Today I drained the hydraulic tank and removed the inlet hose. There was no screen or snap ring. Someone removed it and never installed it. Since I was thar far I removed the entire inlet hose to the pump to make sure nothing was stuck inside it. Nothing was. After putting everything back together I went to the backhoe value block. The boom hoses look to have been replaced not that long ago. The boom valve had the small round can looking cap on the top of it. I removed it. I'm almost sure it is an adjustable pressure relief valve. I took it apart, cleaned and reassembled it the same way it was. It was clean on the inside. After reinstalling it the hoe still works the same way. There is something else on the lower side of the boom valve. I'm not sure what it is. After it was together I had some more time to work all the functions. I now realize that when working the dipper nothing else works at the same time. No swing left to right, no bucket curl, and no stabilizers. When working the boom everything else will work with it but everything seems slow to move.
K5lwq
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It is a flow issue. Take a clean 5 gal bucket and mark it at 2 gallon mark. Then take a hose from a cylinder that is working and time how many seconds to get to the 2 gallon mark. Then repeat with a hose from a cylinder that does not work so well and compare numbers. Then do the math to determine GPM. Tractor data list flow at 31GPM.
At what RPM should I perform this test at? Since it is a flow issue does it matter what cylinder, I check? If I tested the boom and dipper, could they be within spec since my issue is a combination of two or more or would they still show low flow tested individually?
K5lwq
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About 2000 RPM should be sufficient. I like test from multiple spots. Also for over all pump flow you could do it from the pump. Although that is tougher without help.
Testing from the pump would be hard to do. If I have a flow problem when using a combination of functions, would testing individual cylinders probably still show low? Each function by itself seems ok but could be slow and I just do not know it be a new owner. I have noticed lowering the stabilizers, one by itself seems ok but both together are very slow.
rScotty
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Great! It sounds like you are beginning to pin it down. You may want to skip the flow testing. It is interesting, but I can't see how it leads to a solution.
My thought is that without the screen to filter out the inevitable bits of crud that any system has, I'm more convinced that the problem is one of the auxiliary poppet valves associated with the dipper spool valve is being held open. That open valve is diverting the extra flow that would normally be available to the other cylinders. Instead of being available to power other motions, the extra flow is going directly to the return line anytime you use the dipper.
Each major two-way cylinder - boom, dipper, bucket, swing cyiinder set, and thumb if you have one -
is extended or contracted by a spool valve. But because it of the way a backhoe works, each spool valve has to have two relief valves (one for extend & one for contract), plus each spool valve has to have a check valve so it keeps its position when another cylinder is working, and each spool valve has to have an anit-cavitation valve so that if the hoe's motion overpowers one of the cylinders then some reserve fluid is available to prevent cavitation in the cylinder.
That is a minimum of 4 discrete spring-loaded poppet valves per spool valve. I think you need to look at your shop manual and find all those for the dipper spool valve, take them apart and clean them. One of them is being held open and dumping your flow to the return line.
We just went through all this on another thread. It's not unique to Ford 555 hoes.
Backhoe Side to Side -- Stuck?
Thanks rScotty! Funny you mention the pushing it back, that's what I did once on a stump already, just hooked it and drove around to straigthen it out... I don't mind it being random\weird but when I'm going 10mph down a 1 lane road with 200 homes and it randomly slams to the other traffic...
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rScotty
Thanks Scotty. That sound like my issue exactly. I do not have a shop manual yet so I'm kind of guessing at this point. I did take off a valve yesterday that was on the top side of the dipper spool valve. I think it was an adjustable pressure relief valve. Under the cap was a jam nut, adjustable straight slotted shaft/pin, spring and a valve in the bottom. On the bottom of the spool valve is a larger type of valve. I'm thinking this is the one you're referring to. I would think all these poppet valves have to be together and right next to the related spool valve. One thing I think is not the issue but want to mention. I noticed that I have one 90 degree fitting that has a slight bend to it. It's on the hose that would pull the dipper in. I took the hose to a hydraulic shop and was told it was not causing any restriction.Great! It sounds like you are beginning to pin it down. You may want to skip the flow testing. It is interesting, but I can't see how it leads to a solution.
