Stepping motor

A stepping motor comprising a casing, at least one electromagnet disposed in the casing, a shaft which is mounted for rotation in the casing, a rotor fixed to the shaft, an armature rotationally fastened to the rotor and mounted on the shaft for longitudinal sliding and cooperating with the electromagnet, a first ball race concentric to the shaft and fastened to the casing, a second ball race cooperating with the first ball race and mounted for rotation in the casing, balls disposed between the races, the tracks of the races being so shaped that an axial force on the rotatable second ball race results in a rotary movement of the latter, a flange on the armature which engages behind the rotatable ball race and which carries spur teeth having inclined flanks and cooperating with corresponding spur teeth on the rotatable second ball race, restoring springs imparting to the rotatable second ball race an initial force opposite in direction to the rotation produced by the armature, a catch device for determining the steps, pins on the side of the rotatable ball race opposite the ball tracks, said pins extending axially away from the race, and an annular spring casing having peripheral slots which match with and engage said pins with compression springs positioned in the slot, said springs are supported at one end against the spring casing and at the other end act on the pins of the rotatable ball race.