hollym12•19d agoMost Upvoted

Just wasted 6 hours on a door interlock that was off by 1/8th of an inch

I was working on an Otis elevator in a 12-story building downtown last Wednesday. The door interlock kept tripping the safety circuit every third or fourth cycle. I swapped relays, checked wiring, even replaced the contact block and it still acted up. Turns out the door hanger was slightly bent from a previous repair, just enough to throw the alignment off. Has anyone else spent way too long on stuff like this before catching the simple fix?

2 comments

2 Comments

karen_sanchez1019d ago

That 1/8th inch alignment issue is brutal, I've definitely chased ghosts like that before. Anytime you're chasing an interlock problem that's inconsistent like that, check the mechanical side first, the hanger wear or the door track being off will mess with the gap just enough to fool the sensor. Swap the relay last, it's almost always the bent hardware or a loose roller that's the real culprit.

webb.christopher19d ago

@karen_sanchez10 nailed it with checking the mechanical side first. I've been in that same boat more times than I can count, swapping parts when the real problem was just a worn door roller throwing the gap off by a hair. That interlock gap is so finicky on older Otis models, even a little bit of paint buildup on the cam can cause intermittent tripping like you described. Before you go chasing electrical ghosts, take a straightedge to the door track and hanger assembly to see if something is bowed out. One time I spent half a day on a similar issue and it ended up being a missing shim under the door sill that made the whole thing sag when the car leveled. Stuff like that will drive you crazy, but once you know the mechanical tells, you spot them way faster next time.