The diagram gives a breakdown of how a hydraulic lift works, in particular it analyses the steps involved in raising and lowering a lift carriage.
Overall, there are two main components that allow this machine to work: a switch at ground level, activated by an operator, and a hydraulic fluid stored in the basement that responds to commands from the switch.
Firstly, once the switch has been pressed in order to lift an object, the fluid contained in an underground tank starts to flow toward another tank, filling it. The immission continues and it increases the volume of liquid in the second container. This actually leads to the lift of the object above, at the ground floor, through a press connected with the carriage, whose level has risen thanks to the fluid beneath.
However, once the job is done, the switch has to be reactivated in order to lower the object just lifted. Moreover, this is a crucial stage to reset things as they were at the beginning. During this phase the fluid flows in the opposite way, letting the press down and refilling the first tank.