Use the method of the frequency governor with machine speed. Bring about a stepless regulation of all constant power range, in the rotating main movement of universal machine tools.
用变频调速和机械变速相结合的方法，在主运动为旋转运动的通用机床中，实现全部恒功率范围内的无级调速。
2
James Watt's flyball governor (1769) regulated steam flow to a steam engine to maintain constant engine speed despite a changing load.