Deere 260 loader on a 2940

[Chuck1234]

I've got a 260 mechanical self leveling loader on a 2940. Someone (who didn't know what they were doing) mounted this loader on the tractor and has been running it with the tractor's remotes. The top mechanical leveling linkages have been damaged and after some investigation I can see why. Apparantly there is supposed to be a relief valve mounted on the right hand side of the loader that allows the curl cylinders to move when they come under force from the boom cylinders via the mechanical leveling linkages. This valve is missing from my loader.

From what I can see, the factory valve had two inlets, and two outlets to the cylinder plus a return to tank line. I believe that this valve is called a cushion valve or counterbalance valve because you need to transfer oil from one side of the cylinder to the other when allowing it to move. I've found plenty of cushion valves out there, but I've not seen any of them with a return to tank line. Anybody familiar with this system? The part from Deere is over $1000, so thats just not an option.

 

[J_J]

I believe the valves you describe will bypasses to opposite side, and if it does, there is no need for a return line..

1/2 NPT 30 GPM 1500-3000 PSI HYD CUSHION VALVE

Cushioning and Decelerating Methods for Cylinders*|*Womack Machine Supply Company

 

[Chuck1234]

J_J your right, but I believe they are typically used with either a motor or two equal area cylinders. In this application a double acting cylinder is being compressed and stretched so if you feed the oil from one side to the other then when your compressing you've got too much oil and when your stretching you don't have enough.

 

[Zebrafive]

My JD 245 loader has that valve. Wow it costs 30% of what I paid for the complete loader.
I think the only time the valve comes into play is when the bucket hits it stops. So If you are not fully curled and trying to lower the boom or fully dumped trying to raise the boom you should not have a problem.

My JD 640 loader in also mechanical self leveling, but does not have a relief valve in the bucket cylinders. I don't know why

 

[Chuck1234]

My JD 245 loader has that valve. Wow it costs 30% of what I paid for the complete loader.
I think the only time the valve comes into play is when the bucket hits it stops. So If you are not fully curled and trying to lower the boom or fully dumped trying to raise the boom you should not have a problem.

My JD 640 loader in also mechanical self leveling, but does not have a relief valve in the bucket cylinders. I don't know why

Your right about when it functions, but if it's not there it will wreck those 2 inch square tubes. As me how I know....

I've read that some mechanical loaders are designed in such a way that the boom cylinders never put a load on the bucket curl cylinders and therefore are not needed. Can you do me a favor and look at the valve on your 245 to see if there is a name or number on it? Thanks! I believe that it's basically a cushion valve with an extra relief valve that is set at a slightly higher pressure that returns to the tank

 

[Zebrafive]

Here's a thought:
Install the cushion valve AND install a TEE in the line from the cushion valve to the rod end of the cylinders. To this TEE connect a relief valve that has a tank port. Run a line from the tank port back to tractor sump. Set the relief valve greater than pump pressure.

When the cushion valve transfers oil from the rod end to the head end of the cylinders, no problem, there will be more room than oil in the head end.
When the cushion valve transfers oil from the head end to the rod end of the cylinders the excess oil will go through the relief valve to the tractor sump.

This might be how the factory valve works combining a cushion valve and relief valve.

You do this for less than $1K too.

 

[Chuck1234]

Here's a thought:
Install the cushion valve AND install a TEE in the line from the cushion valve to the rod end of the cylinders. To this TEE connect a relief valve that has a tank port. Run a line from the tank port back to tractor sump. Set the relief valve greater than pump pressure.

When the cushion valve transfers oil from the rod end to the head end of the cylinders, no problem, there

will be more room than oil in the head end.
When the cushion valve transfers oil from the head end to the rod end of the cylinders the excess oil will go through the relief valve to the tractor sump.


This might be how the factory valve works combining a cushion valve and relief valve.


You do this for less than $1K too.

That is my guesstimate of how it works and also my plan if I can't find something that is an integrated unit. Of course if I can find the factory equivelant then I'd prefer to go that route. The one problem that I can see is that while the extra relief will get rid of the "extra" oil when compressing the cylinder there will not be enough oil when pulling the cylinder rod out. There will technically be some cavitation on the piston side when that happens. I think it would be minor and not happen nearly as often as the compression scenario.

 

[Zebrafive]

Go to ebay and search: 251002298824
It's a relief valve kit for a JD 265 loader, $75 shipped.
Might work

 

[Chuck1234]

Go to ebay and search: 251002298824
It's a relief valve kit for a JD 265 loader, $75 shipped.
Might work

Great minds think alike. I'm watching that item, but apparently the 265 has a different circuit. I've looked at jdparts.com and have ordered a manual for the 265 so I can see how they are plumbed

 

[Zebrafive]

What it looks like to me is two relief valves, one for each bucket cylinder line. They have three ports, looks like in, out, and a return to tank.
This must be pre cushion/relief valve.
The list of parts included several part numbers for instructions: W38986, W40632, & W43418

Service department of your local JD dealer may be able to print them out for you.

 

[Tx Jim]

Chuck1234
Does your 2940 have the correct mounting frames that go from side mount to rear axle?? If not you may end up with a cracked/broken clutch housing. The utility tractor hyd schematic in the 260 parts cat. shows no relief valve for self leveling that you refer to.

 

[Chuck1234]

Chuck1234
Does your 2940 have the correct mounting frames that go from side mount to rear axle?? If not you may end up with a cracked/broken clutch housing. The utility tractor hyd schematic in the 260 parts cat. shows no relief valve for self leveling that you refer to.

Yes, I do have the mounts that go back to the rear axle.

You do have the return line in your post, but the relief isn't visable because its mounted on the loader frame. See attachment. Item 23 is what I'm looking for.

 

[Zebrafive]

Yes, I do have the mounts that go back to the rear axle.

You do have the return line in your post, but the relief isn't visable because its mounted on the loader frame. See attachment. Item 23 is what I'm looking for.View attachment 344703

My JD 245 loader has the same valve. I had trouble with the tubing (not shown) used for the return to sump line getting pulled out of the fittings so I replaced it with 1/4" hydraulic hose.

 

[Chuck1234]

Zebrafive, could you please take a look at your valve to see if you can find a manufacture or a part number on it? Thanks!

 

[Zebrafive]

Zebrafive, could you please take a look at your valve to see if you can find a manufacture or a part number on it? Thanks!

Will do next time out to the barn (6 miles away)

 

[Chuck1234]

Thanks Zebrafive!

 

[Tx Jim]

Chuck
Sorry I left JD dealership about the time 260's were introduced.
Here's parts key #23
AW34774 Pressure Relief Valve 1 (SUB FOR AW20908)
AW25329 Pressure Relief Valve 1 008001 - (USE WHEN LOADER IS EQUIPPED WITH SPECIAL ROLL-BACK LINKAGE)
Here's the spec's on one valve

Try this schematic for plumbing using remotes..

 

[Zebrafive]

On my valve cast on the front is AW20908 (must be an old one) On the back are two rows of numbers
116804
6479
Also cast on the back is a small rectangle box. Inside the box are four leaves? fanned out. Maybe this is a trade mark of the maker?

 

[Tx Jim]

AW20908 subs to AW34774 Pressure Relief Valve ADD 1,085.51 USD

 

[Zebrafive]

AW20908 subs to AW34774 Pressure Relief Valve ADD 1,085.51 USD

Saw that in your post #17, that's what makes me think I have an early loader.