Why turn 4wd off?

[joshuabardwell]

I've been reading a bunch of threads on here about safe (and unsafe!) tractor operation. One of the things I've read about and personally experienced is how useful 4wd is when going down hills nose-first. I don't have very many big flat spots on my property, and I'm often using the loader, so I pretty much leave the tractor in 4wd all the time.

At first, I thought it was like my truck, and the diffs locked when it was in 4wd, so you couldn't use it on pavement. But then I realized it's got a separate diff-lock lever, so that must not be the case. So that leaves me wondering? What's the down-side of 4wd? Why not just leave it on all the time and enjoy the benefits?

 

[thatguy]

the biggest downside is that on a dry surface or pavement, the front wheels can not slip when making turns.. if they cant slip it puts strain on the front differential - as each wheel needs to turn at different speeds in turns

As long as the surface is slick, or soft enough you could leave it in 4x4 all the time..

Brian

 

[JD 4520]

I agree with Brian and would only add or suggest to disengage 4wd on pavement / asphalt otherwise leave it in 4wd especially down hill in grass or gravel or other slick or loose surface.

 

[joshuabardwell]

How can I determine definitively whether the diff on the front wheels locks in 4wd mode? I've taken some tight turns and I've never noticed the wheels slipping. I know the diff on the rear wheels isn't locked unless I press the diff lock lever, as I have used it to get out of a muddy situation where one wheel kept slipping.

The tractor is a Bobcat CT225, BTW.

 

[JakeBrake]

I leave my tractor in 4wd all the time. On my property I never know when I will need the extra traction. I do know that it's better to already BE in 4wd than try to put it in 4wd when you need it. I almost never drive on pavement or concrete.

 

[k0ua]

How can I determine definitively whether the diff on the front wheels locks in 4wd mode? I've taken some tight turns and I've never noticed the wheels slipping. I know the diff on the rear wheels isn't locked unless I press the diff lock lever, as I have used it to get out of a muddy situation where one wheel kept slipping.

The tractor is a Bobcat CT225, BTW.

The front differential never locks, there is no lock mechanism on our CUT size tractors. there is no center differential on most of our CUTS either (some do have, but not many) On Hard surfaces (asphalt, or concrete) when making turns there can be binding (torque windup) between the front and rear. This results in tire wear, for sure and some extra strain on the front differential. But the danger of going down a steep hill in 2WD with a load in the bucket is very real, even on pavement if it has some loose gravel on it, the rear tires can and will break traction, resulting in a runaway if the hill is steep enough, and there is enough gravel, or going down a grassy slope, or anything that reduces traction. Having a heavy ballast on the back will help prevent this, but don't count on it. 4WD is your friend to prevent this. Been there and done that and have survived. What ever the heck you do, drop the bucket, drop the ballast, keep the steering wheel straight, don't swerve or you will surely overturn. Several guys on here can testify what happens when you swerve to miss something.

James K0UA

 

[rekees4300]

Why not just leave it on all the time and enjoy the benefits?

One reason not to leave it on is that the shaft from the rear to front will be rotating all the time. That will cause the oil seals to wear out faster than they would otherwise.

 

[TerryR]

What's the down-side of 4wd? Why not just leave it on all the time and enjoy the benefits?

When your front and rear tires are at the size for which your tractor was designed (presumably when the tires are new), the front and rear axles turn at a coordinated rate so they both cover the same amount of ground in a given time.

But when you turn, the front and rears travel a different distance, requiring one or the other (guess which) to skid a bit to make up the difference. That's not much of an issue on gravel, grass, or other soft surface. But it is on pavement.

I leave my tractor in 4wd all the time except when I run on pavement, especially when I have to turn on pavement, like when I'm cleaning the ditch along the paved road with the FEL. All the pavement around here is fairly level, so the issues cited by others don't come into play.

Terry

 

[flusher]

I've been reading a bunch of threads on here about safe (and unsafe!) tractor operation. One of the things I've read about and personally experienced is how useful 4wd is when going down hills nose-first. I don't have very many big flat spots on my property, and I'm often using the loader, so I pretty much leave the tractor in 4wd all the time.

At first, I thought it was like my truck, and the diffs locked when it was in 4wd, so you couldn't use it on pavement. But then I realized it's got a separate diff-lock lever, so that must not be the case. So that leaves me wondering? What's the down-side of 4wd? Why not just leave it on all the time and enjoy the benefits?

Scenario: you have a load of sand, gravel, mulch, etc. delivered and it's dumped on a concrete surface. You push your FEL bucket into the pile hard to load the bucket completely. You're in 4WD while you push hard until the forward motion is stopped. Loud noise from the front end. That's your transfer case and/or front axle(s) turning to trash. In 4WD all four wheels need to be able to break traction when you stall the tractor's forward motion as in this case. So--load the bucket while in 2WD. Switch to 4WD for transporting the load.

 

[k0ua]

One reason not to leave it on is that the shaft from the rear to front will be rotating all the time. That will cause the oil seals to wear out faster than they would otherwise.

The shaft rotates all the time whether you are in 2WD or 4wd, When in 4WD it is under power from the rear and applying power to the front differential. When in 2WD the shaft is in rotation from the front differential and while disconnected from the rear the connection point is in the rear not the front.. There are no hubs automatic or manual to disconnect the front differential like in your typical 4wd part time truck or SUV. So the shaft rotates all the time regardless.

James K0UA