1. A LAPPING MACHINE FOR LAPPING CROWNED TOOTH COUPLINGS COMPRISING A BASE, A FRAME EXTENDING UPWARDLY FROM SAID BASE, MEANS TO SUPPORT AND ROTATE A FIRST PART OF A CROWNED TOOTH COUPLING ON SAID BASE, SAID FRAME HAVING A HORIZONTALLY DISPOSED TRACK SPACED ABOVE SAID BASE, A TROLLEY ON SAID TRACK ABOVE SAID BASE, MEANS TO RECIPROCATE SAID TROLLEY IN A HORIZONTAL DIRECTION ON SAID TRACK, A QUILL SHAFT EXTENDING DOWN FROM SAID TROLLEY, MEANS TO ATTACH A SECOND PART OF SAID COUPLING TO SAID QUILL SHAFT, A BRAKE ON SAID TROLLEY, SHOE MEANS ON SAID BRAKE, MEANS ON SAID QUILL SHAFT TO RESIST ROTATION OF SAID QUILL SHAFT, AND MEANS ON SAID TROLLEY TO RECIPROCATE SAID QUILL SHAFT UP AND DOWN.