I skip the door dwell adjustment on most MRL jobs and it works fine

Everyone I work with swears you have to set the door dwell exactly per the manual for every MRL. I tried that on a 2021 Otis install in Denver and it gave me nothing but nuisance reopening calls. Started setting it just under what the book says and knocking 0.3 seconds off the close time. That was 18 months ago and I haven't had a single callback on that bank. I do still set it tight for hospital or nursing home elevators where people move slow. Am I the only one who tweaks this without the factory specs?

3 comments

3 Comments

emma_lee225d ago

You been running into any issues with fire doors or egress doors on your MRLs since you started tweaking the dwell? I'm curious because I had a job in Phoenix where the fire marshal started flagging close times on a couple of modernizations. I dropped the dwell by 0.2 seconds and the doors were fine for the first year but then the closer springs started wearing uneven and I had to go back and adjust the whole bank. Were those Otis units you mentioned running gear end switches or did you reprogram through the controller?

taylor_wells5d ago

Man, I've been there. The closer springs wearing uneven is a dead giveaway you're fighting the door operator's natural curve. I had a similar headache on a Thyssen MRL in Austin where the fire marshal started timing everything after a test failure. What worked for me was going into the controller and adding a slight delay on the final inch of travel instead of just messing with the dwell. That way the closer springs don't get hammered by the sudden stop. @emma_lee22, if those Otis units were using gear end switches I bet that's why the springs went uneven, because the switches are way more sensitive to timing changes than a controller-based adjustment.

kai8395d ago

Dropped the dwell by 0.15 seconds on a bunch of Schindler 330A's in a hotel near Seattle after the fire marshal got real picky about close times. Those doors were slamming hard and yeah the closer springs started binding up real uneven about 8 months later. Ended up going back and reprogramming the whole door operator curve from scratch, basically smoothing out the entire run so the last 4 inches are slower instead of just leaning on the springs to handle the stop. For the Otis units I saw with gear end switches the problem was the switch timing was slightly off on each door so the controller was fighting itself. Had to align all those switches on the door track first before touching any dwell settings. That fixed most of the uneven wear.