One of the more common mechanisms for a residential elevator used is a hydraulic lift. Hydraulic Elevators utilize an oil pump located in a machine room to provide the lifting power. The machine room is preferred to be adjacent to the hoistway, but can be up to 30 ft away. The machine room may be on any level or the house. In flood areas, it is recommended that the machine room is on an upper level. A hydraulic piston is located in the hoistway between the rails, next to the moving car. As hydraulic fluid is pumped into the piston, the car moves upward. As hydraulic fluid is released back to the reservoir in the machine room, the car moves downward.
The benefits include smooth operation, quiet operation, and easy emergency lowering. The hydraulic elevator is nearly silent in the down direction as the pump is not running. In the up direction, the pump is running in a separate machine room, reducing the noise. If the elevator stopped between levels for any reason, it is easy to manually lower it. Every hydraulic elevator has an emergency lowering valve. By pressing and holding a button (in the machine room), the elevator will slowly lower to floor level.
The negative points include hydraulic odor, and cost. If the machine room is located next to common living space such as a kitchen or living room, you may smell the oil from time to time. This can be avoided by placing the machine room in a utility area, or using vegetable based oil. A two or three level hydraulic elevator is not much more cost than other types. As the vertical travel distance increases, the cost of a hydraulic elevator increases more than other types. If the vertical travel exceeds 32 ft, then a split piston is required, which adds significant cost.