Lesson 1 of 8How lifts work
Parts of a lift.
A lift is a set of systems working together: something to move the car, something to control it and several things to stop it safely. Here is each part, where it sits and what it does.
How a lift is arranged.
The lift in this lesson is a traction lift with a machine room above the shaft, a type found in many office and residential blocks. The car hangs from ropes that run over a grooved wheel turned by an electric motor, and a counterweight balances it. Other designs are covered at the end of the lesson.
Whatever the design, every lift has the same four jobs to do. Each part in this lesson does at least one of them.
| Job | Main parts |
|---|---|
| Move the car | Machine and traction sheave, suspension ropes, counterweight, guide rails |
| Control where it goes | Controller, call stations and car panel, travelling cable, limit switches |
| Keep people away from moving parts | Shaft, landing doors and interlocks, car door, light curtain |
| Stop it safely | Brake, overspeed governor, safety gear, buffers |
Explore the parts.
Each number on the cutaway matches a part in the list. Select a number or a part to see what it does and where it sits.
Machine and traction sheave
The machine is the electric motor and brake that move the lift. The motor turns a grooved wheel called the traction sheave, and friction between the grooves and the ropes moves the car. Many lifts use a gearless machine, with the sheave mounted directly on the motor; older lifts often have a gearbox between the two. The brake holds the car whenever it stops and applies automatically if the power fails.
Controller
The controller is the lift’s brain. It registers calls from the landings and the car, decides where to go next, tells the drive how to run the motor and monitors the safety circuit. Modern controllers use a variable-voltage, variable-frequency (VVVF) drive for smooth starts and stops. On a lift with a machine room the controller sits beside the machine; on a machine room-less lift it is usually in a cabinet at a landing.
Overspeed governor
The overspeed governor watches the car’s speed. It is a pulley driven by its own steel rope, which runs down to a tensioning pulley in the pit and is connected to the car. If the car goes too fast, a switch on the governor stops the machine and, at a set tripping speed, the governor grips its rope. That pulls a linkage on the car that applies the safety gear.
Suspension ropes
Steel wire ropes, or on some newer lifts coated steel belts, carry the car and the counterweight. The Lifts Regulations 2016 require a lift suspended by ropes or chains to have at least two independent ones, each with its own anchorage, and most traction lifts have several. Ropes stretch and wear in service, so their condition is checked at maintenance visits and at every thorough examination.
Car and car frame
The car is the compartment you travel in. It sits in a steel car frame, sometimes called the sling, which carries the guide shoes, the safety gear and the rope fixings. Inside are the car operating panel, lighting, the alarm button and two-way communication equipment that keeps passengers in contact with a rescue service. A plate in the car shows its rated load in kilograms and the maximum number of passengers.
Counterweight
The counterweight is a steel frame filled with weights that travels in the opposite direction to the car. It balances the car and part of its rated load, so the motor only has to move the difference in weight. That saves energy and reduces wear on the machine and ropes. It runs on its own guide rails at the back or side of the shaft.
Guide rails
Steel guide rails, usually T-shaped in section, are fixed to the shaft walls and keep the car and counterweight on a precise vertical path. Guide shoes or rollers on the car frame run along them. The rails also give the safety gear something to grip in an emergency, so they must be straight, secure and properly aligned.
Safety gear
The safety gear is a set of wedges or rollers on the car frame, beside the guide rails. When the governor trips, the safety gear is pulled into contact with the rails and brings the car to a controlled stop. It works independently of the ropes, so it can stop the car even if they were to fail.
Landing doors and interlocks
Each floor has a landing door that closes off the shaft. Every landing door has an interlock: a mechanical lock with an electrical contact. The lift cannot start unless all the landing doors are shut and locked, and a landing door cannot be opened while the car is moving outside the zone around that floor. A special release key opens a landing door from outside, and it must only be used by trained, authorised people.
Door operator and car door
The door operator is a motor unit on the car that opens and closes the car door. When the car stops at a floor, the car door couples to the landing door so the two move together. A light curtain, a row of infrared beams across the opening, makes the doors reopen if something is in the way.
Buffers
Buffers sit in the pit under the car and under the counterweight. They are the last line of defence if either travels below its lowest normal position. Slower lifts typically use spring buffers, which store the energy; faster lifts use oil buffers, which absorb it.
Pit
The pit is the part of the shaft below the lowest floor. It holds the buffers, the governor tension pulley, a stop switch and usually a ladder for engineers. When the car is at its lowest point there must still be a refuge space in the pit to protect an engineer. Pits should be clean and dry: water in a pit is a fault to report.
Travelling cable
The travelling cable hangs in a loop from a junction box on the shaft wall to the underside of the car. It carries power to the car and the signals between the car and the controller: button presses, door signals, lighting and the alarm line. The loop moves with the car as it travels.
Call stations and car panel
The buttons beside each landing door are the landing call stations. Pressing one registers a call with the controller. Inside the car, the car operating panel has the floor buttons, the door buttons and the alarm button, which connects passengers to a rescue service through the lift’s two-way communication system.
Shaft and headroom
The shaft, also called the hoistway or well, is the enclosed space the car and counterweight travel in. The headroom is the space above the top floor, which must leave a refuge above the car when it is at its highest point. The size of the shaft, pit and headroom limits which lifts can be installed, which matters when planning a modernisation.
