I have read in a thread when applying the brakes when in 4WD you are in theory applying brakes to the front and rear wheels since they are locked together by the drive shaft. Does this only apply as long as you are using the engine also for braking? So if you apply the clutch then apply the brakes are you disengaging the front from the rear and therefore only have essentially the rear brakes?
Does 4 wheel drive = 4 wheel brakes?
- Thread starter edrobyn
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oldnslo
Super Member
Mechanical front wheel drive you would have front wheel braking do to the mechanical interlock. Pushing in the clutch would not disengage this feature.
gwdixon
Elite Member
I don't think the rear brakes influence the front at all. Clutch engaged or not.
Try this if you have dual brake pedals - In 4WD step on one of the brake pedals hard enough to stop the rear tire (go slowly!!). The fronts will dig in and pull you around. If the front on that side stopped the tractor would plow the front tire on the side that was braked. That front tire does not stop turning.
You could test the same thing by jacking up the tractor off of all fours - but who wants to do that?
My M7040 has limited-slip in front and braking one rear in 4WD will spin the tractor almost in a circle around the braked rear.
RoyJackson
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Not braking by using the brakes, but 4wd will help by use of engine braking (the tractor slows down as you reduce RPM).
DK35vince
Super Member
Rear brakes do influence the front because they are connected through the driveline.I don't think the rear brakes influence the front at all. Clutch engaged or not.
Try this if you have dual brake pedals - In 4WD step on one of the brake pedals hard enough to stop the rear tire (go slowly!!). The fronts will dig in and pull you around. If the front on that side stopped the tractor would plow the front tire on the side that was braked. That front tire does not stop turning.
You could test the same thing by jacking up the tractor off of all fours - but who wants to do that?
My M7040 has limited-slip in front and braking one rear in 4WD will spin the tractor almost in a circle around the braked rear.
There is a hill behind my house. If I try stopping on that hill in 2 WD with wet grass the tractor will take off sliding to the bottom. In 4WD I can stop anywhere on that same hill in the same conditions even with my trailer/water tank behind it.
The front wheels are connected by the driveline. By stepping on only one brake, one rear wheel is still turning free providing no braking through the driveline.
Try the same thing with the diff lock engaged .
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I respectfully disagree. Many larger tractors with electronics involved in the engagement of the four wheel drive, some if not all new 6xxx Deere's, the M Kubota with cabs, ect; lock the tractor in four wheel drive when you apply both brakes. If not to aide in braking functions then why else?
If both back wheels have the brakes applied, then the slowing down/stopping applied to the back wheels will translate through the driveline to the front wheels. If you apply both back brakes, it is still possible to not get braking through the front wheels if one of the front tires are on a much slicker surface- the tire with traction will hold while the tire without will rotate backwards, due to the differential. But, in most cases, using the back brakes while in 4WD will give you 4 wheel braking.
I recently took a spill (just slid, no rolling or flipping) on my B7100. I was in 4WD, but got one front tire over an embankment a little too far. When the axle bottomed and the weight lifted off of that tire, I lost all braking/traction on the front, and also on the back, because the weight shifted, lifting one rear tire enough to slide. Therefore, I only had one tire holding, which wasn't enough.
I recently took a spill (just slid, no rolling or flipping) on my B7100. I was in 4WD, but got one front tire over an embankment a little too far. When the axle bottomed and the weight lifted off of that tire, I lost all braking/traction on the front, and also on the back, because the weight shifted, lifting one rear tire enough to slide. Therefore, I only had one tire holding, which wasn't enough.
k0ua
Epic Contributor
Actually it is both, engine braking and foot braking, but what confuses the issue is the differential action of 2 differentials to take into consideration. in the example of pushing on one brake and the front wheels still turning and not braking at all you are correct, as far as it goes. when you brake one rear wheel. you are JUST braking one rear wheel, not the other rear wheel, and no braking on either front wheel. Because, the rear differential action is allowing all of the other rotating parts to keep rotating. BUT if you brake both rear wheels, the shaft that goes to the front slows down, and applies braking action to the front differential, which if the front 2 wheels have equal traction will brake evenly. If they have uneven traction they will brake unevenly. I can tell you from practical experience, and trust me I have lots of braking on a hill experience, that the difference between 2wd and 4wd braking is dramatic. And engine, (compression) braking is also dramatic. It can make the difference in stopping and sliding down the hill with your rear wheels locked up.
James K0UA
slowzuki
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Like they said, in 4wd, the fronts axle is mechanically linked to the rear. Many larger tractors with electric 4wd engage it every time you push the brake pedal to give 4 wheel braking.
Because it is applied via the pinion, the limit of the braking is 2x the tire with the least traction. If only one front tire out of the whole machine has traction, too bad, the other front tire will just rotate backwards.
In daily use it works well though. We always use 4wd taking big wagons down wet hills to get the braking.
Because it is applied via the pinion, the limit of the braking is 2x the tire with the least traction. If only one front tire out of the whole machine has traction, too bad, the other front tire will just rotate backwards.
In daily use it works well though. We always use 4wd taking big wagons down wet hills to get the braking.