A roller bearing is used where there is a need to support higher loads than a ball because it has a larger contact area. Tapered roller bearings can support large radial and large thrust loads.
The ball in a ball bearing contacts at one small point on the inner and one small point on the outer race. This contact area is adequate as long as you don’t exceed the designed load bearing ability. Overloading leads to distortion of the balls causing early bearing failure. Also the single row angular contact ball bearings used in the front hubs are sufficient for the radial loads that the AD encounters. The fact that we see so little failure in the AD and as Bill points out, in modern ball bearings, is proof that they are more than capable of handling the loads imposed on them under normal use.
I doubt that these front ball bearings would last very long on a high-speed road course or oval track or in a gravel truck. I would bet that ball bearing failure was rather common in any of the ½, ¾ and 1-ton trucks that carried heavy construction materials over their design limits.
DG
