2005 Jinma 284 - 3PH valve binding

[ctusdenny]

Hi folks. I've had a slight issue with my 3PH control valve lately. This is the control valve on the RH side of the seat that lowers/lifts the 3 pt. hitch.

When I actuate the valve to lift the hitch, I feel almost a "grinding" resistance and the lever becomes almost stuck. If I push it forward/backwards a couple times, it works okay. No leaks anyway.

And here's some more info: I just drained and refilled by hydraulic system. new filter, and AW32 oil. Got everything changed, let the tractor idle for about 5 mintues, and then drove around a bit actuating the front FEL, rear lift, etc.

A few days later, when I started up the tractor from cold, the 3PH wouldn't lift at all. I didn't think too much about this as I figure the hydrualic system needs to warm up, etc. It normally comes to life after letting things warm up.

Anyway, while I was waiting for the 3PH to "warm up" and start working like I normally do, I was raising and lowering the front FEL while paying no attention to the rear 3PH. As it turns out, I had pulled the 3PH lever back to the lift position (fully back where it would lift the rear hitch without holding the lever). When I lowered the front FEL, the rear 3PH lifted at the same time. I thought that was odd, so I tried it a few more times, and each time I lowered the front FEL, the rear 3PH would lift (even cold).

So...what's happening here? Is there a check valve somewhere that's clogged? Or is my 3PH control valve shot? Maybe that's part of the "grinding" issue I'm having with this valve?

Thanks
Denny

 

[doxford jim]

Can't help you on the TPH lever and valve, but I would recommend that you put in an external relief valve for the hydraulic pump. This could save you from losing the engine driven hydraulic pump.
I learned the hard way and it cost me a fair bit of money. The hydraulic pumps are around $250 each to replace.
If you find out what you have wrong with your TPH controls - please post as us others could learn from it.
Thanks.
PS - have attached what I did on my tractor for relief valve setup.

 

[ctusdenny]

Can't help you on the TPH lever and valve, but I would recommend that you put in an external relief valve for the hydraulic pump. This could save you from losing the engine driven hydraulic pump.
I learned the hard way and it cost me a fair bit of money. The hydraulic pumps are around $250 each to replace.
If you find out what you have wrong with your TPH controls - please post as us others could learn from it.
Thanks.
PS - have attached what I did on my tractor for relief valve setup.

Thanks. Nice setup.

 

[quicksandfarmer]

It's hard to tell from your description, but I would think it's a mechanical problem with the handle binding or slipping. Here's how the lift control works: First, there's the control handle, obviously. If you look on the right lift arm there is a rod about half the thickness of a pencil connected to it, that goes back to the base of the handle. That rod is called the feedback link and it measures how high the lift arms are. The control handle and the feedback link connect to another link, in such a way that if the handle is higher than the lift arms that link goes one way and if not it goes the other way. That link is connected to the actual valve that controls the lift cylinder. If the handle is higher than the lift arm the valve is opened to allow fluid into the cylinder and lift the lift arm, if the handle is lower than the lift arm the valve is opened to allow fluid out of the cylinder and lower the lift arm, and if they're at the same height the valve closes and nothing happens.

So I guess the point is that the handle itself isn't directly connected to anything, and grinding and sticking in the handle isn't a symptom of anything wrong with your valve, it's more a symptom of the handle itself being bent or catching on something. If you look into the handle area you should be able to see all of these pieces, they're all external, and with the engine off if you move the handle and lift the lift arm you should see the link moving back and forth depending on the relative positions of the lift arms and the handle.

The feedback link does need to be adjusted periodically. There is a turnbuckle on it that adjusts its length. My recollection is that my owner's manual said the adjustment procedure was, with the engine running, put the handle in the full up position, then adjust the feedback link length until the lift arms are at their highest position.

I would inspect the handle for any interference and adjust the feedback link.