2wd Always?

[pitt_md]

Just an FYI on the turning radius between 2wd and 4wd. On my MX5000 in 2wd it's 8.5 ft. and 8.9 ft in 4wd. not much of a difference really.

When I start to do heavy work I put it into 4wd. If I am pulling a wagon load of fencing material or using the PHD 2wd is all I need. I can tell the difference between being in 2wd vs 4wd on flat level ground just by pushing in the clutch. In 4wd the tractor stops a little faster than it does in 2wd so it must be using more fuel just to move in 4wd. Maybe not all that much given the type of work being done.

 

[RobJ]

As posted earlier ..Why do ag tractors have a function that kick out the fwd and diff lock when you raise the 3pt.....To minimise wear and tear / Shorten the lock and hopefully achieve that 10'000hr benchmark that some brands have set

Wait a minute...they do what? you raise the 3pt and things kick out? WTH? Not on the bigger 4020, 4230, 4430's and such I drove at my family farm. Of course none of those were 4wd, didn't need them.

I classify this as dumb.

 

[RobJ]

Well, I've been reading this thread all along and decided to pitch in my comments. I too leave it 4wd all the time except on pavement and flat parts of my dirt road. I need it everywhere else on my property. Plus, I've already rebuilt the front drive gears once, so it's good for another period, but that's a different story, of course.

OK Rob lets make it part of this story... hehe

I read the thread you mention but don't remember the details. Did the front end fail due to over usage, poor design, old age (probably not this one, how many hours), or poor operator knowledge of said function (hey it happens and I had to toss it in for fun), or poor maintenance.

If these things are designed to last thousands of hours, they why the early failures I've seen here. From reading your posts I know a couple things...you use your tractor mostly on the weekends, and you use it a lot and hard when you use it. What if you used it hard 5-6 days a week? for 52 weeks. What would happen then?

I'm not picking on you but you have the noodle up top to look at your tractor and design and make a good guess as to why it failed. (that's a complement BTW).

Rob

 

[N80]

Wait a minute...they do what? you raise the 3pt and things kick out? WTH? Not on the bigger 4020, 4230, 4430's and such I drove at my family farm. Of course none of those were 4wd, didn't need them.

I classify this as dumb.

Rob, of course your tractors didn't have it, they were 2wd! And it seems dumb to me too, but then again I know nothing about big tractors. There has to be a reason for something that complex. D7E says it is to improve turning radius and decrease wear and tear and he seems qualified to know. But I'd still have to guess that 1) Not all modern 4wd ag tractors do this and thus all of them probably don't need it and 2) the ones that do have this feature must need it and 3) for the ones that need it, it must be system specific.

It still sounds dangerous to me. Obviously, swinging a tight turn in a bazzilion acre corn field in Nebraska this isn't going to be dangerous at all. But what about on wet, hilly terrain. Could you imagine swinging a turn on a wet slippery side slope, lifting whatever heavy thing it is you have attached to the 3pt hitch and have 4wd kick out at that very moment? Yikes!

 

[N80]

I checked out the Kubota M125. It does not have the feature that D7E is talking about, but in the world of ag machines it is certainly not a heavy weight.

However, it has a very interesting feature called Bi-Speed Turn in which the the outside front wheel is driven at a higher speed during a turn and significantly decreases the turning radius.

I think at least part of my take on this 2wd vs 4wd debate is shaped by the Kubota bevel gear system. It is simply very different from typical u-joint type front ends and is clearly made to be used.

 

[RobJ]

Rob, of course your tractors didn't have it, they were 2wd! And it seems dumb to me too, but then again I know nothing about big tractors. There has to be a reason for something that complex. D7E says it is to improve turning radius and decrease wear and tear and he seems qualified to know.

Agree, but both 4wd engauge and diff lock are (I think mostly) a mechanical lock (lever for the 4wd, step on the lock for diff), the 3pt is hydraulic. Sounds complicated. Yep a 2wd cultivating tractor needs to ZTR at the end of a row. It's actually very fun when you get the hang of it and try to get in and out asap.

