The situation
A 15-year-old elevator in a commercial building: rated load 1000 kg, around 500 trips a day. The maintenance team inspected it every month, and when the first signs of trouble appeared, every item on the monthly checklist was still within tolerance. By every measure available to them, the unit was fine.
But a Dr. Elevage Fixed Monitor on the car top had been recording vibration and sound on every trip, and comparing each one against the baseline it had built for this unit. The system had already raised a warning.
What the data showed
Three trips recorded by the same sensor on the same elevator, as the fault developed. Gray is the vertical (Z) axis, red is its smoothed trend — and watch the vertical scale grow.
A textbook run curve
- Horizontal (X, Y) vibration stays small.
- Vertical (Z) traces the three phases of a trip cleanly: accelerate, cruise, decelerate.
- Vertical scale: ±0.7 m/s².
The curve starts to bend
- The car is taking impacts; the ride is no longer smooth.
- Up and down speeds begin to drift apart, slightly.
- At down-start, the acceleration curve loses its regular shape.
On the edge of a breakdown
- Vertical acceleration is no longer stable; heavy impacts recur on every trip.
- The gap between up and down speeds has grown from 0.06 to 0.24 m/s.
- Recurring abnormal noise.
Screenshots from the Dr. Elevage mobile app; curves are recorded data, unedited. Unit identity withheld.
Why the monthly check did not see it
In the early stage, the fault usually stays hidden during a routine slow-speed maintenance run. Site visits are short and the anomaly is brief: a barely perceptible sway that is easily written off as normal aging. The continuous data said otherwise — the change had already happened, and that is exactly the moment to step in.
Each bright vertical streak is one abnormal noise: short, sharp, and spread from the low end up into the kilohertz range.
What the team found
The maintenance team received the alert and scheduled an inspection. On examination, a fault was confirmed in the traction machine. If left unaddressed, the condition could have progressed to an unplanned shutdown and increased the risk of entrapment.
The outcome
Because the trend had been visible for two months, the traction machine was repaired in a planned window, with the parts already on site. No business disruption, no emergency call-out rate, no entrapment, and no conversation with a building owner about why their elevator stopped without warning.
The traction machine was going to need work either way. The only variable was whether the building found out on a Tuesday afternoon of its own choosing, or on a Friday evening of the machine’s.