Home Forums General Discussion Technical Questions Dover comp nightmare

How’s everyone doing today? Been coming here for a while but first time posting. I’ve got a early 80s 3 bank with a compumatic dispatcher. 2 cars run like a top zero problems but the 3rd car has had issues for a couple years. Randomly if the car sits in the first floor for 15 minutes and it’s first run after that is to the top floor it will level in open doors and keep leveling up til it hits final. If you jump the final without cycling power it will continue to run up until counterweight is on buffer and it slips traction. Once power is cycled and final jumped car will take right back off into service. The randomness of it is the killer. Might do it 4 times in a day then not do it again for 3 months. Any insight would be greatly appreciated.

Did u check your loop voltage when elevator sitting?
May have problem with your suicide citcuit

Is the brake picked while it’s driving up like this?

When it sits for 15 minutes, does the generator time out? If you disconnected the mg timer, would you have the same problem? Have you checked the Struthers-Dunn relay cores? I don't remember the relay #. I think 10 and something else. These affect compounding. Why doesn't the directional catch the car before it goes into the final. It might be suiciding into the limit.

Yes the brake picks like it has demand to run up. And we’ve jumped out the mgt timer. Does it with the generator timing off and running. The directional not catching is the million dollar question. It’s the craziest thing I’ve ever seen.

Do you have voltage across GF1 to GF4 (Generator Shunt Field) if not need to find out why. If you have voltage possible open field. Also do you have Motor field voltage across fields? Possible open field if you have voltage. If no Motor Field it won't move.

It did it again this morning I’m headed out there so I will check all of above.

I appreciate all the help.

Sounds like you are under compounded and going too fast. how many floors are there? Does this job have comp chains? Try taching the speeds up and down, they should be within 5 or 6 fpm of each other. put a volt meter across 2 adjacent brushes on Generator when it is sitting idling, there should be very little voltage.

I’ll tach it today. Could a compounding issue explain the randomness of the problem? Seems like it would happen much more frequently.

Units are 6 stops no comp chains. No voltage at brushes on generator when sitting idle. So this morning same thing on final. FT timer is on.

So no comp chains means the weight of the hoist ropes are added to the counterweights. When they are near the pit it adds up. if you are under compounded you will be faster in the up direction and slower in the down. If that is the case you would need to add in some series field by removing a shunt, or move a tap in the series field.

None of that would explain the car continuing to run up, with the brake picked with the counterweight sitting on the buffer. There must be a relay sticking, residual magnetism or pitted contacts.

Check that CFC relay picks at the end of the run. Think of it as electric stop. It is how Dover decided to use the comp field.
Maybe if it is working try blocking it and see if you recreate your problem.
But I vote on the side of compounding, without a run box , pull INA wire to put on inspection. Use UA1 and DA1 wire contact relays to jog car up and down at inspection speed . The wire diagram for generator is usually inside wire trough. The fine tuning for low speed series field is usually on 10 o’clock and 4 o’clock field pieces.

Composites seem to stop real well even Compounding gets just a little bit off. But once it gets too far out of whack the affect of CFC relay energizing the comp isn’t enough to stop the car floor level.

If you can lock it into low level speed (2LR) then 10-11 foot per minute is ideal.

The switches I was thinking about were the 14 and 15 switches. The core can unscrew and the switches pick up partway and don't make aand break the contacts properly. This throws the compounding out of whack. Also, if the 14 and 15 don't pick at the proper times, you could have the same result. If you don't have motor field, there is a relay that wont let you run at all. If your shunt field is too low, you will drift up, not run up. Has anyone actually witnessed the elevator have this problem? Or are you seeing the end result and not what is actually happening. When it gets to the top floor, does it slow down normally, or does it come in hot. You had said that the problem only exists if it makes a run to the top floor. If it stops at 5, and then continues to 6, the problem doesnt exist?? Put a diode from 6c to 5c, so if someone or something sets up 6, the car will first stop at 5. Before you jump the final, what motion relays are in? When you jump the final, do the motion relays come in or are they already in? Have you checked for continuity on the directional limit when it is on the final? Paper the directional, if it still moves with motion relays, something is shorting into the up motion circuit. It will be interesting to find out what it was.

“Yes the brake picks like it has a demand”. That’s your clue.
Will the directional stop it on hall access?
And as Johnny asked, what happens if you send it to 5 first?
What might happen if the up stop limit is opened while on Independant, with the car at the bottom with an up direction in? Does LU stay up for some reason at the top only?
If you can prove your trouble at the top only, relay contacts or related hardware (selector contacts/switches) are suspect.

Still brain storming here.
I was fighting a problem a while back and found the wire loop going to resistor door would press in the Potter brumfield relays, with resistor door closed, but I think in my case I think it caused the elevator to stall.

I have also heard of shorts in ribbon cable to logic door causing issues like you describe. But keep in mind, these are long shots.

Its also possible that there are pins touching together on the back side of an IBM relay or ribbon cable terminal block. These terminal blocks are tightly packed and located on the logic door and up on the selector. They are labeled A, B , X, Y, etc.. If someone changed a ribbon cable in the past without proper pin removal and insertion tools , it easy to bend the metal portion enough to touch the neighboring conductor, much less easy to miss wire a single conductor on these terminal blocks. I use a non conductive orange peeler stick to make sure that pins that look a little too close aren't actually touching.

I also wonder if it might be worthwhile to swap optical leveling card with another unit. I wouldn't be concerned about level sensors , because that would just cause failure light to turn on. But perhaps an output component on this card is getting stuck on. These are easy to swap.

Those IBM relays are a punk when you suspect contact troubles. Pulling them out, visually looking through the relay body for debris across NO/NC contacts is time consuming. Pulling and replacing pins is a pain too. Worn NO/C contacts are hard to detect visually. And...got pins? I’ve seen pins x’d over (essentially shorting the contact) and wondered how the unit ran like it did. And you’re right about the relay base socket. Those copper male contacts on the base can fold up upon relay insertion. I’m sure Jim will plug his WizBang tester here if it handles this base.
Would the leveling card you mention fail at only a terminal floor?

If you look at the print, the up directional limit feeds UXA but level up comes in to pick U1, U2 even with UXA de-energized ( Page 3 of the print I’m looking at.) Seems like the car is leveling up but LU never drops. If you can’t catch it in the act with a meter in hand, the optical leveling card might be a good guess. Then again, if it has NEVER kept leveling up through another floor, maybe there is something wrong with the top floor plate. Could the selector carriage stick or bind on level up but the car keep moving?

If you have an optical leveling board, when you get both a LU and a LD signal at the same time, the failure light comes on. This has not been mentioned. Carriage could have a twist and not break the directional. This could happen at the top only, but I'm thinking that the problem would be a lot more obvious. Has anyone actually seen this occur?