Hyd problem

   / Hyd problem #1  

bneal

New member
Joined
Jul 20, 2011
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3
Tractor
john deere skidder 540b
I have a jd 540b skidder I replaced leaky hose in stearing now the hyd stop working after running for a little while. Is there a proper way to bleed lines after replacing hoses.
 
   / Hyd problem #2  
I have a jd 540b skidder I replaced leaky hose in stearing now the hyd stop working after running for a little while. Is there a proper way to bleed lines after replacing hoses.

On most systems just operating them will bleed them. Are you talking ALL the Hydraulics not working or just the steering?
If all, First and foremost, is there oil in the reservoir?

If just the steering, try cracking a fitting loose on hose you changed and turn the steering wheel. Does air bubbles and or oil come out. DON"T get pinched in pivot assembly doing this.

If you do not get air bubbles or oil out this fitting then something in the steering system has failed.

Roy
 
   / Hyd problem
  • Thread Starter
#3  
Thank you for the response. I flushed hydraulic system and put new filters and fluid in. The machine ran fine for about two hours and then stopped, no transmission, sterring, blade or grapple functioning. I turned skidder off and let sit for 10 minutes, started and the machine would operate for about three minutes and quite again. I'm thinking that the problem maybe the pressure relief valve, this will be my next step, any suggerstions?:confused?
 
   / Hyd problem #4  
Not familiar with skidders so these are just some questions to possibly help narrow down the problem.
When it works does everything work properly or does it seem weak and or sluggish?

Is there any unusual noise?

Are the filters return line or does this model have a charge pump and filter system?

Did you mess with any suction lines when doing this work? I guess at this point the best suggestion I have is to start back tracking where you worked and what you changed.

Is a hose getting pinched? Did a fitting work loose? Etc.

Roy
 
   / Hyd problem
  • Thread Starter
#5  
The machine works great when it is running.
There are no unusual noises.
Charge pump and filter system.
There are no leaks.
It just stops operating no hydraulic pressure.
 
   / Hyd problem #6  
How many pumps do you have on the skidder? You probably have more than one. Does the lift/bucket work. Do you have aux pump?

If you have a hydrostatic transmission, is it a closed loop system, kept charged by the charge pump.

If I just motor the pump over on my Case 1845c, I believe the charge pump pressure is up around 450 lbs.

If you are sucking air, you won't be pumping much. Look in the tank for bubbles.
 
   / Hyd problem #7  
Sir, did you find the problem, I have a bobcat 751 that's doing the same thing. I just rebuilt the lift and tilt spool assy. Everything worked OK for about 30 minutes and the everything just slows down and then stops working. No drive and no lift or tilt.
 
   / Hyd problem #8  
This seems like a natural for JJ's oft recommended troubleshooting technique. A pressure guage teed in at various points, assuming they are acessible, will tell you where there is zero pressure. I would try the pump outlet first, sounds like a classic case of a suction leak.

Not that I ever did anything like this but back when diesel equipment was less sophisticated one could drive
an operator/mechanic nuts by dropping a rag in the fuel tank. Rag would find it's way to the fuel intake and either stop or lose all power. Stop engine, rag floats away from intake, engine runs normally until......

Anyway, I would pay special attention to the suction side, clear into the sump
 
   / Hyd problem #9  
Cycle_Gator

I appreciate you taking the time to respond. I do have a filter that comes off the bottom of the hydraulic tank and from the filter it goers to the lift and tilt valve body. There is a second hose that come off the tank and goes to a teed port on the valve body too. If seems like maybe one is the main hydraulic feed to the valve and pump and the other would maybe be a a return line to the tank. After work today I will remove that hose off the bottom of the filter and see if I am getting a gravity flow of oil from this filter.

Maybe J_J can help, he did reply to my post about my problem and ask a couple of questions. I could sure use a hand/mind on this thing.

Thanks again
 

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