Glossary
Traction Elevator
An elevator system that uses steel wire ropes or belts passing over a grooved sheave to raise and lower the car, relying on friction (traction) between the ropes and sheave to transmit motion.
Traction elevators are the most common type installed in mid-rise and high-rise buildings worldwide. The system works by suspending the car from one end of a set of wire ropes that pass over a drive sheave mounted on an electric motor. A counterweight hangs from the other end of the ropes, balancing the car's weight plus approximately 40–50 percent of the rated load capacity.
Traction systems come in three main variants. Geared traction uses a worm gear to reduce motor speed and increase torque, suitable for speeds up to about 2.5 m/s. Gearless traction mounts the sheave directly on a low-speed, high-torque motor, supporting speeds of 2.5–10+ m/s. Machine-room-less (MRL) configurations use a compact gearless motor installed inside the hoistway, eliminating the need for a dedicated machine room overhead.
The counterweight is fundamental to the traction elevator's energy efficiency. When the system is balanced — meaning the car load equals the counterweight offset — the motor does almost no work. Modern VVVF (variable-voltage, variable-frequency) drives further optimise energy consumption and provide precise speed and position control, enabling levelling accuracy within ±3 mm.