Otis 260 duplex 1978

[@musiclabmn]

Absolutely fascinating, not only are you one of the best lift mechanic channels out there, you can actually explain how this all works. If only I got into the elevator trades when all of this was new, but by the time I graduated from high school in 1999 a lot of the relay stuff was well on its way out. Now here in MN, due to over zealous elevator code changes 10-15 years ago, just about everything is gone. Needlessly ripped out well before it was needed and replaced with junk (in my humble opinion).

[@WaygoodOtis]

Very much people have the mindset of "if it aint broke dont fix" so we get to keep all the good stuff for as long as they are practical to keep running.

[@TheTheo58]

These machines were built like battleships an art of engineering with the gear-less traction machines. Designed to last decades, up and down day in and out. And be repairable.

[@WaygoodOtis]

Very nice GNB lifts seem fairly reliable so they are likely going to be the last that will be replaced so will hopefully get to see them for a bit longer.

[@philipcollins3849]

I’m always pleased you always appreciate superior equipment 😂😂😂😉

[@liftguy30]

@@philipcollins3849 It is good stuff but Express managed to do exactly the same thing with about half the relays and were using thyristor control of generator fields rather than stepped resistors which is far less efficient and has a lot more moving parts, however the Otis method of inserting the calls via 1/2 wave valve or touch buttons in to a direction control circuit was quite unique, even if very few could fix them.

[@philipcollins3849]

Yes the touch button is with something else until they went wrong and then I’m a real pain in the arse. Of course the ultimate problem was if there was a fire in the building which meant heat call the Carr to the floor and one other thing I don’t know if you’re aware, but bought express lives for £1. Something fishy went on there.

[@SeanBZA]

Yes those DC units are becoming scarce, even though they can, with standard maintenance, be there for the entire life of the building, unlike the modern replacements.

[@liftguy30]

@@SeanBZA 30-50k$ to rebuild a commutator compared to 5k$ permanant magnet machine means that we are unlikely to ever repair another, sadly it just doesn’t make economic sense, even if the bearings die in the new machine after ten years and the drive blows at every power surge :)

[@TheTheo58]

I would have expected to see gear-less machines like these running at 440-480 VDC, 190VDC pulling 190A seems odd.

[@liftguy30]

@@TheTheo58 most ward Leonard systems are about that voltage, short runs in high current saves a lot on insulation and makes it much safer to work on, most of the upgrade kits GEC or Magnatek used auto transformers to drop to the same voltage that came out of the gen sets.

[@Przekaznikownia]

3:32 - the relays sound is suspiciously similar to the sound made by HAG-IV group control. (compare with this: kzbin.info/www/bejne/gHmnaqyGh8SHgsU ). One book says Asea has adopted this system from American, so maybe there are common roots of those? After making a floor call, does this controller check which elevator is idle and closer to the calling floor?

[@Przekaznikownia]

Btw, i suspect my previous comment was for some reason deleted 😰

[@liftguy30]

@@Przekaznikownia that system seems to work the same as the Westinghouse/Express DMR mk4, the relays would pulse until they decided which lift was best suited to serve the call, Otis used zoning so effectively parked a lift in each zone, when the lobby zone was empty it would be filled with a higher priority than the others and if a car left with four calls it would send a lobby call to all available lifts with a few timers to stope them chasing each other, Express used timers to bring cars to lobby and used up and down peak controls via timers or clocks, Express also used the load weighing to ignore landing calls if the car was full.

[@Przekaznikownia]

@@liftguy30 Sounds like really advanced solution. Do exist any resources about details of this system? Tech or operational docs, schematics? I guess it will be great idea to make a detailed video explaining such systems.