One of the most unique features of the Hummer / HMMWV platform is the Geared Hub.
The Geared Hub provides 1.92:1 gear reduction at the wheel, thus allowing smaller driveline components to be used on these powerful vehicles. It improves ground clearance by raising the outboard end of the axle halfshafts. It also facilitates the Central Tire Inflation System (CTIS).
Here are the most commonly needed parts to keep this vital component working at its best.