Home Forums General Discussion Technical Questions dover oildraulic

I've got an oildraulic that every couple of weeks will shut down at the bottom floor. It usually shuts down at night so by the time i get the call it is at the bottom floor about 2-3 inches below floor level as if it were sitting all night in the failed state. It wants to level up but won't turn on the starter untill i cycle the power . I just need some more ideas of things to look at on this thing because i'm not getting it. It is a duplex and the other car seems to be fine and i have swapped the top three cards in the rack trying to transfer the problem.

What do you mean when it wants to level up? Is the leveling valve getting power and the starter not coming on? Does it up level fine if you manually lower it below the floor?

If this only happens at night I would take a look at the viscosity control. Dover heats the oil by running the pump motor and bypassing the oil thru the valve. I would block calls and force the car on to viscosity control and see if you hold floor level.I would also try the manual lowering as suggested by solidstate and if that checks out fine do a standing load test and see if oil is coming back thru the valve and determine why LU is not keeping you floor level. GOOD LUCK

when the car is running i can manual lower it and it will level up fine. I have the viscosity controll dissconected and what i mean by it wants to level up is the lu sensor and relay are made up. It knows where it is in the hoistway and if i phisically push in U1 relay only the valve coil for up picks i don't get the pump motor.

It sure does sound like an issue with the LOT (low oil timer)-if you power off then power on will it take off and run?

When the car is locked up, put your meter between terminal SC and LOM on the top card which is the Power card. If it is 0 VDC then the cars Low oil timer has expired. you can reset by putting car on inspect then back to normal. with the car reset the LOM test point will read 5 VDC. Check this first if LOM is not expired let me know and i will look at the board prints and try to give you another way to go. If it is in the LOM condition start looking at the usual MLT solutions. bad contacts in the hi speed valve circuit , car jerking off during relevel etc. You can also run the car from the bottom to the top removing the hi speed coil and see if the car will make it to the top, there is a pot on the power card that adjusts the LOM time.

Good info about the low oil timer , I didn't even know it had one. I could see this happening , the car runs so much during the day that the oil gets really hot and I bet it is jerking off at the floor come the end of the day.

Maybe the phrase "jerking off" isnt such a good one to use some people might get the wrong idea

I just recently fixed a problem almost identical to this. Symptom was the car intermittently going out on low oil. There was nothing wrong with either the valve or the oil level.

Two other things you could look at:

Check to see if the top emergency limit is dirty or failing. This is the one between the top terminal slowdown and the up normal(directional) limit. You may not have this if your speed is lower than 150 ft/min.

The other thing, which was the problem in the unit I just fixed, was the one auxiliary "M" contact on the starter relay intermittently failing . What was going on is that the starter was energizing the pump but not getting power to the up valve solenoids. After about 40 seconds the unit shuts down on a LOT fault. This "M" contact is the one in series with your entire up valve solenoid circuit. My unit was using an older Furnace style starter. What I ended up doing was replacing the "M" aux contact and then adding a parallel relay with the starter which gave me a means of adding a couple of contacts to parallel that one starter auxiliary contact.

I have also had that same situation, good posting smitty, my memory is not what it used to be

Yep it finnally happened again and yes it was the LOT timer. I was able to get the building to purchase a solid state starter a year ago so i knew that wasn't it. But this time i knew right what to check , (SC-LOM) thanks for the info.

Dont you love that feeling when you finally fix that one problem thats been plaguing you