🏗️Elevator Systems · 5 min read

Types of Elevators

Traction, hydraulic, and MRL — what makes each different

The EIAT tests whether you understand the three main elevator system types used in commercial and residential buildings. Knowing how each one works — and its limitations — is essential for answering questions about components, maintenance, and application.

Traction Elevators

The most common type in mid- and high-rise buildings. An electric motor drives a sheave (grooved wheel) at the top of the hoistway. Steel wire ropes run over the sheave, connecting the car on one side to a counterweight on the other.

The counterweight dramatically reduces the load the motor must move. At half-rated load, the system is nearly balanced — the motor only needs to overcome friction and the small weight difference.

Two subtypes exist. Geared traction: a worm gear reduction sits between the motor and the drive sheave, giving a large speed reduction (slower elevators, up to ~350 FPM). Gearless traction: the motor drives the sheave directly — used in high-rise buildings, much faster (up to 2,000+ FPM), quieter, and more efficient.

Hydraulic Elevators

A fluid-filled cylinder (the jack or plunger) pushes the car up. A motor-driven pump forces hydraulic oil into the cylinder to rise; releasing a valve lets oil drain back to the tank so gravity lowers the car.

There is no counterweight. The motor must overcome the full weight of the car plus passengers every time it runs, making hydraulic elevators less energy-efficient than traction.

Hydraulic elevators are limited to roughly 6 stories (about 50 feet of travel) and top out at 100–200 FPM. They need a machine room at or below the lowest landing to house the pump unit.

Subtypes: in-ground (jack buried below the pit — most common), holeless (jack sits alongside the car in the hoistway — no drilling needed), and roped hydraulic (2:1 rope from the jack doubles travel distance).

Machine Room-Less (MRL) Elevators

An MRL is still a traction elevator — it uses the same ropes, sheave, and counterweight principle. The difference is that the compact drive unit is mounted inside the hoistway (typically at the top) instead of in a dedicated machine room.

MRL designs have grown popular for mid-rise buildings because they eliminate the cost of building and heating a machine room. The control panel lives in a hallway cabinet at the top floor.

Drum Elevators (Historical)

An older design where the hoist rope is wound onto a rotating drum. There is no counterweight — the drum stores rope as the car descends and unwinds it as the car rises. Travel is limited by how much rope fits on the drum.

Drum elevators are rarely installed today but appear on aptitude tests for comparison. Key disadvantage: no counterweight means far higher motor energy demand.

Key Takeaways

✓Geared traction = worm gear between motor and sheave. This will appear on the test.
✓Hydraulic elevators cannot exceed ~6 floors and have no counterweight.
✓MRL elevators are still traction elevators — just no separate machine room.
✓Gearless traction is used in high-rise buildings (faster, more efficient).
✓Hydraulic cars rise on pump pressure; they lower on gravity (oil drains back).

Key Terms

Sheave

A grooved wheel/pulley over which hoist ropes run. The drive sheave is powered by the motor.

Hoist ropes

Steel wire ropes connecting the car and counterweight over the drive sheave.

Machine room

Dedicated room (typically above the hoistway) housing the motor, controller, and brake.

Hoistway

The vertical shaft in which the elevator car and counterweight travel.

FPM

Feet per minute — the standard unit for elevator travel speed.

Plunger / Jack

The hydraulic cylinder-and-piston assembly that supports the car in a hydraulic elevator.

MRL

Machine Room-Less — a traction elevator with the drive unit mounted inside the hoistway.

Ready to test what you just read?

Head back to your study workspace to take a timed practice quiz.

Practice Quizzes →

← NEIEP / IUEC Elevator Apprentice Oral Interview & Tool Test Guide Elevator Components →