Image Number 3 for United States Patent #6470988.
A differential assembly having a preload or biased differential case. A beveled thrust washer is disposed between each side gear and the differential case. The beveled thrust washer induces a preload between the side gear and differential case to help ensure that each differential side gear and output half shaft are running at the same speed as the differential case is rotated. The preload or bias is set to be slightly greater than the difference in drag forces acting on each output half shaft. Thus, when the transfer case is engaged to bring the differential case up to speed, the differential gears will be prevented from spinning and the output half shafts will rotate at the same speed coincident with the vehicle road speed. The preload facilitates more desirable engagement of the wheeled hublocks in front wheel steerable wheel axle assemblies in selectable four-wheel drive trains.