I am a newbie to the site and have a JD 310A for home use. Yesterday the hydraulic cylinder for the crowd started moving much slower than normal in one direction only. It would come almost to a stop, then when you let up on the control lever and reapply if would go for a little bit and slow once more. It works at normal speed in the opposite direction and all other hydraulic functions are normal for the other hoe and loader cylinders. No leaks on the machine, filters are new this spring and oil is correct. I am guessing the problem is in the control valve, but not sure how big a problem it is to rebuild. Thanks for your help. Ron
First thing I would do if it's possible is swap the hoses going to that cylinder reversing the control function. If the problem changes direction at the cylinder it's in the valve, if it stays basically the same in terms of the cylinder direction then it's the piston packing.
Does the control valve handle move as much as the other handles in the affected direction? and is this affected direction pushing the spool down in the valve? It sounds a little like what happens when the cap on the bottom of the spool gets filled with oil, not letting the valve open all the way, it will be leaking oil if this is the case, just a drip though, not a huge amount of oil. It's easy enough to take the cover off and see if it's full of oil, then you have to take off the spring and replace the o ring (roughly speaking).
I found that the valve that has the slow return on cylinder does not have the travel that the others do. I have removed the handles and mounting frame for the control valves. Do I need to remove the rubber diaphram covering the control valve barrel and pull the valve out?
Is this affected direction pushing the spool down in the valve? If it does, there's a fair chance it's oil leaking into the cover. The cover is probably? a die cast little piece held onto the bottom of the valve block with two tiny bolts, there's one for each section of the valve bank. There's a spring in there that will keep you from pulling the spool out the top if you decide to go that route. I would swap hoses per lantraxco's suggestion before pulling the valve apart. But that bottom cover is super simple, IF you can reach it.
Delmar: In the overhauling of my swing valve, I have managed to get some hydraulic hoses swapped around. I did a great job of making a paper showing which hose went from which control valve to which port on the distribution 6 ports on the distribution block boom, but managed to LOOSE the paper. Do you have anything that would show the routing of the hoses from the control valve to the block? If so it would save me a 40 mile trip to my JD dealer. Thanks, Ron
No I don't have anything that would show that, and I'm not familiar with the hose routing on that model. If you have two hoses coming from the swing control valve, and four hoses going to the two swing cylinders, then you want the front of one cylinder connected to the rear of the other cylinder because one cylinder pulls at the same time the other is pushing. The distribution block should be just two Tees in effect, one side of the valve connects to the front of one cylinder and rear of the other cylinder, the other side of the valve connects to the other front and rear. How did the other valve issue work out?
Had the valve rebuilt. I took it apart, but the outings are in grooves within the control valve body so I took it to a local hydraulic shop for a rebuild. I have everything back together but have a couple of hoses swapped. JD makes everything so tight you have to disconnect a bunch of hoses to get to the one you want. I had a couple showing wear so I swapped put new ones in. I should have used some cable makers when I started removing things.
If anyone might have a JD 310A, I need some help with hydraulic line routing. During the rebuilding of the control valve I have managed to get the 4 hoses from the control valves to the crowd cylinder and bucket mixed up. If anyone can tell me which port from thone two valves correspond to which port on the distribution block on the boom, I would appreciate it. THANKS, Ron