The valve-spool is a core part of the hydraulic control device which is assembled to the valve body of auto transmission. Auto transmission function of D-P-1~8 is actuated by controlling pressure as the oil which is sucked into the oil-fan by oil pump is axially transported to the valve spool with many grooves.

Assembled into valve body, these product springs supports the valve and generate line pressure to constitute a hydraulic channel

The differential shaft supports the differential gear which makes difference of revolving speed between the right and left wheels when the car rotates or runs on the bumpy road.

Screw Parts combind with torque cnverter and transmission lever which are assembled to the transmission clutch of large truck. They take a role of speed control by conducting gear change from low to high speed.