4WD and loader work

[rScotty]

This subject of 4wd and front-to-rear driveshaft windup comes up so often that old mechanics wish someone could explain it well enough that new tractor owners could understand & benefit.

Sure it's difficult to visualize what makes drivetrain windup happen, but even without understanding why, it is simple to use the tractor in a way that avoids the whole problem.

The problem is real. It exists because most of our 4wd tractors DO NOT have a center differential.
Anyone saying that the problem doesn't exist simply because they have used 4wd continuously without a problem isn't helping new tractor owners at all - the newbie may not be so lucky.

I know people who never change oil or antifreeze, just add more as needed. Lots of those old trucks and tractors are still chugging along. Does that mean that changing fluids and filters is a waste? Same thing.

Some people can abuse something and not have a problem.
All that proves is how handy it is to be lucky.

rScotty

 

[bgr]

For any 4WD tractor which does not have a center differential(almost every one I know of), sometimes the front and rear wheels turn at different rates, especially in corners.. This is done without damage to the differentials because the wheels can slip a little on most ground tractors are used on. This is the normal situation.

However on very hard ground or pavement where tires do not slip easily, use 2WD whenever you can. This will save a huge amount of wear on tires and the driveline. You will need 4WD for braking, soft ground, pushing into a pile, and other situations you can easily figure out, but always shift to 2WD when you don't need it and you are on a surface which gives good tire grip.

If you have a manual 4WD engage lever and it is hard to shift out of 4WD, that means there is tension on the driveline that has not been relieved by wheel spin. Just reverse direction for a foot or two to release tension. But use that as an indication that the surface is not letting the tires slip as they should and you should try not to use 4WD on it any more than necessary. If you are seeing a lot of tread wear, especially on the front tires, that is a sign that 4WD is being used too much on hard surfaces.

Unlike tractors, all wheel drive cars have a center differential which compensates for different wheel speeds when the tires have good traction on dry pavement.

 

[HellBender]

Did not read all the replies so this may all ready been said.
Being in 4wd to me is for safety. The first time you start down a hill with a full loader and the weight is transferred off the rear tires you can go for a ride. I have plenty of ballist and a few times I had to jam the tractor into 4wd to get the front tires locked in because I forgot I didn't have it in 4wd to begin with. That is harder on the drivetrain than leaving it in 4wd. When working with the loader, I usually only take it out when I am going on the dirt road or on pavement to save tire wear and can hear the drive line growl when it winds up. After 1500 hours on my first tractor, I would not have any concerns for the drivetrain if I were to leave in 4wd unless on pavement. The rear tires should have enough slip unless it is heavily ballist. I will mention that the front turfs were bald when I traded it. Small price to pay for safety.
If its a steeper hill, I'll back down.

 

[5030]

The manual states to not use 4wd anytime 2wd will do. If you need 4wd to get into the pile then that is fine. The wheels should not be slipping when filling the bucket. It they are you are not loading the bucket correctly or your pile is too solid and needs some breaking up before trying to scoop a bucket up.
Be sure to use proper loading techniques. Enter the pile flat, lift and curl while moving into the pile to fill the bucket.

Exactly what I do. front wheel assist is only there to use when traction becomes iffy, not all the time.

 

[5030]

Unlike tractors, all wheel drive cars have a center differential which compensates for different wheel speeds when the tires have good traction on dry pavement.

If I lock the locking hubs on my F350 with it's limited slip front differential and get in a traction spot and cut the wheels, you can quickly feel the inside tire slipping.

 

[Chewwy]

I have had 3 tractors and one backhoe. Two of the tractors and the backhoe are large machines and are 2wd, the smaller tractor is 4wd. None are ever driven on a hard surface except when being parked under cover or changing an attachment.

I seldom have had to engage the lockers on any of the 2wds. The 4wd often needs the diff locked, so I tend to leave it in 4wd. All of them except the backhoe have loaded rear tires. I chalk it up to the weight of the larger machines and their larger rear tires.

