What is a hydraulic lift?
The car is lifted by one or more hydraulic cylinders.
A hydraulic duct connects cylinder and drive assembly. A pump transfers oil to the hydraulic cylinder which is consequently lifted upwards.
The pump does not run when descending (exception: frequency controlled hydraulic drives). By opening a valve the car moves downwards simply by its own weight. The oil contained in the hydraulic cylinder is transferred back to the oil container.
See also: Direct hydraulic lifts and Indirect hydraulic lifts