The test head manipulator comprises two bearings coupled to a frame. A lead screw is rotatably disposed between the two bearings. A non-translation mechanism is also provided to prevent the lead screw from translating along its longitudinal axis. A lead nut is threaded onto the lead screw, but is prevented...http://www.google.com/patents/US6646431?utm_source=gb-gplus-sharePatent US6646431 - Test head manipulator
