If you have any experience with off-roading, then you may have already heard the term “four-wheel-drive†before. Sometimes, you may see it abbreviated as “4WD†or “4x4â€.
This type of drivetrain is used for vehicles - usually trucks and SUVs - with two axles that are capable of sending torque to all four wheels at the same time. This type of mechanism can be full-time or on-demand (part-time), and it typically comes with several other components. These include extra gears and a transfer case that adds more output.
If the 4WD assembly simply provides torque to both axles, then it can be called all-wheel-drive (AWD). However, once the off-roading elements are brought into play, the terminology changes. A limited-slip differential is included to prevent the vehicle from getting stuck in the mud or hung up on a jagged rock formation. Various operating modes - commonly labelled as “Off-Road†or “Rock†- can also be present. This helps the automobile shift from city/highway driving to roughing it in nature.