Following up a discussion here, when someone asked about the Haldex and another asking about the driveline layout, I've found out some documentation about generation 4 of Haldex systems, used on FL2 cars since year 2008 (MY2009).
It's from the competition (VW Tiguan), but the unit is the same as the one used on FL2. And also the principles and modes of operation.
Here it is: https://www.freel2.com/gallery/albums/user...x_gen4.pdf

Also what LR said in their service manual: https://www.freel2.com/gallery/albums/user...0Drive.pdf

If anyone has another info, please share it and post it here.

Last edited by alex_pescaru on 12th Nov 2011 4:45 pm. Edited 1 time in total

Thanks Alex!

The document says:

Quote:

If only one wheel of the front axle spins, the Electronic Differential Lock (EDL) becomes active.
The spinning wheel is braked and the drive force of the other wheel is increased. At the same time the
all-wheel drive clutch is engaged and a large portion of the drive force is transferred to the rear axle.

The system monitors the wheels' speed and takes as a reference the lower one. This is done through the ABS sensors.
In the case of the same axle, as soon as the difference in rotational speed of one wheel exceed by a certain amount the other one, the system starts to brake the quicker spinning wheel in order to transfer the drive to the other. If it's still spinning, then the system will start to modify the engine torque output, lowering it.
That 3 wheels braking is for the cars that have free center differential. Otherwhise, if they have a transfer case (like Patrol) or a locking center differential (like Defender), who is spliting the torque mechanically 50/50, its a nonsense, because if you brake both wheels on the same axle, you'll end up stalling the engine.
When you don't have the center differential locked, then the TC could brake up to 3 wheels at once.
But as soon as you lock the center differential, then the TC will consider the front and rear axle like two separate entities and will brake up to one wheel per axle, so maximum 2 in all.
The Haldex, when is fully energised, acts like a locked center differential, like in the case above.
So the FL2 has two EDLs. One for the front and one for the rear.
And the Haldex acts like a "progressive locking" center differential. I've put the term between quotes because it's a made-up term, not an acknowledged one.
I've made some experiences with FL2 TC here: http://www.freel2.com/forum/topic6178.html
You can see (in the first 2 video clips) how the system brakes the wheels if two wheels (one front and one rear) slip.