The grooved wheel on the traction machine shaft that grips suspension ropes through friction to raise and lower the elevator car.
Full Definition
The drive sheave (traction sheave) is mounted directly on the motor shaft or gearbox output shaft of the traction machine. Its grooves — typically undercut or semicircular — contact the suspension ropes and rely on the capstan effect to transmit motion. Groove geometry determines traction capacity; undercut grooves provide higher friction but cause faster rope wear. The traction check (EN 81-20 §5.5) ensures the system cannot lift the car when counterweight rests on its buffer, and cannot lower the car when the car rests on its buffer.
