2wd Always?

[john_bud]

That's speculation. I've seen all sorts of things damaged on used tractors. I'd suspect abuse or poor quality before I'd suspect that it was due to a 4wd tractor spending its life in 4wd. I'm not sure why folks can't understand that a 4wd tractor is made to spend its life in 4wd!

I'm personally glad that I don't waste any time wondering if or when I need to be in 4wd and the only time I do waste on the issue.....is here.

N80 - you may not notice the difference in turning radius as your tractor's turning radius is pretty tight. A 5% difference (on firm ground) is about 1/2 foot or less. If you are doing it on soft ground (fresh plowed), 4wd may turn tighter as the tires won't understeer and slide. That sliding is why single rib ag tires are used on the front of 2wd tractors, the rib acts like the keel of a sail boat and grabs to help it turn on soft soils. SPYDERLK pointed out the action of the front tires as there is a tight turn. One side MUST travel farther than the other side.


As you wrote, the tractor is designed with the front's turning slightly (normal range is 5 +/-3%) faster than the rear tires. Run in 4wd on dry asphalt or cement and the front tires will be skidding that 5% every revolution. It's the physics thing, that's where the least resistance is, so that's where the sliding occurs. That is the same as slamming on the brake and skidding 5-7" every rotation of the front tire. Actually, it's more like pealing out and burning rubber as they are overdriven... still it takes energy to do that.


If you read my note closely, you saw that the differences are small. Significant over long time periods and in fleet numbers, but not enought to be a bother.

Enjoy the tractor whether it's in 2wd, 4wd or in 22nd century hover mode!

jb

 

[D7E]

That sounds like speculation too and I'm sure the answer is system specific. Large ag tractors often have little in common with small utility and CUTs. And I wouldn't own a tractor that did that (unless there was a full time override) since that sort of behavior could get you killed on a wet muddy hill.

As far as fuel savings, some owner's manuals say specifically that 4wd is more efficient, though mine does not. An example has already been given above.

I do think people confuse modern CUT 4wd systems with the older automotive systems they are used to.

Have any of you put over 10'000 hours on a tractor as we do ...????
And these things make a difference....Stock farmers tractors (4wd all time) and (loaders) Always breaking up axles .
Grain farm tractors are expected to run to 15000 hrs (Only use fwd when neccessary)and rareley give problems ...I had 3 years with "NH" It aint speculation...?
Stock farmers that use the 4wd full time rebuild axles far more often..
The difference is obvious..Should the rules be different for smaller tractors ,Is there a difference in quality ,What is the life span of a cut ,Size for size you spend more money than we do.....?

 

[billbill1]

I leave black tire marks on my concrete if I leave the tractor in 4wd. If the ground is soft, I run in 4wd because I get lots less damage (ruts) than in 2wd. I use 2wd anytime I can to save wear and tear but as far as fuel usage, I see no difference. 4wd should never be used on pavement , unless there is snow and ice to allow for wheel slipage to the fronts. That's how I do it anyway.

 

[Egon]

For some of us using four wheel drive is not an option.

On my Kubota B7100 HST with a loader and no rear weight It's required to get the tractor up the slopes I work on. A rear weight is not really an option as I transport the the tractor on a regular basis. In town room is an issue and the less sticking out the back the better. On the Farm it`s not an option either as many times the tractor goes up the hills empty but comes back down dragging something.

Just for interest many years ago I was told that the optimum slippage for tires that are pulling is 10 %

 

[Ridgewalker]

For some of us using four wheel drive is not an option.

On my Kubota B7100 HST with a loader and no rear weight It's required to get the tractor up the slopes I work on. A rear weight is not really an option as I transport the the tractor on a regular basis. In town room is an issue and the less sticking out the back the better. On the Farm it`s not an option either as many times the tractor goes up the hills empty but comes back down dragging something.

Just for interest many years ago I was told that the optimum slippage for tires that are pulling is 10 %

Egon, you should consider filling your tires...weight in the back is a good thing, especially when you have a FEL.

As to the OP, I am in the use 4WD only when you need it camp. I can tell a difference when in 4WD vs 2WD when making turns, etc.

 

[N80]

N80 - you may not notice the difference in turning radius as your tractor's turning radius is pretty tight. A 5% difference (on firm ground) is about 1/2 foot or less.

