Slack adjuster for hydro-pneumatic brake unit having automatic air bleed

Claim 2

Slack adjusteR apparatus for a hydraulically actuable vehicle brake unit, said apparatus comprising the combination of: a. a power actuator device including a cylindrical casing mountable in a horizontal position; b. a power delivery piston coaxially operable in said cylindrical casing responsively to hydraulic pressure acting on one side thereof for exerting a brake applying force; and c. a converter device mounted in a vertical position on and above said power actuator device, said converter device comprising: i. a sectionalized casing having formed therein and at the upper end thereof an atmospherically vented hydraulic fluid storage chamber and at the lower end thereof a hydraulic pressure chamber in constant communication with said one side of said power delivery piston, and ii. power input piston means coaxially disposed in said sectionalized casing between said hydraulic fluid storage chamber and said hydraulic pressure chamber and having passage means extending therethrough through which said hydraulic fluid storage chamber may be communicated with said hydraulic pressure chamber, iii. said power input piston means normally occupying a release position in which communication through said passage means between said hydraulic fluid storage chamber and said hydraulic pressure chamber is open, and being operable in response to a control pressure force acting on a control pressure side thereof, to an application position in which said communication through said passage means is cut off and said control pressure force is transmitted by said power input piston means to said one side of said power delivery piston through hydraulic fluid in said hydraulic pressure chamber for generating said brake applying force.

Claim 3

Slack adjuster apparatus, as set forth in claim 1, wherein said power input piston means includes a valve member coaxially operably disposed in said passage means, said valve means being operative, upon operation of said power input piston means to its said release position, to an open position in which communication through said passage means is open, and being operable, upon operation of said power input piston means to its said application position, to a closed position in which said communication is closed.

Claim 4

Slack adjuster apparatus, as set forth in claim 1, wherein said power input piston means includes biasing means for restoring the power input piston means to its said release position upon relief of pneumatic pressure acting on said pneumatic pressure side thereof.

Claim 5

Slack adjuster apparatus, as set forth in claim 1, wherein said power input piston means comprises a power input piston having said passage means coaxially extending therethrough and having said control pressure side disposed at one end thereof and a hydraulic pressure side disposed at the opposite end thereof adjacent said hydraulic pressure chamber, the effective pressure area of said pneumatic pressure side being greater than that of said hydraulic pressure side.

Claim 6

Slack adjuster apparatus, as set forth in claim 1, wherein said cylindrical casing has a passageway formed therein for communicating said hydraulic pressure chamber with said one side of said power delivery piston, said passageway being sloped upwardly in a direction from said one side of said power delivery piston toward said hydraulic fluid chamber.

Claim 7

Slack adjuster apparatus, as set forth in claim 1, wherein said power actuator device comprises a biasing spring coaxially compressed in a spring recess coaxially formed in said power delivery piston for causing the power delivery piston, in the absence of hydraulic pressure acting on said one side thereof, to exert a precalibrated force sufficient for maintaining said power delivery piston in a non-braking position, said spring recess being open at one end to said one side of the power delivery piston and closed at the opposite end and being uniformally tapered from the one end to the closed end thereof.

Claim 8

Slack adjuster apparatus, as set forth in claim 1, wherein said power actuator device includes manually latchable and releasible latching means for latching said power delivery piston in a retracted position within said cylindrical casing.

Claim 9

Slack adjuster apparatus for use in a pneumatically controlled hydraulically actuated truck-mounted brake unit for applying and releasing braking force to and from a brake shoe of a railway vehicle wheel, said apparatus comprising: a. a power actuator device including a cylindrical casing mountable on the truck in a horizontal position; b. a power delivery piston coaxially operable in said cylindrical casing responsively to hydraulic pressure acting on one side thereof for applying braking force to the brake shoe; and c. a hydro-pneumatic converter device mounted in a vertical position on and above said power actuator device, said hydro-pneumatic converter device comprising: i. a sectionalized casing having formed therein and at the upper end thereof an atmospherically vented hydraulic fluid storage chamber and at the lower end thereof a hydraulic pressure chamber in constant communication with said one side of said power delivery piston, and ii. power input piston means coaxially disposed in said sectionalized casing between said hydraulic fluid storage chamber and said hydraulic pressure chamber and having coaxial passage means formed therein through which said hydraulic fluid storage chamber may be communicated with said hydraulic pressure chamber, iii. said power input piston means normally occupying a release position, in which communication through said passage means is open, and being operable, in response to a pneumatic pressure force acting on a pneumatic pressure side thereof, to an application position in which communication through said passage means is cut off and said pneumatic pressure force is transmitted by said power input piston means to said one side of said power delivery piston through said hydraulic fluid in said hydraulic pressure chamber for generating said brake applying force.

Claim 10

Slack adjuster apparatus for use in a pneumatically controlled hydraulically actuated truck-mounted brake unit for applying and releasing braking force to and from a brake shoe of a railway vehicle wheel, said apparatus comprising: a. a power actuator device including a cylindrical casing mountable on the truck in a horizontal position; b. a power delivery piston coaxially operable in said cylindrical casing responsively to hydraulic pressure acting on one side thereof for applying braking force to the brake shoe; and c. a hydro-pneumatic converter device mounted in a vertical position on and above said power actuator device, said hydro-pneumatic converter device comprising: i. a sectionalized casing having formed therein and at the upper end thereof an atmospherically vented hydraulic fluid storage chamber and at the lower end thereof a hydraulic pressure chamber in constant communication with said one side of said power delivery piston, and ii. power input piston means coaxially disposed in said sectionalized casing between said hydraulic fluid storage chamber and said hydraulic pressure chamber and having coaxial passage means formed therein through which said hydraulic fluid storage chamber may be communicated with said hydraulic pressure chamber, iii. said power input piston means normally occupying a release position, in which communication through said passage means is open, and being operable, in response to a pneumatic pressure force acting on a pneumatic pressure side thereof, to an application position in which communication through said passage means is cut off and said pneumatic pressure force is transmitted by said power input piston means to said one side of said power delivery piston through said hydraulic fluid in said hydraulic pressure chamber for generating said brake applying force.