Patent ID: 11951958
Assignee: ZF CV SYSTEMS EUROPE BV
Field: Transport (Mechanical engineering)
Classification: CPC B | IPC B

Claim 5:
6. A spring brake actuator (1) for a commercial vehicle, the spring brake actuator comprising:
a cylinder housing (2) having a housing base (5),
a spring brake piston (9) disposed inside the cylinder housing (2),
a compression spring (11) disposed inside the cylinder housing (2) between the housing base (5) and the spring brake piston (9), wherein the compression spring is effective to push the spring brake piston (9) away from the housing base (5), the spring brake piston (9) configured to transmit a brake force exerted by the compression spring (12), and
a piston tube assembly (17) comprising:
a first tubular body (35) having a contoured inside surface profile (55) for non-rotationally guiding a running nut (21) of a mechanical release mechanism (19, 21), and
an internal breather valve (41) mounted to the piston tube assembly (17) for allowing fluid transport into and out of the piston tube assembly (17) and any volume in fluid communication therewith,
a second tubular body (37) that is made of a different material than the first tubular body (35),
wherein the second tubular body encloses the first tubular body (35) and mechanically supports the first tubular body (35),
wherein the internal breather valve (41) is mounted to the first tubular body (35);
wherein the second tubular body is longer than the contoured inner surface profile of the first tubular body;
wherein the first tubular body (35) includes a head section (39) and a recess (51) disposed in the head section (39) for accommodating the internal breather valve (41).