the ca'm surface 60 acts on arm 62 of lever 64 to move the lever in a clockwise direction about its fulcrum 66. This causes the lever to be moved farther away and web of the cation which has caused member 36 to move inwardly, surface 12 of lever illwill contact stop member 14 when the shoe is slightly farther from the stop member than it was prior to the brake application. This prevents return spring 18 from returning the shoe all the way to its former and thus maintains'a substantially constant clearance between the lining of shoe I6 and the inner surface of drum l2. Assuming the use of a conventional hydraulic system to operate the actuator 24, the left piston in said actuator will be caused to follow the upper end of shoe I6 outwardly, as the released position of the shoe is gradually -changedvby the automatic adjustmelt mechanism. there is a press e urging the piston in actuator 2l to follow up shoe I6 as'the shoe is adjusted, and additional fluid will be drawn in from the reservoir of the hydraulic master cylinder to compensate for the outward displacement of the released position of the piston. The end result the amount of pedall travel reserve regardless of the amount of wear on the lining of brake shoe I6.

It will be apparent from the foregoing description that the several parts of the automatic adjustmentmechanism are positively and emciently lmaintained in operating position by means of relatively simple and inexpensive structural 'features. An additional advantage of the present arrangement is the avoidance 'of structural characteristics which would permit lining dust to clog the parts of the adjustment mechanism land prevent proper operation thereof.

vention has been described, it will be understood by those skilled in the art'that the object of the invention may be attained by the use of` Iconstructions different in certain respects from that disclosed without departing from the underlying principles lof the invention. I therefore desire bythe following claims to include Within the scope of my invention all such variations and modifications by which substantially the results of my'invention may be obtained through the use of substantially the same or equivalent means.

I claim: l

1. In a brake having a drum, a'backing plate, and a shoe adapted to be moved at times against the drum, automatic adjusting means for the shoe comprising a friction block extending through the shoe and the face of the shoe which contacts the drum, said friction block being shifted inwardly relative to the shoe by wear of the shoe, extrusions in the shoe web adjacent the sides of the friction `block in combination with a projection on the friction block extending into an opening of the shoe web for guiding said friction block on the having its face flush with of the lever contacting one side of the friction 4 block and adapted to rotate the f the drum. automatic. adjusting means lfor vthe the shoe opposite that on which In other words,

5o Although a particular embodiment of my inf lever on its pivot as the friction block moves inwardly, and a stop mounted on the backing plateand arranged to contact one end of the lever to hold thel shoe in released position determined by the angular position ofthe lever.

2. In a brake having a drum, a backing plate, and a shoe adapted to be movedat times against shoe comprising a friction block extending through the'shoe and having its face flush with the face of the shoe which contacts the drum, said friction block being shifted inwardly relative to the shoe by wear of the shoe, extrusions in the shoe web adjacent the sides of the friction block in combination with a, projection on the friction block extending into an opening of the shoe web for guiding said friction block on the shoe web, means cooperating with the face of the friction block is mounted and adapted to frictionally engage the friction block on the shoe web, a lever pivoted to the shoe, a portion of the lever contacting one side of the friction block and adapted to rotate the lever on its pivot as the friction block moves inwardly,l and a stop mounted on the backing plate and arranged to contact one end of the lever to hold the shoe in released position V determined by the angular position of the lever.

43. 'In a brake having a rotatable drumand a non-rotatable support member, an automatically adjusting friction element cooperating with'said drum comprising a. r-section brake shoe carried by said support member and having a rim, a web at right angles thereto.' and a layer of friction lining material on the rim adapted to contact the drum during braking, said rim and lining having aslot therethrough, an adjustment control member lying against one side of the shoe web and extending through said slot to bring its outer surface iiush withthe face `of the lining, the shoe web having raised nibs contacting the sides of said adjustment control member to preventA adjustment control member havingv an inclined cam surface formed on one side thereof, alever carried by and fulcrumed on said shoe and contacting at one point the cam surface of the adjustment control member, said lever having a folded over end portion embracing-the shoe web and thereby laterally restraining the lever, and a stop member mounted on the aforesaid support .member and arranged to contact a point on said lever to determine the released'position of the shoe in accordance with the angular position of the lever relative to the shoe. the relative angular position of the lever being gradually changed as lining wear causes the adjustment control member to move radially inwardly with respect to the shoe web. i

