Just learned how much elevator door interlocks vary between older and newer models

I was digging through some old service manuals last night and found out that the original Otis interlocks from the 60s had way fewer safeties than I realized. Like they basically just had a basic mechanical latch and that was it for preventing the car from moving with doors open. Now we have all these electronic monitoring systems and redundant contacts. Saw a statistic that said modern interlocks have cut door related accidents by something like 80 percent since the 80s. Blew my mind because I always thought the older stuff was built tougher but the safety gap is huge. Has anyone else noticed a big difference swapping out old interlocks on modernizations?

2 comments

2 Comments

oscarmurray11d ago

I was the same way. Used to swear by the old Otis stuff, thought it was built like a tank compared to the plastic parts now. Then I had to replace a set of 70s interlocks on a modernization job last year and actually looked at the wiring schematics side by side. The old ones literally had one set of contacts for the door closed signal and nothing else. The new ones have three separate verification circuits plus a separate monitoring system. Changed my whole opinion on which design was actually better.

avery_stone9511d ago

Bro honestly I see this take a lot and I'm kinda like... is it really that deep? Like yeah sure the new stuff has more safety features on paper but how often does that actually come up in real life? I've seen modern boards brick themselves over nothing while old elevators just keep running like it's nothing. Overcomplication isn't always an upgrade.