Actually it would be more than that. The tractor has a turning radius of about 10' but that's using a brake. So its wider than 10' and whoever quoted 5% actually said 5-10% which could put the difference as high as 1.5'. Which still isn't much, and in general practice might not be noticeable. Which begs the question: If we're going to say that .5-1.5' is trivial, then doesn't that just support my basic contention that the difference between turning in 2wd vs 4wd is insignificant?

But yes, I did claim there was no difference with my tractor...so let's go back to that point. I've stated several times but some folks seem to ignore it or disbelieve it, but I tested this. It was on firm ground at slow speed. At a stop I turned the wheels full right in 2wd. Start driving and stop halfway through the turn. Mark outside diameter. Complete turn. Mark outside diameter. Do it again in 4wd. No difference. What can I say? Could I be off by a few inches? Sure...in either direction.

As you wrote, the tractor is designed with the front's turning slightly (normal range is 5 +/-3%) faster than the rear tires. Run in 4wd on dry asphalt or cement and the front tires will be skidding that 5% every revolution. It's the physics thing, that's where the least resistance is, so that's where the sliding occurs. That is the same as slamming on the brake and skidding 5-7" every rotation of the front tire.

I don't think anyone here has advocated running 4wd on pavement. Even the 'always in 4wd folks' take it out for pavement. Its just common sense and is part of our theory of leave it in 4wd until you need 2wd. The beauty of which is that we don't have to spend much, if any time wondering when we need to switch it into 4wd and we are much less likely to find ourselves in need of 4wd.....when it is too late.

 

[N80]

Should the rules be different for smaller tractors

Of course! That's my whole point. Everything is different! Size, weight, usage patterns, 4wd systems, HST's, all that. How many of these big Ag machines you're talking about have bevel gear front drive systems? I doubt such a system is applicable to big heavy machines.

 

[Egon]

Filling the rear tires is not an option as the tractor is trailered on a very regular basis.

Yes, I know I should have weight on the back when doing loader work and many times that is what my back blade is doing. But it is unsuitable as a regular weight due to size and lifting ergonomics.

I also need four wheel drive to rota-till.

On the larger agricultural equipment I can't comment due to lack of knowledge but there are many industrial front end loaders that are constant four wheel drive.

 

[SPYDERLK]

If we're going to say that .5-1.5' is trivial, then doesn't that just support my basic contention that the difference between turning in 2wd vs 4wd is insignificant?

But yes, I did claim there was no difference with my tractor...so let's go back to that point. I've stated several times but some folks seem to ignore it or disbelieve it, but I tested this. It was on firm ground at slow speed. At a stop I turned the wheels full right in 2wd. Start driving and stop halfway through the turn. Mark outside diameter. Complete turn. Mark outside diameter. Do it again in 4wd. No difference. What can I say? Could I be off by a few inches? Sure...in either direction.

Good test. I see you did it slowly and that is a wise choice. There is still an issue with making a stop while turning in 2wd. There is a small outward step in the path as you restart. Starting slowly minimizes this, but slowly is a relative term and so leaving out the stop variable entirely is better still.

We can leave out the measurement variable too. Try this: [Go around the circle at your steady slow speed in 4wd. Then without stopping flip the lever to 2wd while watching the front wheels carefully.] It is likely, almost assured, that there will be some resistance to operating the lever, and that when 4wd disengages the front of the tractor will slew somewhat toward the center of the circle. This is how my BX1500 acts and its driveline is just yours in miniature I think. All three of my Kubotas act this way and Im sure the Mahindra would too, but opposing forces in the linked gearing are too great for me to operate the lever to disengage it.

Whether a difference is insignificant will be relative to the use. An advantage in maneuverability, however slight, becomes less and less insignificant as constrained repetition of movement is required. Your point of having it in 4wd when you need it is well taken. It is a risk not to do the same thing everytime, but the risk is not so much in judgement as it is in forgetting to put it back in 4wd when you are finished with the situation that 2wd provided the benefit. The weighting in the cost vs benefit equation remains personal.

You mentioned that we are wasting time with this. I view it as an opportunity to learn. Your tractor is exhibiting operation in a manner different than any I have encountered. Learning why has value to me.
larry

 

[SPYDERLK]

Filling the rear tires is not an option as the tractor is trailered on a very regular basis.

