Home Forums General Discussion Technical Questions Dashpot OL

I remember hearing about them in IUEC school way back in the day, but can't recall if they taught us how to check/set them up. I have an Otis pie plate car that has tripped the DP OL once a day for the past couple days, it's been stuck OOS about 2-3" above the floor. Anyone have any ideas/info?

I would check to see exactly how much current is being drawn when the car accel's empty down from the top floor. You could have low oil in the dashpot or you may have too much current flowing through your loop circuit.

Thanks. I'm guessing there's a shunt in the back of the controller I can use to measure the current on the loop? Like a 50Ma shunt?

It does sound like it is maybe low on oil when you remove the clip and pop off the top cover of the basin proper level is that the 3 tips sticking up from the bottom of the reservior should just barely be below the level of the oil...spinning the actuator i remember clockwise (down will allow more current to trip...but if the oil is good level..you must find out why you are drawing so much current those otis umv controls 10,20 30,65u systems the dashpot is found in the loop circuit...

yep and you test the timing of tripping by pulling the middle out of the oil then set it back into the unit just at the oil level and see how long it takes to settle down to the bottom. i think between 20 to 30 secs is about the norm.


but you can just top up the oil temperarily to test if it the oil levs or the fact your current in the loop ccts is not right.

Ok thanks. When i go there I'll check the oil level and try and check the current running empty car down from the top.

I remember three dashpots-

2 on the AC end of the gen set.
1 on the loop circuit.

Is this "DP" dashpot the one in the loop? One other thing you might look at, is the brake. Make sure it's not dragging.

Got oil in the gearcase?

Exactly...That's how I used to set them...Single phase the AC to set the AC ones.

On the DC you drop the brake, measuring current with amp probe. I think trip was a bout 150%, but I may be off. Adjust pot, and cover with just enought dashpot oil to cover tips on the plunger..

Ah...So long ago...

These cars have one AC OL and one Dashpot OL in the loop. The DP was a little low so I filled it up to just cover the 3 tips. I tested it before and after with the settling test and it was 16 then 24 seconds. The loop is drawing more current (empty car down from the top) than the other car but I figured the low DP oil would fix it. It ran for about 2.5 hours then tripped again. The machine is full of oil, guess I'll check the brake electrically and mechanically tomorrow...... We just put new door operators and door locks on these cars and the customer can't understand why we're still having problems with these 30 something year old elevators..

what type of machine? i bet you are on the right track with the brake. is the drum hot when it trips?

I'm not sure, I think it's a CT22 or something like that? I have 2 other cars at another building that I think are CT22's.. not sure, I'll check tomorrow. One thing about the machine, the sheave is hanging in the air on one side, no pedestal on the left side looking at machine from the front. I also noticed that the brake "relaxes" as it's coming into the floor. EVERY time the car has shut down it's been about 3" above the floor. I'm assuming it's trying to level in as the brake is "relaxing".

Sorry Mr.GP, by the time I get there it's been off a while. I'm gonna go over the brake tomorrow.

i cant remember whether you said this is a otis machine as ive never seen only a 2 dp dc lift only 1p,2p,3p lift. you settling timing is fine it just proves that the plunger actually moves and doesnt jam therefore doesnt trip. i would definately look at the brake set. this relaxing is worrying but id bet you a buck the fact that the lift is 3" above and not level the lift is stalling. check what levels this is happening(could be the same floor),the brake action(strip it down)and the selector action as clearly the overcurrent is probably the second action and the first action is a stall.

Is it doing it during a relevel? They brake will pick very little during a relevel. I miss the days when we had time to do a brake tear down once a year.

What is the control? 80U 21AUL UCL/UCLS like that. Some Otis controllers have re level circuitry.

I'll check the controller tomorrow, I know it's a UCL but not sure of the number. Otis machine with the flying sheave, pie plate selector up on secondary slab with machine (car calls up here also, what a pain in the ass to run the car), slimline/telephone relays up at top of controller, standard Otis relays and contactors at the bottom, different terminals than the standard C1, C2 etc. etc.. they are MKO-1, MK3-5 etc. One of the big four had this contract for years and didn't do Crap. All the relays, rivots, armatures, selectors.. everything's wore slap out from lack of maintenance.

These cars will re-level on the pie plate if they over or undershoot.

Also-

Is the loop at least in the high k ohms to ground?

I yank all the brushes out of the motor and gen set, and put a megger on the loop. Should be meg ohms, or at least like over 200 k ohms.

Got any brush dust carbon trails, taking the loop to ground?

Sounds like a UCLS -maybe 10-21-30 ?

Carbon everywhere, guess I'll meg it. I forgot to check the controller. The machine says 330DM on the side. Went through and ohmed lots of circuits, those Otis contacts are different than I'm used to, my rubber eraser wasn't working, I forgot an old Otis guy suggested I use krokus cloth - it works well. Replaced a couple rubber band shunts, to short arm leveling switches on the selector and adjusted the brake relaxing voltage from 13v up to 20v like the other car. It never tripped the OL today, be back Monday.