Brake booster having a decompression piston from a plastics material integrated in the push rod

The brake has a brake actuator push rod (46) with a cylindrical front section (64) on which a helical spring (66) is received to support between a front shoulder side (68) and an arm (70) of an unloader piston (62). The front section has smaller diameter (D3) and housed in a rear end of a primary piston of a master cylinder and the unloader piston has larger diameter (D2).