Backhoe 447 backhoe problem

[docjupa24]

hey all, my backhoe suddenly today will not pull the boom in(down), it works fine going in everyother direction but coming toward me, the bucket opens and closes, will swing right to left and back, even will go up and down, the same piston extends and flexes it, it extends out with power, only comes back in with gravity, i had this happen once before and the jd shop told me it had too much fluid in it, it hasn't been touched since they "fixed" it, it has worked without problem for 2 years, worked yesterday and even started ok today, i was cleaning out a ditch line, i took the line off and fluid flowed without problem, any ideas.

thanks in advance....jp

 

[orlo]

hey all, my backhoe suddenly today will not pull the boom in(down), it works fine going in everyother direction but coming toward me, the bucket opens and closes, will swing right to left and back, even will go up and down, the same piston extends and flexes it, it extends out with power, only comes back in with gravity, i had this happen once before and the jd shop told me it had too much fluid in it, it hasn't been touched since they "fixed" it, it has worked without problem for 2 years, worked yesterday and even started ok today, i was cleaning out a ditch line, i took the line off and fluid flowed without problem, any ideas.

thanks in advance....jp

Doc:

This probably isn't it but I had a very weird similar thing happen to me once with the loader. One of the quick fittings (The pressure one on the cylinder in question) looked connected, but it wasn't. I had the same symptoms. One direction under power, the other direction just Gravity but not far.

Worth a check.

 

[AKfish]

The backhoe runs off the Power Beyond circuit at the rear of the tractor. It does have 2 very large quick-disconnects, however. But, if one of them were loose - you would not have complete hoe function for all the cylinders - curl, dipper, left-right, etc.

Sounds like it's a problem with the boom cylinder. Any hyd fluid leaking? I'd check the 2 hyd lines for the cylinder and look over the cylinder end-piece; snap ring come off?

If you cannot see a problem externally - I'd suspect you have a packing "problem" inside the cylinder.

AKfish

 

[Egon]

All the control levers still hooked up and properly adjusted?

 

[docjupa24]

everything appears to be hooked up, it acts like when you activate the lever, nothing happens, it doesn't bog down or anything like when you try against resistance, the cylinder is probably the easiest to get to, i might just have it repacked and see if that fixes it, weird though, it did the exact same thing a few years ago, same motion and everything.

there is no fluid leaking, and i was in the process of working when it decided to stop, i took the quick connects off and put them back on, still nothings, i'll check the contol levers again, i'll keep you posted, thanks for the ideas

 

[xrjohndeere]

It may be something is stuck in the backhoe valve unit not letting the fluid divert to that valve. Try disconnecting that cylinder and cycle it with an air hose. Watch your eyes for spraying fluid. If the cylinder works with the air it is not your packings. Good luck.

 

[Cidertom]

recheck valve linkage from control handle to valve body. I had similar problem with my 448. Forgot exactly which, but the symptoms sound familiar. Other than that, the valve body may have shreded an O ring.

 

[Cocre]

You can order a very good backhoe technical manual from Deere. I bought the PDF and it covers several models. From your description I cannot determine the cause, but they do list these as some of the possibilities; 1) Look for a pinched or restricted line, 2) Oil leakage internal to the cylinder, 3) Load check valve malfunction, 4) Circuit relief malfunction 5) other stuff.

I would also check your loader quick connect fittings. I wouldn't think they would have anything to do with the power beyond circuit, but you never know.

 

[docjupa24]

i'll try to check all links tommorrow, gotta be at hospital at 6a, they are inducing my wife in the morning, so the next 2 days or so might be out, i'll post up with what i find
thanks for the ideas

jp

 

[docjupa24]

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

 

[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.