Rexroth pump can be divided into volumes and non-volume chamber (worm) two. There are non-positive displacement pumps, axial flow, etc., using high-speed rotating impeller to make imported produce vacuum suction fluid and continuous output pressure of the liquid at the outlet. The pump inlet and outlet connected, efficiency decreases with increasing viscosity of the liquid, and the output and significantly reduce the amount of liquid with the outlet pressure. Positive displacement pump through a closed space changes in volume to achieve suction and pressure oil. Perform suction when the enclosed volume from small to big, from big oil pressure-hours. Typically Rexroth piston pump, the plunger is pulled out from the cylinder bore suction pressure when pressed into oil. The pump inlet and outlet are separated, the efficiency of the process depends on the viscosity of each of the structural gap between moving parts and the oil separates suction pressure oil chamber and so on. The higher the viscosity, the higher the efficiency, the amount of oil remained almost unchanged (due to the efficiency of a slight impact, in addition to increased pressure to 18MPa, the oil will be pressed A4VG pressure piston pump Rexroth Rexroth Series - Displacement from 28-250 - General pressure 400bar (40Mpa) - peak pressure 450bar (45Mpa)