2640 Hydraulics

[Danfitz55]

I have been having problems with the steering on my 2640 tractor. It is an early model. When the tractor is running and in park the power steering does not work when I begin the move the steering seems to work as it should. I have a front-end loader, and it is plumbed with a tee on the back of the pressure control valve going to the SCV and is returning through the filter. When I am driving the tractor and operating the loader the steering wheel likes the jerk. After running the tractor for a while I sometimes lose hydraulics completely. I just replaced all seals for the steering valve thinking it would fix the problem, but it didn't. Could I have a problem with the pressure control valve itself. Just looking for some help. Thanks.

 

[Tx Jim]

I suggest to check FEL control valve to be sure it's configured for the 2640's closed center hyd system. Simple test disconnect FEL control valve return hose from tractor & cap open hyd orifice on tractor.

With FEL control valve levers in neutral, engine operating at idle speed, aim open FEL control valve return hose into hyd filler hole behind seat & no oil should exit open return hose.

Also with hyd oil at operating temp, 3 pt raised, engine operating at idle look into hyd filler hole behind seat for moving spraying oil. Moving oil indicates faulty rockshaft control valve seals.

 

[Danfitz55]

The control valve is installed with the loader is for closed center. I believe I had to install a plug to make it closed center. Also, the Rockshaft is operating fine I also replaced the seals a few years ago.

 

[Tx Jim]

I can guarantee that although your FEL control valve had closed center conversion plug installed that if the inner seal(green color) fails your tractors hyd system will suffer & not operate as designed. If steering doesn't operate as designed I fail to understand how 3 pt can operate as designed due to steering has priority hyd pressure over 3 pt hitch.

 

[Danfitz55]

I have the loader hooked up with quick connect fitting with them both disconnected the steering does not work as it should, and the 3 point works fine. I figured that disconnecting the loader would rule that out. I will still try what you suggested.

 

[Tx Jim]

Probably no need to test FEL control valve since disconnecting FEL control valve didn't improve operation of hyd's. I'm guessing 1 or more of the 6 large o-rings in steering valve has failed. If that's correct the o-rings can be R&R by removing steering wheel & large nut then turning steering shaft CCW out of housing then check condition of o-rings with a spotlight

 

[Danfitz55]

I already rebuilt the steering valve and replaced all the O-rings. I was really hoping that it would fix my problem.

 

[Tx Jim]

If the 6 large o-rings are good & in correct "lands/grooves" then only thing left is faulty control spools or not shimmed correctly.

 

[Danfitz55]

I did not do anything to the control spools or shims. Could I have a problem with the pressure control valve or possibly the relief. Today I drained all the oil out and pulled the filter and suction screen did not appear to be plugged or dirty. I also pulled the relief and when I was inspecting it, I pushed down on the spring and the initially it seemed rough or partially stuck and then freed up and moved easily. I am also going to inspect the pressure control valve while I have it drained. Is there anything else I can check? Thanks.

 

[Tx Jim]

Pressure control valve was installed to give priority pressure & flow to power steering. If 3 pt, scv & loader operate correctly then if tractor was under my supervision I would not disassemble pressure control valve. When I served as a JD dealer service manager for 13 yrs I can't remember PCV ever being a hyd problem on these style tractors. Does your tractor have hyd IPTO or hyd hi-lo/reverser?

 

[Danfitz55]

It has an independent PTO and Hi-Lo.

 

[Tx Jim]

I recommend to heck operation of hyd system after hyd oil has reached operating temp in both hi/lo speeds & pto off /on.