Hydraulics Plumbed Wrong?

[Moss Man]

Yet another forum to consume the spare time that I don't really have!

I have a JD Industrial 401 and for some reason the 3-point hitch hydraulics won't lift much of anything unless you bottom out one of the bucket controls, then it will lift about anything. Example; the 3-point has my firewood processor(1700 lbs) on it and the 3-point will not begin to raise it off the ground, by bottoming out the bucket in the tilt position the hitch then raises the processor easily. I suspect someone made some plumbing errors when the backhoe was removed from the machine or maybe something is amok with the rock shaft?

 

[kennyd]

Welcome to TBN

I am not sure how it's supposed to the plumbed, but it sounds like there is a restriction somewhere in the rockshaft valve or the hoses that feed it (are there any QD's? (quick disconnects)in the rear?)

By bottoming out the curl like said-you are raising the system pressure to maximum levels (whatever the relief valve is set at) to overcome the restriction.

 

[rdbrumfield]

Check your oil level. with the loader on the ground and bucket curled back there is the least displacement of oil in the loader. when lifted and buck rolled forward there is more oil in the loader possibly starving the system for the 3pt.

 

[RickB]

Yet another forum to consume the spare time that I don't really have!

I have a JD Industrial 401 and for some reason the 3-point hitch hydraulics won't lift much of anything unless you bottom out one of the bucket controls, then it will lift about anything. Example; the 3-point has my firewood processor(1700 lbs) on it and the 3-point will not begin to raise it off the ground, by bottoming out the bucket in the tilt position the hitch then raises the processor easily. I suspect someone made some plumbing errors when the backhoe was removed from the machine or maybe something is amok with the rock shaft?

The 401 should have the old, pure closed center hydraulic system. It sounds to me like you have a massive high pressure leak to tank in your loader control valve. When you plug the leak by deadheading the bucket circuit, the system builds pressure and the hitch works as it should.

 

[Moss Man]

Welcome to TBN

I am not sure how it's supposed to the plumbed, but it sounds like there is a restriction somewhere in the rockshaft valve or the hoses that feed it (are there any QD's? (quick disconnects)in the rear?)

By bottoming out the curl like said-you are raising the system pressure to maximum levels (whatever the relief valve is set at) to overcome the restriction.

There are no quick disconnects on the rear, it looks like this back there;

The plumbing looks like this for the bucket;

 

[Moss Man]

A friend who works at a JD Dealership mentioned this; "check your stroke control valve on the front pump".......I wouldn't even know where to begin on that suggestion or any of the replies here. I am mechanically inclined, but this might be beyond my skills.

Another thing that I have noticed is that the loader control valve has started to leak and it is hot to the touch, seems to be pressurized while the tractor is setting there running the processor?

 

[kenstrac]

The 401 should have the old, pure closed center hydraulic system. It sounds to me like you have a massive high pressure leak to tank in your loader control valve. When you plug the leak by deadheading the bucket circuit, the system builds pressure and the hitch works as it should.

I would think your right maybe pressure relief blowing by that would cause valve to heat up.

 

[rdbrumfield]

I would have to say by the color of that valve body it has been hot. Put a pressure guage on the pump side of the valve, it should read close to zero just sitting running. If it isn't something in the system is blocking.

 

[kenstrac]

I would have to say by the color of that valve body it has been hot. Put a pressure guage on the pump side of the valve, it should read close to zero just sitting running. If it isn't something in the system is blocking.

This is a closed system the pressure will be about 2500psi

 

[banjodunn]

G'day i think you are spot on ken i would say the relief in the control valve is blowing off way too early need to tighten it right up and allow the tractor relief to control the system pressure good luck