JD 1530 _ FEL & 3pt issue

[rScotty]

If your control valve resembles valve in photo check for failed seal(item 10).

I still remember locating that same seal that had failed on a tractor with a model 48 loader that I was attempting to diagnose a hyd problem about 50 yrs ago

Yes, I agree with that. It might be that he has the correct control valve for the closed hydraulic system and it has a failed seal. But I would have thought that the hydraulic shop he took it to would have caught that with the test they did.
rScotty

 

[rScotty]

There is no factory hyd oil accumulator on a JD 1530 hyd system to become discharged.

That's curious....no acccumulator? What does it use instead? A closed center system has to have something performing the accumulator function to tell the variable flow pump to back off on the pressure when it is dead-headed. Of course I could be wrong about his 1530 having a closed center hydraulic system. I don't have a hydraulic schematic for his 1530 or any 1530 for that matter. I'm just relying on a couple of reference books that say the 1530 has a closed center system, and on the fact that JD's closed center system is pretty standard. TractorData.com also says closed center.

Then again, this is a pretty old tractor. Things could have been changed. While it is just about impossible to convert an open center hydraulic system to closed center, it should be possible to go the other way. I've never done it, but I'll bet someone has somewhere along the line. Done right, it could be a money saver on hydraulic system repairs....
rScotty

 

[Tx Jim]

Scotty
Yes JD 1530 has CC hyd system.. JD closed center hyd systems from '65-'92 are very similar in operation. The stroke-control valve in the frt hyd pump controls pressure. When stand-by pressure reaches set pressure of 2250 psi for majority of models the oil pressure inside hyd piston pump crankcase forces pistons away from rotating pump shaft which causes pump to cease pumping oil. Pressure is trapped in lines. When pressure falls below the "set pressure" springs forces pistons down against the rotating shaft & oil pumping commences. Check out the thread below as it has some utility oil schematics. I've witnessed open center valves installed on CC systems which causes poor hyd performance but I've never seen anyone try to convert a CC system to OC system or vice-versa. I'm not understanding your thought of how changing CC to OC could save $$$$ because not all control valves are convertible from one type to the other & hyd pumps are totally different.
https://www.tractorbynet.com/forums...5618-john-deere-1640-strange-hydraulic-2.html

 

[rScotty]

Scotty
Yes JD 1530 has CC hyd system.. JD closed center hyd systems from '65-'92 are very similar in operation. The stroke-control valve in the frt hyd pump controls pressure. When stand-by pressure reaches set pressure of 2250 psi for majority of models the oil pressure inside hyd piston pump crankcase forces pistons away from rotating pump shaft which causes pump to cease pumping oil. Pressure is trapped in lines. When pressure falls below the "set pressure" springs forces pistons down against the rotating shaft & oil pumping commences. Check out the thread below as it has some utility oil schematics. I've witnessed open center valves installed on CC systems which causes poor hyd performance but I've never seen anyone try to convert a CC system to OC system or vice-versa. I'm not understanding your thought of how changing CC to OC could save $$$$ because not all control valves are convertible from one type to the other & hyd pumps are totally different.
https://www.tractorbynet.com/forums...5618-john-deere-1640-strange-hydraulic-2.html

OK. Glad to hear that all the 1530 had a CC hyd. system. So we haven't been spinning our wheels here advising the OP. The info is all valid.

I didn't know that JD stored their pressure in the elasticity of the lines instead of in an accumulator. I am curious what you think of doing it that way. For my part I'd say that using line elasticity will work, although a more formal accumulator might still be added.

Do you agree that if there is an OC control valve on the 48 loader that it could be causing all the symptoms the OP reported?

As for converting CC to OC, this is something that used to come up in mechanical bull and beer after work sessions back when they were in person rather than online - that all seems a thousand years ago now with the virus. As I said, I don't think anyone ever actually did it. I never did.

