Silly 4x4 question

[TerryR]

Slopes are a key factor to consider. As you read around TBN (ex. Safety forum), you'll come across examples of people who got into trouble going down slopes, esp. with loads, when they didn't have 4wd engaged.

You can potentially make more use of engine-braking on a down-slope if 4x4 is already engaged - that may have been your Dad's reasoning.

It's not only engine braking that you get by using 4wd. When 4wd is engaged the rear differential is tied to the front differential, so applying the brakes to the rear also applies them to the front.

 

[Fastball]

I figure I'll leave well enough alone and keep it in 4x4.

 

[Code54]

I figure I'll leave well enough alone and keep it in 4x4.

If you live on hilly or mountainous land that is a really good idea. We never take ours out of 4x4 due to the risk of sliding going down the hills (mostly leaf or grass covered in our case).
Most accident I have seen around here have been caused by people taking theirs out of 4x4 and sliding going down hill.

 

[airbiscuit]

I figure I'll leave well enough alone and keep it in 4x4.

I would take it out of 4WD every once in a while just to prevent it from getting "wound up" and to keep the linkage free. Just drive 100 feet or so and put it back in 4WD.

 

[kebo]

4x4 is a little misleading.
>It is one wheel drive if the "4x4" lever is not engaged.
>It can be made two wheel drive (both rears) by engaging the differential lock...usually a lever by your foot.
>It is also two wheel drive, one front and one rear, when the 4x4 is engaged.
>It can be made three wheel drive by engaging the differential lock or when one of the rears spins in mud or dirt.
>Only one of the fronts can be driven unless there is a automatic differential lock. The best you can get is three wheels driven. Front locks only come on larger tractors and only work when one front wheel spins. A M7040 has this feature.

Feel free to ask. That is how one learns. This whole forum is dedicated to helping others with their issues so "ask away" and don't feel embarrassed in the slightest.

Other posters with more knowledge: please don't hesitate to correct my post and/or add information.

It is not harmful to run it in 4WD as long as the wheel are in a substance that allows them to spin and relieve tension. Something like sand, loose soil, mud, and the like are fine in 4WD mode.

Avoid hard surfaces like blacktop or highways. The gears get wound up with tension and tires wear as well. Sometimes you have to back up to get it out of 4WD.

Good info there by gwdixon. I can only add that MFWD is probably not needed all the time by the majority of CUT owners, therefore, I think it's a good idea to disengage the MFWD when it's not really needed. This will reduce some wear & stress on the drivetrain (from the binding that's mentioned by another poster). However, if you're in a hilly area, it's probably safer to leave it engaged all the time for the reason cited by Terry R. As for me, I only use it when I really need it. I find that when I'm cutting the grass with the finish cut mower, I can make sharper turns, and it runs smoother (no binding!), with the MFWD disengaged. It also uses less fuel when it's disengaged. So, there are pro's and con's here, and each owner can decide how they want to use their own equipment.

 

[RjCorazza]

Very informative thread. I generally shift in and out of 4wd as necessary... Always out on dry pavement, and in on slopes. It bears repeating that while going downhill (particularly with a loader) in 2wd when the weight comes off the rear the fronts generally have no brakes, and you can be in for a wild ride.
I did this once on a very mild slope at low speed. Unfortunately it's too late once it starts.... Steer straight, drop the bucket, and hang on.

 

[stevem5215]

I use mine the same as the poster above. Put it into 4wd on hills going down and not in at all other times when not. I probably use 4wd about 5 minutes total each time I cut the grass with it. Otherwise it's not needed and will tear the grass up when turning usually.

Remember it's front wheel assist and really not a 4wd system.

Steve

 

[check]

Very informative thread. I generally shift in and out of 4wd as necessary... Always out on dry pavement, and in on slopes. It bears repeating that while going downhill (particularly with a loader) in 2wd when the weight comes off the rear the fronts generally have no brakes, and you can be in for a wild ride. I did this once on a very mild slope at low speed. Unfortunately it's too late once it starts.... Steer straight, drop the bucket, and hang on.

Yup. I learned that right here on TBN! I have one Sandy sloped area at the cottage which is not that steep, really, but it does make a huge difference going downhill when the 4 x 4 is engaged.

 

[LD1]

I know many have repeated what GWdixon has said, about when in 2wd that its actually "one wheel drive" etc etc......but that is technically inaccurate.

Most cars, trucks, and tractors have what is called an "open differential"

And what that means in a nutshell is EQUAL torque....UNEQUAL speed.

Meaning that even though one wheel may be spinning and the other appears to do nothing (which is why people think its "one-wheel-drive") in reality, BOTH wheels are getting the exact same torque. And BOTH wheels are trying to move the tractor with the exact same force.

Kinda like "a chain is only as strong as its weakest link" applies here. The wheel with the least traction, will limit all others to that same amount of force applied. But rest assured, it is still trying to move the tractor.

A differential locker in a nutshell is UNEQUAL torque....EQUAL speed. Meaning that no matter what, BOTH wheels are gonna turn the same speed, even though they may be applying different amounts of torque to the ground.


Scenerio: lets say you have your left tire on a patch of ice and its only able to put 50 ft-lbs to the ground, while the right tire is on pavement and can exceed 500ft-lbs of torque to the ground before slipping.

With an open differential, BOTH tires are going to apply 50 ft-lbs to the ground and in total you will try to move the tractor forward with 100ft-lbs of force. Which may not be enough to move the tractor.

Now you step on the diff-lock pedal. Now the tire on the right can get a full 500ft-lbs of torque applied, and the left is still limited to 50 ft-lbs. That total of 550ft-lbs may be enough to get u moving again. (Or you may just spin in circles around the left tire thats on ice)

 

[CobyRupert]

^ :thumbsup: Good explanation LD1

I thought it was very distracting and probably confusing to the OP who is admittedly inexperienced to go on a tangent about how 2 wheel drive is 1 wheel; 4 wheel rive is 2 wheel, unless you have rear differential lock and then it's 3 wheel, unless front axial has a lock, (but it probably doesn't!), then it's 4 wheel, blah, blah etc..
He was asking basic 4wd level '101' questions, and we're throwing curveballs.