BX25 - Hydraulic Question...overpressure?

logan1211

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SSV65
Jun 6, 2016
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Hi all, apologize if the wording is poor.

I remember when I picked my BX25 up, the service manager spoke about NEVER FORGETTING to complete the hydraulic "loop" when taking the backhoe off. He said if you do, there's no mechanism to relieve the pressure and something will break? (Pump, something..I can't remember)

I've been super anal about this obviously, triple checking the connection each time, etc. But just want to know more specifically what the risk is, etc.

Appreciate any input, thanks all!
 

North Idaho Wolfman

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It's called dead heading, and really any part can be damaged when that happens.
Anywhere from the pump seals, on down the line to where you dead ended the flow.;)
 

Hassman

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The pump creates hydraulic flow and this -if not diverted by you using a valve- is dumped directly back to tank, if the flow is interrupted (deadheaded as previous poster states) then the pressure will increase rapidly until something breaks. As far as I know the hydraulic system has no pressure release valve, if it has then this valve will open and dump excess pressure back to tank, and then in theory nothing should break but the oil will get really hot as the release valve orifice is very small.

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CountryBumkin

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I don't have a BX25 service manual, so maybe the BX25 is different.
But the other BX models have (multiple) pressure relief valves. I would be shocked if the BX25 didn't have a relief valve.

The problem/risk with deadheading, is more that you are running the hydraulic system at full pressure all the time, and therefore wearing out the pump faster and putting full pressure on all the parts/lines. The oil will get very hot and possibly overheat which could then result in a catastrophic failure, and there is the risk that the relief valve could stick/fail thereby over pressurizing the system causing a failure.
 

North Idaho Wolfman

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Well after CountryBumkin's post I was inclined to look at this further.
Most Kubota hydraulic systems have one relive valve and it is after the three point lift control, and is the end of the line.
Yes you can have a second on the loader valve but the BX doesn't even use that.
The BX's relief valve is at the beginning of the loop at the pump so the likely hood of doing any damage to the system is very low, yes it will get hot from bypassing but the system is essentially safe from any damage due to over pressurization.
 

logan1211

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SSV65
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Missouri
That's it! He did call it deadheading. Makes total sense.

Thanks for doing more digging as well. Appreciate the feedback, all.