TC 30 Four wheel drive system

[fctadam]

How does the four wheel drive system work on these compact tractors? I keep seeing 4wd = front wheel assist, and I’m not sure what that means. I definitely want a tractor that has a fully functioning four wheel drive system with power going to all the tires. Is that what these have, or is it some kind of all wheel drive? I'm so confused.

 

[Bob_Skurka]

They have 4 wheel drive. But they typically will not allow wheels to free spin and the systems typically move power to the wheels with traction. Most also have a locking differential lever or pedal so you can engage all 4 wheels regardless. Generally, any compact tractor will go into places, and then get back out of places, that you would not consider taking a 4x4 truck.

 

[fctadam]

So there is a 4 wheel drive for all four wheels to get power, and most have pedal for locking differential which makes both rear wheels have power. So you have a choice of both real wheels with power, and a full time four wheel drive?

 

[Bird]

</font><font color="blue" class="small">( I definitely want a tractor that has a fully functioning four wheel drive system with power going to all the tires )</font>

Someone can correct me if I'm wrong, but most of the CUTs do not have that (although it's available on some larger tractors). You have power to both axles when you're in 4WD. But both axles have differentials, so you could be spinning one rear wheel and one front wheel. Then they have a differential lock (step on a pedal) for the rear axle, so then you have power to both rear wheels and one front wheel if one is stuck. I'm not sure how big a tractor you have to go to, to also get a locking front differential.

Now that's what I'm familiar with. Do any of the small tractors have a locking front differential?

 

[Mrwurm]

Sounds right to me Bird. That's exactly how I understand it.

 

[fctadam]

Still lost, how does that of the compact tractor compare to a pick up truck?

If the tractor is in four wheel drive all four wheels have power from the engine spinning (powering) them, correct? Like the rear wheels aren’t pushing the front wheels. If something hangs it up (gets stuck) then certain wheels can spin faster than the tires with traction, correct? If you then press the differential pedal, it locks all 4 wheels or the rear wheels together? Once locked then power is taken away from any wheel that is free spinning and given to other tires in need of power. The locked differential eliminates tire spin when stuck? What is a differential and how does it work?

Am I even close? I never thought about how my truck worked I just always slapped it in 4 hi and went through the mud.

 

[higgy]

It works the same as your truck for most situations.

If the tractor was stuck it will spin the front and the back tire that has the least traction, just as a truck does. The locker that others have talked about locks the diff so the power on the back axel is forced to both back wheels and "locks them together" if they spin both will spin at the same time.

The front does not have a locker and will spin at the wheel with the least traction. This can go from side to side as you start to get unstuck depending on the traction at any given time.

This is more than you will have with your truck unless you have lockers on your truck, and if you don't know about them you most likley do not have them. 4X4 is a misnomer, there is power provided to both the front and back axel through the transercase to the diffs. If the diffs are limited slip that will help to keep the power to more than two wheels.

These tractors are fantastic at being able to go placese that you would not take a normal 4x4 truck.

Dane

 

[NIXON]

Fctadam
4wd in most cases is a myth . Most 4wd vehicles have what's called an open differential . An open differential by it's very nature puts power to the wheel with the LEAST resistance .
But the good news is most 4wd tractors have selectible locking rear differentials , allowing power to be put to both rear wheels equally . So basically you get 3wd /forums/images/graemlins/smile.gif
A front locking diff. may seem like a good thing , but it will definately affect your steering (you'll go straight no matter how you steer ) I think you'll find even without locking the rear diff. on a tractor that while it's in 4 wd traction will be very much improved . Locking the rear diff does improve traction dramatically , but it does affect your ability to maneuver. one thing a tractor does have over a pickup in most cases is ground clearance , better tires (given the task ) and gearing . so overall traction will be better . I Hope this makes sense to you . John

 

[Bird]

</font><font color="blue" class="small">( What is a differential and how does it work? )</font>

The differential is named that because it allows the two wheels on that axle to turn at different speeds, or roll different distances as in turning, without one or both having to slide. So, yes, the tractor "4WD" will work just like your 4WD pickup if the pickup does not have a "limited slip" differential. If you do have the limited slip rear differential, then the wheel without traction can only spin a little ways before power is shifted to the other wheel. The tractors that most of us are familiar with do not have a limited slip differential (although some tractors do), so instead you have to step on the pedal to lock the differential (same result as having a solid axle), so now instead of one wheel spinning a little ways, then shifting power to the other wheel (as does the limited slip differential in a pickup), neither tire will spin at all without the other one turning the same amount.

 

[fctadam]

It's all clearing up, thanx

 

[frank_f15]

i can't explain it like some of the other guys did , but i will say that 4wd on a tractor is most ammazing, the amt of extra traction and workability is beyond compare.

 

[Bob_Skurka]

Frank_f15 really did the best job of explaining 4 wheel drive on compact tractors.

The reality is that differential locks and all that stuff are technical things that a mechanic understands. . .

BUT in terms of using a tractor in the real world, I will take a 4 wheel drive tractor into places that I could not take a Jeep Cherokee into. Actually the Cherokee probably could go there, but the tractor will come back out and the Cherokee will have to get pulled out.

I get amazed almost every time I take a tractor into a tight, slippery space and get it back out.

 

[AndyMA]

</font><font color="blue" class="small">( I'm not sure how big a tractor you have to go to, to also get a locking front differential.
)</font>

TNS and TND's with the electro hydraulic differential lock have locking front and rear differentials. To lock the differential with the electro hydraulic differential lock all you have to do is flip a rocker switch on the cab column. In one mode stays engaged until not needed. In another mode stays locked. Does make steering hard, but it seems there is still some differential action left.

