Tires spinning

[TimNY]

A question about the wheels on my kubota b7510. I was discing a plowed field with it today and got hung up several times with some deep furrows -- a couple of tires were spinning and two others not moving at all.

I could deal with it, but what's this about?

thanks -- tim

 

[Tags]

Even though you tractor is 4wd it isnt really 4wd, you have differentials in the front and rear end and when one tire gets more resistance the one with less resistance has a tendency to spin. There should be a differential lock pedal for the rear end and when stepped on it will lock the rear diff, BUT, you really should to stop spinning wheels before you apply it, you dont necessarily have to but it is easier on the machine.

 

[k0ua]

Here you go.. this old 1937 video explains how a differential works better than anything I have ever seen. Keep in mind you have 2 differentials a rear and a front. but If you can follow this you will understand. The first 2 minutes seem worthless, but there is a purpose stay with it.


[ame=http://www.youtube.com/watch?v=F9EPf8SJc2Q]Auto Mechanics: Differential: "Around the Corner" 1937 General Motors 9min - YouTube[/ame]


James K0UA

 

[PHILIP8N]

Even though you tractor is 4wd it isnt really 4wd

Curious why you would say that? Then what would you call it?

 

[Bob77064]

Here you go.. this old 1937 video explains how a differential works better than anything I have ever seen. Keep in mind you have 2 differentials a rear and a front. but If you can follow this you will understand. The first 2 minutes seem worthless, but there is a purpose stay with it.


Auto Mechanics: Differential: "Around the Corner" 1937 General Motors 9min - YouTube


James K0UA

James that is a good video, thanks for posting.

 

[k0ua]

Curious why you would say that? Then what would you call it?

It is 4WD as long as the resistive/tractive forces are equal on a per axle basis. In other words, as long as the front tires have have the same load on them they will both turn. Same for the rear's. But if they are unequal on a per axle basis then it is possible to only turn one wheel/tire and the other to be stopped. I have seen many times when only 1 tire per axle is spinning, and many times when all 4 are spinning. If you use your rear differential lock you can guarantee 3 tires spinning .

James K0UA

 

[k0ua]

James that is a good video, thanks for posting.

Yes I was amazed how the narrator and the video start you off slow and through an easy to understand progression takes you deeper and deeper into understanding a fairly complex subject. Who say's Grandpa wasn't a good teacher!

James K0UA

 

[JOHNTHOMAS]

Loved the picture of the car!:thumbsup: My first car I bought in 1964 while a Senior in HS was a 1935 Dodge 4 door sedan that looked pretty similiar to this car. Next car several months later was a 1958 Chevy Impala 348 Auto converted to 3sp in the floor. Lots of tickets 1964-65. Even got one for riding boys on the running board.:laughing:
Sorry, back to 4wd.

 

[PHILIP8N]

It is 4WD as long as the resistive/tractive forces are equal on a per axle basis. In other words, as long as the front tires have have the same load on them they will both turn. Same for the rear's. But if they are unequal on a per axle basis then it is possible to only turn one wheel/tire and the other to be stopped. I have seen many times when only 1 tire per axle is spinning, and many times when all 4 are spinning. If you use your rear differential lock you can guarantee 3 tires spinning .

James K0UA

Thanks James, I understand the operating dynamics of 4wd, open, limited-slip, and locking differentials. I just wanted Tags to explain how a tractor is called 4wd even though it really is not, and what he would call that. Philip.

 

[JOHNTHOMAS]

Interesting info. I've seen men almost fight when one said they had 4wd which to them meant that all 4 wheels would turn at all times , guess I believed that in the beginning and believe most people stll believe that. Course the individual would have to get the 4wd all 4 all the time to get their vehicle and get one wheel or two on one side in mud or on ice or in a ditch to convince them that all 4 wheels do not always turn. That's about when the cursing and fighting would usually start.
I know Kubota calls their tractor or my tractors 4wd and I've often times seen that only 2 of the tires would turn (spin in mud or on ice) when in 4wd unless I stepped on the locking differential which would then make 3 of the tires turn while one was still not moving.
Philip, what would you call that? I call it 3wd.

 

[PHILIP8N]

I know Kubota calls their tractor or my tractors 4wd and I've often times seen that only 2 of the tires would turn (spin in mud or on ice) when in 4wd unless I stepped on the locking differential which would then make 3 of the tires turn while one was still not moving.
Philip, what would you call that? I call it 3wd.

