diagram an area of a parking brake 1 of a motor vehicle not shown parking brake 1 has a caliper unit 2 in which a brake piston 3 is guided longitudinally displaceably brake piston 3 may be acted on by a hydraulic fluid 5 on its one side 4 a force f hydr being applied through the pressure of hydraulic fluid 5 furthermore a mechanical force f mech may act on side 4 of brake piston 3 the two forces f hydr and f mech mentioned above superimposing on one another resulting in a superposition mode and jointly shifting the piston to the right where there is a brake disk of parking brake 1 not shown in fig1 which is acted on by a brake force f n accordingly fig1 shows that mechanical force f mech may be generated by an electromechanical actuator 6 because the schematic diagram shows a spindle drive 7 fig2 elucidates fig1 by illustrating structural features brake piston 3 which is longitudinally displaceably supported in caliper unit 2 is configured to be pot shaped a nut 9 of spindle drive 7 mentioned above being located in interior 8 of the pot nut 9 is situated in interior 8 of the pot to be longitudinally displaceable but is not rotatable and is screwed onto a threaded rod 11.