4.A In a brake havi g a rotatable drum and a non-rotatable support member, an automatically adjusting friction element cooperatingwith said drum comprising a T-sectiony brake shoe carried by said support member and having a rim, a web at-right angles thereto, and a layerv of friction lining'material on the rim adapted to con'- tact the drum during braking, 'said rim and lining having a .slot therethrough, an adjustment control member lying against one side of the shoe webA and extending through said slot to bring its outer surface flush with the face of the lining, the shoe web having raised nibs contacting the sides of said adjustment control member to prevent lateral movement thereof, said shoe web also having-a slot therein extending radially outwardly from the inner edge of the web, said adjustment control member having a raised portion guided in said web slot, a resilient element secured t said adjustment control member and bearing against the opposite side of thev web to relative to the shoe, the relative angular position' of the lever being gradually wear causes the adjustment move radially inwardly with web.

5. In a brake having a rotatable drum and a non-rotatable support member, an automatically changed 'as lining control member to respect to the shoe ladjusting friction element cooperating with said drum comprising. a T-section brake shoe carried by said support member and having a rim, a web at right angles thereto, and a layer of friction lining material on the rim adapted to contact the drum during braking, said rim and lining having a slot therethrough, an adjustment control member lying against one side -of the shoe web a'nd extending through said slot to bring its outer surface flush with. the face-of the lining, the shoe web having raised nibs contacting the sides of said adjustment control member to prevent lateral movement thereof, said shoe web also having a slot therein extending radially outwardly fromthe inner edge of the web, said adjustment control guided in said web slot and also having an inclined cam surface formed on one side thereof, a lever carried by and fulcrumed on said shoe and contacting at one point the cam surface of the adjustment control member, and an abutment on the aforesaid support member arranged to contact a point on said lever to determine the member having a raised portionv lever to determine the released position of the released position of the shoe in accordance with the angular position of the lever relative to the shoe, the relative angular position of the lever being gradually changed as lining wear causes the adjustment control member .to move radially inwardly with respect to the shoe web.

6. In a brake having a rotatable drum and a non-rotatable support member, an automatically adjusting friction element cooperating with said drum comprising a T-section brake shoe carried by saidksupport member and having a rim, a web at right angles thereto, and a layer of friction lining material on the rim adapted to contact the drum during braking, said rim and 1ining having a slot therethrough, an adjustment control member lying against one side of the shoe web and extending through said slot to bring its outer surface ush with the face of the lining, the shoe web having raised nibs contacting the sides of said adjustment control member to prevent lateral movement thereof, said adjustment control member having anvinclined cam surface formed on one side thereof, a lever carried by and fulcrumed on said shoe and contacting at one point the cam surface of the adjustment control member, and an abutment on the aforesaid support member arranged to contact a point on said vshoe in accordance with the angular position of sol the lever relative to the shoe, the relative angular position of the lever being gradually changed as lining wear causes the adjustment control member to move radially inwardly with respect to the shoe web.

'1. In a brake having a drum, a backing plate, and a shoe normally out of contact with the drum and constituted to be moved thereagainst, means for automatically maintaining the` distance between the drum and shoe substantially fixed notwithstanding shoe wear comprising a friction block extending through the shoe and having a face portion terminating in flush relationship with the portion of drum, said friction the shoe which contacts the block being v shifted inwardly Vrelative to the shoe as the shoe wears, guide means for retaining the friction block in position, a lever pivoted to the shoe and having a portion in contact with one side of the friction block which is constructed and arranged to impart rotation to said lever as the friction block moves inwardly, and a stop mounted on the backing plate and arranged to contact one end of the lever to hold the shoe inv released position determined by the angular position of the lever.v

, RUDOLPH A. GOEPFRICH.

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