Andy

 

[Mosey]

I agree with Bird's explanations. My Boomer does not have a locking front differential and I'm pretty sure it's not available, but the rear has a foot pedal to lock it. If the tractor is weighted down good it gets a lot of traction and will usually stall the tractor or trip the hydrostatic drive relief valve before spinning the tires.

I disagree that it will always go places that a 4X4 truck or Jeep will not go. In some cases yes, but not always. In deep mud or snow, my 4X4 pickup, 4X4 Suburban, and my 4X4 Jeep will do better because I can get more speed to start with and keep the wheels spinning faster. I can't get the RPM's up enough sometimes with the tractor.

My understanding of why it's called Front Wheel Assist instead of Four Wheel Drive is because the front tires are smaller than the rear tires. To me, the biggest advantage of a 4WD tractor is when backing up a hill. The weight shifts to the front tires and a 2WD will spin out and not make it up the hill, where a 4WD will keep going. A 4WD is also much safer going down a hill, since the front tires provide braking and help keep the tractor going straight down instead of sideways. A 2WD tractor can be dangerous going down a hill because only the rear tires provide braking and it's easy to start skidding sideways.

 

[KiotiJohn]

<font color="#FF641A"> I know that most tractors only have a rear differential lock, however, the Kioti Dk65C has front lock also. I've never used one, but have heard from others who say it has really come in handy. 4 wheel drive (not front wheel assist) for me every time! John

 

[Bob_Skurka]

Mosey, I probably shouold have been a little more clear in what I wrote. I can take my tractor onto soft ground in the trees where a jeep would not even fit, and I can get the tractor out. I can also take my tractor into tight spaces that a jeep would fit into but should not go, and I can get the tractor out. In terms of sheer deep mud performance, I would agree that a 4x4 is a better choice. In practical terms of what I use a tractor for, I am amazed that I have gotten the tractor out of some places I have got it into.

 

[ShannonCole888]

In my experience, I have not come across a 4wd tractor, that gets better traction, than a 2wd tractor. I am not saying that it doesn't, but I will explain my findings with the 2. Most all 4wd trucks, ATVs, and tractors have open, or limited slip differentials, with possibly the opition of a manual differential lever, or lock. This can be a knob, lever, switch, or button. It is only intended to be used temporarily, and to be taken out. It does cause the vehicle to want to drive straight, and steering can be difficult when the lock is engaged. Limited Slip differentials are necessary for most all vehicles, not just 4x4's. There are other systems, like AWD, that offer added traction for 4 wheeled vehicles. 4wd drive makes a difference with pickup trucks, jeeps, and atv's, but tractors are somewhat different. Tractors tend to be heavy, and where the rear tires is designed to obtain traction, hence the word "tractor". Tractor basically represents traction, as that is what tractors where designed to do, get traction.The original design of the tractor, with the large rear tires for traction, vs the small front tires for steering wasn't intended for 4wd traction. About 70-75% of the tractors weight is placed over the rear wheels, and about 25-30% of the tractors weight is placed over the front wheels. When a tractor is equiped with front wheel assist, those percentages have to change to get the appropriate amount of traction. The point, that the front tire of the tractor is smaller, does factor in, that it isn't like a pickup truck, which has 4 equal tire sizes, provided basically equal 4 wheel traction. On a properly ballast tractor that is 4wd, the percentage of the tractor weight is suppose to be like 45% rear, and 55% front. The thing with buying a 4wd tractor is, the process of ballasting it. You can use liquid ballast in the tires, wheel weights, and front weights. You can also use a weight box on the back, but that depends on you. Adding aditional weight could contribute to quicker mechanical component wear on the machine, though some manufactures compensate for this in the design itself. You would need to take a tractor to some kind of place to weigh it, to see how much weight is placed over each axle to ballast it properly.

 

[billfires]

ShannonCole888, in my experience with a NH 1920 w/ FEL & BH there is an enormous difference with having the front axle engaged or disengaged. When filling the loader bucket, with over 1000 lbs of backhoe as ballast, there is a significant difference in traction.
I have never done typical farming uses ie: a land plow, discs, or any other ground engaging implements, so I can't speak to the traction issue there. Bill C

 

[aczlan]

In my experience, I have not come across a 4wd tractor, that gets better traction, than a 2wd tractor. I am not saying that it doesn't, but I will explain my findings with the 2.

I can say that with our L3830 (4x4 loaded rear tires, nothing on the front) pulling a 3 bottom plow, it spins the rear tires slightly when in 2wd but does not spin in 4wd.

The original design of the tractor, with the large rear tires for traction, vs the small front tires for steering wasn't intended for 4wd traction. About 70-75% of the tractors weight is placed over the rear wheels, and about 25-30% of the tractors weight is placed over the front wheels. When a tractor is equiped with front wheel assist, those percentages have to change to get the appropriate amount of traction.

Not really, if you look at the same model tractor in 2wd vs 4wd, there is no real difference in axle weights

The point, that the front tire of the tractor is smaller, does factor in, that it isn't like a pickup truck, which has 4 equal tire sizes, provided basically equal 4 wheel traction.

A 4wd tractor has differen gearing for the front vs rear tires, so they cover the same amount of ground (rather than one spinning faster or slower)

On a properly ballast tractor that is 4wd, the percentage of the tractor weight is suppose to be like 45% rear, and 55% front. The thing with buying a 4wd tractor is, the process of ballasting it. You can use liquid ballast in the tires, wheel weights, and front weights. You can also use a weight box on the back, but that depends on you.

Most CUT owners add weight to the front or rear to keep the tires on the ground when doing loader work or when using a heavy 3pt implement.

Aaron Z