L48 or L4610?

johnjc · Dec 18, 2001

Re: L48 Loader Problems

Update on the weak loader problem. After getting hunting season out of the way. I was able to work the tractor for several hours and noticed the problem seem to get worse as the tractor gets hot. After working it hard for about 4 hr. it is still as bad as when I first got it.
Talked to the dealer and he wanted me to change the hydraulic fluid, filters and clean the strainer to see if that helped. He had me use regular UDT not Super UDT.
Took it out to my ground and got it hot and it was the same. So its back at the dealers.
This will be the fourth time. Till they call Kubota, figure out what to try and order parts it seems to take 2 weeks till its back. Glad I'm not depending on it to earn a living .
John

MarkV · Dec 19, 2001

Re: L48 Loader Problems

John,

If your dealer has an other L48 on the lot, it would be interesting to see if it does the same thing. I would think you could tell pretty fast. I haven't heard of Rat having problems with his. If a new one works as it should, I think I would be telling the dealer to get me a complete new valve system.

MarkV

johnjc · Dec 22, 2001

Re: L48 Loader Problems

Just got my tractor back from another 2 weeks at the dealer's. In talking with the mechanic I had said that that if hydraulic self leveling caused the problem I would rather not have it. Meaning mechanical. Well they took it off, made up hoses to connect the loader directly to the top valve and removed the bottom one.
Questioned them on weather Kubota had suggested this and I didn't really get an answer. Just told me that they had all the parts in a box and they could be re installed.
I tried moving the tractor back and fourth with the loader curl and it seemed quicker/stronger. But will not know if the power problem is fixed till I take it out to the land and run it hard for a couple of hours and get it hot.
My question is: Would this be considered safety equipment. And if a load fell back on someone because the bucket didn't stay level Who would be responsible ? Kubota, the dealer, or myself?
Also ignoring liability does anyone have an idea how much hydraulic leveling add to the cost of my tractor .
Hope to get a chance to try it out over Christmas week and then I will know if the self leveling is causing the problem for sure. Not sure what to do if it can't be fixed.
By the way I think the dealer (Peterman Power Equipment) has been trying real hard to please me. But maybe their support from Kubota is the problem.
John

kubmech · Dec 22, 2001

Re: L48 Loader Problems

John, Kubota knows they have a problem with this system but I don't think they know what to do about it yet. With the self levelling valve removed you should see a dramatic increase in power as long as there is'nt another problem. If your backhoe has been operating properly with good power you can rule out the main relief valve since both systems operate off of this valve. However if the backhoe does'nt seem to have the power as well as the loader you could be looking at either a pump problem or relief problem. Now I have to "assume" that your dealer flow tested the pump and checked main relief pressure to eliminate those two possibilities. So if power is restored by bypassing the self level valve you have two options: have the self level valve replaced, although a proper operating self level valve will rob a small amount of power it should'nt impact your power severely. Keep in mind you will notice a slight drop in power once the new valve is installed. The upgraded unload spool and or relief valve change (depends on if you have the updated spool on which relief valve is installed) is not intended to solve the power issue. It is for improvement of the inititial drop of the loader after lifting the front of the tractor. The relief we are talking about in this update is a low pressure valve in the self level valve itself. The main relief is a seperate valve installed in the hyd block and provides the entire hyd system/system pressure.
Another option is to run the machine without the self level feature which to me (and obviously to you) is a touchy subject because you did pay for this feature when the tractor was purchased and it is a nice thing to have (keep in mind not all tractors have this feature and a lot of people are used to running there loaders without it). As far as liability issues with running the loader without a system it's suppose to have, I'll leave that up to the lawyers. Now I geuss there is a third option which is the one I would prefer if it was my personal machine, would be to adapt a mechanical self levelling system like the B20, B21, and L35 have. One of the nice advantages of those systems was obviously simplicity, as well as, you can't roll the bucket back on yourself becuase that function is mechanically locked out, which is not the case with the L48 even when the valve is operating properly, you can still roll the bucket back and dump the load on yourself if you choose to do so, or should I say, if part of your brain chooses to overide the part that does'nt want to do that. Hopefully Kubota is working on a plan to solve this problem, you are not the only L48 owner with this problem. As always, Kubota tends to let the dealers take the heat (just a personal observation). But the dealer can only work with what the engineers have provided them, and it is frustrating for the dealer as well as you the customer. By the way, I have noticed very limited availability of the parts in the stateside depots to repair the systems mentioned. So I geuss the bottom line is, if your dealer seems genuinely concerned and is trying to help you, he probably is. So be patient with the guys at the shop and put the pressure on Kubota.

JATO_RaT · Dec 24, 2001

Re: L48 Loader Problems

John, while I can't remember specifically what the issue was with your loader, I can tell you what mine does and perhaps you can tell me if the two are similar. While it has not been a problem for me, I could see where it could for some folks and me sometimes. It has to do with the bucket dump. I believe that what Kubota did was to set the relief pressure for the bucket dump low enough so that when you lower the loader and the bucket is fully rolled back yet the loader still has a ways to go before getting to the ground, it can go down easier or faster. You might know what I mean when I say this as I can see it being very confusing to understand otherwise.
So what my loader does is this. If I want to place the front lip of the bucket in a position to "trowel" the material while going backwards, I must first get the loader raised, get the bucket in roughly the position I want and then lower the loader. There is not enough pressure to lift the tractor off the ground with just the bucket dump cylinders. It has tons of retract or curl power, enough to completely lift the rear end off the ground when I grab onto a stump with the bucket teeth and curl. In other words, the only situation I have is with the dump and its ability to lift the tractor off the ground or at least get it into the position I want for backwards finish grading. Let me know if this is what your talking about. I can see where a simple bypass would work great. The hydraulic leveler works great but I have never personnally really needed it. I would like the oppourtunity to disengage it as needed. Rat...

