Introduction to variable piston pump

Variable plunger pump pressure oil pump body, pump shell oil hole through one-way valve into the variable in the variable shell shell inferior vena, when rod downward movement, servo piston moves down, push on the servo valve valve mouth open, and the oil in the inferior vena pressure variable shell oil hole into the variable in the variable piston cavity on the shell, because of the cavity area is larger than the inferior vena, hydraulic pressure drive piston downward movement, the variable head rotated around the center of steel ball drive pin shaft rotation, change the variable Angle of inclination of the head (increase), plunger pump flow increase. On the contrary pull rod upward movement, the variable head tilt Angle to the opposite direction, the flow of the pump also changes. When the tilt Angle changes to zero, the head of the variable changes to the direction of negative deviation Angle, the fluid flow reverses, and the inlet and outlet of the pump changes.

The above: Piston pumps are classified according to the relevant characteristics. What are the types?