3-Point Hitch Motor Stalls when Arms at full height

RonMar · Aug 2, 2012

Linkage adjustment or no, these valves should have a hydraulic pressure relief valve in them. They should never be able to develop enough pressure to stall the engine. In the case of the OP, Minial, in your pics, it looks like the forward most of the two bolts sticking out of the top may be a pressure relief valve... Don't know how you would get a gauge into the system to set it properly though...

Rhogg, look for a square headed pipe plug on top of your 3ph valve. Under that plug you will find washers, a spring and a valve. The number and thickness of washers sets the spring preload and the relief pressure. Yours is easy to measure. Put a gauge into a guick connect and plug it into that outlet port on the back, then try and send fluid to it. The pressure you read is the pressure that the safety is relieving at... Mine was set way too high, in excess of 3000 PSI and I lost a few loader O rings because of it, untill I pulled a washer out of the 3PH relief.

Thats what hydraulic pressure does, it breaks things. I got lucky...

rhogg4594 · Aug 2, 2012

RonMar said:
Rhogg, look for a square headed pipe plug on top of your 3ph valve. Under that plug you will find washers, a spring and a valve. The number and thickness of washers sets the spring preload and the relief pressure. Yours is easy to measure. Put a gauge into a guick connect and plug it into that outlet port on the back, then try and send fluid to it. The pressure you read is the pressure that the safety is relieving at... Mine was set way too high, in excess of 3000 PSI and I lost a few loader O rings because of it, untill I pulled a washer out of the 3PH relief.

Thats what hydraulic pressure does, it breaks things. I got lucky...

Thanks RonMar but I do not know exactly where you mean to find this square headed pipe plug. My problem now is that I have no pressure at all at the rear. I know this because when I used it to tip the trailer last time it lifted and then there was maybe a hissing sound and the trailer slowly dropped down. Before when all was well if I lifted the control arm all the way to the top the engine note would change to a struggle until I moved the control lever down a bit. Now there is no noticeable effect. I have attached three photos which maybe you could use to pin point this adjustable valve for me.

Thanks
Rob.
PS. Minial, I was born in Wellington and spent most of my childhood growing up in NZ.

greg_g · Aug 2, 2012

rhogg4594 said:
I do not know exactly where you mean to find this square headed pipe plug.

Understandable, Ron's describing the Jinma configuration. Depending upon the age, I'm pretty sure your Mahindra is a rebadged Lenar or DFAM

//greg//

RonMar · Aug 2, 2012

Yep, that was what I was describing. I would look for a plug on top of the 3PH control valve block. The pics the OP posted show two bolt heads on top of the valve block. The forward most one looks like a bolt in a bolt/bushing, that is why I reccomended the forward one. It looks like it may be an adjustable bolt with perhaps a locknut, or a screwin assembly with an adjuster in it. This could indicate a relief valve adjustment.

Yours looks to have the same two bolt heads protruding out the top of the valve. What do those do? An exploded parts view of the 3PH valve would probably help you find the relief valve...

RonMar · Aug 2, 2012

Yep, that was what I was describing. I would look for a plug on top of the 3PH control valve block. The pics the OP posted show two bolt heads on top of the valve block. The forward most one looks like a bolt in a bolt/bushing, that is why I reccomended the forward one. It looks like it may be an adjustable bolt with perhaps a locknut, or a screwin assembly with an adjuster in it. This could indicate a relief valve adjustment.

Yours looks to have the same two bolt heads protruding out the top of the valve. What do those do? An exploded parts view of the 3PH valve would probably help you find the relief valve...

rhogg4594 · Aug 3, 2012

Hi Ron
The 'Distributor (Combined Draft-Position Control)' as it is called in the parts manual looks very similar to the one that Minial pictured so I would assume functioned in the same way. I couldn't find a parts diagram on the web of the Jinma model to compare it with so here is a picture of mine.

It maybe difficult to see on my diagram but the parts are listed as follows: 30 Plug, 24 Seal, 31 Spring, 32 Ball, 33 Valve, 34 Sleeve, 35 Seal, 36 Shims, 37 Pin. Would 36 Shims be the way to adjust it or is it about the 30 and 31 that controls the relief pressure?

RonMar · Aug 3, 2012

That whole assembly looks a lot like the relief cartridge in my backhoe. It might be as simple as adjusting the top bolt to set the pressure. But you must have a way to measure the pressure to set it properly.

You said the lift isn't working now? it could be that there is some crud in the relief that is keeping you from building any pressure in the lift cylinder?

rhogg4594 · Aug 4, 2012

RonMar said:
You said the lift isn't working now? it could be that there is some crud in the relief that is keeping you from building any pressure in the lift cylinder?

OK. So I will undo and withdraw the front valve and check it for crud as you suggest. But I might not do this until after haymaking because it takes an age to get hold of parts here. The weather has been terrible and I have never tried to make hay this late in the season. But there is hope that next week there is going to be a break in the rain for five days. After that I will have a go at cleaning up that valve and let you know how it all went.

Rob.

rhogg4594 · Sep 7, 2012

Hi Ron

I have finally had time to remove the forward valve on the control block. No crud, clean all through. It is a simple arrangement without any way of making any adjustments. The top nut removed releases a small long spring that holds a ball within a cylinder that fits into the outer cylinder that is the bigger bottom nut. There is some wear or shine to a side bit of the spring which may indicate that it is bearing on the inner cylinder and sticking or that maybe normal. Otherwise I cannot see that anything is wrong.

I am having a small crack in the radiator fixed so when I get that back I will try it again to see if the problem still exists.

Rob.