FlyingPete
Well-Known Member
Ok, 4x4 school.
An open diff splits torque equally between the two half-shafts. It might not look like it, but the spinning wheel and the stationary wheel receive exactly the same torque. That's part of the design. Of course, if you've got a wheel spinning away in the air, torque on both sides is limited to nearly zero, and the enginel will spin up as if it's in neutral.
So a defender is four-wheel drive, in that each wheel is being driven by the engine. With all three diffs open, each wheel receives exactly 1/4 of the total torque. Compare this to a 4x2, where two wheels receive half the torque and two wheels zero, and it should be obvious that you can apply twice as much tractive effort without breaking traction.
The locking diff in the transfer box forces both axle diffs to turn at the same rate- this is the same as a part-time 4x4 system with 4wd engaged. If a rear wheel is in the air, 100% of the drive torque goes to the front, split 50/50 between the two wheels. So if one wheel from each axle has no traction you're still stuck. This is where locking axle diffs or traction control can help.
Traction control uses the torque-dividing property of an open diff to its advantage- by applying the brake on the slipping wheel, more torque can be applied to it, and hence the other wheel on that axle.
An open diff splits torque equally between the two half-shafts. It might not look like it, but the spinning wheel and the stationary wheel receive exactly the same torque. That's part of the design. Of course, if you've got a wheel spinning away in the air, torque on both sides is limited to nearly zero, and the enginel will spin up as if it's in neutral.
So a defender is four-wheel drive, in that each wheel is being driven by the engine. With all three diffs open, each wheel receives exactly 1/4 of the total torque. Compare this to a 4x2, where two wheels receive half the torque and two wheels zero, and it should be obvious that you can apply twice as much tractive effort without breaking traction.
The locking diff in the transfer box forces both axle diffs to turn at the same rate- this is the same as a part-time 4x4 system with 4wd engaged. If a rear wheel is in the air, 100% of the drive torque goes to the front, split 50/50 between the two wheels. So if one wheel from each axle has no traction you're still stuck. This is where locking axle diffs or traction control can help.
Traction control uses the torque-dividing property of an open diff to its advantage- by applying the brake on the slipping wheel, more torque can be applied to it, and hence the other wheel on that axle.
TC FTW!
