Hydraulic systems come in all shapes and sizes. Some are designed to work within machinery and others like a Hydraulic Power Unit that you can find from https://www.hydraproducts.co.uk/Hydraulic-Power-Units/Standard-Power-Units help to power other pieces of equipment. They all have one thing in common. They use water and fluid to build up pressure in the system to then allow the hydraulics to work.
Hydraulics are incredibly strong and a small machine can lift tonnes of weight that would seem almost impossible, all thanks to the pressure that is built up in the system. There are some common features of all hydraulics and some very interesting facts about these pieces of equipment and here are just a few of them for you to have a look through.