1942 - 1947 Chevrolet Shop Manual



	3-14

	The steering knuckle arms are installed on the knuckles at an angle, permitting the front wheels to toe-out when making turns. This is necessary so that when turning curves, each wheel may travel in a different arc. This toe-out on curves is known as steering geometry. These five front end factors are built into the axle and must be in proper relation to each other to prevent steering faults and excessive tire wear. CASTER Caster is the amount in degrees of the backward tilt of the axle and kingpin, Fig. 31, A truck without caster would lack steering stability, would tend to wander over the road and would be difficult to straighten out at the end of a curve or turn.	under side. The result would be excessive tire wear on the outer edges of the tread. Reverse camber, or a wheel that is tilted too far in at the top, would result in excessive tire wear on the inner edges of the tread. The center of the tread would remain comparatively unworn.


		Fig. 32—Camber Angle The rule is that if wheels have the maximum of allowable camber they must have the maximum of allowable toe-in. If wheels have the minimum amount of allowable camber they must have the minimum amount of allowable toe-in. KINGPIN INCLINATION Kingpin inclination is the amount in degrees that the tops of the kingpins are inclined toward the center of the truck, Fig. 33.

	Fig. 31— Caster Angle Unequal caster shows itself in the tendency of the truck to pull to the right or left. This condition comes about through the axle having been twisted so that there is a greater amount of caster in one kingpin than in the other. The direction in which the truck will tend to pull is towards the side with less caster. Suppose that an accident has put a twist into the front axle so that the left side is zero caster, while the right side is castered backward five or six degrees, the right wheel will have a strong tendency to turn inward, pulling the truck to the left. CAMBER Camber is the amount in inches or degrees that the front wheels are tilted outward at the top. Fig. 32. When a wheel has too much camber, or the wheel is tilted too far out at the top, the tire is forced by road contact into a conical shape, on its
		Fig. 33—Kingpin Inclination Kingpin inclination tends to keep the wheel spindles pointed outward, in line with the axle, just as caster tends to keep the wheels of an automobile pointed straight ahead. The effect is the same, since if the spindles are kept pointing out at right angles of the truck, the wheels will, as a result be kept pointing ahead. It makes the truck steer easier. We have already referred to the close relationship between the factors that enter into the front axle assembly. It is a point that cannot be over-stressed. One must keep this close interrelation