The hydraulic power station part of the CNC lathe can be placed behind the machine as a module. When the tailstock top is required for mass processing, the hydraulic tailstock top system can be installed to make it another operable module and share the same hydraulic power system.

In processing, when the program runs to the state where speed change is required, the numerical control system first sends out a stop signal, and then the program sends out a control signal to start the hydraulic pump to supply oil. At the same time, the solenoid valve of the hydraulic system sucks in according to the control signal to supply oil to the speed change cylinder, so that the piston rod extends or retracts, and the shift fork is pushed to change the gear. When the gear moves in place, the cam touches the micro switch, then the speed change ends and the program continues to run down to execute the workpiece.

The spindle variable speed module is installed on the spindle box, which is composed of a bracket, an oil cylinder, an oil pipe, and a micro switch. The length and width dimensions of the bracket are the same as those of the top of the spindle box. The whole spindle speed change module is installed on the four screw holes originally used for installing the cover plate on the spindle box, and positioning pin holes are added for module positioning. The middle of the bracket is supported by a partition plate, and the speed change oil cylinder is fixed on the partition plate and located directly above the gear shaft to be controlled sliding, coaxial with the guide shaft; the piston rod of the oil cylinder is located in the guide shaft and connected with the shift fork through a pin shaft; the shift fork is sleeved on the guide shaft and can move back and forth along the guide shaft driven by the piston rod; the two gear shift forks are of downward vertical structure and are respectively stuck in the shift groove of the corresponding sliding gear.

When the oil cylinder supplies oil when shifting, the piston rod drives the sliding fork to move the sliding gear through the pin shaft, so that the gear is engaged in variable speed. After the gear is in place, the protrusion on the shift fork touches the micro switch on the cover plate to send out the gear in place Signal, the shift is over.