 

[Egon]

Did not read all the replies so this may all ready been said.
Being in 4wd to me is for safety. The first time you start down a hill with a full loader and the weight is transferred off the rear tires you can go for a ride. I have plenty of ballist and a few times I had to jam the tractor into 4wd to get the front tires locked in because I forgot I didn't have it in 4wd to begin with. That is harder on the drivetrain than leaving it in 4wd. When working with the loader, I usually only take it out when I am going on the dirt road or on pavement to save tire wear and can hear the drive line growl when it winds up. After 1500 hours on my first tractor, I would not have any concerns for the drivetrain if I were to leave in 4wd unless on pavement. The rear tires should have enough slip unless it is heavily ballist. I will mention that the front turfs were bald when I traded it. Small price to pay for safety.
If it’s rop the bucketa steeper hill, I'll back down.

Drop the bucket

 

[HellBender]

Drop the bucket

That can cause other problems!
Google: "tractor dropped bucket hit road" images no longer active but you'll understand the aftermath. It pretty much folded the tractor inhalf when a young boy riding shotgun dropped the bucket by accident. Looks like a circus elephant standing on a pedistal.

 

[Egon]

Keep the bucket curled back.

when going down very steep grades it is not unusual to have the bucket/blade lowered and pushing dirt to control descent rate.

 

[Gord Baker]

Did not read all the replies so this may all ready been said.
Being in 4wd to me is for safety. The first time you start down a hill with a full loader and the weight is transferred off the rear tires you can go for a ride. I have plenty of ballist and a few times I had to jam the tractor into 4wd to get the front tires locked in because I forgot I didn't have it in 4wd to begin with. That is harder on the drivetrain than leaving it in 4wd. When working with the loader, I usually only take it out when I am going on the dirt road or on pavement to save tire wear and can hear the drive line growl when it winds up. After 1500 hours on my first tractor, I would not have any concerns for the drivetrain if I were to leave in 4wd unless on pavement. The rear tires should have enough slip unless it is heavily ballist. I will mention that the front turfs were bald when I traded it. Small price to pay for safety.
If its a steeper hill, I'll back down.

 

[Gord Baker]

As has been said MANY times in the Past. Do NOT use 4x4 unless you NEED it. This also applies to ATV's. END.

 

[Paystar]

None of my 4WD tractors have ever been out of 4WD except for when roading on pavement.
Never had a problem and no more wear on front tires than the rears get.

I get a kick out of how some people think. A long time ago I worked for a guy and we did snow removal in the winter. I had to plow very large commercial parking lots with a 310 Deere backhoe with only a bucket. (Talk about hating life)
Anyway he always used to get mad at me any time he found it in 4WD or found out I used the steering brakes. Said I was going to wear it out, LOL
So I just ignored him and carried on, because I liked to be able to steer on the ice and get work done.

I also laugh at all the people that won't use 4WD in their pickup truck in the winter because it will use more gas. But they will sit at the traffic lights spinning their tires and revving to get going on the snow and ice.

 

[DGF]

There are always special conditions and they can cloud the issue. The answer to the question about when to use 4 wheel drive is pretty straight forward.

Use it when you need it.

When working in conditions where extra traction is required, kick it in.
When lifting relatively heavy weight with the loader because it adds stability and improves control.
When traveling downhill, as mentioned in earlier post. Even with only moderate weight in the bucket it improves control.
When pulling a load having some weight.
Use it when it makes sense.

What not to do.
Turn tight corners with 4 wheel engauged unless it's necassary. Tight corners places high stress on the gears and other components which is intensified when driving on a hard surface including dirt.

A comment about hard surfaces. For the most part ( as I mentioned there are always special conditions ) a tractor does not know the difference between a hard or soft surface and driving in 4 wheel drive on a hard surface will not ruin anything as long as the direction remains reasonably straight. Example: Clearing snow from a driveway with a plow or snowblower. Yeah.. I know a film of snow remains to "grease" the pavement, however it may help it doesn't matter. Just no tight turns.

 

[D'oh]

your going to learn people have no idea what they are talking about, gear grinding is clear as can be, do you hear it? prolly not, its generally a open differential, there is a reason they have lockers. if your not hearing noise, your not doing damage. i use 4x4 constantly and was slipping non stop today dealing with a flood.

do you know how much my wheels slip while plowing?

Exactly, you bought 4WD, use it. There should be No Grinding, just Wheel Slip.

