Home Forums General Discussion Technical Questions Otis 21 260 VIP problem

Hi all this is my first post and was hoping some one can help me fix this problem.
The job is 260 VIP with touch buttons and no advancer on the selector in a 3 car bank.
The issue is with the car calls in the down direction when you put in multiple car calls from the top floor down the lift will miss all the calls on the way down travel to the lowest call answer the call then pick up all the calls in the up direction. Or if only one car call is put in the lift will travel to the ground floor then pick up the call in the up direction.
Funny thing is the lift will answer the call if put on independent service and not have to go to the ground floor.
I have narrowed the fault down to hg pulling in shortly after LG when the lift takes off anyone had something like this?

Check wiring on carbon brushes in the CAC circuit. Does the car make a one floor run down? HG pulling in after the car takes off indicates that it sees a call above the car. LG being in makes the car run down in answer to the calls. CAC sees the call and fires CST or SE reset to tell the car to decelerate. The carbon brush in the CAC circuit is split and the bottom half looks for car calls in the down direction. Independent service usually only takes one call at a time and therefore stops on loss of LG and HG. Does the car resspond to hall calls properly? This uses DHC and UHC brushes. Has the car always done this? Or has it just started having a problem?

Does the lift stop on those middle levels on independent service when doing it floor by floor? The reason I say this is it proves that the trailing cables on the selector will be ok. As Johnny stated look at the CST function.

Clean the Pawl Magnet Core inside the Pawl Magnet Coil. This is a common problem with a 6850BJ (Advancer) Selector. It will hang up in one direction from residual and will soon not reset in either direction if not cleaned. Make sure your getting reset voltage to the coil. Do not Lower the resistor value in the reset circuit. If the reset coil is energized to strong the reset will swing to set and never release the stop lugs.

How to Clean a Pawl Magnet Core:
Park Elevator at Bottom Floor.
Pull Main line.
Remove the screws holding the Advancer Motor.
Carefully Remove the Advancer Motor and rest it
on the bottom of the selector or if distance to
far for wires, rest it on the travel cord loop.
Loosen the Allen Set Screw holding the core in
until it can be pulled out.
Insert a 10-32 screw into the tapped hole of the core.
Use the screw to pull the core out.
Clean the core and look for any place it may have touched
the moveable part of the pawl magnet.
Use emery cloth to thoughly clean.
Reassemble core and motor.

I would also like to know if the lift works ok in the up direction. If so then the pawl action would seem to be ok and I would be checking the CAC/ DCS/ 1DAS for the ST action to work. There is also some links/leads in there as well that needs checking. Anyway food for thought of the top of my head.

Uppo.. not true about one direction working on a reset of pawl on an advancer 6850BJ meaning the pawl core is ok. On the advancer selector the same brush is used for Up and Down Car Button Stops. CAC picks CBS(car button Stop BOTH DIRECTIONS. If your getting reset voltage to the PM coil and it is not an open coil the core is dirty.

Yes isn't that the point tho Rolly? If your using the same brush to stop, and your volts are good then the core most likely be sticking in both direction, not just 1. This has been my experience. When I said good I was meaning if it 'was' working in the other direction. Anyway all good. As to this situation im sure the poster stated this has no advancer panel anyway.

Can anyone answer what the difference is?

I thought the 6850 selector has the cross head panel & advancer panel.

And the 6850BJ just had the cross head panel.

JKH I'm not actually sure but there is many various types made which depends speeds and floors levels. I think there was a "A, BH, BJ" type of selector but I think you can have crosshead only or advancer on the same type depending on if the ratio of the selector can slow down the lift in time. If it cant then the advancer is added to the job.

Rolly?

Uppo: It ALWAYS fails with a sticky core in only one direction first. Guarantee it. Have had 48 years experience with them.
JKH: The 6850BJ has the advancer panel and can be two different gear ratios. 111:1 and 138:1. The 6850DK has no advancer panel and also comes in two ratios. 60:1 and 111:1. The DK was used for 350fpm and below and the BJ for up to 500fpm at 111:1 and for up to 800fpm the 138:1. What the 111:1 and 138:1 means is with one full turn of the vernier dial (100 divisions) the car traveled 111 inches or 138 inches. 1000frm used a totally different selector. 6104AY which covered all speeds above 1000fpm.

Rolly is absolutely correct, I have seen this many times in the last 30 years also, Unforturnately the mechanic will sometimes increase the voltage to the coil, which seems like it should work, but as rolly has explained earlier it will not. the scenario, usually goes like this the mechanic can't get the pawl to reset, he decrease resistance in reset circuit, it still does not reset, he decreases resistance again, still won't work, car is left down for new coil, new coil is replaced, but unfortunately this does not fix the problem, and to make things worse, now it does not reset in either direction. then the call for help comes, the help will move the reset resistance tap back to where it was, and he looks like the hero,

Thanks for the reply Rolly. I guess I mustn't have been exposed to a single direction non stopping fault in the early situation as when ive had this it has been not stopping in both directions. All good mate I know better now. Cheers for that.

Thanks Rolly,
I was able to dig up a 1966 write up. The write up describes 4 variations of the 6850 selector. They are CA, CK, BV & BJ. It goes into detail describing each of their differences. I will try to read it this weekend. But, the wife is away! I can't comit to it though. I am planning on doing some house projects & cracking the seal on a bottle of whiskey. Wish me luck.

Thanks guys, I fixed it it turned out the coil for dgf was faulty and was causing a host of other issues but once replaced problem was rectified.