Was removing some stumps and suddenly the vertical lift went limp. It lifts the arm but when you release, it just relaxes. I had to work it, pull in the bucket and elbow, then work the main arm up and engage the "tow" lock. I can raise the main arm, but as soon as I let up on the control, it just relaxes all the way down. I don't see any hydraulic leaks, so assume something in the control is seeping fluid. Anyone experienced this before?
Woods BH75 Hydraulic issue with main arm
- Thread starter filldirt
- Start date
Either seals blown out in control valve or seals gone in cylinder. Would probably hear hydraulic oil bypassing in cylinder. Likely in cylinder.
I can hear fluid flowing when I release the handle and the boom just lowers to the ground. But no leaks. I assume there is a seal kit rather than replacing the whole cylinder?
I got the boom cylinder off; trying to unscrew the rod guide (had to use pipe wrench). It turns (ccw) but doesn't appear to be doing anything. I've made probably 20 revolutions and still doesn't seem to have "unscrewed". Manual says there is a set screw, but I don't see one. Any clues? BTW, learned lesson while compressing cylinder - make sure you have a deflector on the elbow. Can you say "hydraulic fluid shower?"
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I believe there is someting in the tube,may have to buff paint off to see it. It may not be threaded, but a stop screw to retain it. Some cylinders have odd ways to keep them together.
Lil Foot
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Equipment
1979 B7100DT Gear, Nissan Hanix N150-2 Excavator
Sounds like it may have a wire retainer, many styles, here's one, just so you get an idea:
http://www.princehyd.com/portals/0/techFAQ/CylinderSquareWireRemovalInstallation.pdf
http://www.princehyd.com/portals/0/techFAQ/CylinderSquareWireRemovalInstallation.pdf
Thanks Tooljunkie, and that makes sense. Been all around the end, and don't seem to find any retaining mechanism. Here's a 360 deg view of the piston end. Note the "teeth" marks on the rod holder endcap, Turns freely with pipe wrench. I agree there must be something else holding it - just can't figure it out.
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While you have it out, consider applying a little air to one fitting or the other, once ram reaches end of travel if its leaking it will let air out other end. I air test the cylinders when i repair. I know its not hydraulic pressure but its enough to find a leak. So you thought you got an oil bath before,prepare for another. Or take necessary precautions. Ram will move so watch your fingers and other body parts. It will push hard. At least you will know for sure if thats the problem.
Thx. Yeah, I really feel "lubricated". Will try this. $200 for the entire cylinder; not sure if this will fix, maybe something in the control
OK, ToolJunkie, that worked. cylinder responded both directions (minimal oil bath). So, does that point me to the control assy? I have a video, but too large. I noted that there was still "flow" from each connection after the piston reached it's limit. I would have thought that the seals would prevent that. Should I see "blow by" after the piston reaches the limit? I'm thinking not.
Lil Foot
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Equipment
1979 B7100DT Gear, Nissan Hanix N150-2 Excavator
filldirt- In the #2 pic of post #7, there appears to be a shiny round dot on the cylinder, not the cap. Optical illusion? Spring-loaded ball? End of a retaining wire?
That's all I can think of....
That's all I can think of....
I think you nailed it. Applied compressed air and, yeah it was blowing out the other connection when the piston reached it's limit. Ditto when reversing the air.
Lil Foot
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Lifetime Member
Equipment
1979 B7100DT Gear, Nissan Hanix N150-2 Excavator
Damn, thought we were on to something.
Neighbor suggested that there might be a retaining wire under the seal, but I think that's unlikely- on reassembly, you would have to put the seal on the ram, install the ram & end cap assemblies in the cylinder, install the retaining wire, then seat that outer seal. Sounds like too much of a PITA to be practical for a mass produced cylinder.
I guess I'm stumped.
Yeah, me too. ToolJunkie really helped out to identify the issue. the compressed air trick says it is definitely the cylinder and not the control. Might have to order the whole cylinder if I can't get it apart. Dang, $200 vs $30 for the seal kit
Try buffing paint off cylinder just below the end cap that turns. It may reveal something. There are some cylinders that have a set screw, others use a wire and some just turn in.
They are painted after assembly.
Thanks Jim L, I do have that manual. Tooljunkie, I huffed and buffed, grandma's house remained but still no set screw. It does appear there are threads on the inner endcap piece.
I'm surprised no one has commented on my "clean" work bench
I'm surprised no one has commented on my "clean" work bench
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If I can make sense of this I rebuilt all the cylinders on mine just like yours. There is a ring inside. What I had to do is clamp the very top end of the cylinder in the vise where the cap unscrews from the internal part this is what is turning on you the internal piece or nut if you will is floating and held in with a ring. You want to put just enough pressure on the outside of the tube to hold the inside nut from turning. You will not collapse the barrel due to the internal part just clamp the sides so it has resistance and can not turn. Once you unscrew the cap you can get the ring out with a small screw driver and pull the piston out by hand. The new seals are available on line or through a Woods dealer. I found all of mine at a local hydraulic rebuild shop for 30.00 average per cylinder if you have one in your area carry the cap and they can match them up for you. Hope this helps.