I was looking into going on some light off-road trips in my new car, and while browing related info, I ran into this a lot: that all serious off-road vehicles require a locking differential.
My understanding of the locking differential is that the differential can be locked, meaning the left and right wheel are required to spin at the same rate. That is useful for situations where one wheel might not have traction, which would normally (without locking differential) cause it to spin and get the most torque. Locking differential prevents this by forcing both wheels to spin at the same rate, preventing the no-traction wheel from getting all the available torque. This much, I think I understand.
What I don’t understand is, how is that better than a traditional AWD system, where the car can decide which wheel gets the torque? In my mind, this is even better because as soon as the car detects loss of traction, it will cut the torque, achieving basically what the locking differential does without the downsides (like worse corner handling). For example, my new car, a Subaru Outback, supposedly comes with this kind of AWD system that can distribute torque as needed.
So my question is, why is a locking differential better than just having a normal AWD?
In: Technology
A traditional AWD system doesn’t really work the way that you are implying. The torque distribution is set by gearing in the transmission which some system could change but in descretw steps. In order to replicate the benefits of a locking differential cars like the Outback use independent control of the brakes to lock up any free spinning wheel. However, this requires sensors and algorithms that will allow slippage since you cannot just permanently lock the brakes the same way you can lock a differential. A locking differential can just be locked and that is that, no slippage.
Something like a Rivian quad motor is able to achieve the level of torque vectoring that you are describing and they don’t have locking difs
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