L48 strange hydraulic problem...

OldRedTractors · Nov 17, 2005

I have an L48 TLB, which is a great tractor and really a work-horse. However, I have a strange problem with my hydraulics, which has existed since I bought the tractor new about 3 years ago. It has the hydraulic auto-level on the loader, and an optional external valve plumbed in intended for future 4-way bucket use. It's been an annoyance for a while, and it's finally bugging me enough to really want to resolve it.

The behavior is:

1) with the hoe stabilizers off the ground, the loader has no problem lifting the front of the tractor off the ground, but at that point, the stabilizers can just barely raise the rear of the tractor clear of the ground.

2) with the loader off the ground, the stabilizers have no problem lifting the rear right off the ground, but at that point, the loader is not able to lift the front of the tractor. Also, if the loader is flat on the ground, and you curl-out the bucket, it will not lift the front, and the loader arms seem to "float" up almost as if the loader is in the float position (it's not).

3) If I lift the rear with the boom, which is no problem at all, the stabilizers have no problem holding it. Thus, what I end up doing is raise the front, use the boom to raise the rear, and set the stabilizers.

When I had it checked shortly after I got the tractor, I was told "they all do that". Checking one at the dealer a bit ago, which did not have the hydraulic bucket level, it worked exactly as I would have expected - i.e., no problem at all.

Any ideas? Could there be a issue with how the remote was installed, relief pressure, or something with the auto-level?

Thanks for any and all ideas!

Dave

_RaT_ · Nov 18, 2005

I think the auto level really affects the bucket curl/dump function. Stabilizers on the ground is more of a leverage issue.

slowzuki · Nov 18, 2005

I think you have 2 issues, one is a bit of air in the lift cylinders, possibly due to difficult bleeding due to the leveling valve?

The second is I bet your system relief is set too low.

It can tip the tractor about its tires but putting the stabilizers / bucket down moves the pivot point enough to make it too heavy.

Their are shim packs available to precisely adjust the pressure of the relief although I though the L48 had an externally adjustable relief.

OldRedTractors · Nov 18, 2005

I was thinking it may be something to do with the system relief, as when you try to lift the front, the hoses off the valve body jump around, as if it's bleeding off pressure suddenly somehow.

Do you think it could have anything to do with how the remote valve was installed?

I will take a look in the service manual and see if there is an external adj on the relief.

Thanks,

Dave

_RaT_ · Nov 18, 2005

I still say it is the auto level unit. The older L48's like mine was had hydraulic leveling and with all the issues it had, my understanding is they went to a mechanical setup. Had I had the ability to bypasss it, I would have. Mine worked fine but some things about an auto level that you cannot turn off are really annoying. For example, when I would dump/curl the bucket to the exact position I wanted and then lowered the boom, the bucket of course would also change its angle. There were times when trying to get the tooth bar into a root or small rock that it became a real challenge. I had my auto level replaced once and it increased my curl dramatically.

Ed_L295DT · Nov 21, 2005

When you try to lift the front end with the bucket, the PIVOT point is the rear wheels, which also ROLL as the bucket is lowered. (remember pivot and roll). With the rear stabilizers down, the PIVOT point is further back and the bucket now has more weight to lift off the ground. Also, the geometry of the loader arms tries to move (ROLL) the machine because the bucket is going down in a different direction than an arc scribed around the FIXED pivot point (stabilizers).

I see two solutions. Increase main system relief valve pressure which may cause premature component wear. The other solution re-directs the operator's thinking that the machine has to be off the ground in order to dig. Actually the STABILIZERS STABILIZE the machine while digging. The tractor does not have to be in the air when digging, only STABILIZED. The STABILIZERS do not move in respect to the ground when you put them down by themselves.

My basis for this opinion is 40+ years repairing heavy construction equipment in the field.

OldRedTractors · Nov 23, 2005

I understand the leverage-arm difference with the stabilizers down, but I don't buy that being the issue.

1) The new L-48 I tried had absolulutely no issue raising the front with the stabilizers holding the rear off the ground, and popping the rear off the ground with the bucket down.

2) My L-48 loader doesn't even work hard lifting the front without the stabilizers down, and I don't get the "float" sort of extension action from the loader cylinders unless the stabilizers are down. Seems strange to me.

3) Why would my stabilizers go from lifting the rear with no strain, to not being able to lift it at all when the loader bucket is on the ground? Surely they should be able to raise the rear with or without the bucket on the ground (and again, the new L-48 had no problem with this.

The problem I have is not so much getting the machine off the ground, but getting it level. On a slope, it's a real pain to level out the maching if the stabilizers can't lift and level the rear with the font bucket down. Without the bucket down and "dug-in", as you know, it can be a real problem keeping the machine from creeping/sliding when digging. You really need all the weight on the bucket and stabilizers to hold the machine steady from my experience.

I have to dig out the books and see what they say about the relief operation. I still believe it may have something to do with the aux valve installation for some reason.

Thanks for all the ideas and suggestions!

Dave