Patent ID: 6988596

Claim:
A mechanically and hydraulically actuated brake cylinder for a motor vehicle having a body ( 1 ) with a bore therein for receiving an axially movable piston ( 4 ) to define a chamber therein and a pivoting shaft ( 11 ) that has a part thereof accessible from outside the body ( 1 ), said chamber receiving pressurized fluid to move said piston and hydraulically actuate a brake, said pivoting shaft ( 11 ) receiving a rotational torque for mechanicaly actuating a brake through a ball-ramp mechanism that converts the rotational torque of the pivoting shaft into translational movements of the piston ( 4 ) and comprising a rotary plate ( 28 ) that rotates as one with the pivoting shaft ( 11 ), a moving plate and balls ( 33 ) housed between a first ramp rib ( 31 ) located on a face on said rotary plate ( 28 ) and a second ramp rib ( 32 ) located on a face of the moving plate, characterized in that said moving plate is said piston, said brake cylinder being further characterized by a screw-nut assembly having a screw ( 22 ) that is secured to the rotating plate ( 28 ) and a nut ( 15 ) that is located in bore of the body and means ( 18 , 19 ) that blocks the rotation of said nut ( 15 ) on receipt of a high-pressure hydraulic fluid by the chamber to hydraulically actuate the brake.