In recent years, the mainstream design is a built-in type system which a machine tool manufacturer creates by purchasing motor components from a servomotor manufacturer and setting the motor's rotor directly onto the hollow main shaft. Tsubaki's specially designed, dedicated Power-Locks, SL type and EF type, are used to connect the hollow main shaft and rotor. Due to the high-speed rotation of the rotor, the end face of the Power-Lock is screw-tapped for balance adjustment. Furthermore, the EF series is tapered in the opposite direction to prevent the hub from moving during assembly.

The SL series has been adopted for fastening the motor shaft of a blade stage (turret). Since a turret which holds several tools requires precise indexing accuracy, the backlash-free Power-Lock is used to lock the rotation axis.

A tool change arm is used not only in machining centers but also in combined lathes. Today, tool change arms receive alternating load at astonishingly high speed and high frequency, so that key fastening cannot be used. The Power-Lock EF series and KE series are used for such tool change arms.