4x4 Question

[ahoude]

I should have mentioned that my property is primarily flat with no steep hills. A few wet spots but the tractor bairly misses a beat going through them.

 

[Soundguy]

Seriously though, this is not exactly what has been said here. There is the idea that the front drive train is a weak link that is not made to last as long as the rest of the tractor components. If this is true, then leaving it in 4wd all the time, whether you need it or not, is tempting failure of a system not designed for constant use.
.

Hmm.. I havn't seent hat spelled out here.. I don't think the front axle is any less durable than any other part of the tractor.. i just think running it in 4wd, when not needed, adds wear that is not needed... I don't drive my truck in 4wd just because I pull off the pavement, unless I think I'm gonna get stuck, or need to pull something.

Soundguy

 

[Soundguy]

Anyone here really think it neccessary to constantly be shifting in and out of 4X4, in just when really needed and out when not? My tractor maint guy (damned good mech) and the Kubota manuals don't think there is a problem with the way I do it. I'd be more concerned with the wear caused by constantly shifting in and out than using it.

What about Nh sensitrack?

Most CUT can do in 4X4 the work that a 4X2 tractor needs about 50% more HP to perform (generalization/rule of thumb recommended to me by several sources.) Said another way you can get by with a smaller less powerful tractor if it has 4X4. If you use your tractor to anywhere near its capacity you will be hampered by wheel slipage much more if you run in 4X2.

That's a big difference there...50%.. and is so general as to be almost useless. You have to take other factors into comparison.. like weight and size. Also.. hp? drawbar hp? pto hp? engine hp? again.. to vauge... No reason why you would be able to run a 4x4 tractor with 50% less hp and get the same work down on a stationary power setup.. like a sawmill or genny...

Or pulling a big mower.. Or a hay baler... While some tractors may have the hp.. you still need the weight to be safe.

I think it is more accurate to say that a 4x4 can perform some of the drawbar tasks that would require a larger 4x2 tractor, simple due to traction .. not specifically hp.

Soundguy

 

[Soundguy]

Would it hurt to use 4wd all the time? .

I think many people here are confusing 'hurt' with 'wear'. I'm advocating that using 4wd under a laod adds wear to the system.. I did not say it hurt it. ( vs using 2wd ).

Obviously as has been pointed out manny times. if 4wd is needed.. by all menas.. use it. If your land changes so much that you can use 4wd and would have to be shifting in and out.. I'd agree... just leave it in 4wd, save for the high traction areas.

Soundguy

 

[Soundguy]

In spite of what happened.. I think he still should have taken it out of 4wd at the blacktop..... though obviously not before.. especially considering the teraine he was crossing to get to the blacktop. His method sounds more like an airplane pilot turning off his engine as he is coming in for a landing.. so that he doesn't forget to turn it off after he lands... Unfortunately.. the engine would be a real help while landing..e tc..

Soundguy

Just last week a friend of my brother took his JD 4410 tractor out of 4 wheel drive because he did not want to forget to take it out when he got onto the blacktop. As he was traveling on a logging road headed off a hill it broke traction and slid about 50 feet, hit a dirt bank and rolled, coming to rest on its side. Just shows what can happen when someone thinks they don't need 4 wheel drive.

 

[ovrszd]

Okay, let's try for some clarity in the discussion about the strength of the front drive setup versus the rear drive setup. I have a parts manual that I downloaded for my B2910. So I'll try to describe the drivetrain for each end of the tractor based on that manual.

First the rear. A straight shaft enters the rear axle case and has a pinion gear attached to the end which drives a ring gear that is fastened to the carrier containing the spider gears (which allow the two axles to spin at different speeds). The spider gears are directly fastened to the axle shafts using splines. Very few spots for wear and an expected life span in the thousands of hours easily. Very rare to see someone have to rebuild any of this driveline with the exception of maybe the spider gears under severe abuse of the rear locker. This driveline takes stress every time the tractor is moved, regardless of whether we are in 4x4 or 2x4. Do we all agree to this???