Are you so close to the trailer weight limit that 200# or so would be critical to trailering??
larry

 

[patrick_g]

I used to shift in and out of 4x4 more with my Kubota 4610 with HST but last few years just leave it in 4x4 unless I am driving on pavement or even driving fast where I know 4x4 is not needed such as on a gravel road if I am going very far. Otherwise I just leave it in 4x4.

If anyone could make a good argument for needing to "manage" it more and swap it back and forth, I'd be happy to reconsider my actions. I don't care about a couple inches of turn radius or a little more surface disturbance.

Pat

 

[N80]

We can leave out the measurement variable too. Try this: [Go around the circle at your steady slow speed in 4wd. Then without stopping flip the lever to 2wd while watching the front wheels carefully.] It is likely, almost assured, that there will be some resistance to operating the lever, and that when 4wd disengages the front of the tractor will slew somewhat toward the center of the circle.

I'll give it a try next weekend.

Whether a difference is insignificant will be relative to the use. An advantage in maneuverability, however slight, becomes less and less insignificant as constrained repetition of movement is required.

Very true.

You mentioned that we are wasting time with this. I view it as an opportunity to learn. Your tractor is exhibiting operation in a manner different than any I have encountered. Learning why has value to me.
larry

The waste of time usually comes from the repitition of things already said. But, on this site, rarely does any thread fail to teach me something new.

My tractor surprises me too. I've driven 4wd things all my life from Willys jeeps, early Scouts, AM General trucks to modern 4wds and a few modern 4wd tractors. I can say without hesitation or exaggeration that I cannot sense in any way when my tractor is in 4wd in terms of steering or feedback through the steering wheel or resstance to turning. Obviously I can tell in terms of traction and I have also inadvertantly left it in 4wd on pavement. Even then, there is no feel of binding or scuffing. But the front end whines and I notice that pretty quickly and take it out. That's my biggest argument against leaving it in 4wd......but then again, I only hit pavement maybe 4-5 times a year and then just a short distance.

 

[Egon]

Spyderlk:

Nope, not even close to the trailer maximum. It's just the way way I like to keep it.

And yeah, I may not be too wise but I do know what I'm doing! Sometimes!

 

[Mighty Dodge]

I only use 4wd when necessary. The county road boarders two sides of my property so to cut down on wear and tear on the lawn I use the road a lot. You could leave it in 4wd all the time but you'll wear out your tires faster if you run on pavement in 4wd.


M.D.

 

[EddieWalker]

When I bought my tractor, I kept it in 2wd as often as possible. My thought was that I'd save fuel and there would be less wear and tear on the front driveline. Every time that I used it, I would need to put it into 4wd for one reason or another.

Then it hit me, this is a tractor, not a Jeep. I was thinking of my tractor in the same terms that I applied to my vehicles. This is/was a mistake on my part. The fuel savings is so insignificant as to be impossible to measure. Did I burn a percentage more of fuel in 4wd then 2wd? Probably, but with a ten gallon tank and running it all weekend, I don't know how to measure the difference.

I run my tractor on dirt all the time. I'm sure there is some small amout of wear that comes from leaving it in 4wd all the time, but again, it's not like I'm driving it 10,000 miles a year like I would in one of my vehicles. I doubt I'll put 1,000 miles on it in ten years!!!!! The wear issues just isn't enough to be measurable.

There is the getting stuck consideration. If you get stuck in 2wd, then hopefully you can get unstuck in 4wd. This never worked for me on the tractor. If I got stuck in 2wd and locking in the rear diferential didn't get me out, then 4wd didn't either. For me, when I get stuck, it's because I've sunken into a pit of mud and there's no hope of getting out without the backhoe to pull me out. It's always when mowing and the weight of the mower is the biggest issue. Without the mower on the back, I can drive through just about any puddle or mudhole and not get stuck. The R1 tires are awesome. In fact, if somebody in a car/truck/van gets stuck at my place, the first choice to pull them out is the CUT. I have three tractors, but that small 35hp 4wd tractor is the easiest and most reliable at pulling them to solid ground.

My full sized backhoe is 2wd and pretty much useless in my mud. There is no comparison between them in traction and their ability to get around in wet conditions.

I don't see any difference in turning radius from 2wd compared to 4wd. I guess if I spent allot of time doing really tight U turns, I might consider this imporant, but it's not an issue either way. Sharp turns mean I'm tearing up the ground, so I try to avoid them anyway.

