Unfortunately, hydraulics isn’t a topic that most people are knowledgeable on. So, to try and increase the level of awareness and knowledge surrounding this niche topic, we’ve put together 14 little-known facts about hydraulics and hydraulic equipment. 


  1. Hydraulic power is nearly always generated from mechanical power. Example: A hydraulic pump driven by an engine crankshaft.
  1. Hydraulic power output is nearly always achieved by converting back to mechanical energy. Example: A cylinder, which raises a heavy object.
  1. There are three types of hydraulic energy: potential or pressure energy, kinetic energy (the energy of moving liquids) and heat energy (the energy of resistance to flow, or friction).
  2. Hydraulic energy is “neither” created nor destroyed; only converted to another form.
  3. All energy put into a hydraulic system must come out either as work (gain) or as heat (loss).
  4. When a moving liquid is restricted, heat is created and there is a loss of potential energy (pressure) for doing work. Example: A tube or hose that is too small or is restricted. Orifices and relief valves are also restriction but are purposely designed into the system.
  5. Flow through an orifice or restriction causes a pressure
  6. Oil must be confined to create pressure for work. A tightly sealed system is a must in hydraulics.
  7. Oil takes the course of least resistance.
  8. Oil is normally pushed into a pump, not drawn into it. (Atmospheric pressure supplies this push). For this reason, an air vent is needed in the top of the reservoir.
  9. A pump does not pump pressure; it creates flow. Pressure is caused by resistance to flow.
  10. Two hydraulic systems may produce the same power output, one at high pressure and low flow, and the other at low pressure and high flow.
  11. A basic system must include four components: a reservoir to store the oil; a pump to push the oil through the system; valves to control pressure and flow, and a cylinder (or motor) to convert the movement into work.
  12. Compare the two major hydraulic systems: the open centre systems where the pressure is varied but the flow is constant and closed centre systems where the flow is varied but the pressure is constant.

Want to learn more? Contact the team at Gerrard Hydraulics today!