Abstract
The authors developed the new type hourglass worm gear of plastics involutes helical gear wheel. The theory, the calculation of the tooth contacts analysis for the prediction of the performance of the gear and the production method of the steel worm and the plastics wheel are reported. A set of the hourglass worm gears was manufactured. And the accuracy of the transmission was measured by the measuring machine for the angular transmission error (abbreviated to ATE) of the reducer invented by A. Horiuchi and others. The efficiency was tested by the power absorption type worm gear testing machine, designed and made by the authors. The efficiency of the hourglass worm gear was compared with the cylindrical worm gear of steel worm and plastics wormwheel whose dimensions was the same of the hourglass worm gear proposed in this report.
