How Do Elevators Know Where to Stop?
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How Do Elevators Know Where to Stop?
An elevator stops within millimetres of your floor, every time, while carrying a small car’s worth of weight. Here is the positioning system hiding in the shaft.
Counting the climb
Most modern elevators track position with an encoder on the motor shaft — a sensor that counts rotations and converts them into distance travelled. The controller always knows, to a fraction of an inch, where the cab is. Older systems used magnetic or mechanical switches at each floor; many buildings blend both.
The slow-down dance
- Far from target: full speed.
- Approaching: the controller ramps speed down in a smooth curve — that gentle glide you feel.
- Final approach: creep speed plus fine sensors confirm the exact floor level before the doors open.
It is the same find-and-home logic as our explainer on how AirTags find lost keys, just with tons of steel instead of a keyring.
The counterweight secret
| Part | Job |
|---|---|
| Counterweight | Balances the cab plus about half a full load |
| Encoder | Counts motor rotation = position |
| Governor | Trips the safety brakes if speed runs away |
Why leveling matters
A cab that stops even an inch off creates a trip lip at the door. Modern controllers re-level automatically as passengers board and the cables stretch microscopically under load — that tiny nudge you sometimes feel after the doors open is the system correcting itself.
Your turn
Have you ever ridden an elevator that stopped noticeably off-level — did it shake your trust in the whole building?
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