Second the front. In the bottom of the rear axle assembly is an additional gearbox bolted on that has a sliding gear that engages and disengages the 4x4 when you move the lever thru a counter shaft and gear assembly coming off the pinion shaft described above. This in turn drives a forward shaft that goes into a ujoint, then a mid shaft transfers the power forward to another ujoint, then another mid shaft transfers the power forward to a shaft coupler, the coupler is fastened to the pinion gear in the front axle assembly. That pinion drives a ring gear that is fastened to the carrier containing spider gears (which allow the two axle shafts to spin at different speeds). The spider gears are directly fastened to the axle shafts using splines. These axle shafts extend outward into the front wheel spindles where there is another angle gear which drives against an opposing angle gear that is fastened to a vertical shaft to transfer the power downward thru a shaft on each side into another pinion gear. That pinion gear drives another ring gear that is fastened to a carrier that transfers that power into a horizontal shaft which is fastened to the front wheel assembly. So this system contains 3 ring gear/pinion setups, 4 angle gears, 1 set of spider gears, 1 shaft coupler, 2 ujoints, 3 straight cut gears, 1 sliding gear and 9 splined shafts. Do we all agree to this??

Can we agree that the complexity and thus the lifespan of these two drive systems is considerably different?? Can we agree that if used under equal conditions and stresses and number of hours that the front drive system could be expected to fail earlier than the rear drive system simply because of complexity?? If you cannot find it in yourself to agree to this then simply stop reading and ignore anything else I have to say about this subject, that's your privilege.

If you agree with my explanation, description, and final analysis about the above drive system, then wouldn't you also agree that you should minimize the amount of stress being put on the front drive system?? If you agree wouldn't you also agree that you should use your 4x4 when you need it and disengage it when you don't?? That's why they put that lever there, to use.

Now in regards to N80's (Hope I remembered his name right) comments about his L4400 not getting "bound up" when he turns in 4x4. As I said way back a few posts ago, some tractors have traction sensitive setups and will not bind. I'm not personally familiar with an L4400 so maybe it has this system. It uses a complex speed sensitive system that locks and unlocks the 4x4 system based on need. When you make a tight turn such as at the end of a field, the tractor's system recognizes that difference in wheel speed and allows the 4x4 system to unlock for the turn. If you put the tractor in a situation where the wheel speed variance between front and back exceeds what you encountered in a turn, it locks and offers 4x4 drive. This type of 4x4 system is very common in SUVs on the road today. Most offer some sort of "full-time" 4x4 using a method similar to this. They usually use the Anti Lock Brake sensors to activate and deactivate this system.

In regards to taking more HP in 4x4. If you believe my above statements then you must also agree that it would take more HP to drive all of the above described systems versus just the simple rear drive system. Again, that's just simple physics. I refer back to example of getting "bound up" and how much force it takes to move the tractor in that condition. If you have a traction sensitive 4x4 system this may not apply to you. Your burden is that when you are driving around with this system engaged you are wearing out the parts that are constantly engaging and disengaging without any input from you.

Bottom line, use it when you need it, disengage it when you don't. Your tractor will thank you!!!

 

[neverenough]

How about I inject some facts into the thread, sort of kicking the bee hive.

Fact: Buy a tractor from a company who knows tractors, like John Deere, and they will tell you, right in the "operating the tractor" section of the owners manual, to only use the MFWD when needed for added traction and braking. The proper way to use MFWD. For all the newbies, MFWD stands for Mechanical Front Wheel Drive. Technically, unless the front and rear wheels are the same size, like on a truck, or large ag tractor, it's not 4X4 or 4 wheel drive (6 times a year).

