Electronic Differential Lock (EDL) all wheel drive explained

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Electronic Differential Lock (EDL)

This video shows Audi's EDL (Electronic Differential Lock) in action. Both left wheels are placed on the rollers, which simulate slippery surface (ice, mud). Both right wheels are on a dry surface. To get the car moving in these conditions, a front or rear differential lock is needed to transfer torque from left to right. Because this Audi has open (non-lockable) differentials front and rear, EDL plays the role of a locking differential. The system must brake the wheel that spins (the left wheel) and transfer torque to the wheel with traction (the right wheel). However, as seen on the video, Audi's EDL is not as effective as a real mechanically locking differential. The system is not capable of bringing the spinning wheels to a full stop and transferring most of the torque to the right. If there was a real differential lock installed in either front or rear axle, the vehicle would have moved with little or no wheelspin. So EDL is a differential lock imitation.

Then, when wheel speed increases, the car finally takes off the rollers. EDL is defenetly a helpful traction device, but for on-road conditions only. If the vehicle was on a slope, it is doubtful EDL would make the vehicle move.

The next video shows the Volkswagen's EDL (Electronic Differential Lock) in action. This is a Volkswagen Bora/Jetta with Haldex Generation I automatic all wheel drive. On this model, the EDL is installed on the front wheels only. EDL helps some, but it is not a full replacement for a real differential lock.

This video shows a Subaru Legacy Outback 2.5 4AT VTD hill climbing with VDC off and VDC on. VDC is Subaru's electronic stability and traction control system that works on all four wheels. You can see that when VDC is turned on, the wheelspin is minimized.

Last updated: 2010-05-18 21:54

There are 2 comments

JonathanC

December 31, 2008 - 04:30

Subject: This is great!

I have been looking for videos like this for years. Are you going to be adding more?
Where did you get the rollers? I'd like to try this with my car.

Reply to JonathanC

awd.ee

January 01, 2009 - 22:08

Subject: Re: This is great!

Hi, this is a video I found on youtube, it's not mine. I will be adding more of these soon.