hydraulics question

arborworks1

arborworks1

Treehouser
Joined
Oct 17, 2006
Messages
2,754
Location
hartsville, sc
Hydraulics, man what a pain. The chipper quit feeding yesterday. When you put a limb in the feed wheel stalls. Turns fine when no load. Everything else works no problem. I have isolated it down to the feed roller motors. Woodsman so dual drives on one large wheel. I had noticed when we where crushing brush sometimes the feedwheel would stall out but pick back up as soon as I let of of the down pressure. My question is do hydraulic motors wear out and instantly lose power?
 
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  • #4
The only thing that had a small leak was the valve that runs it, Bypassed that with the crush valve and still the same thing, I took everything out of the equation, autofeed. I straight plumbed it from the valve right to the motors and the same deal. I did all this at a hydraulic shop, I am just a little shocked that the motors just completely stop working all together. Never got slow when feeding, just stopped completely. the shop said they see it all the time, Just wondering if anyone else has experienced anything like this
 
Not normally ,they do it over time . You obviously have something bypassing and lowering the pressure .

Every hydraulic system has a pressure relief valve somewhere in the system ,start there . Check the filter ,anything that could hinder the flow .

Oh say ,I just remembered some thing .Some if not all auto feed chippers have a valve the works off of engine speed .If the speed dies down to a certain level it cuts off flow to the feed wheels .It's actually a type of flow valve .

Tom the tree guy had one on demo this past summer that did the same thing and that was the area I traced it down to . I can't remember the brand of chipper but it was painted a color of red .
 
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  • #6
Al, I disconnected all the lines from the autofeed, plumbed it straight from the valve to the motor. all my reliefs were letting the correct pressure through. I can't think of anything else, but that the motors were bypassing somewhere internal. They were not leaking anywhere, no seals or blocks around the case all dry. They motors are plumbed together so if one is bypassing then the other is going to follow suit, I would assume.
 
Put a tee in the line and plumb in a gauge .

I suppose the wear plates could give up the ghost if it's a gear motor .If It's orbital I haven't a clue . Just seems odd for it to die on the vine out of the clear blue like that .:?
 
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  • #8
I left it with the boys at the shop. They are going to take the motors apart and see if they are worth rebuilding. I was hoping it was just my leaky valve, But it can never be cheap, never.
 
arborworks1 said:
They motors are plumbed together so if one is bypassing then the other is going to follow suit, I would assume.
Click to expand...
Aha ,hold the phone .In series ,one after the other or in parrellel like the lift cylinders of a dozer .

In one after the other ,it won't make any diff because if one bypasses the other one still gets full pressure and flow .In tandom one could bypass to the tank and rob flow to the other .

If in tandom ,block off one of the pressure lines and see what happens .
 
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  • #10
guess they would be parellel, or tandem. There is a tee off the top of one motor with lines to the other. I just ran out of time and patients with the shop guys. They were slow and it was hot. Kinda Like the crane operator from last week(that is for another thread)
 
I think they're usually in series that way they both go approximately the same speed. It also seems odd to me for them to give up quickly. I had a similar problem once and the problem was the rod connecting the push bar above the chute to the hydraulic valve was bent, and therefore not opening the valve all the way.
 
stehansen said:
I think they're usually in series that way they both go approximately the same speed. It also seems odd to me for them to give up quickly. I had a similar problem once and the problem was the rod connecting the push bar above the chute to the hydraulic valve was bent, and therefore not opening the valve all the way.
Click to expand...
That is one of the feed valves if I get the picture clearly .Kind of a safety deal .

Oh Lawdy troubleshooting a hydraulics problem is almost as bad as a chainsaw at long range over the net --but we try ;)
 
I had a similar problem with my old Bandit chipper, but it turned out to be simply low fluid level. My crew tightened up a loose fitting a few days before but apparently it lost a good amount of hydro fluid before they noticed.
 
This is just a thought and Im sure not the case but wtf worth a few key taps. Is your pump direct drive off the motor or belt driven off the pulleys. If it is belt driven it could just be a loose belt. Too simple??
 
Hydraulics can drive you nuts at times ...

Not to sidetrack but recently I experinced problems on the splitter I am building .Wrong pump ,wrong rotation .I tried my hillbilly enginerring to retro fit the damned thing but to no avail .

Bite the bullet and order the correct one .:whine:
 
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  • #18
ITs direct drive off the motor. I Have ruled out all the simple things. I wish it was one of them though! The only thing that I can deduct from all the tests and troubleshooting is that one of the motors is bypassing and will not continue to turn the feed wheel when a limb is contacting it. It will turn like its suppose to all day long. There is some play in the feed wheel when the chipper is shutdown. Would that be indicative of bad motors. The woodsmans have a direct connect to the hydro motors no bearings involved
 
My guess would be the control valve before I would go after a hydraulic motor. If you can find the manufacturer you can buy internal parts instead of replacing the whole motor. Did that once also instead of buying a whole new motor.

Had this happen twice, once on a chipper, same problem, also a stumper that wouldn't swing the cutter head. The valves were bypassing internally and would not hold pressure under load. A hydraulic motor could do in therory do the same thing but would probaly be leaking like a sieve. The valve has o-rings inside of it that go bad
 
The valves are a possibility . I had a bad one on a splitter I worked on last winter . Actually I would have never thought in a million years a valve could go bad but in fact it was . A call to Northern hydraulics and about 90 bucks fixed the problem .
 
My chipper has a flow divider that splits the flow 50/50 so the wheels spin the same speed regardless of load.

I believe Woodsman chippers only have one feed wheel eh?
 
I believe that chipper Tom had was a Morebark or something like that and it was the valve that caused the problem . The dealer claimed it was okay but Tom sent the darned thing back ,figured it had more problems that what the dealer admitted to .

It fed just fine on 4 inch stuff but would not feed at all on 8 inch stuff . It was supposed to be able to gobble up 12 or larger .
 
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