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
Imagine your left 2 wheels are on ice and right 2 wheels are in a snow. All the wheels have very little grip. Where should AWD send the power? While it searches for the wheel that has grip, you are likely to dig yourself in with the right wheels. With locked diff, you simply put the same power everywhere and maximize your chances of going.
In off-road situation you may have a combination of gravel, stone, mud and loose mud under all of your wheels. First, computer will struggle to figure out what to do. Second, the last thing you want to do when going through the hard surface is for the computer to change your torque. Suddenly shifting all the power to the front right wheel will send your car to the left – and you may not want that at all. Keeping it stable and predictable is very important.
Most importantly – you never lock your diff on hard surface. And on the loose surface locking diff doesn’t affect steering.
Latest Answers