school of shifting :-)

[Rockbadchild]

All the new pickups that I have ordered I ordered positraction and I
could go where some of the 4x4 pickups were getting stuck with no
problem but I put weight in the truck bed. With the possi both back
wheels would turn and the 4x4's did not have the possi

willy

which is limited slip, most differential are equip with this in one form or the other... however some form are outdated and you have to get out of the truck and go to each wheel to lock them up lol.

 

[mo1]

Thanks!
So, it's not "four wheel drive"?
What is the alternative to "mechanical" in this context?
Unlike cars, there are no "front wheel drive only" tractors, or tractors with AWD, are they?
You've got me curious now. I thought it was just rear, or rear+front, and maybe a differential lock or two.

The original front wheel drive (really, front wheel assist in that case) was hydraulically powered, such as a few 4020 Deeres had. It was not very powerful or efficient, which is why it was dropped in favor of a mechanically-driven axle.

Four wheel drive tractors are the center-articulated units with front wheels that are the same size as the rears, such as 9R Deeres and T9 New Hollands.

The only 2WD tractors drive the rear wheels as that is where the vast majority of the weight is on those units.

"AWD" is really an automotive term meaning to differentiate between a setup where there is a center differential or viscous coupling and can be safely left engaged at all times. vs. a part-time setup which must be disengaged on dry surfaces or the driveline will bind up. Some tractors do have automatic MFWD engagement/disengagement so I suppose this would be somewhat analogous to automotive AWD but nothing in the ag world is called "AWD."

What 4wd means for compact tractors - and also most 4wd PU trucks - is that there is an operator control that tells the transmission to send power to drive the front axle as well as the rear axle. When the front axle is also powered it is then possible for any of the 4 wheels to be driven...hence: 4wd

But a because each axle has a differential, driving all 4 tires at the same time also requires some way to lock the differentials. So without "lockers" you only get 2 of the 4 driven at any time....but that's another level of complexity.

You also asked what is the alternative to "mechanical". It is "hydraulic" - drive via a fluid motor in the axle or hub instead of by driveshaft and gears. MFWD vs HFWD.

HDFD and AWD is not nearly so common as 4wd via MFWD in the under-100 hp tractors.

However, MFWD is simple and relatively cheap to manufacture since the invention of the front bevel drive - about 1975. The big downside to 4wd MFWD is that it is a part time traction improvement for getting through difficult places & not for using full time. 4wd is not AWD; it lacks the necessary center differential that all AWD have.

There are a few compact tractor sized AWD full time true 4wd tractors with Hydraulic Front Wheel Drive instead of MFWD. The Bobcat Toolcat is one, the USA made Ventrac is another. Both excellent, not too common, and relatively expensive. Also you will find that type of hydraulic drive on larger European tractors and big construction machines like skip loaders.

Hope this helps,
rScotty

The first MFWD setups were planetary gear setups like you see on ag tractors. Bevel gear MFWD is used on compacts as it allows for the hub centerline to be dropped relative to the axle centerline, allowing for a reasonable turning radius from running smaller-diameter tires but yet preserving some ground clearance. It is noticeably weaker than planetary gear MFWD which is why it is not seen on the larger machines.

 

[SmallChange]

Four wheel drive tractors are the center-articulated units with front wheels that are the same size as the rears

Wait, wait -- there are four wheel drive tractors that are not articulated and do not have front and rear wheels of the same size. My NH WM25 can engage or disengage the front wheels through use of a "Four-Wheel Drive (4WD) lever". I think this is pretty common these days.

 

[mo1]

Wait, wait -- there are four wheel drive tractors that are not articulated and do not have front and rear wheels of the same size. My NH WM25 can engage or disengage the front wheels through use of a "Four-Wheel Drive (4WD) lever". I think this is pretty common these days.

That is not 4WD, that is MFWD. Sometimes people will refer to MFWD as "4WD" or "4x4" but that is not correct. A 4WD tractor has a front axle setup that provides roughly half of the total traction of the machine. A MFWD axle provides a lot less than half the traction, it provides roughly 15% or so of the total traction. That is the real reason for the distinction.

 

[ning]

That is not 4WD, that is MFWD. Sometimes people will refer to MFWD as "4WD" or "4x4" but that is not correct. A 4WD tractor has a front axle setup that provides roughly half of the total traction of the machine. A MFWD axle provides a lot less than half the traction, it provides roughly 15% or so of the total traction. That is the real reason for the distinction.

I don't think this "15% of total traction" is a function of the MFWD, but more of the weight distribution of the tractor, which varies depending on equipment and loading - also note that the front & back axles turn at essentially the same rate.

Given that the front drive is mechanically connected to the rear, there's no set "torque distribution" like in an AWD system, where you can literally design it so that the front gets X% and the rear gets (100-X)% (eg, 60/40, or 50/50). Some modern automotive AWD systems have a variable torque split and will be practically 100% FWD until some slip is detected whereupon the computerized system will "shunt" more torque to the back.

Check this thread for more: Difference Between 4WD and MFWD ?
TL;DR - "MFWD" is to clarify because some people used to call a tractor with duals on the back a 4WD, or because there were earlier lousy attempts to make a 4WD tractor with hydraulic front drive, etc, and MFWD makes things more clear.

 

[bigtiller]

If we all could drop the "D" in MFWD and replace it with an "A" ,,some of the misinterpretation could be resolved.

Mechanical Front Wheel Assist is the correct term.
We could drop the "M" because it came about when Deere switched from hydraulically powered to mechanically powered front wheels and Deere quit making the hydraulic powered one a long time ago.

 

[ning]

If we all could drop the "D" in MFWD and replace it with an "A" ,,some of the misinterpretation could be resolved.

Mechanical Front Wheel Assist is the correct term.
We could drop the "M" because it came about when Deere switched from hydraulically powered to mechanically powered front wheels and Deere quit making the hydraulic powered one a long time ago.

It's definitely mechanical front wheel DRIVE when the rears are on slime and the fronts are on something solid

 

[bigtiller]

I prefer to call it assist because there is a reason the front gears fail when engaged on hard surfaces under heavy continuous use and not the rear gears.

 

[SmallChange]

That is not 4WD, that is MFWD.

Says who? The manufacturer thinks it's 4WD. I actually copied and pasted from the manual. Their brochure refers to "4WD traction and rear differential lock", "Standard four-wheel drive" on page 5 (see link below):

https://cnhi-p-001-delivery.sitecorecontenthub.cloud/api/public/content/64cb47095ede4f8cb6469e69398687eb?v=d175d103

 

[charlessenf]

this thing should dig up sandy soil like digging up butter

I dis agree! Itsa FEL - a Front End Loader. It is not a backhoe nor an excavator and is not intended for digging holes in the ground beneath the LOADER bucket.

Pile up some gravel our a couple tons of sandy soil and you should be able to (as advised, above) dance your way to gathering a load "Keep a long gentle slope into the pile. Raise the bucket as you go in and curl to fill."

You are trying to coax a bit of sand onto the front lip, tilt the bucket back (curl) to 'toss' it into teh back of the loader then got at it again and again until you've filled your loader with material.

I bought teeth for my bucket and with them or the box blade or both, been able to widen a 'drive' behind the barn and a steep rise by digging up the flat part with the BB Teeth and scraping the 'wall' with the FEL Teeth to dislodge the soil. Then I can slip the FEL under a pile of teh stuff and carrying off to fill a hole somewheres else.

Now, I've only a little biddy B7800, but digging a hole with the FEL does not work for me at all.