T-rotor pump is one of the gear pump comprises a pair of inner and outer rotor contacting inside and outside and covers wide range from low to high rpm(500¡­3000RPM) since it rotates on one point contact rolling movement. And it's superior to other volumetric pump on high machine and volume efficiency and advantage in manufacturing price and productivity. It may applied to machine tool, locomotive, lubrication and hydraulic boiler, etc.