While the difference between all-wheel drive (AWD) and four-wheel drive (4WD) can seem perplexing, perhaps the most widely-accepted qualifier is this: whether or not there is some sort of center differential between the front and rear axles, where AWD systems have one, and 4WD systems do not. The presence of a differential ensures that AWD vehicles can operate on pavement without binding occurring within the drivetrain during cornering; 4WD vehicles should be taken out of 4WD mode on paved roads to avoid damage.
When Ford decided to grace its latest F-150 Raptor high-performance off-road pickup with both AWD and 4WD, the company committed to building a truck with strong all-weather performance on the street, and of course, superfluous performance off-road. How the engineers at Ford Performance were able to do it gets a bit complicated, but thankfully, Engineering Explained has taken on the topic of the Ford F-150 Raptor’s AWD/4WD system in a recent video.
In short, it all comes down to the supertruck’s unique transfer case, which features both a locker and a multi-plate wet clutch to connect the front and rear axles. When the truck is in 2WD, neither is used, and locking hubs at the front axle leave those wheels free to rotate as they will. When “4 Auto” is called upon, the wet clutch engages as needed to send torque away from the rear axle and to the front. Finally, when “4 Hi” or “4 Lo” is engaged, the locker connects the front and rear axles at a fixed 1:1 ratio, with a high-range or low-range gear multiplying torque from the motor.
For the full skinny on the 2017+ Ford F-150 Raptor’s unique drivetrain, watch the video above from Engineering Explained.