The force trying to lift the front of the crankshaft can easily be as much as 3000 pounds. The distance from the centerline of the blower belt to the front main bearing is approximately 5 inches. This translates to a bending moment of 1250 foot-pounds! Consider the #1 and #2 pistons and rods are pushing down on the other side of the front main bearing and you can see that the crankshaft needs some added help in this area.
A unique feature of a crankshaft bearing support is the hub which is machined from one-piece, heat-treated, chrome-moly steel billet. This insures the end where the ball bearing mounts will run true with the end of the crankshaft. The hub has a wall in the center for a bolt to mount it on the crank and double keyways. The front slots are used to drive another accessory like oil pumps.