Elephant Fluid Power Co., Ltd.
Elephant Fluid Power Co., Ltd.

How to Use Hydraulic Pump Correctly?

Nowadays, the development of the machinery industry is more and more advanced, and the hydraulic industry is also born. The hydraulic pump is the power component of the hydraulic system, its function is to convert the mechanical energy of the prime mover into the pressure energy of the liquid, which refers to the oil pump in the hydraulic system, which provides power to the entire hydraulic system.

The structural forms of hydraulic pumps generally include gear pumps, vane pumps and plunger pumps. Through the introduction of this article, you will have a better understanding of hydraulic pumps.

1. Classification of hydraulic pumps

According to whether the flow can be adjusted, it can be divided into: variable pump and quantitative pump.

The output flow can be adjusted according to the needs called variable pump, the flow can not be adjusted called quantitative pump.

According to the pump structure commonly used in the hydraulic system, it is divided into three types: gear pump in hydraulic system, vane pump and plunger pump.

Gear pump: small in volume, simple in structure, less strict on oil cleanliness, and cheaper in price; but the pump shaft is subject to unbalanced force, serious wear, and large leakage.

Vane pump: divided into double-acting vane pump and single-acting vane pump. This kind of pump has uniform flow, stable operation, low noise, higher working pressure and volumetric efficiency than gear pump, and more complicated structure than gear pump.

Plunger pump: high volumetric efficiency, small leakage, can work under high pressure, mostly used in high-power hydraulic systems; but complex structure, high requirements for materials and processing accuracy, high price, and high requirements for oil cleanliness.

2. The composition of the hydraulic pump 

The hydraulic pump consists of three parts: coupling, hydraulic oil tank and oil filter.

Coupling: The hydraulic pump drive shaft cannot withstand radial and axial forces, so it is not allowed to directly install pulleys, gears, and sprockets on the shaft end. Usually, a coupling is used to connect the drive shaft and the pump drive shaft.

Hydraulic oil tank: The main function of the hydraulic oil tank in the hydraulic system is to store oil, dissipate heat, separate the air contained in the oil and eliminate foam. The capacity of the oil tank should be considered first. Generally, the maximum flow rate of the pump should be 2 to 3 times for mobile equipment, and 3 to 4 times for fixed equipment. Secondly, the oil level of the oil tank should be considered. When all the hydraulic cylinders of the system are extended, the oil level of the oil tank should not be low. At the lowest oil level, the oil level should not be higher than the highest oil level when the oil cylinder is retracted; finally, considering the structure of the oil tank, the diaphragm in the traditional oil tank cannot play the role of depositing dirt, and a vertical diaphragm should be installed along the longitudinal axis of the oil tank.

Oil filter: Generally, pollutants with a particle size below 10 μm have little effect on the pump, while those larger than 10 μm , especially above 40 μm, have a significant impact on the service life of the pump. The solid pollution particles in the hydraulic oil can easily aggravate the surface wear of the relatively moving parts in the pump. Therefore, it is necessary to install an oil filter to reduce the pollution degree of the oil. Filtration precision requirements: axial piston pump 10 ~ 15μm, vane pump 25μm, gear pump 40μm. The pollution and wear of the pump can be controlled within the allowable range. At present, high-precision oil filters are widely used, which can greatly extend the service life of hydraulic pumps.

3. How hydraulic pumps work?

A hydraulic pump is a hydraulic component that provides pressurized liquid for hydraulic transmission, and is a type of pump. Its function is to convert the mechanical energy of the power machine into the pressure energy of the liquid. Its cam is rotated by an electric motor. When the cam pushes the plunger to move upward, the sealing volume formed by the plunger and the cylinder is reduced, and the oil is squeezed out from the sealing volume and discharged to the required place through the one-way valve. When the cam rotates to the descending part of the curve , the spring forces the plunger downward to form a certain degree of vacuum, and the oil in the tank enters the sealing volume under the action of atmospheric pressure. The cam makes the plunger rise and fall continuously, the sealing volume decreases and increases periodically, and the pump continuously absorbs and discharges oil.