The mechanical arrangement of suspension ropes between the car, counterweight, and drive sheave that determines the relationship between car speed and rope speed, and the torque load on the traction machine.
Full Definition
The roping ratio (or reeving ratio) defines how many rope segments support the car. In 1:1 roping, the rope runs directly from the car over the drive sheave to the counterweight — rope speed equals car speed. In 2:1 roping, the rope is dead-ended on the machine room structure and passes under a pulley on the car, over the drive sheave, under a pulley on the counterweight, and back to a dead-end — rope speed is twice the car speed, car speed is half the rope speed, and the machine torque requirement is halved (at the expense of doubled rope travel). 2:1 roping is used for high-capacity or high-travel elevators where the required rope tension would otherwise demand a very large machine. 4:1 roping is used for some very high-capacity hydraulic-like indirect-drive traction systems. The roping ratio also affects the required rope diameter and the minimum number of ropes per EN 81-20 (minimum 2 independent ropes). Rope equalisation devices ensure equal load sharing between ropes in multi-rope arrangements.