I keep my tractor in 4wd all the time now. For me, and as far as I can tell, there is no measurable advantage to 2wd over 4wd, yet there are all sorts of advantages of 4wd over 2wd. Mostly traction and the ability to keep on moving instead of hitting a spot that I can't move, spin my tires or bog down the engine. When I'm on the tractor, I want to keep working, not fiddle around with anything more then I have to. Changing from 2wd to 4wd and back again is just not something that I'm going to deal with anymore.

Eddie

 

[patrick_g]

About the turn radius thing...

If you are puling something heavy or say dragging a box blade with it full and scarifiers digging in then your turn radius is increased and the front tires have to provide more steering force to turn you. If you are on a hill side that is slippery the front wheels when in 2x4 don't PULL the front of the tractor in the direction they are pointed. In these situations 4x4 will turn quicker.

I think the turning radius of a tractor being driven in circles with no working load to compare 4x4 to 2x4 is perhaps interesting as a discussion topic but not too useful to me as it doesn't relate to the situation when doing real work. If I am working the tractor and not practicing square dancing with it then most of the time it turns shorter with 4x4 as the driven front pulls the front of the tractor around instead of plowing along some.

I do not claim that you can't find some particular situation where 2x4 will turn sharper. I claim that is not the case for me in most working situations.

Pat

 

[N80]

I think the turning radius of a tractor being driven in circles with no working load to compare 4x4 to 2x4 is perhaps interesting as a discussion topic but not too useful to me as it doesn't relate to the situation when doing real work.Pat

Well, you have to have a point of reference. A baseline. Without that you get everyone claiming disparate experiences based on varying loads, configurations, soil types, tire types, etc etc and that usually provides no useful info for anyone either. My point is that the baseline for a tractor like mine is that there is no significant change in turning radius between 2 and 4wd and therefore that need not be a major consideration when it comes to deciding when to use 4wd or not. In other words, on my machine there is no 'penalty' to leaving it in 4wd in regard to maneuverability. And based on your experience there are situations where it can be a benefit and I concur with that. And that sort of sums it up for me. Plenty of practical, day-to-day benefit of leaving it in 4wd vs a few theoretical benefits to leaving it in 2wd.

Have we made 4 pages yet?

 

[RobJ]

Well, you might not believe the earth is round either, but that doesn't make it flat! My tractor has a bevel gear front drive system. There is no difference in feel or turning radius between 2 and 4wd. Sorry if that seems inconceivable, but welcome to the 20th century....Kubota has been making them this way for years.

What's a turning radius? I think any L or bigger has a separate brake so I have a ZTR...so to speak.

And isn't this the 21st century?

BTW, you should operate your 4wd lever from time to time to make sure it works and all. Call it PM.

 

[RobJ]

Yes, it must be some difference in models. Theres some sort of magic going on. The problem that arises with 4wd turning is that the tighter the radius being turned the more discrepancy exists between the summed distances moved by the fronts and the rears. The tighter the turn the further the fronts go compared to the rears. Fronts that are well overdriven are great for turning, but fronts that are driven just right to work neutrally along with the rears when going straight are not. In turning these fronts are being pushed by the rears, but being forced to run at the same tread speed as the rears by the linked system. They slide causing a wider circle. Normally, fronts are overdriven slightly, gently sratching along trying to stretch the tractor. More would be better for maneuverability, but with a loaded loader and counterweighted tractor the forces on the drivline would be abusive when going straight. It becomes a balancing act. I dont see any way this system dichotomy can be fully resolved in a system hard linked front to back.
larry

This is funny... oh your serious....my bad.

 

[RobJ]

I have been told, or I read it in the shop manual, that the fronts on the L4400 are slightly overdriven.

I think you heard it from Spyderlnk.

But I will repectfully ask that you prove it by showing me in the manual. Then I will gladly have some blackened crow with some honey mustard for lunch and dinner.

If you think about the design, lets have the smaller front drive parts try and pull around the rest of the tractor(think Tweety bird pulling Fog horn Leg Horn around all the time). And an overdriven ratio would be all the time. Talk about some excessive wear on the drivetrain and tires.

If this is the case, then I would not recommend leaving it in 4wd all the time. Otherwise, whatever, I have a 2wd tractor.

But for the record I do leave my ATV's in 2wd most of the time, on the Rancher I even installed a Warn 424 to allow this. Much easier to steer but of course my ATV's do not have power steering.

Rob (stomach growling!! )