圈上海文通大华 0 Pressure angle():angle between force and motion Pressure angle rotated in direction of driven gea Velocity at pitch point Axis of transmission or line of action (common nommal)is tangent to Addendum of pinionp both base circles Pitch radius Common tangent Pitch radius of gear g Pitch point Driven (CCW) Driving (CW) Base circle of pinion Base circle of gear Pitch circles Addendum of gear ag 园 上游充通大￥ Why use involute profile? Advantages using involute profiles ● 2000-D0UGR Line of action is a fixed line(common normal). 1717  Pressure angle (Φ): angle between force and motion  Advantages using involute profiles Line of action is a fixed line(common normal). Why use involute profile？