ABSTRACT
Gears are used widely and constitute one of the most important machine elements. Gears are considered motion transformers as opposed to power transmitting elements. Noncircular gears will be considered together with other forms of gears. Special tooth shapes will also be considered. Gears can transmit a constant or varying transmission ratio. When the transmission ratio is varying, noncircular gears are employed. C. F. Reuleaux was a German kinematician and is considered to be the father of kinematics. He established that the fixed link of a mechanism is kinematically the same as the moving links. He also established the notion of kinematic pairs. Circular gears transmit rotary motion to rotary motion with a constant transmission ratio. The transmission ratio varies for noncircular gears, which are not really popular with designers. However, once they are understood—and it really does not take much effort to learn—they can get a designer out of a bind.