johnjc · Dec 24, 2001

Re: L48 Loader Problems

Yes Not being able to curl the bucket back into position for back dragging with the bucket on the ground is one of my complaints. Also if I am dragging a big (heavy) load the bucket will uncurl. Particularly If I have the bottom of the bucket perpendicular to the ground.
It is also weak in the curl position. For instance I was pushing a stump down over the bank so I could bury it. The ground was wet and muddy so when I tried to back up the wheels spun. I curled the bucket back pushed it to the ground and tried to uncurl it to help push my self back up the bank. Good luck! I was able to do this with both my Case 580B and Kubota L305DT
You stated that the curl will lift the back of the tractor off the ground. From some of your other post I believe you didn't order a backhoe. How much of a counter weight are you using.
Another thing have you had a chance to try this after the tractor is hot. Seems to take about 3 hr of hard use for mine to get the oil hot witch makes the problem worse .
Will let you know how it works with the leveler removed weather permitting. They are calling for a high of 30 and a low down in the teens for the rest of the week.
John

JATO_RaT · Dec 26, 2001

Re: L48 Loader Problems

John, I have a 1000lb box scraper and ballasted tires. The loader has plenty of rollback power, again its just the dump where the relief mechanism cuts out prematurely. In normal loader dumping situations, you would have the full load of the bucket helping to dump, but I would like to have the ability to have bucket dump pressure increased. I want to look into the ability to bypass the whole thing and not take it out of the circuit. The hydraulic leveler is made by Eaton. I need to know whats in the guts of this thing. Rat...

JATO_RaT · Dec 28, 2001

Re: L48 Loader Problems

Johnjc, I was hoping John Miller would jump in with full spreads of the Eaton self leveling valve hydraulic schematic used on the L48 as well as the joystick schematic. Apparently there are limitations even for Mr Miller, yes, John didn't quite come through for us here did he, hmmm, just a little disappointed in John Miller III, sure thought John would be the one to do it if anyone could. Maybe it doesn't exist, Rat...

kubmech · Dec 29, 2001

Re: L48 Loader Problems

Rat, I take it your looking for a way to bypass the self leveling valve when your looking for extra power. if this is the case I'll throw a few thoughts out there for you. If I had the "technology" to scan you schematics or breakdowns I would, just to see what you come up with, as I'm really not sure if they would do you any good. I've studied them some and I'm convinced (esp. after a few calls to the factory Kubota "Gurus") that they are not only somewhat inacurate, but also stray to the side of completely confusing the way they are depicted. However I'll let you in on what I have "grasped". The loader control valve is nothing cosmic and follows all reasonable laws of physics in that it works just like most any loader control valve, and this I am sure of. Now the self level valve appears to be somewhat of a different animal. The hyd. power supplied to the loader control valve is routed in the standard way. Flow from the pump goes in the in port, you have a standard return hose and of course power beyond. None of these connections runs through the self level valve so we're talking standard stuff here. This is where it gets a little wierd so try to follow me, in the self level valve there are 4 check valves, two unload spools, two flow dividers, one low pressure acting relief valve which appears to act in conjuction with the unload spools, and two adjustable variable orifices that appear to act with the flow divider spools. One flow divider, one unload spool, Two check valves and one adjustable variable orifice comes into play in the loader raise sequence and the other "set", respectively, comes into play in the loader lower sequence. The low pressure relief appears to come into play on both unload spools. Now (you asked!)

Basically what all this boils down to is: If your raising the loader, hyd. fluid flows from the the loader control valve to the self level valve (and the way the schematic shows it) runs directly to the raise side of the loader boom cylinder (this is where the schematic gets kind of schetchy) (why run through the self level valve, as the diagram shows nothing happening at this point/been through this already and don't have a good answer for you yet) any way the "majic" happens when the return oil from the cylinder enters the self level valve through the variable orifice and the flow divider spool then pops the low pressure relief and through the unload spool which allows oil to flow to the bucket cylinder to extend, to allow self leveling to occur at a predetermined/adjusted rate due to the variable/adjustable orifice (are we having fun yet?)/w3tcompact/icons/tongue.gif Now I'm working from memory only here so bare with me......
With the loader in the raise position, fluid flows from the loader control valve to the A port of the self level valve and comes out of the B port to the raise side of the cyl. (the self level valve ports are marked with letters) Now, you can pretty much forget about everything I just told you about the self level valve and add either quick couplers or a series of diverter valves into the lines coming from the loader control valve ( if you follow the hoses in/versus the hoses coming out) to the self level valve to have a bypass option for your tractor. Geeze I hope that all makes some sense......

JATO_RaT · Dec 29, 2001

Re: L48 Loader Problems

kubmech, thanks for the information, I just got some cut sheets on the various Kubota L48 controls. I need to do a little digesting to start getting things figured out. If you get any info from Kubota please let us know. Do you know if Kubota issued any bulletins about this and possible modifications. My local dealer (I did not buy from him) told me that Kubota sent replacement spring's? or something else to correct the problem. I'll need to check with him again, thanks, Rat...