The Remarkable Ability of an Hydraulic Power Unit Tree surgeons, road builders, factory workers and emergency rescue workers - they all have something in common. In addition to making a huge difference to society through the work that they do, they also work with some seriously powerful machinery on a daily basis. How is it that a man can lift such a heavy weight as the trunk of a mature oak tree, pull a car out of a ditch or move a vast amount of soil? Behind any of these operations is the power of hydraulics. Small in size, but vast in its ability, the hydraulic power unit can be fitted to almost any piece of machinery and using the motion of liquid, it can deliver a formidable mechanical force. When it comes down to it, a hydraulic motor is quite a basic arrangement of parts. Made up of just a power unit, a reservoir and a machine, the power comes from the hydraulic power unit pressurizing the fluid. One of the unique features of fluid is that it cannot be compressed. This means that any pressure will result in the fluid moving and it’s this fact that hydraulic power is built upon. Using a design in the hydraulic system that includes a number of valves, the fluid will move forward – it cannot go backwards to ensure the protection of the pump. At the other end of the line, the fluid will move into position. It may fill a piston which will extend as it is filled, and there we have it. A log can be lifted, or earth moved from one area to the back of a waiting truck. The fluid may have been pushed into a propeller which would generate rotational force to make it possible to pull a car out of a ditch. The amount of applications for a hydraulic power unit are practically endless. Once the fluid has finished its task, it will return to the reservoir along another line and wait until it’s needed again. With electric motors, the way to generate more power is to increase the size of them. Hydraulic power doesn’t work like that, it can operate the same job without needing to be huge. Hydraulic power really is one of those discoveries that has made an enormous difference to how we can run society and business.