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Hydro Ax 611 EX hydraulic issues

Started by MarkShaw, May 03, 2019, 11:37:21 AM

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MarkShaw

One of my guys has a 1996 Hydro Ax 611 EX w/ 2 post hydro ax saw head that he's having hydraulic issues with.  It was getting to where it was having pulling issues.  Not wanting to go up a steep hill and if he got it up against a stump, it wouldn't want to go over it.  Now the disk won't turn on.  I can't find any kind of service manuals available.  Where should we start checking?  He does have a gauge.  We just haven't been able to figure what the pressures should be or how to isolate stuff in the system to figure it out.  Any help is appreciated. thanks,
Mark

kiko

Are boom and arm function operational?

MarkShaw


kiko

The drive and saw functions are separate except for common tank .  As far as the saw goes, there is a electric solonoid valve in the control valve compartment that applies pilot pressure to the saw control valve when activated. This valve is usually in small blue aluminium block.  It has two wires , one powers from saw switch and the other is frame ground.   Other possibility is that the drive for the saw pump has stripped out or pump has failed.  
Any time a hydrostat drive system power fades as the oil heats there is usually internal leakage .  Also on this machine the hydrostat charge pressure is tapped to provide pilot pressure for the joysticks and solonoid control valves.

MarkShaw

He may have figured out the saw issue. He's got a chunk of wood stuck in it.....duh..lol.  As far as the pulling, he says it doesn't change if it's hot or cold.  He says it'll throw you back in the seat when you mash the pedal hot or cold from a level start.  But, if you stop at the foot of a hill, or up against a stump, it won't hardly go.

mike_belben

Either the fluid that powers the drive section is not being pumped or it is being pumped and is leaking back to tank before doing the work.  A temp gun will help find the hottest spot in the system which will point toward the location where this unutilized energy is bypassing the circuit before doing work. 

 Bad pump, bad relief valves, bad control valve or bad drive motor are the frequent culprits.  A mechanics stethoscope can also help find it.. Listen for high pitched whines and such while under load.  Trash in a valve seat.  Worn or cracked gear roller faces in motors, broken relief springs or even worn out linkage pins in the control rods that move a valve.  Remember that spools must be moved a metered amount for correct operation so positional drift can be a simple mechanical issue on spool control. So for example, a nail in place of a 5/16 pin doesnt cut it. That sort of thing.  I dont know much about servo controls but obviously that offers a whole nother tier of fail to diagnose.
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