Lesson 8 of 8How lifts work
What happens when you call a lift.
Pressing a call button starts a chain of checks and commands that takes a few seconds. Here is what happens at each step, from the button to the doors opening at your floor.
The journey, step by step.
A lift journey looks simple from the landing: you press a button, the doors open and you travel. Behind the scenes, the controller, the drive, the doors and the safety circuit work through the same sequence every time. Step through it below. The building has four floors, and you are waiting on floor 2 while the car is parked at the ground floor.
You press the call button
The button at the landing sends a landing call to the controller, and its light shows that the call has been registered. Pressing it again does not bring the lift any sooner: the call is already on the controller’s list.
The controller chooses a car
A single lift answers calls in the order it reaches them in its direction of travel. Where several lifts serve the same floors, group control gives each landing call to the car best placed to answer it, based on where each car is, which way it is going and the calls it already has.
The doors are proved shut and locked
Before the car can move, every landing door must be closed and locked and the car door must be closed. Each lock and door has a contact in the safety circuit. Only when the whole circuit is complete can the controller start the journey.
The drive starts the motor
The drive powers the motor, the brake lifts and the car accelerates smoothly. On a traction lift, the counterweight comes down as the car goes up. The controller watches the safety circuit for the whole journey: if any switch opens, the motor stops and the brake applies.
The car slows and stops level
Sensors on the car read markers in the shaft, so the controller always knows where the car is. As the car nears the floor with the call, the drive slows it down and stops it level with the landing.
The doors open
The door operator opens the car door. A coupler on the car door unlocks the landing door and takes it along, so the two open together. A light curtain watches the opening and reopens the doors if anything breaks its beams while they are closing.
You choose your floor
Inside the car, you press the button for your floor on the car operating panel, registering a car call. After a short pause the doors close, the safety circuit is proved again and the journey repeats.
How the lift decides where to go.
Most lifts use collective control. The car keeps travelling in one direction, stopping for every call in that direction, until there are no more calls ahead. Then it turns round and answers the calls the other way. That is why a lift on its way down will pass you if you are waiting to go up, and come back for you afterwards.
Landings between the top and bottom floors usually have an up button and a down button, so the controller knows which direction you want. Pressing both does not help: the lift stops for each call and then carries on in its own direction.
Several lifts together
Where two or more lifts serve the same floors, a group controller shares the landing calls between them. It looks at each car’s position, direction and existing calls, and sends the car that can answer soonest. Some buildings use destination control instead: you enter your floor on a keypad or screen at the landing, and the system tells you which lift to take, grouping people who are going to nearby floors.
The way calls are shared, and how long the doors stay open, are settings in the controller. They can often be adjusted to suit how a building is used, and our lesson on lift controllers and drives explains more about what the controller does.
Why a lift sometimes seems slow.
When a lift takes a long time to arrive, there is usually a reason in the sequence above:
- It is answering calls in the other direction first, as collective control intends.
- Its doors are being held open at another floor, or keep reopening because something is breaking the light curtain.
- It is nearly full. Many lifts use a load sensor to pass landing calls by when there is no room for more passengers.
- It has been switched to a special mode, such as independent service for moving furniture, or fire service operation.
- It is out of service. If one landing door does not close and lock properly, the safety circuit stays open and the lift cannot move at all.
If the car is overloaded, the lift does not start. On a lift built to BS EN 81-20, the overload device must act by the time the load is 10 per cent over the rated load, or 75 kg over if that is more. A sound and a visible signal warn passengers, automatic doors stay fully open, and the lift waits until someone steps out.
Stopping level with the floor.
The controller uses the positioning system to slow the car down as it approaches a floor and stop it with the car floor level with the landing. As people get in or out, the ropes stretch or relax slightly and the car can move a little. Many lifts correct this automatically by re-levelling, moving the car back to the floor while the doors are open.
BS EN 81-20 sets the standard for new lifts: the car must stop within 10 mm of the landing, and if loading moves it more than 20 mm away, it must be brought back to within 10 mm.
A car that regularly stops above or below the landing is a trip hazard, especially for people using wheelchairs, walking aids or trolleys. Report it to your maintenance provider rather than waiting for the next routine visit.
When the journey goes wrong.
Most faults interrupt the sequence at a particular step, which is why engineers often start by asking what the lift was doing when it stopped. Doors that keep reopening point to the light curtain or something in the door track. A lift that will not move at all often has an open contact somewhere in the safety circuit. A car that stops short of the floor suggests a positioning or levelling problem.
Our guide to lift faults covers common symptoms and what engineers check.
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.
Check your understanding.
Three quick questions on this lesson. Choose an answer to check it, or open the answer below each question.
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Why will a lift not move while a landing door is open?
Show the answer
B. The landing door’s contact is part of the safety circuit, which must be complete. Every landing door lock has an electrical contact in the safety circuit. Until every door is closed and locked, the circuit is incomplete and the drive cannot start.
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What does pressing the call button again do?
Show the answer
B. Nothing more: the call is already registered. Once the button lights up, the controller has the call. Pressing it again does not change the order in which the lift answers its calls.
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How does the controller know where the car is?
Show the answer
A. Sensors on the car read markers or a coded tape in the shaft. A positioning system on the car reads markers, magnets or a coded tape fixed in the shaft. The controller uses it to slow the car and stop it level with the landing.
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
Is your lift slow, noisy or stopping out of level?
Talk to an engineer about what is happening and what it might need.
Common questions.
Quick answers to common questions about this topic.
Does pressing the lift button more than once make it come faster?
No. Once the button lights up, the call is registered with the controller. Pressing it again does not change the order in which the lift answers its calls.
How does a lift know which floor to stop at?
Sensors on the car read markers, magnets or a coded tape in the shaft, so the controller always knows where the car is. It slows the car as it approaches a floor with a call and stops it level with the landing.
Why does a lift sometimes go past my floor?
A lift usually answers the calls in its direction of travel before it turns round, so it may pass you on the way to another call. Many lifts also pass landing calls when the car is nearly full, because the load sensor tells the controller there is no room.
What should I do if I am stuck in a lift?
Stay calm and press the alarm button, which connects you to a rescue service through the lift’s two-way communication system. Do not try to force the doors or climb out. If anyone is in danger, call 999.