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One way to determine whether or not it is time to replace a hydraulic pump is by calculating how efficient it is. An inefficient hydraulic pump not only makes the whole system under-perform, but it poses potential safety and financial risks. 

Sometimes when hydraulic equipment slows down significantly it may not be necessary to calculate pump efficiency before replacing the pump. However, at other times it can be helpful to understand how efficient a pump is compared to its theoretical efficiency.

What are the different categories of efficiency?

The efficiency of a hydraulic pump can be broken down into three categories: volumetric, mechanical or hydraulic and overall efficiency.

  • Volumetric Efficiency

Volumetric efficiency is often the most common type of efficiency used to assess the condition of a hydraulic pump based on its internal leakage. Volumetric efficiency considers how much hydraulic fluid a pump delivers compared to what it should theoretically be delivering. 

Before calculating it, you need to know what the pump’s theoretical flow is by multiplying the pump’s displacement by its driven speed. 

Theoretical flow = displacement per revolution X driven speed

Once you know theoretical flow, you can calculate the actual flow using a flow meter. Then the hydraulic pump’s volumetric efficiency by dividing the actual flow by the theoretical flow.

Volumetric efficiency = (actual flow ➗ theoretical flow) X 100

  • Mechanical/Hydraulic Efficiency

Mechanical efficiency compares the actual torque required to drive the pump and its theoretical torque. 

Mechanical/hydraulic efficiency = (theoretical torque ➗ actual torque) X 100

If mechanical efficiency is 100% it would mean the hydraulic pump requires no torque to deliver flow at zero pressure. However in reality this is not possible because of mechanical and fluid friction.

  • Overall Efficiency

Overall efficiency is calculated by multiplying the other two efficiencies together. You can use overall efficiency to calculate how much drive power is required for a hydraulic pump at a given flow and pressure. More efficient pumps will obviously require less power for the same flow and pressure output. Less efficient pumps will have greater energy loss in the form of heat.

When to change-out a hydraulic pump?

A hydraulic pump should be replaced if its efficiency is too low. Ignoring or failing to recognise the signs of a failing hydraulic pump is unsafe and may lead to other costly damages. As well as calculating the efficiency of a hydraulic pump, there are several warning signs that may indicate it’s time to change-out your hydraulic pump: 

  • Loud noises coming from the pump
  • Internal leaks
  • External leaks
  • High working temperatures

Need advice? Speak to a hydraulic pump expert today

The hydraulic pump is a key component of every hydraulic system, and that’s why it’s important to ensure your hydraulic pumps are in good working condition. If you need assistance with assessing the health of your hydraulic pumps, or are looking for high quality replacement products, get in touch with our friendly team at Hydraulic Solutions and Sales. We can assist with replacements and repair Australia wide.