Fact: The MFWD system is designed to give added traction in sub standard conditions. Using MFWD in on high traction surfaces, including dry lawns and packed gravel and dirt, WILL result in added driveline stress, and premature failure. Chances are, this failure will occur when you are decending a steep hill with a heavy load, or stuck up to the axles in heavy mud becouse you went into the mud with the MFWD locked in, and kept going, hoping it would also get you out. My 4 wheel drive ag tractor has pulled out MFWD tractors almost as many times as it has gone out to the field to disc.

Fact: Using a MFWD tractor to do more work than the tractor was meant to do, just becouse it has MFWD, will cause serious saftey issues and premature wear on the tractor.

Fact: The most important part of a tractor is an operator who knows how to operate the tractor, and when to use each of the features on the tractor.

Fire away boy's and girl's....

 

[ovrszd]

How about I inject some facts into the thread, sort of kicking the bee hive.

Fact: Buy a tractor from a company who knows tractors, like John Deere, and they will tell you, right in the "operating the tractor" section of the owners manual, to only use the MFWD when needed for added traction and braking. The proper way to use MFWD. For all the newbies, MFWD stands for Mechanical Front Wheel Drive. Technically, unless the front and rear wheels are the same size, like on a truck, or large ag tractor, it's not 4X4 or 4 wheel drive (6 times a year).

Fact: The MFWD system is designed to give added traction in sub standard conditions. Using MFWD in on high traction surfaces, including dry lawns and packed gravel and dirt, WILL result in added driveline stress, and premature failure. Chances are, this failure will occur when you are decending a steep hill with a heavy load, or stuck up to the axles in heavy mud becouse you went into the mud with the MFWD locked in, and kept going, hoping it would also get you out. My 4 wheel drive ag tractor has pulled out MFWD tractors almost as many times as it has gone out to the field to disc.

Fact: Using a MFWD tractor to do more work than the tractor was meant to do, just becouse it has MFWD, will cause serious saftey issues and premature wear on the tractor.

Fact: The most important part of a tractor is an operator who knows how to operate the tractor, and when to use each of the features on the tractor.

Fire away boy's and girl's....

No rounds fired from this side. You effectively made my case. Also cleared up the technical definition of 4x4 versus MFWD. Thanks for the technical input!!!

 

[Soundguy]

Good posts guys.. nice and lean too.. no fat.

Soundguy

 

[OkieG]

Everyone who intends to use 2WD on pavement, but has forgotten to disengage the 4WD a time or two...raise your hand! I hope mine isn't the only hand raised.

One of the many times I've forgotten resulted in catastrophic front axle damage...Maxing out the loader forks with a partial pallet of bricks I needed to move a half mile on asphalt. At the end of the trip I noticed fluid leaking onto the pavement. The lower spindle shaft bearing had "exploded" and broke a hole in the cast iron spindle housing.

The front axle MFWD drive train on my tractor doesn't look to be built nearly as heavy as the rear drive train. I believe the front axle is relatively delicate compared to the rear and certain "bonehead" situations will make that weakness painfully clear.

My intent, even before the accicent, was to use MFWD whenever needed, but only when needed. ie 2WD unless MFWD is required.

OkieG

 

[ovrszd]

Everyone who intends to use 2WD on pavement, but has forgotten to disengage the 4WD a time or two...raise your hand! I hope mine isn't the only hand raised.

One of the many times I've forgotten resulted in catastrophic front axle damage...Maxing out the loader forks with a partial pallet of bricks I needed to move a half mile on asphalt. At the end of the trip I noticed fluid leaking onto the pavement. The lower spindle shaft bearing had "exploded" and broke a hole in the cast iron spindle housing.

The front axle MFWD drive train on my tractor doesn't look to be built nearly as heavy as the rear drive train. I believe the front axle is relatively delicate compared to the rear and certain "bonehead" situations will make that weakness painfully clear.

My intent, even before the accicent, was to use MFWD whenever needed, but only when needed. ie 2WD unless MFWD is required.

OkieG

Do Jeeps count???? My Hand Is Up!!! Sorry for your breakdown!!! Ouch!!!

 

[JerryG]

Correct on ALL counts.

