How do hydraulic pumps work?

When it comes to your Earthmoving and Construction machinery, your hydraulic pump system plays a crucial role in its effective operation. To understand your entire machine, it is important to build a solid understanding of how your hydraulics work. Having a solid foundation of knowledge about parts of your machine, such as the hydraulics, the undercarriage or the fuel injector system, will enable you to diagnose problems quickly and keep your machine running efficiently. As specialists in replacement parts for heavy-duty engines like Komatsu, Cummins, Volvo or Caterpillar, we frequently deal with hydraulics here at Jaytrac. We have compiled a quick guide to give you a better understanding of how the hydraulics of your machine function.

Conversion of energy

The hydraulic pump system in your heavy-duty machine works by generating power through pressurised liquid. As a result, mechanical energy is converted into hydraulic energy, generating a large power output and hence increasing the efficiency of machine systems. Pressurised hydraulic fluid can then be delivered to any part of your machinery where hydraulic power is required.  


There are three main types of a hydraulic pump on plant and machinery, Gear, Axial Piston or Vane. When hydraulic fluid first enters the system at low pressure, the rotation of the pump draws the fluid through the pump. The movement of the gears, pistons or vanes creates pressure, causing the fluid to flow out the other side under high pressure. This pressurised fluid is transferred through valve blocks and relief valves to the hydraulic cylinder or motor.

Delivering fluid

As liquid cannot be compressed, the delivery of fluid is a constant process. If your heavy-duty machine is not calling for hydraulic power, the relief valve will open and return the fluid to the tank. At this stage, it is important to ensure that there are no leaks in the hydraulic system. This is a crucial safety consideration, as it can be dangerous if fluid escapes at high pressure.

Effective performance

When operating your hydraulic system within the heavy-duty machine, it is important to ensure that there is the correct amount of oil in your hydraulic system, and it is vital that your filters and oil are changed regularly.  If your hydraulics are sluggish or lacking power, this can be a sign of a worn pump that may need replacing. Consult a trained technician who can run diagnostic checks on the system.

Here at Jaytrac, we stock a range of quality hydraulic replacement parts for Caterpillar, Komatsu and Volvo machines. Since 1995, we have been committed to reducing your parts spend and operating cost. Alongside this, we boast over 100 years of combined staff experience of the industry, including repairing and rebuilding earth-moving machines and engines. To discuss your needs, get in touch on 01604 49133, email or send us an enquiry today. We look forward to hearing from you!