All wheel drive?

All wheel drive?
All wheel drive,also known as 4wd is when all 4 wheels spin to give you traction. 4wd systems are all not the same,there are limited slip differentals,and true 4wd. The limited slip differental is when all the wheels spin,but when you hit a log or a large rock it leaves you stuck in 3wd you aren't going anywhere, the only advantage is you get good traction in wet areas. True 4wd is when just the two back wheels spin,and when you hit a log or large rock the system will scence that the back wheels are slipping and deliver full tourque to both front wheels and you will climb right over the log or large rock,true4wd also has better traction than the limited slip differental in wet areas.If you have a true4wd system and you want all the wheels to spin without having to hit a log,just back up about 10 feet.