Oil & Fuel Cost of operating in 4WD- just rubber and fuel?

[flINTLOCK]

I don't know if my soon to be delivered tractor is full time 4-wheel drive or not. It's a 2002 NH TC40DA. Any help. It would be nice to switch out of 4WD for road trips I guess.

 

[texasjohn]

4 wd all the time, except on pavement.

 

[cp1969]

That extra throttle and fuel was needed in 2wd to move the "dead" axle. The bottom line here is that if you want to save fuel, you should leave it in 4wd almost all the time unless you are on the road.

The physics of the situation are not with you.

The amount of frictional forces that have to be overcome are the same whether the front axle drive machinery is being driven by the ground or by the engine.

 

[wolc123]

Hey 69, I see you do not believe me so why not try the little test I suggested? You may find that physics are on my side. I doubted it myself until I tried it. It sounds like your confusion, like mine, was based on automotive experience. Keep in mind that pavement can not absorb energy like soft ground can and that it is easier to pull than push in these conditions which is why the front does so much. How do you explain the absence of big 2wd's doing tillage work in the big fields? Dont feel bad as you are certainly not alone in the belief that one gets better fuel economy with his tractor in 2wd. Maybe a few of the doubters will try this test and we can settle this old argument.

 

[texasjohn]

Am sure it would take a multisample, multi-operator, multi-task scientifically measured approach to determine if 4wd saves or costs fuel.

I know that it costs more for a road vehicle to simply have 4wd... more weight if nothing else.

I can see that in an application where ineffective 2wd tractor tire slippage would result in repeated attempts/more tries than a 4wd vehicle that would roll right on thu something. Thus cost more time and fuel.

In your application of sifted loose soil leveling... I would highly recommend 4wd to reduce wheel slippage and the time required for the task.

 

[cp1969]

If I built a shaft that had a frictional load of some sort in the middle and cranks on each end, would it matter which crank I turned?

My 'confusion' is not based on automotive experience. It's based on the science of Statics and Dynamics. You know, that F=MA and all that springs from it stuff. I have never seen the coefficient of rolling resistance change because an axle is powered or not.

 

[Timber]

Oh no not this one again. I'm too tired

 

[CDsdad]

I think....Never mind. I'm with Scotty.

 

[SPYDERLK]

The physics of the situation are not with you.

The amount of frictional forces that have to be overcome are the same whether the front axle drive machinery is being driven by the ground or by the engine.

wolc123 is right. It is a matter of pushing vs climbing. When an undriven wheel sinks in it skids as it is pushed thru the rut. This is due difference in relative motion between the tire and the ground at different parts of the circular contact. The phenom is more easily seen if you imagine a limiting case where you sink deeply. A driven tire climbsout as it pulls. Also seen when you try to push a tire over a tall obstruction. It will stop you whereas a driven tire would just climb over.
larry

 

[Gordon Gould]

I use 4wd in the woods or where it is soft other wise 2wd unless 4wd needed. Run rear chains and vastly reduce need for 4wd.
Steer with the split brakes when in the woods.