How a Lift Works

What is inside a lift shaft?

A traction passenger lift is a simple idea built with a lot of safety around it. The car hangs on steel ropes that pass over a grooved wheel in the machine room, with a counterweight on the other side to balance it. These are the main parts you can explore above:

• Traction machine: the motor, drive wheel (sheave) and brake that move the car and hold it still.
• Controller: the lift’s brain. It answers the call buttons, drives the motor and watches every safety switch.
• Overspeed governor: a wheel linked to the car by its own rope. If the car goes too fast, it sets the safety gear.
• Hoist ropes: several steel wire ropes, each able to hold the car on its own with a large safety margin.
• Counterweight: moves the opposite way to the car, so the motor only has to move the difference in weight.
• Lift car and guide rails: the car runs on guide shoes along steel rails so it travels straight and smoothly.
• Car door and door operator: opens and closes the doors, with a safety edge to stop them closing on people.
• Landing doors and locks: each floor’s door has a lock and contact that must prove it is locked before the lift can move.
• Safety gear: clamps the car to the guide rails if the governor trips.
• Buffers: stops in the pit for the car and counterweight.
• Travelling cable and halfway box: carry power and signals between the moving car and the fixed wiring in the shaft.
• Car top control station: lets engineers switch the lift to inspection and move it slowly while they work on the car roof.

Why does a lift stop? The safety chain

Every lift has a safety chain: a line of switches wired one after another, from the pit stop switch and buffers to the governor, the car’s stop switches, the car door and every landing door lock. Each one has to be closed and proven safe before the controller will let the lift move. If any single switch opens, the chain is broken and the lift stops or will not start. That is the system doing its job. Our engineers trace the chain to find exactly where it is open, put the fault right, then test the whole chain before the lift goes back into service.

Common lift faults

• Landing door lock not making contact: the lift will not come to your floor or stops between floors.
• Doors keep reopening: usually a dirty or misaligned safety edge.
• Car stops out of level: a step at the doorway, often from brake wear or a positioning sensor needing adjustment.
• Governor tripped: the car is held on its safety gear until an engineer finds the cause and resets it.
• Lift left on inspection: the lift ignores the call buttons after work on the car roof.
• Faults that come and go: often a damaged travelling cable or a loose connection in the halfway box.

If your lift has stopped, our engineers can find the fault and fix it. See our lift repairs page or call us on 01708 986845.

Keeping your lift running

Most of the faults above are found early on a planned service visit, before they stop the lift. We look after passenger, goods and platform lifts and dumbwaiters, and we are based predominantly in London, Essex and the South East, working nationwide. Find out more about our lift maintenance and lift modernisation, or ask us for a free lift survey and quote.

The Lift Explorer is a simplified guide to show how a lift works. Lifts must only be inspected, tested or repaired by a competent lift engineer. Never try to open lift doors, enter a lift shaft or bypass a safety switch.