Radial piston pump heats up at recommended pressure 2

[AamerK]

Hello,

I'm a technician at a concrete products plant, and we're having problems with our hydraulics.
Our main pump is a radial piston pump (Moog D954-2011 RKP 63) & the problem is that if we set the pressure to the recommended 200bars then the pumps' body heats up very quickly(10-15mins), the oil in the tank doesnt heat up that much, currently we have set it to a measely 120-130 bars to keep our machine running although at a very slow speed ofcourse.

The setup is shown in the drawing attached.
Things we have already tried:

1) Replacing the pump with a spare
2) Checked the pressure relief valve(unadjustable, fixed at 280bars)

Is it possible that both the main pumps are worn out?
Also, if we set the pressure to 200bars, then the 30KW motor running the main pump also starts drawing too much current.

 

[AamerK]

hydtools

Yes thats exactly whats happening but its a really big hydraulic system so to find the problem will be difficult, however the IR camera is a good way as Stick. suggested.

 

[AamerK]

Just wanted to give a final update. The issue has been resolved after taking temperature readings. Two valves we're bypassing a lot of the oil back into the tank, causing the pressure to drop & the system was left with very little oil flow to work with. This also meant that the pump would never de-stroke & would get hot quickly.

Thank you everyone.
Just leaving some of the lessons learnt for future if someone gets into the same problem:

1. When a radial piston pump with load-sense de-strokes, the motor returns to no-load condition & takes approx 20% of the FLA. Also, this type of pump does not reduce pressure when de-stroked, it just allows enough oil to move "forward" to maintain the set-pressure.
2. Best way to test a pump is by measuring the case-drain flow (or better yet just install a correctly sized flow sensor permanently)
3. A thermal camera is excellent for hydraulic troubleshooting. Start in the morning with the entire system at ambient temperature & you'll immediately find the faulty part.

 

[hydtools]

Thank you for the resolution followup. We all continue to learn.

Ted

 

[Stick.]

Thanks for following up. Which two valves ended up being the ones that were bypassing? Were you able to find out why they were bypassing?

On a side note, if you want to get an IR camera for future problems and need to justify it to your boss, they're also really handy for troubleshooting some kinds of electrical problems (I don't know which types of problems you can use it on unfortunately).

 

[AamerK]

The following valves were bypassing oil:
Y432/433 (Size: NJ6) connected to 4 cylinders size 63/28 -50mm
Y420/421 (Size: NJ16) connected to 2 cylinders size 63/40 -250mm

We checked the valves to the best of our ability but nothing was out of place. We think maybe over the years either the spool or the body is worn & there is enough clearance for the oil to go around the spool(its a 23-years old valve, working 16hrs a day)
We have replaced the valves with new ones.

The IR camera is a great addition & the electrical dept has already started their own preventative maintenance with it. And I got a raise thanks to you guys, got more help from here than the OEM.