Commonly used hydram pumps in hydraulic systems include gear pumps, vane pumps, and piston pumps. Although the structures of different types of hydram pumps are very different, there are many commonalities in installation, use, and maintenance. If not operated properly, it may cause faults.
The function of a hydram pump is to convert mechanical energy of a power unit (such as an electric motor or an internal combustion engine) into hydraulic pressure. A variable pump whose output flow can be adjusted according to needs is called a variable pump, and a pump whose flow cannot be adjusted is called a fixed-displacement pump. Although the structures of hydram pumps are highly variable, there are many commonalities in installation and use. So what should be noted when connecting the hydram pump?
Hydram pumps can be installed with brackets or flanges. The pump and the power unit should use the same basic bracket, and both the flange and the foundation should have sufficient rigidity. Pay special attention that the piston pump with a flow rate greater than or equal to 160 L/min should not be installed on the fuel tank.
An elastic coupling should be used to connect the hydram pump and the output shaft of the power unit. It is strictly forbidden to install a pulley or gear on the hydram pump shaft, if it is necessary to use a pulley or gear to connect with the pump, a pair of brackets should be added to install the pulley or gear, and the coaxiality error between the support and the pump shaft should not be greater than φ0.05mm.
The suction hose should be as short, straight, large, and thick as possible. The suction pipeline generally needs to be equipped with a coarse filter with a nominal flow rate not less than twice the pump flow rate (the filter accuracy is generally between 80 and 180μm). The pump's oil return pipe should be directly connected to the fuel tank, and the back pressure of the oil return should not exceed 0.05MPa. The suction port and the oil return port of the oil pump should both be at least 200mm below the lowest oil level of the fuel tank. It is especially noteworthy that a filter cannot be installed on the suction pipeline of the piston pump, and the valve diameter of the cutoff valve on the suction pipeline should be one gauge larger than that of the suction pipeline.
The inlet and outlet ports of the hydram pump should be installed firmly, and the sealing device should be reliable, otherwise, it will cause air suction or oil leakage, affecting the performance of the hydram pump.
The self-suction height of the hydram pump does not exceed 500mm (or the inlet vacuum does not exceed 0.03MPa). If a replenishing pump is used for oil supply, the oil supply pressure should not exceed 0.5MPa. When the oil supply pressure exceeds 0.5MPa, pressure-resistant sealing rings should be used. For piston pumps, inverted self-suction should be used as much as possible.
Before installing the hydram pump, check whether the depth of the installation hole is larger than the shaft extension length of the pump to prevent the top shaft phenomenon, otherwise, the pump will burn out.