According to the invention, two redundant parking brake control circuits (13; 18) are provided. In the first parking brake control circuit (13), energy is supplied via the vehicle battery or an alternator. In contrast, as a second electrical power supply (19) in the second parking brake control circuit (18), a battery or an accumulator (14), a generator, a pulse generator, a piezoelectric element and/or a propellant cartridge is provided.
