BRAKE ADJUSTING SCREW AND CLIP ASSEMBLY

Abstract: Drum brake assembly (10) includes a drum (12) and a fixed support (14) mounted adjacent the drum. A pair of brake shoes (18,20) are mounted on the fixed support (14) and a pair of actuator housings (38,40) are mounted between the brake shoes. Each of the actuators includes an adjusting screw (50) and a clip (58) which connects the screw with the corresponding brake shoe (18 or 20) while permitting the screw to turn, thus facilitating manual adjustment of the brake. The clip (58) includes a body portion (60) and a pair of arms (74,76) which wrap around the periphery of the flange. Each of the arms (74, 76) carries a detent (78, 80) for engagement with the recesses (82) on the periphery of the flange. A Belleville washer is mounted between the clip (58) and the flange (54) and yieldably urges the clip (58) toward the corresponding brake shoe (18 or 20).

Description: BRAKE ADJUSTING -SCREW AND CLIP ASSEMBLY This invention relates to a drum brake assembly and, more particularly, to an adjusting screw and clip assembly therefor. Brake assemblies actuated by, for example, wedge-shaped actuators, have been used for several years on heavy-duty vehicles. These brake assemblies are of the type having a drum mounted for rotation with a member to be braked, a fixed support mounted adjacent the drum, and a pair of brake shoes mounted on the support for movement toward and away from the drum. The brake shoes have corresponding pairs of contiguous ends, and a pair of actuators- are mounted on the support between corresponding pairs of contiguous ends.of the brake shoes. The actuators include apparatus for engaging the contiguous ends of the shoes for forcing the latter toward the drum. Return springs yieldably urge the brake shoes away from the drum. The actuators further include an adjusting screw and clip assembly that engages the ends of the shoes. This assembly includes a flange member, a clip having a body and a pair of projecting portions projecting away from the body and cooperating with each other with the body to define a recess receiving an end of the brake shoe. The clip assembly must permit the adjusting screw to rotate relative to the clip so that the brake may be adjusted manually, yet must prevent rotation at all other times to maintain brake adjustment. These prior art devices, unfortunately, cannot accommodate the widened ends.now used on brake shoes used by at least one major vehicle manufacturer. Furthermore, these prior art devices are composed of many parts which have a tendency to corrode together so that manual adjustment cannot be accomplished, cannot accommodate the wider brake shoe ends and are sometimes difficult to assemble. Some parts tend to distort permanently# when stressed, resulting in unsatisfactory performance. Accordingly, the advantage of the present lnvention lies in that the adjusting clip can be designed to accommodate brake shoes having ends of virtually any width. It also has the advantage of providing a brake adjusting screw and clip assembly in which: the torque req#ired for manual adjustment and for maintaining adjustment can be predetermined withdin-.a relatively narrow range. These and other features of the invention will become7apparent in view of the following description, with.reference to the accompanying drawings, in which: Figure 1 is an elevational view, partly in section, of a wedge brake made pursuant to the teachings of my present invention; Figure 2 is a view taken substantially along lines 2-2 of Figure 1; and Figure 3 is a cross-sectional view taken substantially along lines 3-3 of Figure 2. Referring now to the drawings, a wedge brake assembly generally indicated by the numeral 10 includes a drum 12 which is mounted for rotation with a member to be braked, such as a vehicle wheel. A fixed support 14 is installed on a non-rotating portion of the vehicle adjacent the drum 12, such as the vehicle axle flange. Attachment of the fixed support 14 to the axle flange can be accomplished, for example, by installing conventional bolts (not shown) in apertures 16 provided in the fixed support. A pair of brake shoes 18, 20 are slidably mounted on the fixed support 14 for movement toward and away from the drum 02. The brake shoes 18, 20 are held on the fixed support 14 by conventional hold-down clips 22. Each of the brake shoes 13, 20 is of conventional construction having a T-shaped cross-s=t-sur consisting of a web 24, a shoe table 26 secured to the web 24 and fricti-on material 28 mounted on the shoe table 26. The brake shoe 18 has widened, roller-like ends 30, 32 and the brake shoe 20 has similar ends 34, 36. A pair of actuator housings 38, 40 are mounted on the fixed support 14 between the ends 30, 34 and 32, 36 of the brake shoes 18 and 20 respectively. The actuator housings 38, 40 each contain actuator assemblies of the type shown, for example, in copending U.S. Patent Application Serial No. 345,970 filed February 5, 1982. Since the actuators are fully disclosed in the aforementioned patent application and form no part of the present invention, they will not be further described herein. However, the actuating mechanism does include pistons 42, a pair of which are slidably mounted in each of the actuator housings 38, 40, and are connected to the corresponding ends 30-36 of the brake shoes 18, 20 by mechanism generally indicated by the numeral -44 (see Figure 3). When the aforementioned actuating mechanism is actuated to effect a brake application, the pistons 42 urge the corresponding ends of their corresponding brake shoes 18, 20 toward the drum 12. When the brake is released, return springs 46, 48 urge the brake shoes 18, 20 away from the drum 12. Referring now to Figures 2 and 3 of the drawings, the connecting mechanism 44 includes an adjusting screw 50 comprising a threaded shank 52 and a flange 54 which projects radially from the shank 52. The shank 52 is provided with screw threads (not shown) which threadedly engage corresponding screw threads (not shown) provided on the inner bore 56 of the piston 42. The adjuster screw 50 can be extended from the piston 42 to thereby accomplish adjustment of the brakes by moving the released position of the brake shoes 18, 20 closer to the drum 12 to compensate for wear of the friction material 28. This adjustment is accomplished either automatically by mechanism well known to those skilled in the art, or manually as will hereinafter be described. A clip assembly generally indicated by the numeral 58 includes a body portion 60 which extends generally parallel to the side 62 of the flange 54 which faces away from the actuator assembly 38 and toward the brake shoe 20. The body portion 60 is provided with an aperture 62 which receives the head 64 of the screw 50. A pair of forward facing projections 66, 68, which face toward the brake shoe 20 and away from the side 62 of the flange portion 54, cooperate with the body portion 60 to define a recess which receives the enlarged end 34 of the brake shoe 20. The clip 58 further includes a pair of arms 70, 72 which wrap around the periphery of the flange portion 54 and terminate in sections 74, 76 which face the side 78 of the flange 54 opposite the side 62. The arm sections 74, 76 are provided with detents 78, 80, which are small rounded projections received in corresponding detents defined by recesses 82 which circumscribe the periphery of the flange portion 54. The recesses 82 also function to receive a conventional adjusting tool (not shown) by which the adjusting screw 50 can be rotated, as will hereinafter be described in detail. A conventional Belleville spring washer 84 circumscribes the head 64 of the adjusting screw 50. The inner edge 86 of the Belleville washer 84 engages the surface 62 on the flange portion 54, and the outer edge 88 of the Belleville washer 84 engages the body portion 60 of the clip 58. The Belleville washer is conventional, and acts as a spring which collapses when a predetermined force is applied thereto. In the absence of such force, the Belleville washer 84 resiliently urges the body portion 60 of the clip away from the surface 62. In operation, the braking mechanism 10 operates as described hereinabove, in which operation of the aforementioned actuation mechanism shown in copending U.S. Patent Application Serial No. 345,970 forces the brake shoes 18, 20 towards the drum 12, thereby effecting a brake application. Upon release of the brakes, the return springs 46, 48 urge the brake shoes 18, 20 away from the drum 12 toward the position illustrated in Figure 1. Manual adjustment of the brakes may be effected by Inserting a proper brake adjustment tool into one of the exposed recesses 82 on the periphery of the flange 54. When a predetermined torque is applied to the adjusting screw 52, the Belleville washer 84 partially collapses and the detents 78, 80 are forced out of their corresponding recesses 82. As the flange portion 54 is turned, the detents 78, 80 are received into an adjacent recess 82, whereupon the Belleville washer 84 springs back to the shape illustrated in Figure 3, thereby applying a predetermined force to the clip 58. Accordingly, the torque required to turn the adjusting screw 50 in either direction is a function of the strength of the Belleville washer 84, which remains substantially constant.