My thought is that without the screen to filter out the inevitable bits of crud that any system has, I'm more convinced that the problem is one of the auxiliary poppet valves associated with the dipper spool valve is being held open. That open valve is diverting the extra flow that would normally be available to the other cylinders. Instead of being available to power other motions, the extra flow is going directly to the return line anytime you use the dipper.
Each major two-way cylinder - boom, dipper, bucket, swing cyiinder set, and thumb if you have one -
is extended or contracted by a spool valve. But because it of the way a backhoe works, each spool valve has to have two relief valves (one for extend & one for contract), plus each spool valve has to have a check valve so it keeps its position when another cylinder is working, and each spool valve has to have an anit-cavitation valve so that if the hoe's motion overpowers one of the cylinders then some reserve fluid is available to prevent cavitation in the cylinder.
That is a minimum of 4 discrete spring-loaded poppet valves per spool valve. I think you need to look at your shop manual and find all those for the dipper spool valve, take them apart and clean them. One of them is being held open and dumping your flow to the return line.
We just went through all this on another thread. It's not unique to Ford 555 hoes.
Backhoe Side to Side -- Stuck?
Thanks rScotty! Funny you mention the pushing it back, that's what I did once on a stump already, just hooked it and drove around to straigthen it out... I don't mind it being random\weird but when I'm going 10mph down a 1 lane road with 200 homes and it randomly slams to the other traffic...
rScotty
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Well after looking at the hose routing I realized I made a mistake. The pressure relief valve I took off yesterday was for the boom and not the dipper. Today I took off some kind of valve for the dipper spool valve and took it apart. I did not see anything wrong with it. There is a part of it I cannot get apart. It's in the first picture. It's the very top left part. There is a spring and a valve inside it. It must come apart somehow. I did kind of screw up slightly. I did not realize that was a jam nut for the cap on the very top and did not count the turns when unthreading it. There is discoloration on the threads on the inside and the picture should help some putting it back together.
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rScotty
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Yep. Just for review.....A backhoe spool valve array is composed of a bunch of identical spool valves bolted together like a sandwich so each spool can work individual BH cylinders while sharing common high pressure and return circuits. And each spool valve has its own team of small identical protection poppet&spring valves mounted on it.
Most common is for each spool valve to carry an upper combination reliefs/anticavitation valve, a lower comination relief/anticavitation valve, and a single centrally located load check valve.
So one guess now is that one of those safety valves associated with the dipper or boom spool valve has some crud caught under it and is providing a path for high pressure fluid to escape.
If you had the shop manual, with decent hydraulic diagrams you probably could figure out which particular valve is not working right by logic & comparing which functions are not working.
Some people even claim they have gotten BH checks and reliefs working again by extending a boom or dipper and then letting it drop an inch and "bouncing" it repeatedly to get crud to move. It might be worth a try...but I'd be careful and if it doesn't work not pursue it.
luck,
rScotty
Last edited:
rScotty
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Some pictures from Messicks.com
Looks like it only has a single system-wide load check valve (24 or 29)
But there are the paired relief valves we were discussing clearly shown. From their complexity I would guess that the anit-cavitation function is included.
Text says parts are discontinued... That's something I haven't run into much with our JD310.
Where do you go for parts? A spare brand new set of relief valves would sure be handy.
New Holland 555C - 4 CYL TRACTOR LOADER BACKHOE(11/88 - 08/93) Parts Diagrams
New Holland Parts Catalog Lookup. Buy New Holland Parts Online & Save!
www.messicks.com
But there are the paired relief valves we were discussing clearly shown. From their complexity I would guess that the anit-cavitation function is included.
Text says parts are discontinued... That's something I haven't run into much with our JD310.
Where do you go for parts? A spare brand new set of relief valves would sure be handy.