Hydraulic lifts depend on the presence piston down the elevator cabin and underneath there is a special oil works by raising and lowering the elevator
And the rise in oil and thus higher cabin through the oil pump is operated by an electric motor is controlled (usually three phase induction motor)
It is typically used elevator hydraulic speed until 13:00 in the second (low speed to the speed of the elevator ropes, which drain get used to it)
To achieve economic interest shall not exceed the height of the elevator about 25 meters away (too high too small for the elevator ropes drain that connects to the role of 20 or more)