L39 loader problem

KennyV · Sep 28, 2005

Jim...
The dirty connections are probably leaking, but for this to be your down pressure problem, you would be spraying fluid all over the place.
I think your first assumption was probably accurate. Hydraulic fluid is bypassing, (leaking) somewhere in the system. This can happen in the cylinder(s), control valve, or the pump bypass. Since you have not noticed a reduction of the back hoe performance, I would not first suspect the system pump pressure relief.

You should be able to lift your tractor with the bucket dump cycle. While doing that the boom cylinders should not expand. If they do disconnect them at the quick disconnects and try it again.

You can check the control valve by switching the quick disconnects for loader curl and boom… that will isolate the individual valves.

If you have rear remotes, run the output from a rear remote set to your loader cylinders that also should check the cylinders. Rear remote should have the same PSI as loader valve at full.

This is getting long but unless your complete hydraulic system is low on pressure one of the above checks should isolate a problem. KennyV.

mike69440 · Sep 29, 2005

</font><font color="blue" class="small">( Mike and Sky,

Can you do me a favor...I need to know how each of your machines react to these two simple tests:

1. With brake on, curl your bucket with the cutting edge straight down and attempt to lift the front wheels of the machine. Result? How far in inches lifted...

MCW Ans.
My loader is a weakling. Dealer cranked up the relief valve, which helped a bit. Main pump Pressure is not right. Only 2650 PSIG.
Loader Arms will Lift the machine all the way just barely.

If I try to lift machine using the bucket curl

2. Engauge the rear stabilizers fully and then attempt to lift the front wheels of the machine with the bucket curled. Result?

MCW Ans.

I should lift, but never could. Skypup's can I think. Mine never could. Dealer replaced defective loader valve and said plunger was mushroomed over on original loader valve from Factory? New Loader valve made no difference.
I need this input for the dealer when he shows up.

Thanks /forums/images/graemlins/smile.gif )</font>

Main Pump Pressure only 2650 Psig

We need to find out how to get in touch direct with Kubota Engineering!

JimMorrissey · Sep 29, 2005

What should the main pump pressure be? I thought 2650 psi was correct......

Sky says he can lift the front end with the stabilizers down. Mine can't...not even two inches. No problem with the brake on....lifts it right up without hesitation.

SkyPup · Sep 29, 2005

The main pump is factory preset for 2,650psi.

JimMorrissey · Sep 29, 2005

OK, with the help of SWinTexas05 (Simon) I'm thinking I might be OK. He pointed out something that I should have realized. Basically there is no way for the L39 to lift itself with the stabilizers down. The machine weighs close to 9,000 lbs and the loader would be tasked with an impossible feat being that the stabilizers don't roll easily and primarily that the fulcrum is much further back adding a tremendous amount of weight. Simon mention that he has the same problem with much larger equipment.

My machine currently lifts the front end with the rear wheels on the ground...effortlessly. So how did I get it up in the air so high with the stabilizers down (in the picture)? I remember now....I lifted the front with the rear tires on the ground as high as it would go, then I used the BH to lift the rear end and drop the stabilizers, then I'd lift the rear a bit more until the stabilizers were fully extended. Maybe I'm not having problems after all and I'm just trying to lift 3,000 lb boulders? Could it be that I'm asking too much of a small TLB?.....Never /forums/images/graemlins/tongue.gif

I'm still going to have the dealer check the hydro connections and check the pressure. I have a feeling all is well and I cried wolf with the dealer. Not good. Oh well.

Thanks for the PM Simon! Appreciate clear thinking.

BTW: Does anybody know if a loaders down force is equal to the lift force?

KennyV · Sep 29, 2005

Jim
The lift force is greater than the down… more piston surface on the lift side. On the down side there is a rod taking up some of the piston face.
I thought your first picture was what your tractor was originally able to do… glad it is not a degrading problem with your hydraulics… all is well. KennyV.

JimMorrissey · Sep 29, 2005

It was....but I forgot how I got it in that position /forums/images/graemlins/tongue.gif Then I figured out that I must have done it by lifting the front end and easing up the rear end with the hoe. I think I just convinced myself that something was wrong. Stupid.

So if the lift force is greater than the down force, then that totally makes sense that it can't lift basically the whole machine with the stabilizers down.