Vehicle parking brake system

A parking brake system (10) for vehicles, having a power assistance generating actuator unit (12) for pulling or releasing at least one control cable (14) for a braking device (16) of the vehicle, having an electronic control device (18) whose output variable is used to activate the actuator unit (12), the control device (18) being supplied with input variables, in particular from an operator device (20), from sensors and/or switches or the like, and it being possible to change the output variable as a function of the input variable, wherein a force sensor (22) for directly sensing the force exerted on the control cable (14) is arranged on or in the control cable (14), the signals of the force sensor (22) being supplied to the control device (18) as an input variable, wherein the control cable (14) is assigned a displacement sensor (24) for sensing the travel of the control cable (14), the signals of which sensor (24) are supplied to the control device (18) as an input variable and the control device (18) has a memory device (26) and a comparator (28), one of at least pairs of values and pairs of data items being stored as reference values in the memory device (26) and the reference values being compared with the current values in the comparator (28).