How does four wheel drive work? This video explains the workings of four wheel drive (4WD), and gives a definition in order to differentiate different types of four wheel drive and all wheel drive. Four wheel drive simply means 4 wheels are driven, and many times this is accomplished through the use of a transfer case.
Note: I have a poor vocabulary, and may end up calling the transfer case a transaxle. Please ignore it when I say "transaxle" and replace with "transfer case." Thanks!