Road-end cap for two-function pneumatic master cylinder for vehicles - is rotatably sealed cover locked into end of hollow piston rod attached to sprung piston in emergency and parking brake cylinder

摘要

Membrane cylinder (4) is operated by compressed air through port (14) and controls braking during motion. Piston (6) is operated by spring (9) against compressed air in chamber (3) and pushes hollow piston rod (10) against membrane and piston (11,16) to control braking in emergency and parking. Upper chamber (13) communicates with lower chamber (7) by pipe (18). The top end of the hollow piston rod (10) is closed and sealed by cap (30). This has a skirt (30a) with projections at its end engaging a groove (32) in the wall of the hollow rod (10) thereby permitting rotation. A groove in the skirt (30a) has an elastic seal (33). ADVANTAGE - The cap at the top of the hollow piston rod being free to turn overcomes the problem of screwed caps which tend to unscrew due to rotation of the spring in operation.