Four Wheel Drive

[lungdoc]

....I would recommend to simply let conditions decide whether or not to engage the 4wd: Soft ground, mud, snow, front loader use - 4wd, Dry lawns, pavement - 2wd. I do not think leaving it in 2wd unless you get stuck is a good idea since you will be giving away the momentum that may have carried you thru had you started out in 4wd, and by then, it may be too late for the 4wd to get you out.

Words of wisdom and fully agree. If anyone doubts picture a slick muddy hill, and what would happen if you wait until you stall in 2WD and then apply 4WD.

 

[ovrszd]

It's been a while since this discussion has come up on this site. Several logical posts so far. Some not so logical. I'm always amused that there are a lot of people that buy 4x4 vehicles with no knowledge of their functionality.

I totally agree with wolc123. He also understands that he's unigue in this discussion. :thumbsup:

But for most of us, who are usually puttering around, different rules apply.

There's a lot of different designs offered in different applications or intended uses. In the CUT world most are strictly gear driven, non synchronized, simply in or out of 4x4. In that design most are geared slightly faster in the front axle. With that said, on solid footing they are rarely not bound up by that differing speed or gearing. So,,,, 99% of the time the front or rear tires are required to slip to relieve that pressure. During that time unnecessary wear is inflicted on the tractor tires or it's powertrain. If you question this theory, engage 4x4 on your tractor, drive it straight forward on solid footing for 100 feet or so, stop the tractor, now try to disengage the 4x4. The resistance you feel in the lever/pedal is the bound up drive system. If you jacked up a tire in that situation it would spin and relieve that pressure. I see nothing good about operating in that situation. So I never engage and leave my 4x4 engaged unless it's needed to complete that particular function. Sometimes it's unavoidable, but never should be the standard in operation.

I'm waiting for the guys who claim their CUT tractor is "special" and it doesn't bind up like that. Especially the Kubota CUT owner. :laughing:

 

[shaley]

Thanks Ovrszd
32 post and finally the mechanics behind the decision "to 4 wheel or not to 4 wheel. It's a matter of mechanics on tractors. The front wheels are driven 5% to 7% faster than the rear in 4WD. This means they must slip. The faster speed is absolutly essential if you are using a loader on a soft slope. The front end will tend to head more downhill with an increasing load in the bucket w/o 4wd. This is why 4wd was developed on tractors. Some European tractors have a more advanced 4wd where by the lead of the front tires increases with the turn angle.
If you are operating on pavement with 3000 lbs of dirt in the bucket you will notice the rubber marks on the concrete.

 

[ovrszd]

Thanks Ovrszd
32 post and finally the mechanics behind the decision "to 4 wheel or not to 4 wheel. It's a matter of mechanics on tractors. The front wheels are driven 5% to 7% faster than the rear in 4WD. This means they must slip. The faster speed is absolutly essential if you are using a loader on a soft slope. The front end will tend to head more downhill with an increasing load in the bucket w/o 4wd. This is why 4wd was developed on tractors. Some European tractors have a more advanced 4wd where by the lead of the front tires increases with the turn angle.
If you are operating on pavement with 3000 lbs of dirt in the bucket you will notice the rubber marks on the concrete.

We'll see if the majority agrees. :confused2:

 

[RoyJackson]

...
There's a lot of different designs offered in different applications or intended uses. In the CUT world most are strictly gear driven, non synchronized, simply in or out of 4x4. In that design most are geared slightly faster in the front axle. With that said, on solid footing they are rarely not bound up by that differing speed or gearing. So,,,, 99% of the time the front or rear tires are required to slip to relieve that pressure. During that time unnecessary wear is inflicted on the tractor tires or it's powertrain. If you question this theory, engage 4x4 on your tractor, drive it straight forward on solid footing for 100 feet or so, stop the tractor, now try to disengage the 4x4. The resistance you feel in the lever/pedal is the bound up drive system. If you jacked up a tire in that situation it would spin and relieve that pressure. I see nothing good about operating in that situation. So I never engage and leave my 4x4 engaged unless it's needed to complete that particular function. Sometimes it's unavoidable, but never should be the standard in operation.

I'm waiting for the guys who claim their CUT tractor is "special" and it doesn't bind up like that. Especially the Kubota CUT owner. :laughing:

About the same here...only as needed.
Also, if your tractor has a loader, lift the front end (axle off the ground) now and then and the front drive wind-up (that "binding" ovrszd describes) will relieve itself. It will be easier to shift out of 4WD.

 

[SPYDERLK]

I use 4 wheel assist only when traversing steep inclines where additional traction is needed.

Actually, this 4 wheel assist is only 2 wheel drive; 1 front tire pulls and 1 rear tire pulls when the 4 wheel assist is engaged.

I guess that technically I could get 3 wheel drive if I locked the rear axle in and had the front wheel assist on.

This is an incorrect analogy. All wheels on engaged axles drive.
larry

 

[SPYDERLK]

I don't know why anyone would leave their tractor in 4wd unless they needed the additional traction at the time.

Braking.
larry

 

[SPYDERLK]

Thanks Ovrszd
32 post and finally the mechanics behind the decision "to 4 wheel or not to 4 wheel. It's a matter of mechanics on tractors. The front wheels are driven 5% to 7% faster than the rear in 4WD. This means they must slip. The faster speed is absolutly essential if you are using a loader on a soft slope. The front end will tend to head more downhill with an increasing load in the bucket w/o 4wd. This is why 4wd was developed on tractors. Some European tractors have a more advanced 4wd where by the lead of the front tires increases with the turn angle.
If you are operating on pavement with 3000 lbs of dirt in the bucket you will notice the rubber marks on the concrete.

My Mahindra has almost no front lead. Sure wish it had more for side hilll work. Actually Ive not done a test to see if they lead or trail. I just know that there is a small bind going straight and all it takes to disengage is let off the throttle. Im going to have to check whether it has lead or trail.
larry

 

[Short Game]

I am in the hills. There is only thin topsoil over a sandstone and volcanic tuff base. The choice for me, especially in this very wet year, is when to lock the rear diff. I think of 2WD as out of control and headed (sooner, more likely than later) for some kind of trouble. I have a 12,000# winch on my box scraper, but that's not there to help me when I slide into a bog while mowing. I have the room for a permanent mount 8,000# winch on the front. I think I'm going to do that.

Now, if I were a flat-lander...

 

[dex3361]

I agree that there is more wear on the drive system running in 4wd (FWA, MFWD). I understand the wear cost and there will be some. The real issue for me in running in 4wd while using my CUT and SCUT tractor is safety. I can repair a machine. Operating in hilly or steep areas it needs to be in 4wd for safety. IMHO