Home Forums General Discussion Technical Questions Dover DMC-1 Viscosity control

Hi everyone,

I recently faced a strange problem with a DMC-1. I responded to a call and when I got there the motor overload was tripped. We had very cold temperatures and the machine room got cold enough to go into viscosity control. Problem is, the valve is leaking in the up direction, so whenever the pump started to bypass and warm up the oil it would leak to the jack and push the car up out of leveling zone, kill the pump, level down and start again every 15 seconds or so. It did it for long enough to trip the overload. Has anyone experienced a valve leaking like that before? It holds perfectly in the down direction.

Seb

either the valve is not adjusted properly or it is bad. The viscocity control sounds to be working properly

What valve is it? I-2 or I-3 by chance? If it is, the low pressure for bypass has not been set correctly. Remove valves, inspect car up, adjust screw til you get 0 motion, turn screw in until it creeps, then back it out slowly til zero again. Stop pump, take screw out 1/2 turn again, and voila, low pressure has been set for the I-2 or I-3.

This can contaminate the up leveling speeds so you may need to re adjust that as well.

@Boa: Thanks, I looked over the SOOP for viscosity control and it is indeed working as it should.

@Silly: I assume by "remove valves" you mean to pull the coils off? It is an I-2 valve. But as far as I understand if it was a bypass issue it would go back to the tank (as it should in viscosity control) and not to the jack. What do you think?

Seb

CB,
It's sounds like oil is bleeding through your up pilot piston for the pressure to build in the regulator piston allowing oil to flow to the jack.

Did you check the up pilot piston and spring? We're any adjustment changes made to the up side? More specificly was the low pressure or up stop adjustments changed?

Hi JKH:

I didn't have the up pilot out yet. No adjustments were made lately. It could have been like that for a long time though, it probably hasn't gone into viscosity control for years so no one would notice. Is there a rebuild kit for the up pilot?

S�bastien

Try the following

LindenValve repair (800)769-5438
EMI valve (847)593-4900
Vertical Express (Dover, TKE) (866)558-3789

CBass the "bypass" is a function of pressure. If the pressure is too high, it will get into the up pilot, moving the car. Great example for the guys that do not do much new construction, our TKE hydros can run at around 20-30 FPM with the valve coils completely unplugged, because this low pressure setting has not been completed yet.

I have seen this before, in Alaska, on a TAC 20 that was creeping while on viscosity. Give it a try and let me know if you need some help. It's a very straight forward adjustment, and the up leveling is also cake to dial back in.

Silly is all over this one......

Silly is right, this is the most common reason.

Thanks a lot for your help Silly, I'll have a look next time I go there and post on here.

S

Silly is 100% correct. I would recommend disconnecting the wires from the up solenoid and not just pulling them off the stem. If you run too long without the coils around the solenoid stem you could fry your coils. Ask me how I know.

When you pull your coils off, slug them with a screwdriver or long bolt and you won't burn them up.

Good morning guys:

I went to this job yesterday and sis exactly as Silly said. All it needed was the low pressure setting readjusted. Now with the coils off the car won<t move at all.

Thanks a lot for your help, Seb

Had the same problem on a Maxton before car would move on Y and fault out before Delta would even pick. Then the whole thing would start over. Took me a bit to figure out the car was actually moving as soon as Y picked......