A spring brake actuator (1) for a vehicle, in particular a parking or emergency brake actuator, for use in a commercial vehicle, includes a cylinder housing (2) having a cylinder housing base (5) and a spring seat (7) on the base, a spring brake piston (9) located in the cylinder housing (5) for applying a braking force, and a compression spring (11) arranged between the spring seat (7) and the spring brake piston (9). The cylinder housing (2) is divided into a spring chamber (12) and a pressure chamber (14), the compression spring (11) being arranged in the spring chamber (12) and the pressure chamber (14) being supplied with pressurized fluid. An elastically deformable diaphragm (16) is sealingly mounted to the cylinder housing (2), with an inner periphery (18) sealingly mounted to the spring brake piston (9) to fluid-tightly isolate the pressure chamber (14) from the spring chamber (12).

A pressure-medium-actuated brake cylinder of a rail vehicle has a housing, a translationally movable brake piston rod extending through a bore in a housing base, a guide ring which is received in the bore, encloses the brake piston rod and is intended for guiding the brake piston rod in the bore, and at least one sealing ring which is received in the bore, encloses the brake piston rod and is intended for sealing an interior of the housing with respect to a space outside the housing, wherein the guide ring and the at least one sealing ring are designed as a guide and sealing ring combined to form a structural unit.

In the case of a hydraulic vehicle brake, having a brake caliper (12), having a brake piston (16), having a receiving bore (14) for the brake piston (16), and having a brake piston seal (32) that acts between the brake caliper (12) and the brake piston (16), the brake piston seal (32) is designed as a composite part, with a composite of a base component (34) and a reinforcement insert (36). The reinforcement insert (36) provides the brake piston seal (32) with a degree of elasticity in an axial direction, whereby, after the brake piston (16) has been displaced in the direction of brake pads (22), the brake piston seal (32) displaces the brake piston (16) in the opposite direction.