Key Takeaways:
A hydrostatic spindle integrates a liquid-hydrostatic bearing with a torque or direct-drive motor in one rigid assembly. Marusaku's MRDY series covers grinding, turning, and cylindrical/internal grinding.
Two Technologies in One Body
A hydrostatic spindle combines a liquid-hydrostatic bearing—where the shaft rides on a pressurized oil film—with a torque or direct-drive motor in a single, highly rigid assembly. The bearing keeps the shaft floating non-contact while the motor delivers smooth, high-torque rotation.

Why Integrate
Integrating the bearing and motor removes couplings, belts, and intermediate gearboxes that would otherwise add backlash and vibration. The result is a spindle with radial runout at or below 0.1 μm, stiffness 5–10× that of rolling bearings, and theoretically infinite life.
The Marusaku MRDY Approach
Marusaku's MRDY hydrostatic spindles are built for precision grinding, lathe/turning, and cylindrical or internal grinding, with models spanning MRDY-120 through MRDY-200 plus 190DC and 195DM variants.