Too much pressure? Blowing hydraulic lines.....

[tho2nd]

Hey all,

I’m running an M7060 with a Wallenstein GX920 backhoe.

Within the last three days I’ve blown two hydraulic lines. One was a line for the main boom, and the other was the main line that connects to the tractor valve body. (The lines blew at different times)

I was digging a stump and putting significant pressure on things.....

Is it possible that the tractor generates too much pressure for the hoe? The hoe specs say its operating pressure is 2250psi. I am running the tractor at around 2200-2500 RPM.

Thoughts? Thanks for any feedback,

TH

 

[bernhardine]

The operating pressure of your M7060 should be 2830 psi.

Maybe thats higher than the backhoe should work with, but it's far below the burst pressure of the lines.

How old are the Lines of the backhoe and at what point did they burst?

 

[tho2nd]

Tractor and backhoe were new last year......and I can***8217;t say exactly when the lines burst. I can say I was definitely putting pressure on things to break roots and pry the stump.

When I first starting using the backhoe (as in when I first bought it), any amount of pressure would cause the valve lever in the cab to ***8220;trip***8221; and return to neutral shutting off hydraulics to the hoe. The dealer told me to manually hold the lever in position to prevent this from happening so Once engaged, I wedge the lever into place. Any experience with this?

 

[Dave_eng]

Do you have a loader on your M7060?

How many rear remote valves do you have?

Did the hoses break just at a fitting or in the middle of a hose?

Can you invest $30 in a 0-3,000 psi pressure gauge and a quick coupler male fitting so you can plug the gauge into your rear remote?

Dave

 

[tho2nd]

Hi Dave,

I have the LA1154 loader (with 1 remotes on front for grapple) and two remote valves on rear.

Both hoses blew out the hose itself.....not at a fitting.

And sure, I'd be willing to put some sore of valve inline.....I'd have to do a little research on that one...

 

[tho2nd]

I use the detent valve for the backhoe. As mentioned earlier the valve self-cancels with hardly any pressure while using the backhoe, so I lock in in place which essentially prevents it from self canceling. This was recommended by my dealer.

The owners manual states this valve will remain open until pressure reaches a predetermined level.

Is this predetermined level adjustable?

 

[North Idaho Wolfman]

I use the detent valve for the backhoe. As mentioned earlier the valve self-cancels with hardly any pressure while using the backhoe, so I lock in in place which essentially prevents it from self canceling. This was recommended by my dealer.

The owners manual states this valve will remain open until pressure reaches a predetermined level.

Is this predetermined level adjustable?

I would get a pressure gauge on it and find out what it's doing exactly.

 

[Dave_eng]

I use the detent valve for the backhoe. As mentioned earlier the valve self-cancels with hardly any pressure while using the backhoe, so I lock in in place which essentially prevents it from self canceling. This was recommended by my dealer.

The owners manual states this valve will remain open until pressure reaches a predetermined level.

Is this predetermined level adjustable?

The remote valve detent is just a convenience feature and does not provide high pressure protection in the way you are experiencing the hose rupture.

Something other than the remote valve is going on.

Getting relief valve pressure readings on the tractor rear remote is imperative.

See attached image for the pressure gauge setup. Gauges available at any hydraulic shop or on line.

Dave

 

[GreensvilleJay]

I'd be contacting Wallenstein PDQ ! Send them pictures of where the TWO hoses ruptured, or at least the distance from a the fittings. It is possible they got a substandard batch of hydraulic hose and that extra 500# pressure IS enough to make them burst. Ask them if anyone else has had blown hoses. Be sure to document ( write down) everything if you can, how old, +-hours of actual use, what operation blew the hose.
While hoses are usually tested at 3X operating pressure, that means nothing if the hose is 'bad'.
It's also possible the tractor's putting out ,say 3000# and THAT is well above the 2250# number for the BH.
Frankly I'd be 'gun shy' ...waiting for the 3rd hose to blow, hopefully NOT get hit with high pressure oil.

 

[tho2nd]

Thanks for all the input. I’ll build a gauge and test some pressures.

Probably dumb questions, but I’ll ask anyway:

-Is it possible to incorrectly connect the backhoe’s supply/return lines?

-So far, no negative comments about locking the detent valve open.......safe to assume that’s an acceptable way to operate?

Getting a line built today and also will build pressure gauge.

Message in to dealer. Waiting for response.

 

[GreensvilleJay]

re: -Is it possible to incorrectly connect the backhoe’s supply/return lines?

i don't have any first hand knowledge but...

It shouldn't be possible as there should be male/female couplers to make it 'goof proof', same as snowplow setups for Jeeps......

I KNOW the BX23S is goof proof....

IF it isn't M/F.....replumb as required

 

[boz1989]

There is a backhoe that has a low pressure return line, 500psi, I believe it was Kelley. If that backhoe was hooked up backwards, you would blow the return line, but nothing else.

Personally, I think you have a bad batch of hoses, but I would check the pressure.

Sent from my LGMP260 using Tapatalk

 

[tho2nd]

I put together a gauge and tested pressure. Nearly a constant 2650psi.....idle and at 2200RPM.

Dealer is also suggesting bad batch of hoses. They're a pretty reputable place and they said if I have any more issues, they'll take care of things.

Thanks a lot for all the input. I definitely learned a little with this thread.

TH

 

[North Idaho Wolfman]

Thanks for all the input. I’ll build a gauge and test some pressures.

Probably dumb questions, but I’ll ask anyway:

-Is it possible to incorrectly connect the backhoe’s supply/return lines?

-So far, no negative comments about locking the detent valve open.......safe to assume that’s an acceptable way to operate?

Getting a line built today and also will build pressure gauge.

Message in to dealer. Waiting for response.

Yes it is possible especially if they are the same fittings.

Doing so could cause relief valves to not operate properly.

 

[Dave_eng]

re: -Is it possible to incorrectly connect the backhoe’s supply/return lines?

i don't have any first hand knowledge but...

It shouldn't be possible as there should be male/female couplers to make it 'goof proof', same as snowplow setups for Jeeps......

I KNOW the BX23S is goof proof....

IF it isn't M/F.....replumb as required

On the M7060 machines, the rear remotes are made to operate double acting cylinders.

The factory single remote, before the up to two more optional ones are added, will also handle single acting external cylinders.

The remotes are not like a power beyond backhoe loop on smaller machines.

Dave