It is still a 4wd tractor, okay, so you have 2 or 3 tires spinning, but is it always the same 2 or 3 tires that does the spinning? With open diffs front and rear, manually locking diff rear, when 4wd is engaged, all 4 tires are pulling equally until the torque of one tires exceeds the traction capabilities of the surface it is gripping. The open diff is designed so tires on the same axle can travel at different speeds, ie, turning a corner. Air locking diffs front and rear would solve problem, but would make it difficult to steer. My F250 is the same way, but I have a limited-slip diff in rear, which is probably worn out by now. Chevy and Dodge same as well. Just not noticed as much in trucks cause you cant see the tires! Philip.

 

[Ken45101]

Well, there is drive to all four wheels....just not at always the same time :laughing:

Cars and trucks are the same way except that many (most?) do not have the locking differential pedal.

But at least sometimes, having one front and one rear with power beats only have one rear with power:thumbsup:

The other big advantage of 4wd on a tractor (vs 2wd) is that it give you breaking on the fronts. Very important sometimes when going downhill!

Ken

 

[Tags]

It is 4WD as long as the resistive/tractive forces are equal on a per axle basis. In other words, as long as the front tires have have the same load on them they will both turn. Same for the rear's. But if they are unequal on a per axle basis then it is possible to only turn one wheel/tire and the other to be stopped. I have seen many times when only 1 tire per axle is spinning, and many times when all 4 are spinning. If you use your rear differential lock you can guarantee 3 tires spinning .

James K0UA

Philip, I think James explanation is perfect, but just assume you are not a mechanical person and you purchase your first 4wd tractor, you head out into a muddy field and get stuck and only two tires are spinning, do you still think it is 4wd? I have a quad that says 4wd and when I lock the front diff it is TRUE 4wd because it has no rear diff, is it tiring to drive like that, of course it is because it isn't practical to have a front AND rear diff locked all the time. Would I rather have a 4wd tractor/truck without locking diffs over a 2wd tractor/truck? 1000 out of 1000 times I would. I'm sorry if the way I proposed it offended you...

 

[PHILIP8N]

Philip, I think James explanation is perfect, but just assume you are not a mechanical person and you purchase your first 4wd tractor, you head out into a muddy field and get stuck and only two tires are spinning, do you still think it is 4wd? I have a quad that says 4wd and when I lock the front diff it is TRUE 4wd because it has no rear diff, is it tiring to drive like that, of course it is because it isn't practical to have a front AND rear diff locked all the time. Would I rather have a 4wd tractor/truck without locking diffs over a 2wd tractor/truck? 1000 out of 1000 times I would. I'm sorry if the way I proposed it offended you...

No offenense taken, just trying to clear up an explanation for others that might be following. They are 4wd until the torque of one tire in a non-locking differtial exceeds the grip level of the surface it is operating on. Mainly happens to me when pulling a ground engaging implement in muddy soil or on ice. Philip.

 

[TimNY]

Appreciative of all the great replies. This is a good forum. Tim

 

[k0ua]

I have tried to explain how differentials work to many people, and usually without a lot of success, but I think that video explains it so well. Sure it does not cover lockers, air lockers, limited slips, spools or even the simple mechanical rear differential lock most of our tractors have on them. But it sure is a good foundation to move on to those subjects in my opinion. And yes I guess it is an eye opener to get stuck in the mud and maybe only see 2 wheels spinning, but hey it is better than just 1 wheel spinning... Been There, Done That..didn't like it much:laughing:

James K0UA

 

[chopped]

I agree good video. I wonder if I had seen it in school, but i probably dozed throught it or was watching girls lol Thanks for posting it. it really gave me insight into a differenctial, Even though I have changed a few gears in them over the years I never gave much thought to how they worked.

 

[OrangeRidge]

Your diff is only half the story ; don't forget the trans ----

[ame=http://www.youtube.com/watch?v=rLDgQg6bq7o]Turbo Encabulator - YouTube[/ame]

 

[yelbike]

Your diff is only half the story ; don't forget the trans ----

Video Link: http://www.youtube.com/watch?v=rLDgQg6bq7o

Real funny.

 

[rambler]

Well, a 2wd cor or tractor really only has as much traction as the lowest traction of one wheel.

A 4wd tractor has the traction of the 2 lowest value wheels.

A diff lock will add one more wheel to the above.

Pretty simple, really. Differential splits up the power to both wheels, either wheel on the axle can get any % of the available power.

--->Paul