The grooved wheel on the elevator traction machine shaft over which the suspension ropes run, transmitting motor torque to move the car and counterweight by friction traction.
Full Definition
The drive sheave (also called the traction sheave or drive pulley) is the central component of the traction system. Its circumferential grooves hold the suspension ropes in contact under the differential weight between the loaded car and counterweight. The traction force is generated by friction between the rope and groove: groove profile (V-groove, U-groove, or undercut groove) and groove geometry determine the traction coefficient. Undercut grooves provide higher traction but accelerate rope wear. As ropes wear and groove surfaces change, traction must be checked periodically using the slipping test (EN 81-20 §9.3). Sheave diameter governs rope fatigue life — EN 81-20 sets a minimum sheave-to-rope diameter ratio (D/d ≥ 40 for most installations). Grooves must be inspected for wear, recut, or the sheave replaced when groove depth variation exceeds the rope diameter tolerance.
