very slow boom travel on L555

[gregb]

Hello - I've got a 1985 New Holland L555 with the Perkins diesel. The boom travel up and down is suddenly very slow. Bucket cylinder works like normal. Boom cylinders were rebuilt by a local shop two years ago. I can hear the engine work when I raise or lower the boom, like the system is constricted. In float position the boom moves down just as slow. I used it this winter to push snow and then a little this spring to push up a manure pile. No problems. Had it parked in my shop barn after the last work with the boom raised and pinned. Went to do some more work and the starter was out. One month later the starter was replaced, and when I went to move it out the boom circuit was acting up. Pulled the seat and checked continuity in the pressure switch under the seat and it seemed to be stuck. Flushed it out with WD-40 and it is working again. I haven't checked the boom lock solenoid yet. Can it get stuck part way where you have some boom lift and lower function? Or should I focus on the control valve assembly or a relief valve. I haven't had any problems with this portion of the machine and I don't have a lot of experience with this area either. One little possible clue was last year loading manure when I wanted the boom in float position it wouldn't lock in after I ran it for a while, like when it got hot. This winter the float position seemed to work ok, so I don't know if it's connected somehow. Thanks in advance for any suggestions. I do have the operator's manual, the service manual and the parts manual for this machine. Thanks, Greg

 

[skidsteer.ca]

Seem to me the boom lock safety valve if the loader is restricting flow going both ways. Or perhaps a kinked steel line or hose.
often the float on the bobcat brands will quit when the detents balls on the spool wear down do much for them to catch.
Ken

 

[Earthwerks Unlimited]

Seem to me the boom lock safety valve if the loader is restricting flow going both ways. Or perhaps a kinked steel line or hose.
often the float on the bobcat brands will quit when the detents balls on the spool wear down do much for them to catch.
Ken

Have you cleaned the mesh fliter that is in a vertical tube under your right leg when in the op seat?

 

[Mike10]

A relief valve problem should also slow down your bucket circuit. Also a weak relief valve will not labor the engine during a normal raise or lower cycle. You can attach a pressure gauge at the bucket cylinder to check if the relief valve is working. Since you mentioned that the engine works during raising or lowering I am assuming you are getting an adequate oil supply to the pump. That leaves two possibilies, control valve or the boom lock solenoid. There is an orifice plate in the top of the control valve under the fitting that the boom lines attach to. I don't remember if it is the front or rear fitting. It is possible that some debris is lodged in the small hole blocking oil flow. As for the solenoid valve it is possible that something has gotten into it and blocking the flow. There is just no easy way to check it. Since you had the cylinders rebuilt it is possible part of the old seals could have gotten into the hyd circuit. With the standpipe screen mentioned by the other poster there should not be anything getting to the control valve from the hyd pump.

 

[gregb]

Thanks for the suggestions! I got lucky and found the problem. I was confused about where to look partly because I have never actuated the boom lock-out circuit and didn't know what effect it would have on the hydraulics. The impression I got from the manual was that it just stopped travel completely and I had travel but it was slow. So I decided I better start with the electrical circuit that powers that solenoid. Turns out I had wire break right at the quick disconnect plug to the right of the seat. Couldn't get power to the switch. Also turns out that in rooting around for a replacement disconnect I had a brand new pigtail that goes to the seat switch and a brand new switch that I must have bought years ago and forgot I had. So I replaced that stuff. Getting old I think. A little bit of continuity testing of the wiring and I found it. BTW, I did check the mesh filter and it was clean. I had a drive chain break on the right side a while back and drained all the oil, changed filters, etc. in the process of fixing that so the oil is in pretty good shape still. Thanks again for your feedback. Greg P.S. Once I got it fixed I went and pushed up the manure pile that was starting to get kind of spread out. So two headaches gone tonight.

 

[Mike10]

Thanks for the suggestions! I got lucky and found the problem. I was confused about where to look partly because I have never actuated the boom lock-out circuit and didn't know what effect it would have on the hydraulics. The impression I got from the manual was that it just stopped travel completely and I had travel but it was slow. So I decided I better start with the electrical circuit that powers that solenoid. Turns out I had wire break right at the quick disconnect plug to the right of the seat. Couldn't get power to the switch. Also turns out that in rooting around for a replacement disconnect I had a brand new pigtail that goes to the seat switch and a brand new switch that I must have bought years ago and forgot I had. So I replaced that stuff. Getting old I think. A little bit of continuity testing of the wiring and I found it. BTW, I did check the mesh filter and it was clean. I had a drive chain break on the right side a while back and drained all the oil, changed filters, etc. in the process of fixing that so the oil is in pretty good shape still. Thanks again for your feedback. Greg P.S. Once I got it fixed I went and pushed up the manure pile that was starting to get kind of spread out. So two headaches gone tonight.

The Solenoid valve should stop all flow to and from the boom cylinders. If you can get your boom to move when you are not in the seat, even if it is slow, you still have a problem. This is a safety issue and I would advise that if the boom moves when you are not in the seat that you should consider fixing it.