Brake cylinder device including means for automatically compensating for brake pad wear

A brake cylinder device for use in brake apparatus and comprising:

• a. a casing;
• b. a piston reciprocably disposed in said casing and effective when axially moved in one direction out of an initial release position, in response to pressurized hydraulic fluid supplied to a primary pressure chamber formed in said casing adjacent one side of said piston, for providing an application force for the brake apparatus;
• c. a sleeve member coaxially disposed in said casing and normally occupying a spaced-apart position relative to said piston at a certain axial distance therefrom,
• d. said sleeve member being engageable by said piston for movement therewith upon movement of the piston in said one direction in excess of said certain axial distance and having a pressure face at one end thereof subjectable to hydraulic pressure in an equalizing chamber formed in the casing adjacent said pressure face, said equalizing chamber being communicable with hydraulic pressure in said primary chamber via a passageway extending coaxially through the sleeve member for effecting equalization of hydraulic fluid pressure between the two chambers;
• e. a precalibrated spring coaxially disposed between said piston and said sleeve member for biasing the piston and the sleeve member to said spaced-apart position relative to each other;
• f. positioning means for positioning said sleeve member at said certain axial distance from said piston incidentally to return of the piston to a subsequent release position, notwithstanding that said subsequent release position does not coincide with said initial release position;
• and
• g. a one-way check valve interposed in said passageway in said sleeve member providing flow in a direction from said primary pressure chamber to said equalizing chamber only.