Limit switches
Switches near the top and bottom of the shaft are operated by a cam on the car. Normal terminal switches slow and stop the car at the end floors. If the car ever travels beyond them, a final limit switch opens the safety circuit, which cuts power to the machine and applies the brake.
Engineer’s note
Our engineers treat doors as the busiest and most fault-prone part of a lift. A proper maintenance visit checks, cleans and adjusts the door operators, tracks, safety edges and interlocks. See what a maintenance visit includes.
What moves the lift.
On a traction lift, the machine turns the traction sheave. The ropes sit in grooves around the sheave, and friction between the two moves the ropes, raising the car on one side as the counterweight descends on the other.
The counterweight is what makes traction lifts efficient. Because it balances the car and part of its load, the motor only has to move the difference in weight, not the whole car.
On some lifts the ropes pass around pulleys on the car and counterweight, so the car moves at half the speed of the ropes. This is called 2:1 roping, and it is explained in how a traction lift works.
What controls it.
The controller takes calls from the landing buttons and the car panel, decides the order to serve them in and tells the drive how to run the motor. Signals reach the car through the travelling cable.
Running through the whole lift is the safety circuit: a chain of safety switches wired one after another. It includes the contact on every landing door, the car door contact, the final limit switches, the governor switch and the stop switches in the pit and on the car roof. If any switch opens, the circuit is broken and the lift stops.
That is why one landing door that has not fully closed can take a lift out of service, and why engineers often start fault-finding by tracing the safety circuit. Our guide to lift faults describes common symptoms and what engineers check.
What keeps it safe.
Several parts exist only to stop the lift safely when something goes wrong. The brake holds the car whenever it stops. If the car overspeeds, the governor trips the safety gear, which grips the guide rails. If the car or counterweight travels too far down, the buffers absorb the impact. And interlocks stop the lift moving unless every landing door is shut and locked.
The law
The Lifts Regulations 2016 treat the most important of these as safety components. Schedule 3 lists devices for locking landing doors, devices that prevent the car falling or moving uncontrolled, overspeed limitation devices, buffers, safety devices on hydraulic jacks and electrical safety devices in the form of safety circuits.
At a thorough examination, a competent person examines these and the other safety-critical parts. HSE’s guidance lists items such as the landing and car doors and their interlocks, the main drive, governors, safety gear, suspension ropes, braking systems including buffers and overspeed devices, and electrical devices. Our guide to LOLER explains when examinations are due.
Safety first
Never open lift doors with a release key, enter a lift shaft or pit, or try to free trapped passengers unless you are trained and authorised to do so. If someone is trapped, use the alarm or call your maintenance provider. If anyone is in danger, call 999.
Other designs.
Machine room-less lifts
A machine room-less (MRL) lift is a traction lift with a compact machine inside the shaft, usually at the top, and the controller in a cabinet at a landing. The parts are the same as in the cutaway, arranged to fit without a machine room. Read more in machine room-less lifts.
Hydraulic lifts
A hydraulic lift is moved by a ram, or jack, driven by oil under pressure from a pump unit. Some rams push the car directly; others use ropes and a pulley on the ram. The car lowers under its own weight as the oil returns to the tank, so there is usually no counterweight. Hydraulic lifts suit low-rise buildings, and our hydraulic lifts page compares them with traction lifts.
Whatever the design, the principles in this lesson apply: something moves the car, something controls it and several independent systems stop it safely. See how we support passenger lifts.
Check your understanding.
Three quick questions on this lesson. Choose an answer to check it, or open the answer below each question.
-
What stops a car that is travelling too fast?
Show the answer
B. The overspeed governor and the safety gear. The governor detects the overspeed and trips the safety gear, which grips the guide rails. Buffers are the last line of defence at the bottom of the shaft, not a speed control.
-
Why does a traction lift have a counterweight?
Show the answer
B. To balance the car, so the motor only moves the difference in weight. The counterweight balances the car and part of its rated load. Stopping the car in an emergency is the job of the safety gear, which works independently of the ropes.
-
What must happen before the car can start moving?
Show the answer
A. Every landing door must be shut and locked. Each landing door has an interlock. The lift cannot start unless all the landing doors are shut and locked.
Sources.
The primary sources for this lesson. We checked them when the lesson was last updated on 18 October 2026. How we research and check our lessons.
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Related reading
Questions about a lift you look after?
Talk to an engineer about what your lift has, how it is maintained and what it needs next.
Common questions.
Quick answers to common questions about this topic.
What are the main parts of a lift?
The main parts of a traction lift are the machine and traction sheave, the controller, the suspension ropes, the car and car frame, the counterweight, the guide rails, the doors and interlocks, and the safety systems: the overspeed governor, the safety gear and the buffers.
What is the difference between the lift car and the lift shaft?
The car is the compartment that carries people or goods. The shaft is the enclosed vertical space it travels in, with the pit below the lowest floor and the headroom above the top floor.
Which parts of a lift are safety components?
The Lifts Regulations 2016 list safety components in Schedule 3. They include devices for locking landing doors, devices that stop the car falling or moving uncontrolled, overspeed limitation devices, buffers, safety devices on hydraulic jacks and electrical safety devices in the form of safety circuits.
Do all lifts have a machine room?
No. Many traction lifts are machine room-less, with the machine inside the shaft and the controller in a cabinet at a landing. Hydraulic lifts have a pump unit instead, usually in a small room or cabinet near the shaft.