Measuring the kinematic accuracy of worm gears

A special-purpose machine has been designed and installed to measure the ki nematic accuracy of precision worm gears. The primary measurement is the tr ansmission error (TE) between the worm and wheel, and several measuring met hods were considered. The chosen method uses optical gratings and a digital system to process the signals, which has particular advantages for this ap plication. This method then makes it a straightforward step also to measure pitch errors of both the worm and the wheel, and lead errors of the worm. A novel method of measuring backlash very accurately is also described.