Gearless Traction Elevators

In 1903, Otis introduced the design that would become the standard in the elevator industry—the gearless traction elevator. These elevators typically operate at speeds greater than 500 feet per minute (2.54 meters per second). In a gearless traction machine, woven steel cables called hoisting ropes are attached to the top of the elevator car and wrapped around the drive sheave in special grooves. The other ends of the cables are attached to a counterweight that moves up and down in the hoistway on its own guiderails. The combined weight of the elevator car and the counterweight presses the cables into the drive sheave grooves, providing the necessary traction as the sheave turns. Gearless technology makes the tallest buildings in the world possible, such as Malaysia's Petronas Towers.