4wd?

[LD1]

All this talk got me looking for a definitive definition, and it seems that SAE uses the two ranges to define 4WD and AWD.....it seems if it has a low range, they consider it 4WD....but only one range makes it AWD. Clear as mud I guess......:confused2:

That would make the old NP203 a 4wd then. Even though it has a diff in the t-case, it has a high and low range.

Bu now what about tractors that dont have a high-low in the t-case per-say??

 

[Buckgnarly]

Bu now what about tractors that dont have a high-low in the t-case per-say??

Good question....but I guess SAE does not care about tractors:laughing:

 

[brain55]

Well I guess all of those times I was told by the factory reps at Kubota that they tried to match the wheel speed I was being mislead. Even if the optimum lead is 2% there is still only a limited window of tire inflation and tire wear where this is actually achieved.

 

[LD1]

Good question....but I guess SAE does not care about tractors:laughing:

I wonder if there is a STE??:laughing:

Well I guess all of those times I was told by the factory reps at Kubota that they tried to match the wheel speed I was being mislead. Even if the optimum lead is 2% there is still only a limited window of tire inflation and tire wear where this is actually achieved.

I am not denying what you are saying. And maybe kubota does try to do a 0% lead/lag. But these discussions have come up several times on this very website. And it is generally agreed upon that up to 5% lead is accepted as normal. Otherwise, when the fronts do wear down, you would end up with a lag condition, which is not desirable.

Here, this is a good read http://www.firestoneag.com/webres/File/Tire-Info/TireInfo-LeadLag.pdf

 

[piller]

Think about it for a minute. Suppose that the fronts were driving slower than the rears, then the rears would end up pushing the fronts which would not be good. It would also be bad for steering if the fronts were driving slower than the rears.
Having a little bit of lead for the fronts will improve traction and steering.

 

[buck12]

Using automotive world terms, AWD and 4WD are NOT the same.

An AWD car has some form of "slip" built into the transfer case, be it viscous coupler or mechnical means. A true 4WD will have the front and rear locked by means of gears or chain in the transfer case. There is no slip between front and rear axles, hence no driving(or more appropriately, TURNING) on hard pack surfaces while in 4WD but an AWD is OK. The slip is necessary b/c the front and rear axle will be turning at different rates due to different arcs while in a turn.

I am guessing that the makers of the 4WD tractors factor the tire size difference and adjust the front and rear gear ratio accordingly to get rid of as much rotational difference from front to rear. Even some OEM trucks have a slight difference (like 4.11 front and 4.10 rear )but if using on a slick surface it does not cause binding.

Open, L/S, and locked axles only affect the two wheels on that axle, not make it "4wd". The transfer case is what makes it AWD or 4WD.

Also all the AWD vehicles (mostly station wagons on steroids) I have seen don't have low range like a typical 4WD truck.

 

[MBTRAC]

By Agricultural Tractor design.manufacturing nomenclature/definition:-

- a 4WD has equal size wheels, is capable of taking equal loading/power through only the front axle & running constantly as a 4WD, 4WD may be selectable together with independent engagement of centre, front & rear diff locks
- a FWA (front wheel assist) or MFWD has unequal sized axles/wheels with a noticeably smaller front set & cannot take equal loading/power through solely the front axle, FWA/MFWD is selectable, rear diff lock is also usually selectable & a front diff lock may or may not be fitted.

4WD's, FWA's & MFWD's can all run single, dual or triple tyres on one or all axles, the number of tyres does not dictate the drive definition, afterall equal size single or dual tyres can be fitted on both axles of a 2WD tractor.........

As for AWD vs 4WD SUV's/Trucks:-
- in a AWD, power is transmitted/biased via either only the front or rear axle, all wheel drive is only available "on demand" via auto engagement & cannot be engaged manuall for constant AWD running, they do not have mechanical transfer boxes & rely usually upon a viscous or electro mechanical coupling type intermediate reduction drive/variance on diff ratio's front to back (e.g Toyota Highlandger/Kluger)
- 4WD's, can be constant all wheel drive applying drive at all times to front & rear axles (e.g Range Rover, Subaru, Toyota 200 Landcruiser) or with manually engaged selectable 4WD (Landcruiser 78 series, Unimog, Pinzgaur) the vehicles may or may not have low range/centre or axle diff locks but will have a mechanical transfer box coupling the front/rear axles by viscous, mechanical or electro mechanical means..etc

 

[whistlepig]

All 4wd's have the front working against the back to some degree. If not, one end or the other isn't doing the job at the same time. If one end is freewheeling while the other is end not then 4wd it isn't. These are not true "lockers". Both the front and rear have differentials. They wouldn't steer very well if they didn't have differentials. Try leaving your truck in full time 4wd all the time. You will be shopping for some universal joints very quickly.

 

[lsmurphy]

Tyres for B6100 or B7100 4x4 with grip

--------------------------------------------------------------------------------

I have been looking for a replacement set of tyres for my 6100 for ages and have a solution that works. I wanted wide tyres that would not cut up the grass but also wanted them to grip the snow and mud as I use a FEL.

So as I have seen others asking the same questions on Orange I thought I would pass this on.

The problem is the interactual ratio, get it wrong and its going to cost you! We know what Rolling Circumference (RC) we need and the gear ratio (1.464) but can we find front and rear tyres that work? No! You get a good Agri rear but have to go turf on the front.

