Four Wheel Drive (4WD) and All Wheel Drive (AWD) ultimately perform the same function: turning all four wheels of a vehicle to propel the automobile down the road. They go about this in different ways, however. If you are having problems with your 4WD or AWD system, let Express Auto Repair and Emissions Service help! Stop by or call us at (847) 895-9131
Four-Wheel Drive
4WD is the older of the two versions, and is most often seen on off-road vehicles or trucks. These use a complex mechanical system called a transfer case, which sends power to the two axles, 
each with a differential, where the power is sent to the respective pair of wheels and the vehicle is sent forward. Unlike AWD systems, these aren’t on all the time, and many older models required drivers to physically lock the hubs into place before the 4WD system could be engaged.
All-Wheel Drive
AWD is the more recent technology, and is more complicated. This technology is often seen on crossovers and SUVS. Unlike 4WD systems, AWD is always on and isn’t operated by the driver. There are two types of AWD systems seen on the market today: mechanical and electronic.
Mechanical AWD systems employ 3 differentials, and in both electronic and mechanical systems sensors are installed on each wheel to monitor traction and wheel speed, which the computer can then adjust. Differentials can split power at different levels between the two wheels, allowing for a smooth ride under a variety of conditions. AWD systems aren’t as powerful as 4WD systems and aren’t designed for rigourous off-road driving.