Go BottomBackhoe major jerky
 | rpuffd
Join Date: Jan 2005 Posts: 20 Snohomish WA 
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2005-03-09 107664
I have a backhoe that for the most part, works very well. But no matter what speed the engine is running at, the up/down on the boom is always very jerky and fast. Is there any way to adjust this ?, or is there some part that has worn out and needs replacing ? All other movements, left/right, bucket, and the bucket arm work very smooth with no jerky action. It is just the up/down on the main boom. Any advise is welcome and thanks in advance.
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York 
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2005-03-09 107676
Look for loose lines that might be leaking! If oil can get out it also can let air in! It could be anywhere on the main hydraulic system so don't rule anything out. ....
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| rpuffd
Join Date: Jan 2005 Posts: 20 Snohomish WA
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2005-03-09 107679
Art, I did find a bit of leakage yesterday, but not much. Had to tighten down what appeared to be some kind of adjustmenet on the main valve body. But, it was for the left/right movement which is smooth, and not for the up/down. Tried up/down after tightening anyway and still the same jerky action. I will have a look for other leaks but the valvle body is clean as a whistle. Thanks for the advice. ....
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 | DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2005-03-09 107698
My BX22 spoiled me. My JD 46 hoe is not the same quality.
It does just what you describe, and I have narrowed the problem down to sloppy fitting joints. ....
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| rpuffd
Join Date: Jan 2005 Posts: 20 Snohomish WA
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2005-03-10 107711
This BH is certainly not what I would call a quality unit. I compared it to the BH on my neighbors Kubota and there is no comparison, the Kubota BH is clearly the winner. I will have a look at the joints and replace the bushings if necessary. Thanks for the input. ....
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 | earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2005-03-10 107748
Have you checked the reservoir fuild level? I have a medium-size dedicated TLB and when (shame on me for not checking) it get's low on fluid that's what is does--it sucks air and the pump cavitates. My hoe's "stick" cylinders are relativley large compared to its other system cylinders and require much more fluid and therefore suck the (unchecked) reservoir clean. My bad. Note to self: Fix leaks in morning. ....
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| rpuffd
Join Date: Jan 2005 Posts: 20 Snohomish WA
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2005-03-10 107762
I did check the resivour fluid level and it was right up there on full and clean as a whistle. I think at this point,I will just have to live with it the way it is. I may be shoping for a better BH soon ! It is very hard to work with in this "jerky" condition. Thanks for the input. ....
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| rpuffd
Join Date: Jan 2005 Posts: 20 Snohomish WA
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2005-03-11 107774
I have remembered one other clue that may be part of the problem. If you park the BH all the way up and dont latch the safety, the main arm(up/down) sinks to the ground by the morning. Would this have anything to do with it being jerky ?, and if so, how does one fix this ? Thanks again. ....
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 | beagle
Join Date: Jan 2004 Posts: 1333 Michigan 
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2005-03-11 107775
Don't know how many hours you have on the BH, but you may have a worn spool in the control valve. This cetainly would explain the drift down, although some of that is normal, but could also expalin the lack of control you have while operating. Pulling the spool isn't a real big job, but does require care. If you aren't confortable with it, take the valve to a hydraulic shop and have them do it.
If you don't have any kinks in the line, faulty quick connects, or leaks, your problem is probably in the valve. If your work ports have load checks, you could also have a bad load check that is sticking and causing the jerky motion, or a worn spool like I mentioned earlier. With the other functions operating fine, I would have the valve section checked. There is an outside chance that the seals in the cylinder are worn, but with the drift down, I would check the valve first. Sounds like a valve problem. ....
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| earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2005-03-11 107779
I'm still fuzzy on the term "jerky". A siezed up pivot joint would give that effect if it overcomes being stuck and suddenly releases. My front loader bucket started doing that one day and all of a sudden I went to curl the bucket and the piston rod snapped in two. Siezed pivot.
Also the wrong kind of hydraulic oil will allow the oil to become filled tiny airbubbles (aeration) which causes a loss of pressure and volume in the cylinder not only at the cylinder but at the pump (cavitation). And if you combine that with sticking pivots and seals that are possibly stiff or sticking, all that adds up to pent-up added friction. ....
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2005-03-11 107780
Just a little on how hard things might be to locate. Had a local TLB full size that nobody could fix! We did and it took quite a bit to figure out. We worked on the lift cylinders,valve and the complete system as the main loader boom jerked while raising,the bucket worket fine and there was a jerk on the main backhoe boom while raising. Under the right step was the fiter for the hydraulic system,which we did change the filter and did notice a dent in the cover but there was no visual leak of oil at all. It did allow air to be sucked into the system and cause the jerkyness!!!! ....
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 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2005-03-11 107784
The other possibility is the valve itself, but not from wear or leaking.
Some valve banks are visually all the same, but internally different, as is the case with the float function on a FEL.
If the valve running the boom operation is letting too much fluid past then the result will be as described.
Some valves have a hex-head screw with a locknut that can be turned to adjust the flow rates. Check if that is the case on your valve.
The other possibility is that at some point in time somebody replaced the valve and the new one is the wrong specification. Often they use several different flow rates withing one bank of valves as a way of evening out the operation of various sized cylinders.
Best of luck. ....
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| rpuffd
Join Date: Jan 2005 Posts: 20 Snohomish WA
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2005-03-14 107965
Well I believe I have my problem solved. I had my neighbor who operates heavy equipment take alook. In about two seconds of operation, he had it figured out. The main bolts holding the BH to the subframe were loose. Tightened them up and the difference is like night and day. I likley would never have spotted this on my own. Thanks for all the suggestions. ....
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| DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2005-03-14 107974
I figured it was something slopping around. I am going to check mine for the same problem today. ....
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| RELISH21
Join Date: May 2005 Posts: 10 ROCHESTER NH
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2005-05-22 111366
My backhoe on my Kioti CK20HST model KB2365 is alot smoother and more responsive than what I had on my Kubota BX23. I think it is the weight difference the quality of the backhoe manufacterer. ....
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