Hydraulic elevators are supported by a piston at the bottom of the elevator that pushes the elevator up as an electric motor forces oil or another hydraulic fluid into the piston. The elevator descends as a valve releases the fluid from the piston. They are used for low-rise applications of 2-8 stories and travel at a maximum speed of 200 feet per minute. The machine room for hydraulic elevators is located at the lowest level adjacent to the elevator shaft.
The main reason hydraulic elevators are popular is because they are more affordable to set-up and still have relatively lower maintenance costs when compared to other elevators.
Hydraulic elevators utilize more energy because they use an electric motor that works against gravity. You should regularly check the hydraulic fluids because a small leak could easily lead to a catastrophic event or become an environmental hazard.