Glossary
Hydraulic Elevator
An elevator system that uses a hydraulic jack — a cylinder and piston driven by pressurised oil — to raise the car, with gravity providing the force for descent.
Hydraulic elevators are the standard choice for low-rise buildings of two to six storeys where speed requirements are modest and upfront cost is a priority. Instead of ropes and a counterweight, the system uses a hydraulic power unit (motor, pump, reservoir, and control valve) to pressurise oil and push it into a cylinder, extending a piston that lifts the car platform.
Two main configurations exist. Direct-acting (in-ground) hydraulic elevators sink the cylinder into a borehole beneath the pit, allowing the piston to push the car from below. Holeless configurations mount the jack above ground beside or behind the car and use a roping arrangement to multiply the piston stroke. The holeless design avoids the environmental risk of underground oil leaks that can occur with in-ground jacks.
Hydraulic elevators do not use counterweights, so the motor must lift the full weight of the car and passengers on every up trip. Descent is gravity-driven, with oil flowing back to the reservoir through a metering valve that controls speed. This makes hydraulic systems less energy-efficient than traction systems, but their mechanical simplicity, lower purchase price, and flexible machine room placement continue to make them practical for many low-rise applications.