The hydraulic oil pump cannot suck oil or has no pressure.

Causes.

1. The rotation direction of prime mover and oil pump is inconsistent.

Troubleshooting: correct the rotation direction of the prime mover.

2. The oil pump transmission key fell off.

Troubleshooting: reinstall the drive key.

3. The oil inlet and outlet are connected reversely.

Troubleshooting: select the correct connection method according to the instructions.

4. The oil level of the oil tank is too low, and the oil suction pipe is exposed.

Troubleshooting: replenish oil.

5. The speed of prime mover of truck oil pump is too low and the suction is insufficient.

Troubleshooting: increase the speed to above the minimum speed required by the oil pump.

6. The oil viscosity is too high.

Troubleshooting: select working oil with recommended viscosity.

Working principle of hydraulic oil pump.

Constant pressure variable pump is composed of plunger pump, variable oil cylinder and pressure regulating valve.

Before the constant pressure pump reaches the set pressure of the pump pressure regulating valve, the swashplate of the variable pressure pump is at the maximum deflection angle, the pump displacement is the largest, and the oil pump volume in the exhaust cab is constant. In fact, the constant pressure variable pressure pump is quite a quantitative pump at this stage.

After reaching the set pressure of the pressure regulating valve, the control oil enters the variable displacement cylinder, which pushes the swashplate to reduce the pump displacement.

In the constant pressure variable pump system, if there is an overflow valve, the set pressure of the pump pressure regulating valve should be less than the set pressure of the system overflow valve by 0.5-1mpa, otherwise the pump pressure cannot reach the set value of the pressure regulating valve, and it cannot be variable.