The HPU or the Hydraulic Power Unit will provide pressurized oil to the present hydraulic actuation system. There is a redundant pump system, which charges bladder accumulator in an automatic manner and at high pressure for utilizing ability of actuators for storing energy. A pressurized reducing valve provides system with consistent stable system pressure. For ensuring oil cleanliness, the supervised filters are used on pump and return side. Filtration then takes place whenever pumps are running. So, the HPU comes with analogue transmitter for the temperature, oil tank level and pressure.

The main features of HPU:

It is better understand some of the major features revolving around HPU for a better understanding in here. Let’s get straight to the points:

Features Characteristics
Redundant hydraulic pumps
  • Electrically driven high pressurized gear pumps, under one standby and one operation.
  • Each pump is connected to supervise the pressure filter. Changing the filter elements can be done while full operation is in place.
Constant form of output pressure
  • Logical element together with pilot pressure reducing the valve controlling outlet pressure.
  • Output pressure is monitored through pressure transmitter.
  • Pressure relief valve installed for limiting the output system pressure
Accumulator system
  • HPU is equipped with around 1 to 3 accumulators each coming to a volume of 20 to 50 liters.
  • By using proportional valve to create smooth transition between idling modes and charging modes, pressure peaks are reduced.
  • Accumulator pressure can be monitored through pressure transmission and regulated by IPC.
  • Sealed pressure relief valve will limit maximum accumulator pressure.
Return filter along with the oil filling or draining
  • Supervised low pressurized oil filter is properly mounted on top of tank.
  • It helps in filtering oil from idling valve or return oil from system.


The best hydraulic pump for HPU design:

The best type of Hydraulic Pump you plan to choose for the power unit will affect the nature of the said HPU build. The pump type will be depending on the complexity, cost and performance. There are mainly three pump types available and those are vane pump, gear pump and piston pump. There are some other less known pumps available too.

  • The most economical choice is gear pump but on lower end of efficiency range. They are mainly reliable and also durable. However, the efficiency will drop with time. Always remember that the job of the pump is mainly to convert present mechanical energy into hydraulic one. The more efficiently it is able to do so; it will help you to save money over time. The traditional gear based pumps are known for average 80% efficiency, which means 10 input horsepower will bet around 8 hydraulic horsepower.
  • One premium example of hydraulic pump for the HPU design will have to be piston pumps. They are well capable of high pressure with infinite methods of control. Those are load sensing, servo control, pressure compensation and horsepower control. They are rather efficient and some designs have 95% efficiency, which will help you to get the most from prime mover. The downside is cost for service and repair, and even for the initial investment.
  • Another prime example of hydraulic pump type to consider is vane pump. These pumps mainly reside in middle ground between piston and gear pumps. They are quite efficient when compared to the gear ones but less than piston pumps. The vane ones are quiet. So, the industrial applications are looking for these pumps too. Furthermore, vane pumps are widely available in various control options. Some of those are load sensing, pressure compensation and even displacement control. These pumps might not be able to handle high pressure circuits.

The best choice is hard:

Each type of hydraulic pump has its share of pros and cons. So, making one choice is pretty tough in here. For example, in piston pumps, you will enjoy high pressure, efficient and several control options. But as a downside, piston pumps come with higher investment. Similarly, vane pumps are quite with multiple controlling options but only capable of lower pressure applications. Therefore, it is really important that you get to choose the perfect hydraulic pump depending on your requirements. The more you research, the higher you will come to know about it.