Combined Vane Pump ZYB-50/ZYB-80

Combined vane pump ZYB-50/ZYB-80 has two upper cover structures A & C to choose, suitable for connecting different pipelines. With built-in oil and gas separator and relief valve, this kind of pumps have advantages of low noise, large flow and long lifespan.

Working Principle of Vane Pump

The combined vane pump is a vane pump and oil-air separator combined into one component. In terms of working principle, the combined vane pump can be divided into 2 main parts: vane pump & oil and gas separator. The vane pump assembly press-fitted in the combined pump housing together with the filter screen, overflow valve and oil outlet valve are collectively referred to as the vane pump part. And the part of the combined pump other than the vane pump part is the oil and gas separation part. Besides, the function of the oil-gas separator is to separate the gas in the oil and discharge it outside the machine. It can filter out the impurities in the oil, which provides pure oil without gas and impurities for users.

The location of the filter is a low-pressure chamber, the oil inlet of the low-pressure chamber is connected to the bellows, and the part where the oil-gas separation pipe is connected is a high-pressure chamber. In general, oil-gas separation pipe communicates with the oil outlet of the vane pump below one end, and the oil outlet of the vane pump below the other end. Moreover, relief valve and the oil outlet chamber behind the oil outlet valve are connected. Meanwhile, the cavity where the float is located is an atmospheric pressure chamber, and the atmospheric pressure chamber communicates with the atmosphere through the exhaust pipe.

Working Process of Vane Pump

When the high-pressure oil output by the vane pump enters the oil-gas separation pipe from the oil outlet of the pump, under the action of the deflector at the inlet of the oil-gas separation pipe, most of the oil advances in a spiral shape along the inner wall of the oil-gas separation pipe. Finally, it flows from the oil outlet of the oil-gas separation pipe to the oil outlet valve. The gas mixed in the oil is less dense than the oil, so it is concentrated in the middle of the official cavity, and finally discharged from the oil-gas separation pipe to the normal pressure cavity. After the oil-gas mixture enters the atmospheric chamber, the gas floats up, discharged into the atmosphere through the exhaust pipe. And the oil is stored in the normal pressure chamber.

When the oil accumulates to a certain amount, the float floats up, driving the connecting rod to open the oil return valve, and the oil flows to the low pressure chamber through the oil return valve. While when the oil level drops to a certain height, the float falls back under the action of gravity, the oil return valve closes the valve, and the oil return function stops.

When the rotor rotates continuously, the vane pump outputs a certain pressure and flow of oil. The size of the oil delivery pressure depends on the pressure adjustment state of the relief valve and the load resistance. And the pressure oil coming out of the vane pump enters the oil-gas separation pipe for oil-gas separation. Part of gas-free oil coming out of the oil-gas separation pipe will return to low-pressure chamber through relief valve. And the other part will enter the flowmeter via the oil outlet valve.

When fuel nozzle is open, the load resistance would be small, and the pressure oil overcomes the spring force of the oil outlet valve and enters flow meter from the oil outlet valve, and the relief valve is closed or slightly opened. When fuel nozzle is closed, the oil pressure rises, then relief valve is completely opened. Next the pressure oil in the high-pressure chamber flows through relief valve to the inlet of vane pump and recirculates. Usually, the pressure and output flow of hydraulic system can change by adjusting the stud of relief valve.

Technical Parameter of Vane Pump ZYB-50/80

Model ZYB-50 ZYB-80


630 RPM 630 RPM

Flow Rate

45~65L/min 75~85L/min


≥0.054㎫ ≥0.054㎫


≤72dB ≤72dB

Working Pressure

1.6-2.0Bar 2-2.5Bar


35*28*38cm 35*28*38cm

Net weight

15kg 15kg

Gross Weight

16kg 16kg


1 pc/ctn