The pump is a variable displacement piston pump that discharges two identical flows from one cylinder block. Although it has a dual pump structure, and the 3 pump and the pilot pump are connected on the same axis through the coupling sleeve, its structure is very compact. Because the pump has only one swashplate, the inclination angle is the same. The inclination angle of the pump can change the total flow q1+q2. The output power is constant, so the product of outlet pressure and flow is constant, i.e. (q1+q2) × P=p (constant).
Pump control function
The angle of swashplate is determined by the oil discharge pressure of PL pump and P2 pump, and the force of power spring is opposite to the oil discharge pressure. When the pressure is less than the set load of power spring a, the swashplate is at the maximum tilt angle position. When the pressure exceeds the set load of power spring a, the inclination angle of swashplate will change to a small angle, and will be fixed at the balanced position under the pressure of hydraulic oil and the force of power spring a. When the inclination angle of the swashplate continues to decrease due to the increase of the pressure of the hydraulic oil, the Spring B that has not been working starts to work. To overcome the elasticity of the two spring forces, it is necessary to reach the highest lower dead center of the oil pressure. When P3 hydraulic oil pushing the servo piston flows in, the control shift curve will be changed.
