Elevator Component Glossary

Key terms for elevator traction machines and safety components.

Traction machine: A traction machine raises and lowers the elevator car and counterweight by driving the wire ropes. It consists of a motor, a brake and a sheave around which the ropes are wrapped, and is classified as geared or gearless depending on whether a reduction gearbox is fitted. Capacity and speed ratings are selected to match the car’s rated load and rated speed. Older Korean regulations, certificates and drawings sometimes call the same unit a "winding machine" (권상기).; Related product: Traction Machine (TM)
Gearless: In a gearless machine the motor drives the sheave directly, with no reduction gearbox. Fewer moving parts mean higher drive efficiency, lower noise and vibration and less maintenance, which is why gearless machines are now standard on new installations.; Related product: Traction Machine (TM)
Sheave: A sheave is a grooved pulley that carries the wire ropes, changing their direction or distributing load. The traction sheave, coupled directly to the machine shaft, drives the ropes that move the car; other sheaves take different forms depending on where and why they are fitted.; Related product: Sheave
Overspeed governor: An overspeed governor continuously monitors car speed and trips the safety gear if the car exceeds its rated limit. Mounted at the top of the hoistway, it follows the car through the governor rope, which together with the tension device forms the governor rope circuit.; Related product: Overspeed Governor
Safety gear: A safety gear grips the guide rails and mechanically stops the car when it descends faster than the permitted speed. It is actuated when the overspeed governor detects overspeed and grips the governor rope. Safety gears are a certified safety component in elevator regulations.; Related product: Safety Gear
Buffer: A buffer absorbs the impact if the car or counterweight travels below the lowest landing, protecting passengers and equipment. It is installed in the pit at the bottom of the hoistway; spring or oil-hydraulic types are chosen according to the rated speed.; Related product: Buffer
Interlock: A landing door interlock prevents the car from starting until the landing door is fully closed and locked, and prevents the landing door from opening when the car is not at that floor. An electronic interlock confirms the locked state through electrical contacts and reports it to the controller.; Related product: Electronic Interlock
Tension device: The tension device keeps constant tension on the governor rope so the overspeed governor senses speed accurately and trips reliably. It is installed at the bottom of the hoistway and, with the governor, forms the governor rope circuit.; Related product: Tension Device
Roping: Roping describes how the wire ropes are routed around the traction sheave. In 1:1 roping the rope passes the sheave once; in 2:1 roping additional pulleys wrap it twice. The roping ratio changes the load on the machine and the speed it must deliver.; Related product: Traction Machine (TM)
Rated speed: Rated speed is the maximum speed at which the elevator is designed to run carrying its rated load. It follows from the building’s height and use, and the specifications of the traction machine, governor and other major components are selected against it.; Related product: Overspeed Governor
Rated load: Rated load is the maximum load the elevator is designed to carry in normal operation. It follows from the car’s capacity and use, and machine capacity and safety component ratings are selected against it.; Related product: Safety Gear
Deflector sheave: A deflector sheave redirects the ropes leaving the traction machine towards the car or the counterweight. Unlike the traction sheave it does not drive the ropes; its position and number depend on the layout of the machine room or hoistway head.; Related product: Sheave
Hoistway: The hoistway is the vertical shaft in which the car travels. It contains the machinery and sheaves at the top, the guide rails, and the pit where the buffers sit, giving the car and counterweight a protected path.
Pit: The pit is the space at the bottom of the hoistway, below the lowest landing floor. Car and counterweight buffers are installed there, leaving clearance for the buffers to absorb the impact if the car overtravels the bottom landing.; Related product: Buffer
Counterweight (CWT): The counterweight offsets the mass of the car and part of its load, reducing the force the traction machine must supply. It moves opposite to the car on the ropes, improving drive efficiency and allowing a smaller motor. Specification sheets and drawings often abbreviate it as CWT.; Related product: Traction Machine (TM)
Guide rail: Guide rails keep the car and counterweight travelling vertically without sway inside the hoistway. When the safety gear operates it grips these rails directly to bring the car to a stop.; Related product: Safety Gear
Brake torque: Brake torque is the braking force the machine brake must apply to stop the sheave rotating. It is designed to match the machine capacity so that a car carrying its rated load can be held safely at a standstill.; Related product: Traction Machine (TM)
Duty: Duty states the proportion of time a traction machine can run continuously at rated load. "S5 – 40% ED", for example, means the machine is designed to run at rated load for 40% of a given cycle; it bears directly on motor heating and service life.; Related product: Traction Machine (TM)