Coaxial twin pistons in hydraulic brake cylinder - are radially coupled by friction segments, resulting in being subjected to similar hydraulic pressure

摘要

The hydraulic cylinder (22) for operating a disc brake, locates a ring piston (11). The ring piston locates a coaxial secondary piston (12) so that both pistons are subjected to the same hydraulic pressure. When pressurised, the inner, secondary piston (12) which has less friction resistance, moves first against the brake pad. When the main piston (11) starts its axial movement, radial friction segments (13) produce a rigid coupling with the secondary piston (12). The axial forces are transmitted across radially inclined shoulders (16,19) on the two pistons.