How about I inject some facts into the thread, sort of kicking the bee hive.

Fact: Buy a tractor from a company who knows tractors, like John Deere, and they will tell you, right in the "operating the tractor" section of the owners manual, to only use the MFWD when needed for added traction and braking. The proper way to use MFWD. For all the newbies, MFWD stands for Mechanical Front Wheel Drive. Technically, unless the front and rear wheels are the same size, like on a truck, or large ag tractor, it's not 4X4 or 4 wheel drive (6 times a year).

Fact: The MFWD system is designed to give added traction in sub standard conditions. Using MFWD in on high traction surfaces, including dry lawns and packed gravel and dirt, WILL result in added driveline stress, and premature failure. Chances are, this failure will occur when you are decending a steep hill with a heavy load, or stuck up to the axles in heavy mud becouse you went into the mud with the MFWD locked in, and kept going, hoping it would also get you out. My 4 wheel drive ag tractor has pulled out MFWD tractors almost as many times as it has gone out to the field to disc.

Fact: Using a MFWD tractor to do more work than the tractor was meant to do, just becouse it has MFWD, will cause serious saftey issues and premature wear on the tractor.

Fact: The most important part of a tractor is an operator who knows how to operate the tractor, and when to use each of the features on the tractor.

Fire away boy's and girl's....

 

[SPYDERLK]

Good posts guys.. nice and lean too.. no fat.

Soundguy

You guys have it right. One added thing - - the tractor takes more HP just to move when the 4FD is engaged - - not so much due to spinning added parts, but from the stresses on these parts due to the overdriven front wheels. The fronts are clawing their way along a little faster than the backs so the front/back drives are loaded against each other. Lots of drive friction - HP converted to heat. Those w/o the fancy systems will definitely notice that the tractor coasts to a stop quicker when in 4WD. Also youll notice this when your tractor engine can barely pull a gear in some field task. Shifting into 4FD will bog it due the extra HP used by the fighting components.
Larry

 

[ovrszd]

You guys have it right. One added thing - - the tractor takes more HP just to move when the 4FD is engaged - - not so much due to spinning added parts, but from the stresses on these parts due to the overdriven front wheels. The fronts are clawing their way along a little faster than the backs so the front/back drives are loaded against each other. Lots of drive friction - HP converted to heat. Those w/o the fancy systems will definitely notice that the tractor coasts to a stop quicker when in 4WD. Also youll notice this when your tractor engine can barely pull a gear in some field task. Shifting into 4FD will bog it due the extra HP used by the fighting components.
Larry

I tried to make that point but got shot at several times. Maybe your viewpoint will get along better!!

 

[Timber]

I don't think comparing you Pickup truck to your tractor is a fair argument at all. The applications are completely different. I have always owned 4 wheel drive trucks. They are apples and oranges. Your pickup is designed to run on asphalt and your tractor is designed to run in the dirt. You will never generate the speed out of a tractor you can with a pickup and a tractor is a work horse and designed for that purpose and run it how you use it, The soil will give long before your drive line and if you use you loader your just a fool not to use it in 4 wheel drive. The only reason I see for not using 4 wheel drive is transporting down the road or grass cutting and then only for tire ware and lawn care. Abuse anything and you will tear it up. I have 2 trucks now with a limited slip option on 4 wheel drive and another with 150 thousand miles on it. I cant tell you how many times I have run it in 4 wheel at 60 miles an hour on pavement in the winter and never a problem. If you tear it up it is usually on you

 

[ovrszd]

I don't think comparing you Pickup truck to your tractor is a fair argument at all. The applications are completely different. I have always owned 4 wheel drive trucks. They are apples and oranges. Your pickup is designed to run on asphalt and your tractor is designed to run in the dirt. You will never generate the speed out of a tractor you can with a pickup and a tractor is a work horse and designed for that purpose and run it how you use it, The soil will give long before your drive line and if you use you loader your just a fool not to use it in 4 wheel drive. The only reason I see for not using 4 wheel drive is transporting down the road or grass cutting and then only for tire ware and lawn care. Abuse anything and you will tear it up. I have 2 trucks now with a limited slip option on 4 wheel drive and another with 150 thousand miles on it. I cant tell you how many times I have run it in 4 wheel at 60 miles an hour on pavement in the winter and never a problem. If you tear it up it is usually on you

I guess I don't know what a limited slip option on 4 wheel drive is??

