The vehicle parking brake system is actuated by an adjusting unit (4) which creates an external force. There is also an emergency actuation system (2) for which muscle power is used. Both systems have gears (5, 12), acting with a common threaded spindle (3). The gears are designed to lock automatically and reciprocally as a function of the type of actuation. External force and muscle power actuation can be used in any sequence with without restricting the adjusting path or paths.