Basically the point is that if the "set pressure" of a CC pump is somehow locked so that the variable pum always runs at full capacity, then it is behaving just like a constant volume pump in an OC system. We were not talking about changing the pump itself. Just the way it works....how to make a CC pump work like an OC constant volume type. A person might concievably want to do so if their expensive variable flow pump wore so much that the pistons and wobble plate were stuck in the wide open flow condition. The idea being that an OC control valve (or just the conversion plug) might be a cheaper fix in that case than a variable volume pump replacement. I agree that would be difficult to impossible to pull the pump itself and try to replace it with another type. But there would be no need to change the pump, as by preventing the pump from changing to the no-flow condition it has become an OC pump.

I guess that the point of the bull session is that by locking the set point to full "ON" a CC pump can be made to work like an OC pump, but there is no similar way to make an OC pump reduce its output like a CC pump can. Also that CC pumps are WAY more expensive than OC pumps.

Hey, thanks for the references. I'll look them up.
rScotty

 

[cjburke42]

Took the valve out.
It appears to be the correct one only missing most of the oring.
Now I will have to wait until Tuesday to go to hydraulic shop after the holiday unless Oreilly would carry a square oring box.
John Deere can get the part but its not in stock.

 

[Tx Jim]

Yepper reminds me of a similar failed o-ring I finally located many yrs back when I first started diagnosing closed center hyd system problems. Replace that seal with a good seal & you'll be amazed how much better your tractors hyd system will operate.

United Ag & Turf in Magnolia Ar. shows to have 3 ea-U30255 in stock

 

[Tx Jim]

Scotty
I still think from diagnosing hyd problems on CC hyd systems for yrs it wouldn't be ""easy or cheap"" to change from CC to OC or vice-versa.

 

[rScotty]

Scotty
I still think from diagnosing hyd problems on CC hyd systems for yrs it wouldn't be ""easy or cheap"" to change from CC to OC or vice-versa.

Congrats to CJ for taking the valve out and having a look. It's amazing what you can find by taking something apart.

Yes, Jim. I agree. The change is mostly interesting because it just might be possible. The special case where it might be worth doing would be where a very expensive variable volume pump had a mechanical failure of some kind that caused it not to be able to move its wobble plate & pistons to "full off".

There's a good reason why we only see Closed Center systems on the more expensive and sophisticated machinery. Open Center isn't better, but it gets the nod when the goal is less expensive & simpler. So OC is what is used for most homeowner and small Ag machines.

Obviously the goal is to understand both, and maybe we have done some of that in this thread.
rScotty

 

[Tx Jim]

JD CC pumps utilized from '65-'92 do not utilize a wobble(swash) plate. I'll reiterate IMHO changing hyd system from CC to OC might be doable but will cost more $$$$$ & time than the cost of hyd pump to replace/alter valves from CC to OC configuration.

I remember attending JD sales & service meetings declaring how great CC hyd's were when compared OC hyd's utilized on other new tractor brands such as Ford & how much more fuel efficient CC hyd's were compared to OC hyd's. Today as you stated most lower priced new equipment has OC hyd's leaving some higher priced equipment to CC & CCLS hyd's. Having spent yrs diagnosing CC hyd malfunctions I'd choose OC hyd over CC hyd's any day for general farming operations.

 

[rScotty]

....snip...... Having spent yrs diagnosing CC hyd malfunctions I'd choose OC hyd over CC hyd's any day for general farming operations.

I agree. In fact, all of my equipment is OC. But I don't want to give anyone following along the wrong idea. OC vs CC isn't the most important thing that makes a tractor a good one or not.
IMHO, some of the best ever 2wd farm machinery ever was the 20 thru 40 series JDs built in the mid 1960s and thru the 1970s. Most of that was CC (not all), but the quality of those tractors was so high that it compensated. A lot of them would compete well on the farm today. You still see them in use around here, especially for haying & 80 acre crop farming. Working well and running fine.