Usually, four-wheel drives run with one of two types of transfer case: on-demand systems using a clutch pack to shunt power to the front axle, or electronic switchable systems that use mechanical locks to power the front and rear axles at the same time. Electric systems are generally associated with family SUVs and crossovers, because they don't require the same heavy hardware as a mechanical diff-lock.
On road, electronic systems also allow owners to leave the car in four-wheel drive mode without worrying about driveline binding, something that can happen when you leave mechanical locking systems in four-wheel drive mode on the tarmac.
The electronic system in the Raptor is designed to blend the best of both worlds. Although it can mimic a full, low-range four-wheel drive lock in Rock Crawler mode, the electrically controlled clutch pack in the transfer case allows the driver to leave the car in 4Auto on the tarmac without fear of damaging the drivelines.
The system is able to actively modulate the clutches on the fly, varying the amount of power sent to each axle as surface traction levels or the drive mode changes. In Sport Mode, the system sends more power to the rear wheels for a sportier feel, while Rock Crawl mode locks the differentials for four-wheel drive and engages a special gear reduction ratio for better low-rev performance.
Along with its usual armada of durability tests, Ford put the Raptor transfer case to the test at the 2016 Baja 1000. You can get a look at the dune-jumping Raptor in the video below.