Whether it is a hydraulic pump or hydraulic motor, overpressurization will create serious damage to the entire hydraulic system. For a hydraulic pump, the primary duty is to pressurize the fluid in the reservoir and pumping it to other components at the required pressure. Overpressurization means, the hydraulic pressure inside the system exceeds the normal range due to a single component failure or due to the failure of multiple components. This article will focus on some of the key reasons for pump overpressurization and its impact.
At first, we can discuss hydraulic system impacts due to hydraulic pump overpressurization. The key impacts include loss of lubrication, cylinder barrel and valve plate separation, and mechanical damage.
Loss of lubrication means, between every component surface, there will be a cohesive film of lubricant known as hydrodynamic (full film) lubrication, that prevents wear and tear in moving components due to friction. The increased load on lubricating film will reduce the lubrication resulting in damage of components. The load is calculated as the product of pressure and area, and when the pressure spikes up, the load will also increase.
Component separation(i.e; cylinder barrel and valve plate separation) is another impact of overpressurization. When considering the axial piston pump as an example, the cylinder barrel of the pump is hydrostatically loaded against the valve plate. For maintaining the hydrodynamic lubrication between components, hydrostatic forces are required. When the pressure is high, the hydrostatic forces will perform the desired operation effectively. But, the pumps will easily separate the cylinder barrel from the valve plate when the pressure exceeds the designed range.
Mechanical damage is also a serious impact of pump overpressurization. Overpressure will cause hose and seal failure, and damages to other connected components like motors, cylinders, valves, and more. Excess pressure will also cause buckling of smaller metal parts and components, leading to catastrophic system failure.
Next, we can discuss some of the reasons for hydraulic pump overpressurization. This includes fluid hammer (shock wave produced by the sudden stoppage or reduction of a fluid flow), unintentional heat, and faulty pressure regulator.
Hydraulic pump failure due to overpressurization can be prevented to a greater extend with regular inspection and maintenance. The symptoms of pump failure include abnormal noise, increased fluid temperature, and slow operation. If these symptoms are ignored, the result will be complete system failure. It is possible to monitor the pressure at both inlet and outlet of the pump. This will help to prevent issues related to overpressure. It is also possible to set a maximum pressure range with a pressure transducer.