When the point moves along the plane curve , the trace curve of the point is called the evolute of the curve , denoted by, and is called the involute of the curve .
当点沿曲线移动时，相应的曲率中心的轨迹曲线称为曲线的渐屈线，而曲线称为曲线的渐伸线。
2
Fuel pump (unloading pump, high viscosity pump, asphalt pump) gear wear and tear parts mainly is the tooth meshing, involute face and gear ends plane.