Servo drive, particularly for driving output shafts of slide valves

摘要

A servo drive for driving an output shaft of a valve comprises a gear housing on which is mounted an electric driving motor which drives an eccentric through back gears. A planetary gear train includes an externally toothed inner gear engaged on the eccentric and driven thereby. The output shaft extends through the eccentric. An internally and an externally toothed outer gear has an internal gear portion and engageable with the external gear of the inner gear and has an outer gear portion engaged with a worm in a fixed self-locking manner. A plurality of wound bolts of equal diameter are arranged in spaced circumferential locations along a first circle around the center of the inner gear and they are spaced from each other by equal lengths of arc which protrude in one axial direction. A perforated disc connected to the output shaft has a disc portion oriented parallel to the inner gear and has a plurality of circumferentially spaced round holes in the same number of the number of bolts. The holes are spaced around a second circle which is of a diameter which is larger than the first diameter in an arrangement such that the round bolts engage through the holes and touch the wall bounding the associated hole. The construction is such that the torque transmitting components, the toothed inner wheel and the internally and externally toothed outer wheel as well as the perforated disc may be arranged in either dual or multiple numbers parallel to the same axis.