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Finally got that weird hum out of the gearless unit at the old library building

Spent three days last week on a 1980s Otis, and the sound was driving everyone nuts. Turns out it was a slightly worn motor coupling that only vibrated at a specific speed. Anyone else run into a noise that was super specific like that?
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2 Comments
wesley_grant33
Ever check if the motor mounts were still solid? On an old Schindler I worked on, a cracked mount let the whole assembly shift just enough to cause a gear whine only when the car passed the counterweight. That one was a real head scratcher.
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karent75
karent7527d ago
We had a 90s Dover at a medical center that only made a high pitched whine on the down run between the 4th and 5th floors. It was a bent guide shoe that just kissed the rail at a certain angle under load. Took forever to find because it was silent on the way up.
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