Claims: CLAIMS 1. Drum brake assembly comprising a drum mounted for rotation with a member to be braked, a fixed support mounted adjacent said drum, a pair of brake shoes mounted on said support for movement toward and away from said drum, said brake shoes having corresponding pairs of contiguous ends, an actuator mounted on said fixed support, said actuator being mounted between a corresponding pair of contiguous ends of the brake shoes, said actuator including means for engaging said contiguous ends of said brake shoes for forcing the latter toward said drum, and resilient means yieldably urging said brake shoes away from said drum, said engaging means including a flanged member pre senting a radially projecting flange, a clip having a body, a pair of projecting portions projecting away from said body, said projecting portions cooperating with each other and with said body to define a recess receiving an end of one of said brake shoes, said clip being mounted on said flanged member, said clip having detents cooperating with corresponding detents on the flange of the flanged member to releasably restrain the clip and the flanged member for rotation relative to one another, and yieldable means urging said clip toward the corresponding end of the corresponding brake shoe and yieldably maintaining the detents on the flange and the clip in engagement with one another. 2. Drum brake assembly as claimed in claim 1, wherein said clip includes a pair of arms which wrap around the edge of said flange whereby said clip includes said body on one side of said flange and a portion of said arms adjacent the other side of said flange, said detents on said clip being on the portions of said arms adjacent the other side of said flange. 3. Drum brake assembly as claimed in claim 2, wherein said flanged member includes a shank from which said flange extends, said resilient means being a Belleville washer circumscribing said shank and bearing against said one side of said flange and against said body of said clip. 4. Drum brake assembly as claimed in claim 1, wherein said flanged member includes a shank from which said flange extends, said body of said clip circumscribing said body and being disposed adjacent one side of said flange, said clip including portions extending around the periphery of said flange and terminating in sections disposed adJacent the other side of said flange, said detents on said clip being located on the sections of the clip disposed adjacent said other side of the flange, said yieldable means being disposed between the one side of said flange and said body of said clip to yieldably urge the detents on said sections into engagement with the other side of said flange. 5. Drum brake assembly as claimed in claim 4, wherein said yieldable means is a Belleville washer circumscribing said shank. 6. Drum brake assembly as claimed in claim 5, wherein the periphery of said flange is serrated to define the detents on said flange.

Inventors: WOLFLI, CLYDE ROY
Applicants: ALLIED CORPORATION
Application year: 1984
Main classification: F16D65
IPC codes: F16D51, F16D65