MF 1835M loader support collapsed on tractor

[CE2]

That’s a couple really bad breaks. I have MF1533 with a 120 FEL and my mounts look a lot more structural stronger than yours. The only problem I’ve had is broken and loose bolts that attach the loader mount to the tractor frame. I’m definitely going to add looking for cracks to my maintenance list.

 

[ROUSTABOUT]

No one said 'can't', only that it shouldn't be trusted.

First off, he should have been inspecting regularly and caught it when it started cracking.

 

[sjmedin]

Looks like bad design, with not enough support for the load. If you repair it, I would weld a plate behind
it to increase support.

 

[Retired LE]

Was moving dirt today when all of the sudden my loader started going down all by itself. This was crazy looking. You can see in the photos that the loader sub frame View attachment 802798 gave way on both sides. It appears to be either bad welds or cheap metal. Either way, it’s nuts that it would do this with only 140 hours on it.

It least it failed slowly and not catastrophically.

 

[BCLoco]

I hate to tell you that is not correct. Once the spool is centered it is the same as if the hoses were capped. No way for the relief to do anything for the loader hoses and cylinders. In an open center valve that utilizes the power beyond feature then any valve after the loader valve would be protected by the loader relief. Often times the loader valve is first valve in series and would be plumbed straight from the pump. The tractor relief is after the loader and can be set lower to release before the loader valve.

You could set the second valve to 100 psi and the loader would still produce the pressure that it’s relief is set at.

No. My post is completely correct in how my hydraulic system works (and that's the one we're talking about here since the OP has the same system), and it's how most--if not all--modern open-center hydraulic systems work.

Lets sort two things out:

1. Main relief valve is located immediately after the main hydraulic pump, in the transmission-mounted hydraulic block. Not after the loader valve.
2. Power-Beyond (PB) port in the loader valve has nothing to do with what we're talking about here. Forget about it.

Ok, so the loader valve spools, once in the neutral position, have separated the hydraulics into two circuits:

1. The main system hydraulics, which are still running and cycling fluid at almost zero pressure since this is an open-center system.
2. The loader circuits, where all ports are closed and the hydraulic pressure is relative to whatever weight is on the cylinders.

The loader circuits pushing back against the spools, are also tapped to a pressure relief valve, mounted on the loader block. If the pressure in any cylinder circuit exceeds 2610psi, the loader relief valve opens and sends that fluid down the Return line, back to the hydraulic sump or tank.

Honestly that's as straightforward as I can make it. If you still don't understand how the system works, Google it or go to Youtube since a picture or video is going to be way more helpful to you.

 

[ptsg]

No. My post is completely correct in how my hydraulic system works (and that's the one we're talking about here since the OP has the same system), and it's how most--if not all--modern open-center hydraulic systems work.

Lets sort two things out:

1. Main relief valve is located immediately after the main hydraulic pump, in the transmission-mounted hydraulic block. Not after the loader valve.
2. Power-Beyond (PB) port in the loader valve has nothing to do with what we're talking about here. Forget about it.

Ok, so the loader valve spools, once in the neutral position, have separated the hydraulics into two circuits:

1. The main system hydraulics, which are still running and cycling fluid at almost zero pressure since this is an open-center system.
2. The loader circuits, where all ports are closed and the hydraulic pressure is relative to whatever weight is on the cylinders.

The loader circuits pushing back against the spools, are also tapped to a pressure relief valve, mounted on the loader block. If the pressure in any cylinder circuit exceeds 2610psi, the loader relief valve opens and sends that fluid down the Return line, back to the hydraulic sump or tank.

Honestly that's as straightforward as I can make it. If you still don't understand how the system works, Google it or go to Youtube since a picture or video is going to be way more helpful to you.

Unless the loader valve in that tractor in particular has work port relief valves, which I doubt it has, then there is absolutely 0 protection from the loader main relief valve with spools centered, just like K5 said.

 

[CE2]

Do you know the rated capacity of you FEL? It might be that the FEL mounts on the tractor are not rated for that specific model FEL. My FEL is rated for 1000 lbs and hopefully the mount rating matches also.

 

[BCLoco]

Unless the loader valve in that tractor in particular has work port relief valves, which I doubt it has, then there is absolutely 0 protection from the loader main relief valve with spools centered, just like K5 said.

Maybe I'm misunderstanding the hydraulic diagram, but is that not a 2610psi pressure relief valve in the top middle? If I'm wrong, then I do apologize for the misinformation.

 

[aircommuter]

Interesting. Do you happen to have a diagram how this works? I always thought when the spool is centered it closes all other ports off so no way for the relief to work.

The valve banks have reliefs built in often for each circuit so one function doesn’t overload another. Most noticeable in a backhoe. Perhaps some budget machines don’t employ a system like that.

 

[sea2summit]

Looks to have been cracked for a little bit too.. then finally gave way while you were working.

Agree. Looks like the corner wasn't welded at all and the crack probably started there.

*not a professional, just a WAG