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

What Are the Reasons for Power Loss in Hydram Pumps?

Hydram pump is a hydraulic component that provides pressurized liquid for hydraulic transmission and is a type of pump. There are two types of power losses when the hydram pump works, one is the volumetric loss and the other is the mechanical loss.


The reason for the mechanical loss caused by the hydram pump 


  • During operation, there is mechanical friction between the various relatively moving parts, such as between the bearings and the shaft, between the shaft and the sealing components, and between the blades and the inner wall of the pump body, resulting in frictional resistance loss. This loss is related to the output pressure of the hydram pump. The higher the output pressure, the greater the friction resistance loss.

  • When the oil flows in the pump, the viscous resistance caused by the viscosity of the liquid will also cause mechanical loss. This loss is related to the viscosity of the oil and the speed of the hydram pump. The higher the viscosity of the oil and the speed of the pump, the greater the mechanical loss.


Due to the above reasons, the actual input power of the hydram pump is greater than the theoretically required power. The ratio of the theoretical input power to the actual input power of the hydram pump is called mechanical efficiency, which indicates the degree of power loss. The ratio of output power to input power of the hydram pump is called total efficiency.


The reasons for the volumetric loss caused by the hydram pump


  • Although the suction and discharge chambers of a volumetric hydram pump are separated in the pump, there is always a certain gap between the relative movements. Therefore, the oil in the high-pressure area of the pump must inevitably leak into the low-pressure area through the gap. The lower the viscosity of the hydraulic oil and the higher the pressure, the greater the leakage.

  • During the suction process of the hydram pump, the phenomenon of pumping air will occur due to factors such as excessive suction resistance of the oil, too viscous oil or too high speed of the pump shaft. As a result, the working volume of the sealed cavity cannot be fully filled with oil, which means that the working chamber of the hydram pump is not fully utilized.


Due to the above reasons, the hydram pump has volumetric loss. However, as long as the pump is designed correctly and used reasonably, the second reason for loss can be overcome, that is, the volumetric loss of the pump can be reduced.


However, the volumetric loss caused by leakage when the hydram pump works is inevitable. In other words, the volumetric loss of the hydram pump can be approximately regarded as being entirely caused by leakage, which makes the actual flow rate of the hydram pump smaller than the theoretical flow rate. The ratio of actual flow rate to theoretical flow rate is called volumetric efficiency, which indicates the degree of volumetric loss of the hydram pump.