Five types of hydraulic system

Hydraulic systems are based on the use of fluids/liquids to transfer energy from a motor to an actuator.

There are five common types of hydraulic systems: pumps, motors/cylinders, aviation, open-centre, and closed-loop ┬áLet’s take a look at these in more detail:
1. Hydraulic pumps

Hydraulic pumps are used to convert mechanical power into hydraulic energy. These can be either hydrostatic (where the fluid is ‘at rest’) or hydrodynamic (where the fluid is ‘in motion’). These pumps can be driven by a variety of power sources. There are three main types: gear pumps and fixed/variable-displacement piston pumps.

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2. Hydraulic motors and cylinders

Hydraulic motors are actuators that convert hydraulic pressure/flow into torque and rotation. There are several types, including radial piston, gear, and vane. Hydraulic cylinders, on the other hand, are used to push force in a single (linear) direction. This force can be reversed.

Hydraulic power units

A hydraulic power unit is the ‘driving’ component of any hydraulic system. If you feel that a hydraulic power unit could be useful for your application, there are a number of firms that specialise in these. Contact a specialist such as to find out more.

3. Aviation hydraulic systems

This type of system draws fluid from a source, which is usually referred to as the reservoir, and then applies pressure to pass to the other components. When finished, it returns the fluid. The main components of this system are the pump, the reservoir, the actuating cylinder, the pressure-relief valve, and the heat exchanger.

4. Open-centre hydraulic systems

Open-centre hydraulic systems use fluid, but there is no pressure. The fluid moves from the actuator to the reservoir, enabling new fluid to flow to the pump inlet. Open-centre systems use a directional control valve, which means they generate less heat.

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5. Closed-loop hydraulic systems

In closed-loop systems, the fluid flows continuously between the pump and the actuator. This means it doesn’t enter the reservoir. An additional pump known as a feed pump is used instead of a directional control valve. These systems can provide a precise response in terms of actuation.

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