A novel hydraulic disc brake system with a closed-loop control of the braking torque is under development at the Institute for Fluid Power Drives and Systems (ifas) of RWTH Aachen University. During the braking process, the torque on the caliper acts on a supporting rod. It has been found that the resulting supporting force is proportional to the braking torque. Thus, this force is utilized as a feedback variable for a hydro-mechanical control unit. In this paper, a simulation model of a spring-applied disc brake is introduced and the behavior of this brake is investigated. Based on those results, necessary requirements on the control unit are deduced and a suitable prototype for the investigation on a test rig is developed. Finally, the behavior of the control unit is analyzed using the simulation model.