A redundant parking brake apparatus is provided for a vehicle having components of a parking brake system. The redundant parking brake apparatus comprises a first parking brake controller arranged to (i) monitor a first signal indicative of a request to apply parking brakes of the vehicle, and (ii) provide one or more control signals to be applied to components of the parking brake system to apply the parking brakes in response to receiving the first signal. The redundant parking brake apparatus also comprises a second parking brake controller arranged to (i) initiate a timer counter in response to receiving the first signal, and (ii) provide one or more control signals to be applied to components of the parking brake system to apply the parking brakes when the timer counter has reached a predetermined count.

A redundant parking brake apparatus is provided for a vehicle having components of a parking brake system. The redundant parking brake apparatus comprises a first parking brake controller arranged to (i) monitor a first signal indicative of a request to apply parking brakes of the vehicle, and (ii) provide one or more control signals to be applied to components of the parking brake system to apply the parking brakes in response to receiving the first signal. The redundant parking brake apparatus also comprises a second parking brake controller arranged to (i) initiate a timer counter in response to receiving the first signal, and (ii) provide one or more control signals to be applied to components of the parking brake system to apply the parking brakes when the timer counter has reached a predetermined count.

A spring brake actuator (2) for use in a commercial vehicle includes a cylinder housing (4) including a spring brake piston (10) for applying a braking force, a spring guide (12) attached to the spring brake piston (10). The spring guide (12) includes a valve (14) and a retaining device (16) for retaining the valve (14). The retaining device (16) includes a basic body (34) and clamping portions (36) for clamping the retaining device (16) to the spring guide (12). The clamping portions (36) are arranged at the basic body (34) along a circumference (38) thereof, and the clamping portions (36) are spaced apart from each other forming slits (40) between the clamping portions (36) to allow for a circulation of air through the slits (40).