Hydraulic Power Unit (HPU) Repairs

Hydraulic Power Unit (HPU) is used in any application that requires heavy and systemic lifting. Anything that requires a powerful and directional force that is used repeatedly is a suitable candidate for HPU.

Hydraulic Power Unit which is also called a hydraulic power pack is a self-contained system that generally has a fluid reservoir, a pump, and a motor. It operates and applies hydraulic pressure to drive motors, cylinders, and other parts of the unit. The hydraulic system uses the confined fluid to transfer energy from one point to another, which can then produce force or linear or rotary motion.


Operation of Hydraulic Power Units

A hydraulics system transfers energy through the fluid. The energy contained in the fluid is used to generate force or directly provide linear or rotary motion. The way hydraulic systems operate can range from fairly simple to extremely complex. Hydraulic power units use multiple stages to move and pressurize the fluid to generate power.

When a hydraulic power unit begins functioning, the process begins when the pump draws the fluid from the tank and transfers it into the accumulator. The pump will continue to move fluid into the actuator until the desired level of pressure is achieved. Once optimal pressure is reached, the fluid will begin to circulate in the system. The unit is designed with a control system to maintain the required pressure and temperature.


Common causes of Hydraulic Power Unit failure

When a hydraulic system fails, it is often indicated by slow or erratic operations, abnormal noises high temperatures, low-pressure levels of the fluid.


Following are the most common causes of hydraulic systems failures:

  1. Air and Water Contamination

Air and water contamination are often the main causes of hydraulic failures. Leaky seals, damaged pumps, and high temperatures are often the causes of both types of contamination.

Air contamination results in aeration and cavitation of the fluid. It is very bad for the unit and can cause severe damage to it over a short time as it wears down the pump and its related components contaminate the hydraulic fluids and overheat the unit.

Water contamination is also a common problem in hydraulic systems, often caused by system leaks or condensation due to temperature changes. Water damages the components over time by oxidation and freeze-damage. A milky appearance of hydraulic fluid is a clear sign of water contamination.


  1. Temperature Problems

Hydraulic systems that run too hot or too cold can have severe problems over time. Some of these challenges include the following.


  1. Fluid Levels and Quality

Fluid quality and quantity can impact the unit’s performance. Low fluid levels and poor filtration causes air contamination and residue build-up. Always use correct type and quantity of hydraulic fluid should be used as specified for the unit.


  1. Human Error

Human error is the cause of many hydraulic system problems. Some of the most common human mistakes include the following.


Hydraulic Power Unit Troubleshooting

The sources of hydraulic system failures can be difficult at times, but an experienced technician can narrow down to locate the problem.


Here are some troubleshooting tips:


Hydraulic Power Unit Repair

Hydraulic power units (HPUs) have many pumps for various functions. Pump failures will lead to unit failure. In most units used in critical applications, there are one or more backup pumps so that a pump failure may not result in unit failure.


Consider the following points while repairing HPUs:


When you have completed all these essential checks and repairs, turn on the system and monitor it for pressure and temperature fluctuations, as well as abnormal sounds.


e2b calibration is an ISO/IEC 17025:2017 accredited laboratory. We are experts in repairing all types of hydraulic systems. We are registered with ANAB. We are also ANSI/NCSL Z540-1-1994 certified. Please contact e2b calibration for preventive and maintenance services for your Hydraulic Power Units.



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