If the hiway is slick enough in the winter to need 4x4 is it safe enough to drive 60 mph? Does your truck stop quicker on ice slick hiways when it's in 4x4??

 

[Timber]

There is a period of time after a storm were some roads a clear and some are not so 4 wheel drive is the safest option to leave my truck in. You should also know I am a professional driver and have logged well over 1 million miles in full season weather driving running 80,000 pound semis in the mountains.
A limited slip 4 wheel drive option is where your in 4 wheel drive but your rear wheels have power and your front wheels free wheel till the rears slip and then your front axle auto engages. My driving experience exceeds in less than 5 years more than what most people will do in a lifetime

 

[ovrszd]

There is a period of time after a storm were some roads a clear and some are not so 4 wheel drive is the safest option to leave my truck in. You should also know I am a professional driver and have logged well over 1 million miles in full season weather driving running 80,000 pound semis in the mountains.
A limited slip 4 wheel drive option is where your in 4 wheel drive but your rear wheels have power and your front wheels free wheel till the rears slip and then your front axle auto engages. My driving experience exceeds in less than 5 years more than what most people will do in a lifetime

Oh, you are talking about a full-time 4x4 system like was introduced in the mid 70s?? If so, it's using the front and rear axles equally. The T-case is just a splitter like a rear axle splits power to each wheel. Just like the tandem drive on your semi splits power to each rear axle and the one with least traction spins out until you lock the splitter.

There are some systems on new trucks that are traction sensitive like larger Ag tractors use. That's what was referred to back a few posts on this thread which engages and disengages depending on traction needs.

I have had a couple full-time 4x4 pickups. Very dangerous to drive on slick roads because you are unaware they are slick until you tap the brakes, then life changes quickly.

I didn't realize your driving experience or history were in question. Sorry if you felt offended by my questions. I just thought you had something that I wanted to learn about.

 

[cp1969]

A limited slip 4 wheel drive option is where your in 4 wheel drive but your rear wheels have power and your front wheels free wheel till the rears slip and then your front axle auto engages.

How does this work? I'm not familiar with any kind of transfer case/power divider that will do this, with the possible exception of a viscous coupling made by VW back in the 80's. I didn't know anybody had adapted that to their vehicles. Anything that is full-time 4wd (with a power divider, such as tandem axle trucks or full-time 4wd), both axles are receiving power all the time unless one wheel spins. Then all the power is wasted on that one spinning wheel until you lock the power divider.

My driving experience exceeds in less than 5 years more than what most people will do in a lifetime

There is a lot of experience to be gained from years of driving, too, not just miles. In five years, you could have no more than five winters under your belt.

 

[N80]

How about I inject some facts into the thread, sort of kicking the bee hive.

Fact: Buy a tractor from a company who knows tractors, like John Deere, and they will tell you, right in the "operating the tractor" section of the owners manual, to only use the MFWD when needed for added traction and braking. The proper way to use MFWD.

I consulted my Kubota manual. It says nothing of the sort. It lists a _wide_ range of areas in which 4wd is helpful. It says that running in 4wd on pavement _could_ result in premature wear of the tires, but it doesn't even say not to do it, and believe me, this manual is packed full of things _not_ to do. The only other warning regarding the 4wd system is not to engage and disengage it at road speeds.

So either your "Fact" only applies to JD or it isn't a fact at all, which seems to be the largest part of the problem here. There are very few facts going around.

In addition, at least one poster mentioned that his manual (Mahindra?) indicated that 4wd was the more efficient way to operate.