Gordon - First, some definitions: (You probably already know all this, but I just wanted to make sure we're on the same page because it's a little complicated.) The loader valve is a two-spool valve manufacturered by, as you said, Husco. The valve block is the casting that the two shiny chrome rods, the spools, slide in. The spools are connected to the joystick in such a way that when you move it forward and backward (or up and down, or in a plane parallel to the longtitudinal axis of the tractor, however you prefer to say it /w3tcompact/icons/wink.gif) the leftmost spool (as viewed by the operator when sitting on the tractor) moves out and in, causing the lift cylinders to lower or raise, respectively, the bucket. When the joystick is moved right to left (or side to side, or in a plane perpendicular to the longtitudinal axis of the tractor, however you prefer to say it), it causes the rightmost spool to move in and out, causing the bucket to dump or roll back, respectively.
The rightmost spool (the dump circuit spool) has a normal rollback circuit, and a regenerative dump circuit. The advantage of a regenerative circuit is that the volume of flow is as much greater than the flow of a non-regenerative circuit as the volume of the sectional diameter of the rod in the cylinder. (Meaning that you can't predict exactly how much faster it will be in general because it depends on the volume of fluid displaced by the rod, which can be different sizes.) The disadvantage is that the force generated is reduced by the same amount. Generally, this isn't a problem in the dump side of a dump/roll back circuit, because dumping is gravity-assisted anyway. There's pretty much always enough force available to lift the front of the tractor (as when backdragging under pressure), so any more force isn't usable anyway.
The problem comes in when you're trying to use the dump/rollback circuit to actuate a 4-in-1 bucket. The preferred way (from a usability standpoint), as I mentioned in the earlier posts, is to clamp with the roll back circuit and open with the dump circuit. When you try to open with a regenerative dump circuit, however, it won't work, because you can't retract a cylinder using regeneration - by definition it can only extend the cylinder because that's the only way there's a pressure differential. And extending the cylinders on a 4-in-1 bucket causes the bucket to close. Therefore, the result is that the bucket closes when you use the roll back mode (with the thumbswitch actuating the solenoid valves, causing the fluid flow in the dump/roll back circuits to be diverted to the 4-in-1 cylinders) the bucket closes, and when you use the dump mode to try to retract the cylinders to open the bucket, they extend and the bucket still closes. The result: You can't open the bucket, period.
There are two (technically three) solutions: (I'm repeating what I said in the earlier posts here, but it's relevant) reverse the hoses so the the roll back circuit opens the bucket and the regenerative dump circuit can close it (since that's the only thing it will do anyway). Disadvantages to this approach: The 4-in-1 bucket is a royal pain to use this way (from a usability standpoint) for reasons I mentioned in the earlier posts, and just as important, the clamping force available is reduced as described in the discussion on regenerative circuits above - not a problem in dump circuits, but a big problem in 4-in-1 clamping circuits.
The second solution: Get rid of the regenerative dump circuit. The only way to do this is to change the rightmost spool in the valve body.
The third (technically the same as the second, except in usability) solution: Have both a regenerative and a non-regenerative dump circuit. The only way to do this, as with solution two, is to change the rightmost spool in the valve body.
Fortunately, Husco makes a spool that has both a non-regenerative and a regenerative dump circuit. It works much like the float circuit on the lift spool: If you push the joystick to the right about halfway, you get a non-regenerative dump. If you push it past the detent and hold it (it won't stay there like it does with the float mode, for obvious reasons), you have a regenerative dump. This is, obviously, the way to go.
Next problem: How do you get your hands on this spool? I'm afraid I can't help you with this, except to say that if you have a highly motivated dealer, he can get his hands on one through Kubota. Husco doesn't sell in quantities less than a 1000 or so, so that's out. The problem in getting it from the dealer is that he most likely won't have a clue what you're talking about and you're not likely to be able to explain it to him, either (because he won't understand, not because you can't explain it). My suggestion is that you tell him you need a replacement dump/roll back spool for the Kubota L-series remote-mount loader valve. This valve comes with the combination non-regenerative/regenerative dump circuit described above. Reason: it's made to work with stuff other than just loaders, and they know you can't retract a cylinder with a regenerative circuit.
So, to answer your questions: Yes, the best approach is to replace the dump/roll back valve spool. It's a 10-minute job, as long as you have the right size allen wrenches (the ball-type ones make the job a lot easier). And keep everything very clean. (The rest of the answers assume that you take this approach.)
You will still have some chatter when using regenerative mode to dump the bucket, unless you forego Long's electrically actuated valves and use a higher capacity valve block. I can give you details on this, if you need them (but I think they're in the 'L4310 Enhancements' thread).
Dumping will be just a little slower in regenerative mode unless you forego the Long valves to eliminate the chattering as mentioned above.
In roll back mode you have the same power - no change.
As for durability: Long makes two different versions of the 4-in-1 bucket for tractors. (They may make a huge one for very large ag-class tractors, but I'm not including that one.) The Hydro-Jaw I and II. I think (but I'm not sure) that the Hydro-Jaw I is the heavier-duty one. At any rate, there's a significant difference in the duty class and weight between them. The heavy duty one is not suitable for anything smaller than the LA-681 (1500 lbs bucket capacity) loader, in my opinion, because it's just too heavy. I've seen the lighter duty one (belonging to a friend of mine) get bent by extremely heavy usage, but I've not bent the heavy duty one at all, except for some bulges in the back of the bucket where I've rolled very large rocks into it. This bucket is much heavier duty than Kubota's heaviest bucket. My guess is that if I haven't bent it, it's just about impossible to bend it. Remember, too, I've got the 2 1/2" lift cylinders.
Also, I do think it's an extremely good investment - I wouldn't want a tractor without one anymore, that's for sure.
I wouldn't do anything different with the 4-in-1 than the way mine is set up right now, except that I'm planning to weld some teeth to the side of the jaw to assist in picking up logs. And I'm thinking about installing a quick-attach mount, which answers that question, though I don't have any ideas yet on the best way to do it.
I went with a 5 foot bucket. The 6 foot one is just too heavy, in my opinion. That means it doesn't cover the tire tractors, at least not
my tire tracks. /w3tcompact/icons/wink.gif
Sorry for the verbosity - hope it helped.
MarkC
