Backhoe 447 backhoe problem

[AKfish]

update:
no loose fittings, linkages are tight, all quick connects are tight, piston(boom cylinder) moves fine with air only

what i've found is that when the lever is actuated(pushes down) nothing happens, it just releases the pressure, does this mean something is wrong in the "switch" it acts as if its not activating when pressed?

it looked as if there were just 2 allen bolts holding down the bracket around where the switch is, i didn't take them off wanted to check here first and see if this helps anyone

thanks again......jp

Hmmm... from your description of symptoms - sounds like a valve body issue.

I'd go to JDPart's (if you don't already have the Technical Repair manual) and look for a detailed printout of the 447 valve body to help clarify the likely next step in the troubleshooting/repair sequence.

AKfish

 

[kennyd]

The next step in trouble shooting is a pressure gauge before you tear the valve apart...you need to attach it to the hose and see if the valve is supplying proper pressure.

 

[docjupa24]

I don't hear anything when I press the lever, no change like with the other levers, I tried to purchase the manual online, I'm gonna call my dealer tommorrow and see if they have or can get one, what is round about cost if the valve needs repair

 

[AKfish]

The next step in trouble shooting is a pressure gauge before you tear the valve apart...you need to attach it to the hose and see if the valve is supplying proper pressure.

Yep... maybe I got ahead of myself! I'd guess you should quantify/verify just how bad the valve really is... and then rebuild the valve body or have it rebuilt in a local machine shop that can repair cylinders, etc.

AKfish

 

[kennyd]

There is not much to go wrong in a spool valve. There is a sliding "spool" that moves to direct fluid from the IN port to either work port. There is not usually any seals in them as they are honed/lapped for a precision fit. Most of the time the problem is linkage related.

 

[docjupa24]

if u can see the lever moving the piston up and down, can it still be a linkage problem

 

[J_J]

Try removing the hose that pulls the boom, and activate the lever to see if any fluid is coming out the hose, or put a gage in the work port that controls the pull. Maybe a work port relief stuck open.

 

[kennyd]

if u can see the lever moving the piston up and down, can it still be a linkage problem

Is it moving the spool (what you called the piston) all the way? I don't know...but like I said, there is just not a lot of things to go wrong in a spool valve.

 

[docjupa24]

seams to be moving the spool up and down, just like the other levers, its just nothing happens when spool gets pushed downward

 

[Cocre]

Perhaps I missed it, but this is the boom cylinder, right? Is it when the cylinder extends? If so, I would think it is the circuit relief. According to the schematic there is such a valve on the extend side of the boom cylinder. If it is stuck open no pressure would develop.