Recirculating ball disc actuator

摘要

A linear actuator in which a pair of relatively rotating thrust members have opposing surfaces on which are formed a plurality of concentric circular races in which a plurality of balls circulate. Each race is in the form of a helix over substantially the full circular length of the race with a step joining the ends of the helix. The steps in adjacent concentric races are spaced apart by 180 DEG . Each race over half its length is recessed so that the balls engage the opposing races along approximately half the length of each race, the recessed half of adjacent concentric races being offset by 180 DEG so that the thrust load is shared by substantially the same number of balls around the respective half-circular of the two sets of races.