Glossary term
obstruction sensor
Any sensor that stops travel when something is in the way — under a stairlift footplate, beneath a platform, or across a doorway.
What it means
Obstruction sensors are the devices that stop the machine when something is where it should not be. On a stairlift they sit under the footplate and along the carriage. On a platform lift they cover the underside of the platform. On a passenger lift they guard the doorway. They all do the same job: interrupt travel first and ask questions later.
Where you see it
Wherever a moving part could trap something. The important ones on home equipment are underneath, because that is where feet, pets, walking frames and stored boxes end up.
How it works
Most are simple switches behind a sprung panel: press the panel and the switch opens. Others are pressure-sensitive mats or infra-red beams. In every case the signal goes straight to the controller, which cuts the drive rather than trying to push past.
The sensor cannot tell the difference between a foot and a rolled-up rug, so a lift that stops at the same place every time is usually reporting a real obstruction, even if the obstruction looks harmless.
Why it matters
Repeated obstruction stops at one point are worth mapping. Note the position, look at what is there, and report it. That single note often turns a two-visit repair into one, because the engineer arrives knowing where to look.
Commonly confused with
Obstruction sensor is a general term covering several different devices: sensors under a stairlift footplate, edge sensors under a platform, and detectors across a doorway. They all stop travel, but they are checked and cleared in different ways, so it helps to say where the lift stopped rather than naming the sensor.
Wear, service and lifespan
These sensors are deliberately sensitive and they are supposed to stop travel for very small obstructions. Service work tests each one individually and checks that it stops travel immediately and that travel resumes once the obstruction is removed. Damaged trim, loose carpet and stored items are the everyday causes of trips.
Signs to watch for
- The unit stops in exactly the same place on every journey.
- It stops without any visible obstruction.
- It reverses a short distance and then refuses to continue.
- The stop happens only in one direction of travel.
- It began after a rug, mat or piece of furniture was moved.
Troubleshooting obstruction sensor
Travel stops at the same point every time
What it usually means: A fixed obstruction such as a skirting, banister or step nosing
Safe check: Look along the route at that point from a safe standing position and report exactly where.
Random stops in different places
What it usually means: A sensor fault or a loose linkage rather than a real obstruction
Safe check: Note three or four stop positions with dates and report them together.
It stops and will not restart even when clear
What it usually means: The sensor has latched or failed
Safe check: Leave the lift where it is and report it. Do not press repeatedly to force travel.
How to report it
Say where along the run it stops, whether the path is clear, and whether it happens both directions. That distinguishes housekeeping from a genuine sensor failure and avoids a call-out where all that is needed is moving a plant pot.
Ask us about obstruction sensor on your lift
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Related terms
Definitions that usually come up alongside obstruction sensor when you are describing a fault.
- footplate
The fold-down platform a stairlift passenger rests their feet on, carrying obstruction sensors on its underside.
Safety devices
- platform lift
A slow-travelling lift with an open or enclosed platform, used mainly to move a wheelchair user over a short rise.
Lift types
- safety edge
A sprung or sensitive strip on the leading edge of a door that reverses it the moment it touches an obstruction.
Safety devices
- emergency stop
A latching switch that cuts the drive immediately and holds the equipment stopped until it is released.
Controls and electrics
- inclined platform lift
A folding platform that travels on a rail along a staircase, carrying a wheelchair user up the same flight the stairs cover.
Lift types