US 4,733,602 A · Hydraulic brake actuator with parking brake

Abstract

A hydraulic brake actuator including a hydraulic parking brake that can be applied by mechanically locking up either a normal service brake application or a hand pump operated brake application. The lock-up mechanism includes a friction collar that surrounds the piston push rod and a hand pump actuated locking member that surrounds the friction collar. The friction collar and locking member have complementary conical surfaces that are engageable when hydraulic hand pump pressure is applied to a piston face of the locking member to wedge the friction member into pressure engagement with the piston push rod, as a means of locking up the push rod to obtain a parking brake. The locking member also includes a plurality of spring-like fingers that project axially from the periphery of the locking member and are provided with latching tabs adapted to enter a recess in the body to prevent return-movement of the locking member when the hydraulic hand pump operation is terminated. A plug member is provided to prevent the tabs from being disengaged from the recess. This provides a means for releasing the locking mechanism by either manually or hydraulically withdrawing the plug member, thereby allowing the hand brake to be released by separation of the conical surfaces of the locking member relative to the friction collar.

Claims15

Dependent claims

A brake actuator device comprising:

(a) a body;
(b) a push rod;
(c) a sleeve member disposed on said push rod so as to be axially slidable thereon;
(d) a parking brake piston engageable with said push rod to effect movement of said push rod relative to said sleeve member to a brake aplication position in response to the supply of fluid under pressure thereto;
(e) a locking piston member movable to a locking position in response to said supply of fluid under pressure to said parking brake piston following movement of said push rod to said brake application position, said locking piston having wedging engagement with said sleeve member in said locking position to force said sleeve member into tight engagement with the periphery of said push rod and accordingly lock said push rod against further axial movement relative to said sleeve;
(f) first spring means acting on said locking piston member in opposition to said fluid pressure thereat, for preventing said movement of said locking piston member to said locking position, until the fluid pressure effective at said locking piston member exceeds a predetermined value;
(g) a bore in said body in which said locking piston member is operative;
(h) an annular recess formed in said bore;
(i) a plurality of elongated fingers projecting longitudinally from the periphery of said locking piston member;
and
(j) an outturned latching tab formed on at least one of said fingers, so as to enter said recess in said locking position of said locking means.

8 more elements

Dependencies are inferred from the claim text.

Hydraulic brake actuator with parking brake

Life of this patent

Hydraulic brake actuator with parking brake

Life of this patent

Abstract

Claims15