Well I now have a set on my tractor that meets all the requirements above. They are as follows:
Rear - 29 x 12.50 x 15 (RC = 88 inch @ 15psi) Carlisle TRU POWER
Front - 20 x 8 x 10 (RC = 62 inch @ 25psi) Kenda K378

Tyre Inner Tubes, Quad Bike Tyres, ATV Tyres, Turf Tyres, Wheelbarrow Tyres, Ride On Lawn Mower Tyres, Golf Buggy Tyres, Sack Truck Tyres

62 x 1.464 = 90.768 divided by 88 = 1.0314 minus 1 x 100 = 3.14 %

well within the 0-5% lead reccomended by Kubota

Both front and rears have Agri tread pattern and grip very well, but are wide so do not sink. Best of all is they look fantastic.

I'm also changing out my tire size. The above is a quote pasted from another site..........I used a similar formula to change my size.

From everthing I read there is a front wheel lead.



When you move up from a 2wd to a 4wd (FWA).........call it what you want.........it's a world of difference.



Yeah I drive Jeep............Only in a Jeep 4.10 front and 4.11 rear

 

[LD1]

The difference between 4.10 and 4.11 is 0.24%. Almost negligible. On a 30" tire, that would be 1/16" difference in overall height. (or 1/32" difference in tread wear). Again, negligible.:thumbsup:

Same thing with 3.54 and 3.55 gears.

 

[mikehaugen]

4WD's, FWA's & MFWD's can all run single, dual or triple tyres on one or all axles, the number of tyres does not dictate the drive definition, afterall equal size single or dual tyres can be fitted on both axles of a 2WD tractor.........

yeah but with duals on the rear aren't you technically always running in 4wd?

... sorry, I couldn't help it

 

[Jimh4662]

Greetings : I've been looking far and near on the cyber treads trying to find 4wd specifics. Been a 4wd drive owner for 40 of my 60. Truck and tractor. All been get wet and lock to the toggle from the cab lock. Up to this point I have known the do's and wish I didn't. Well I cannot determine whether the new JD 758 4wd will be able to cut grass while turn and return on dry pavement. It appears it is full time. Any you folks have any suggestions or comments. Thanks

 

[jenkinsph]

Greetings : I've been looking far and near on the cyber treads trying to find 4wd specifics. Been a 4wd drive owner for 40 of my 60. Truck and tractor. All been get wet and lock to the toggle from the cab lock. Up to this point I have known the do's and wish I didn't. Well I cannot determine whether the new JD 758 4wd will be able to cut grass while turn and return on dry pavement. It appears it is full time. Any you folks have any suggestions or comments. Thanks

The traction with these mowers is great, no issues imo. No scuffing in sharp turns, no grass to repair, seems to go everywhere I wan't to go.

 

[JasG]

My understanding is similar to others.

This is my general guide, but there are no set rules. This is based on the "common" usage of terms around here.

4wd/AWD - is the large tractors that all 4 tires are the same size. They may steer by wither turning the tires or articulation of the frame.

MFWD - Mechanical front wheel drive, or assist. These are row crop all the way down to the small compacts. You can select to put power to the wheels or not. As others have said, my understanding and experience is the front tires turn a little faster than the back. Kubota even has "bi-speed" where once the wheels turn past a certain point they speed up even more. Deere has "caster action" which the front wheel lean into a turn which for a couple of reasons helps with turning. Some have called it others things some have open, limited slip or locking front ends.

HFWA/HFWD - Hydraulic front wheel assist is a system like some road graders have where hydraulic motors are used in the front wheels. This gives a very tight turn. The problems were because the rear tires were driven by the trans and the front by hydraulics the speed difference was usually a large amount. The Deere system had a 2 speeds but you also had large changes with engine speed. This was used on the 20, 30, and 40 series Deere row-crop tractors. I believe Oliver and Allis Chalmers among others also had systems similar. The biggest problem was if left on it would get very hot and put enough power to the tires. It is still used today on most brands of combines and forage harvesters, but both ends are hydraulic driven. That seems to work much better being the system isn't fighting it's self.

There are some less common systems out there.

This is on the front tires being faster.
Frequently Asked Questions | Firestone Agricultural Tire

The problem could be the result of "lead/lag," a condition found on MFWD tractors that can shorten the life of the front tires and cause wear and tear on the tractor's transfer case. Lead/lag refers to the relationship between the speed of the front wheels and the speed of the rear wheels. If the front tires' speed is faster than the rear tires' speed, the tractor has a lead condition. If the front tires' speed is slower than the rear tires' speed, the tractor has a lag condition. The desired amount of lead is 2 percent, which means the front wheels turn 2 percent faster than the rear wheels. The Firestone Farm Tire Data Book contains information about how to accurately measure and correct lead/lag on your tractor, or you can click here. Rapid MFWD front axle wear can also be caused by misalignment (toe-in) or worn tire rods.

Mechanical Front Wheel Drive tire recommendations for best performance

Mechanical Front Wheel Drive (MFWD) tires are designed to travel faster than the rear tires. This reduces front tire wear, improves front wheel traction, reduces transmission wear from gear "windup," and allows easier shifting of the MFWD.