brake in different phases of operation the phase in which the electric motor 10 rotates the shaft 151 and with it the driver 21 clockwise is shown in fig5 a in which the radial protrusions 216 lie on the inside with their drive surfaces 211 against coupling surfaces 234 of the coupling protrusions 236 on the outside against mating drive surfaces 221 of clamping device 22 because of this the clamping devices 22 are held in a neutral position in which no clamping effect occurs the mating drive surfaces 221 border recesses on the edges of clamping devices 22 the phase in which a back driving torque comes from drive output 23 and acts on brake 2 is shown in fig5 b in which case the coupling protrusions 236 of the coupling output lie with their coupling surfaces 234 against the drive surfaces 211 whereas an additional pivoting through the oblique coupling surfaces 225 of clamping devices 22 may lie against the complementary mating surfaces 235 of coupling protrusion 236 so that a radial force component is produced that forces the clamping devices 22 against the inside surface of the clamping ring and therefore causes friction until clamping occurs the phase in which motor movement has just started until drive surfaces 211 lie against the mating drive surfaces 221 is shown in fig5 c in this state in which clamping is still present a drive free space 201 remains between the drive protrusions 216 of driver 21 and the coupling protrusions 236 of the brake output 23 this angle which is defined by.