Abstract
Tooth profile used for watch or clock is formed with a part of circle and radius line, as the modified cycloid gear. The torque variation of gear positioned near the barrel gives the large influence on the accuracy of time-keeper. Therefore, the tooth profiles of these gears are determined from the view point of smooth torque transmission rather than from that of smooth rotation of gear.
The author has tried to get the tooth profile to make the transmitting torque constant, taking into account the friction arised from the sliding contact of teeth, and obtained such a profile from the theoretical considerations and compared it with the conventional profile.The tooth profiles and the error of the transmitted rotating angle are shown in diagrams.These diagrams will serve to determine the tooth profile of gear in the case where the small torque variation is required, for instance in the gear used for time-keeper positioned near the barrel.
