DISC BRAKE WITH INTEGRAL PARKING BRAKE

• US 3,724,605 A
• Filed: 11/03/1971
• Issued: 04/03/1973
• Est. Priority Date: 11/03/1971
• Status: Expired due to Term

• Current Assignee: Ronald L. Shellhause, Thomas D. Naismith
• Original Assignee: Ronald L. Shellhause, Thomas D. Naismith
• Inventors: Shellhause, Ronald L., Naismith, Thomas D.
• Primary Examiner(s): Wood, Jr., M. Henson
• Assistant Examiner(s): Mar, Michael
• Application Number:
  US05/195,285
• Time in Patent Office: 517 Days
• Field of Search: 188/71.7,71.8,196P
• US Class Current: 188/71.8
• CPC Class Codes: F16D 2121/02 Fluid pressure
• CPC Class Codes: F16D 2121/14 Mechanical
• CPC Class Codes: F16D 2123/00 Multiple operation forces
• CPC Class Codes: F16D 2125/40 Screw-and-nut
• CPC Class Codes: F16D 65/54 by means of direct linear adjustment

Abstract

A disc brake caliper assembly includes a hydraulically actuated first piston, a second piston engagable with the first piston, a mechanical actuating mechanism which moves axially into the housing when actuated, and an extendable member acting between the adjuster piston and the mechanical actuating mechanism and including an apertured locking plate closely surrounding a shaft to form a one-way clutch. The extendable member provides a rigid force transmitting linkage between the mechanical actuating mechanism and the pistons for mechanical actuation of the brake. An adjuster spring increases the length of the extendable member to move the adjuster piston into closer relationship with the disc to adjust for lining wear.

Claims

1. A disc brake assembly having a disc and a brake shoe assembly and comprising:

a housing including means associated therewith and movable axially therein;

first piston means in the housing engaging the brake pad assembly and forming with the housing a fluid chamber;

means communicating fluid pressure to the fluid chamber to selectively displace the piston toward the disc to actuate the brake and permit retraction of the piston into the housing to release the brake;

adjuster piston means in the housing engageable with the first piston to limit retraction thereof;

extendable force transmitting means extending between the associated means and the adjuster piston means and including, shaft means engaging one of the piston means and associated means, apertured locking plate means closely surrounding shaft shaft means and engaged by the other of the piston means and associated means at only a limited circumferential portion thereof, spring means acTing between the shaft means and the locking plate means urging extension of the extendable member to move the adjuster piston in closer wear adjusting relationship to the disc and cocking the apertured locking plate means into frictional engagement with the shaft means so that upon axial movement of the associated means the locking plate means, shaft means, the adjuster piston and the first piston are forced toward the disc to actuate the brake.

2. A disc brake assembly having a disc, a caliper housing, and a brake shoe assembly and comprising:

first piston means in the housing engaging the brake pad assembly and forming with the housing a fluid chamber;

means communicating fluid pressure to the fluid chamber to selectively displace the piston toward the disc to actuate the brake and permit retraction of the piston into the housing to release the brake;

adjuster piston means in the housing and engageable with the first piston to limit retraction thereof;

shaft means engaging the adjuster piston means;

apertured locking plate means closely surrounding the shaft means;

spring means acting between the shaft means and the apertured locking plate means;

means associated with the housing and movable axially therein, the associated means engaging the apertured locking plate means at only a limited circumferential portion thereof whereby the spring means cocks the apertured locking plate means into frictional engagement with the shaft so that upon axial movement of the associated means the locking plate means, the shaft means, the adjuster piston means and the first piston are forced toward the disc to actuate the brake; and

seal means associated with the adjuster piston means in a manner to provide upon hydraulic actuation a force acting on the adjuster piston means in the retracting direction whereby the spring means may move the apertured locking plate means on the shaft means to position and hold the second piston means in closer wear adjusting relationship to the disc only when the fluid chamber pressure has permitted retraction of the first piston into the housing.

3. A disc brake assembly having a disc, a caliper housing, and a brake shoe assembly and comprising:

first piston means in the housing engaging the brake pad assembly and forming with the housing a fluid chamber;

means communicating fluid pressure to the fluid chamber to selectively displace the piston toward the disc to actuate the brake and permit retraction of the piston into the housing to release the brake;

adjuster piston means in the housing and engageable with the first piston;

shaft means engaging the second piston;

apertured locking plate means closely surrounding the shaft means;

spring means acting between the shaft means and the apertured locking plate means;

means associated with the housing and movable therein when actuated, the associated means engaging the apertured locking plate means at only a limited circumferential portion thereof whereby the apertured locking plate means is cocked into frictional engagement with the shaft so that upon axial movement of the associated means the locking plate means, shaft means, the adjuster piston means and the first piston are forced toward the disc to actuate the brake;

the housing and the means associated therewith having limited axial relative movement therebetween independently of said movement when actuated; and

second spring means acting between the housing and the associated means to hold the associated means toward the disc and yielding to permit the limited movement of the associated means away from the disc when the brake pad assembly expands into forced engagement of the disc.

4. The disc brake of claim 2 further comprising movable means within the housing engageable with the locking plate means diametrically opposite its point of engagement with the associated means;

and an axially extending passage through the associated means permitting inserTion of a tool to forcibly urge the movable means into engagement with the locking plate means to cock the locking plate means out of frictional engagement of the shaft whereby the shaft means, second piston means, and first piston means may be fully retracted into the housing.

5. The disc brake of claim 2 wherein the means associated with the housing comprises;

a rotatable member received through the wall of the housing and having circumferentially spaced axially extending grooves formed on the periphery of the portion thereof within the housing;

sleeve means within the housing having circumferentially spaced axially extending grooves formed on the peripheral portion thereof surrounding the grooved portion of the rotatable member and having on the outer periphery thereof a helical groove;

a helical groove formed on the housing and mating the helical groove of the sleeve;

bearing balls located in the respective grooves whereby upon rotation of the rotatable member the bearing balls impart rotary and consequent axial movement to the sleeve.