The start buttons Sb3 and Sb4 in the control circuit are remote control buttons, which are respectively installed in two places of the machine tool for convenient operation. SB1 and SB2 are stop buttons. KM1 is the starting contactor of the spindle motor M1, Yc1 is the electromagnetic clutch for the spindle brake, and SQ1 is the travel switch for the spindle variable speed impulse. The main shaft motor is driven by the gear transmission chain of the elastic coupling and the variable speed mechanism, which can make the main shaft obtain eighteen different speeds.