On the basis of analying the engaging character of the circular-arc gears with circular-arc tooth trace

in this paper

the engaging motion between circular-arc gears with circular-arc tooth trace and its basic rack are studied by using the principle of engaging surfaces. The calculation formulasincluding the mesting function

the instantaneous comtact line、the normal vector of tooth surface、the relative velocity are derived. The common tooth surface equation is built

and the shape of tooth surface is drawn with aid of apollo computer.