RMC70E, hydraulic problem

This seems to be a real head scratcher but shouldn’t be.

What I have is a press, upper and lower cylinders that come togethor to form powdered wax into a candle. System has been in production for around 5 years. Well last week the upper cylinder wouldn’t come down more then a quarter inch before it gave a following error. After come investigation I thought the problem was simple, we have a PO check on the upper cylinder so it don’t fall down under a power loss situation. Took that out of the system and nothing changed. Cylinder will fall now when you lose power. It will go back to full retracted just fine but won’t extend. It goes to Output Saturated. With my meter I can only read a 3.5Volt coming out of the output, but I’m wondering if my meter isn’t fast enough to read it.

The bottom works fine, but the top won’t extend.

Switched valves, no change.
Switched Wires no change
flopped the hoses on the valves, put upper on the lower and lower on the upper. Top would jump around crazy and bottom wouldn’t extend. I think that’s because the stroke of the bottom cylinder is about half of what the upper is.
Now we are back to original configuration and problem is right back where it was, I’m convinced it’s not a RMC problem but a physical hydraulic problem.

Out of ideas now, can anybody see anything that I’m missing? Of course we needed this thing running last week.

Let’s see if I have this right. The top cylinder would not extend, and no changes affected it. When you swapped hoses, the problem of not extending switched to the bottom cylinder. It sounds like you may possibly have a problem in the manifold. However, it could be something else. From past experience, I know this type of problem can be difficult to pinpoint.

When troubleshooting, the RMC’s Open Loop Rate command can be very useful. It sends out a constant Control Output which is then easy to verify with a voltmeter.



Yes you are correct.

So just do a manual command from the sidebar and do open loop control and put in the forces and such. That’s what it seemed to me as well was there is something in the manifold block. We had the valves off and tried to look down in there and couldn’t see anything. They are just straight holes though. It’s been an aggrivating situation for sure. I will try this and see what I come up with. I was wondering about the cylinder but seems like we have ruled that out with the line switches that we have done.