Wheel Slip is a fact of life, turning a 4WD the front Axle can travel near twice the distance as the Rear Axle, there is Slip there regardless.

 

[Bob_Young]

If you don't need 4WD, why use it? I view it as either a necessary evil or a useful tool, to be used only when circumstances dictate. On those occasions, I'm glad its there to either get me out of trouble or prevent trouble. But like the crescent wrench in the toolbox, I'd be just as happy not having to use it.

FWIW, all of my 4WD tractors seem quicker and more responsive in 2WD. They accelerate quicker and turn much better. The whole operation seems much more relaxed in 2WD. If I get on a tractor and it seems sluggish, the first thing I check is whether someone left it in 4WD. To date, that has always been the case.

 

[rScotty]

Exactly, you bought 4WD, use it. There should be No Grinding, just Wheel Slip.

Wheel Slip is a fact of life, turning a 4WD the front Axle can travel near twice the distance as the Rear Axle, there is Slip there regardless.

That's not how it works. The slip is deliberate, not "regardless". Put on your thinking cap. The internal gearing is different for the front axle and back axles.
The front to rear ratio can be made to be any ratio wanted. It could be zero slip.
A couple of percent mismatch is designed there deliberately. It is a consequence of making the front axle turn slightly faster to maintain steering control.
Think about it.
rScotty

 

[rScotty]

We've been over this too many times. Please figure out how the system works before spreading misinformation. The mismatch that leads to windup or slip is deliberate. It is there for steering control. It is necessary because there is nocenter differential between front and rear axles on a tractor - or on old part time 4wd pickups. It has nothing at all to do with turning or driving straight. It has a lot to do with traction.
Sometimes - not always - it has to do with reliability.
rScotty

 

[D'oh]

Ever make a turn in Snow or Loose Dirt? Why are the 4 Arcs and not 2?

Ever turn your F150 on a Boat ramp in 4x4 and have it hop? That is because the Front Axle is traveling farther than the Rear Axle.

Any "Max Force Conditions" (something's Break Point) would be limited to the tire slip.

We are arguing the Same Thing, you are just hearing it different. Yes there is No Center Clutch or Differential, so both axles are trying to go the same distances, (give or take your Steering equations) The Tractor's Max Capacity, would account for Driveline Stresses, (or should be) being in a Dirt Pile even reduces Traction Abilities of the tires.

 

[Bentrim]

While all the experts chime in so will I. I worked at a dealer and found the following in formation.

1. The front wheels on a tractor are geared slightly faster than the rear. It was explained to me you want the front slightly faster so as not to cause the rear wheels to push the front wheels. The front wheels are supposed to pull not ****** the back wheels. This makes the drive parts of the front axle load up and adds a lot of stress when on hard dry surfaces.

2 Loader work. If you are depending on the front axle to drive the tractor with a bucket full and very little tractive force from the back wheels you risk overloading the front axle drive components and risk breakage. The front axle is to assist not take the whole load.

3 But, But. I leave mine in 4wd all the time and never take it out, or I only use 4wd when it rains or snows. Yep heard all these stories as I was repairing the front axle. The choice is yours. It is your money invested in the tractor, and you that will pay needed repairs if any. So use common sense wisely.

 

[JWR]

We've been over this too many times. Please figure out how the system works before spreading misinformation. The mismatch that leads to windup or slip is deliberate. It is there for steering control. It is necessary because there is nocenter differential between front and rear axles on a tractor - or on old part time 4wd pickups. It has nothing at all to do with turning or driving straight. It has a lot to do with traction.
Sometimes - not always - it has to do with reliability.
rScotty

Alright now Scotty -- I have no idea who you are saying is spreading 'misinformation' (don't care; can't be me because I haven't expounded on it yet ) but let's not label misinformation while spreading some of it. Most of us reading this needlessly long dialog understand and know that tractors with MFWD are designed and built with intentional slightly faster forward motion in front than rear for all the reasons described ad nauseum. But turns left or right do generate differing distance traveled by the two front tires so there ARE both kinds of slippage. It does have to do with turning versus driving straight as well as the designed-in other reason. And if you happen to be on high traction surfaces like pavement you will feel the jerkiness of tires slipping on the pavement. Not all windup or slip is deliberate, there is also some of it inherent and unavoidable.