 

[RobJ]

I think at least part of my take on this 2wd vs 4wd debate is shaped by the Kubota bevel gear system. It is simply very different from typical u-joint type front ends and is clearly made to be used.

Knowing about things that I know about you have to remember your bevel gear system might also be there to provide more ground clearance. A standard u joint comes in at the middle of the wheel, the bevel comes in from the top thus allowing more ground clearance!! A good think on a 14" tire. Not needed as much on a big tractor that is running a 11.2x24 on the front (pssst, that's the same tire that's on the rear of my little L).

 

[3RRL]

OK Rob lets make it part of this story... hehe

I read the thread you mention but don't remember the details. Did the front end fail due to over usage, poor design, old age (probably not this one, how many hours), or poor operator knowledge of said function (hey it happens and I had to toss it in for fun), or poor maintenance.

I'm not picking on you but you have the noodle up top to look at your tractor and design and make a good guess as to why it failed. (that's a complement BTW).

Rob

I know you're not picking on me and I'll tell you what I think.
Most of the smaller 4wd tractors we have use a reduction gearing for the front drives, like you say for more ground clearance. They do it through a combination of small bevel or miter gears driving (in my case) fairly large and heavy front tires. IMHO, this is an inherently weak configuration. The larger Ag and industrial tractors use a direct drive with a "U" joint to the wheel for the front drive which is much stronger. It can be made much beefier and has less parts to break.

So in my case, I loaded the fronts for more traction, (mine are 6.00 x 16) which added to weight the front drives had to move ... this is not recommended by most manufactures, but I did it anyway. I also used 4wd while having a super heavy load in the bucket doing loader work on my muddy road. This is also not recommended but I did it anyway. Since it was pouring, muddy and slippery, I used my shuttle shift forward and backwards at in a higher gear than normal, slamming forward and backward with many heavy loads in the bucket while in 4wd. That kind of work places enormous stress on those little driving gears in the front and consequently I sheared the teeth off one of the small gears.

OK, Ok, so I screwed up and pushed the intended usage over the recommended limits. Better stated is I abused it. It was not wear, it was breakage due to excessive stress placed on the design by overloading what the teeth could take. Kind of like ramming a tree with your bucket and FL and bending or breaking something. But in any case, the way I use my tractor, I think that gear reduction front drive system is a weak design. In fact, the small gear on the other front drive showed excessive wear from having used it like that from the beginning. I think if I didn't have an excessive load or if I didn't ram it back and forth it would have lasted a lot longer. But I don't use it like that.

No doubt, the more you use anything the more it will wear. It comes down to what you got and what you want to do with it. I've blown up lots of good tools doing similar abusive things. Every tool has it's limits.

Mine is a 55hp tractor on the larger side, where some manufactures make the break off and switch to the direct front wheel drive system. I've seen it on a new 55hp 4wd DF, which I think is a real plus, but it was not available when I made my choice of tractors. It is usually available on larger 4wd tractors though.
So I would say it was a case of flagrant operator malfunction.

 

[Charlesaf3]

I'm not sure flagrant is right from the sounds of things...

Do you think having HST would make that sort of failure less likely?

 

[N80]

Knowing about things that I know about you have to remember your bevel gear system might also be there to provide more ground clearance. A standard u joint comes in at the middle of the wheel, the bevel comes in from the top thus allowing more ground clearance!! A good think on a 14" tire. Not needed as much on a big tractor that is running a 11.2x24 on the front (pssst, that's the same tire that's on the rear of my little L).

I think that is probably true, but Kubota mostly hypes the turning radius as the primary reason for the bevel gear system. For all I know these bevel gear systems might be WWII surplus.....although I don't think Japan finished the war with much surplus of anything.

On most of the SCUTS, L's and Grand L's the fronts tires do look comparatively small and the added clearance is certainly a benefit. However, the M's, all the way to the M125 have pretty large front tires. And Kubota maintains the bevel gear system all the way to that level. Thats is a 10,000 pound tractor with 103 pto hp. That may be pushing the limits on a bevel gear.....but that's a big machine.