Trapezoidal Screw Drive

In this most economical form of lead screw, the negative profile of the trapezoidal lead screw is cut into the nut, so the transmission of the feed motion takes place via sliding friction. The advantage is self-locking at pitches of less than 4°, which is why trapezoidal screw drives are used in lifting and clamping devices. The disadvantage, however, is the larger clearance and the higher friction.