Spring-applied, air-released, slack-adjusting parking brake
AssigneeAmerican Standard Inc.
InventorsQuentin T. Clemmons, Paul F. Czerniewski
Life of this patent
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Abstract
A parking brake, primarily for use with railway vehicles, including a friction clutch associated with a fast-travel nut which is locked by the clutch against rotation on a threaded spindle connected to a brake head, under a force exerted by a plurality of stacked Belleville-type disc springs. The spring load may be overcome by air pressure acting on respective faces of a plurality of serially connected pistons, which, in effect releases the fast-travel nut for free spinning to thereby accommodate axial displacement of the spindle during normal service application and release of the brakes.
Claims6
A spring-applied, fluid pressure released parking brake device for use on a railway vehicle equipped with a conventional tread brake unit including a brake lever for operating brake shoes, said parking brake device comprising:
- (a) a cylindrical housing;
- (b) a non-rotating spindle coaxially disposed in said housing and provided with a fast-pitch screw thread, said spindle being connectable to such brake shoe such that when moved axially in a first direction, a brake application occurs, and when moved in a second direction opposite to said first direction, a release of the brake occurs;
- (c) a fast-travel nut rotatably carried on said spindle;
- (d) a clutch seat member axially slidable in said housing in surrounding relation to said spindle and adjacent said fast-travel nut;
- (e) clutch means formed partly on said nut and partly on said clutch seat member, said clutch means being effective, when engaged, for locking said nut in coupled relation with said spindle for causing axial movement of said spindle coincidentally with axial movement of said nut and being effective, when disengaged, for permitting free rotation of said nut to allow axial movement of said spindle independently of said nut;
- (f) a plurality of axially aligned, substantially similar, stacked pistons coaxially disposed in said housing in consecutively abutting relation with each other and in abutting contact with said clutch seat member;
- (g) pressure chambers formed on one side of each of said stacked pistons and vent chambers formed on the side opposite thereof;
- (h) spring means disposed in said housing and acting through said stacked pistons for exerting an axially directed spring force in a direction coinciding with said first direction, on said clutch seat member for causing engagement of the clutch means and consequent movement of said spring in said first direction;
- (i) said pistons being subjectable to a control fluid pressure for exerting an axially directed force effecting disengagement of said clutch means, and
- (j) a hollow guide rod coaxially mounted in said housing and extending through said pistons and threadedly engaged with said clutch seat member, said hollow guide rod being surrounded by a spring sleeve on at least a portion thereof, said spring sleeve being further in contact with a threaded nut which is threadably engaged to said hollow guide rod such that axial movement of said pistons can cause axial movement of said spring sleeve.
Dependencies are inferred from the claim text.