Specifications

ManualsBrandsAirTek ManualsDehumidifierAT90

17730-248 39 Alignment & Adjustments

AIRTEK

•

SOFTEK

for Blue Bird Buses

FIGURE 8-4

Kingpin Inclination (KPI) — The inward tilt of the kingpin from the vertical. This

front suspension parameter has a pronounced effect on steering effort and return-

ability. As the front wheels are turned around an inclined kingpin, the front of the

truck is lifted. This lifting of the vehicle is experienced as steering effort when the

turn is executed and exhibits itself as recovery force when the steering wheel is

released.

Kingpin Offset — The distance between the center of the tire patch and intersec-

tion of the kingpin axis with the ground. This parameter of front end geometry is

important in vehicles without power steering and has a major effect on static

steering. If there is no kingpin offset, the tires must scrub around the center of the

pin patch when turned in a static condition, resulting in higher static steering

efforts.

Steering Arm — The component that connects the drag link to the axle knuckle

assembly.

FIGURE 8-5

Thrust Angle, Tracking, or Square

— The angle formed by the center-

line of the vehicle frame (geometric

centerline) and the direction that an

axle points. As indicated by the

term “square”, the ideal value for

the angle is 0° or when the axle

centerline is at 90° or perpendicular

to the geometric centerline. Thrust

or tracking to the right is positive, and to the left is negative.

A steering correction is required to offset the effect of the thrust angles and keeps the vehi-

cle traveling in a straight line. It results in a lateral offset between the steer and drive axle

tires commonly referred to as “dog tracking.”

Tie Rod Arm (Ackermann-Arm, Cross Tube Arm) — The component that transmits steer-

ing forces between left and right axle knuckle assemblies through the cross tube assembly.

FIGURE 8-6

Toe-in — is when the horizontal line intersects in front of the wheels, or the

wheels are closer together in front than in the back. Toe-in is commonly

designated as positive, toe-out as negative. Excessive toe-in wears the out-

side edge of the tires. Steer axle toe is adjustable to reduce wear to the

leading edge of the tire and also to avoid road wander. Toe is adjusted in a

static, unloaded condition so that the tires will run in a straight line under a

dynamic, loaded condition.

FIGURE 8-7

Toe-out — Is when the horizontal lines intersect behind the wheels, or the

wheels are closer together in back than in front. Toe-in is commonly des-

ignated as positive, toe-out as negative. Excessive toe-out wears the

inside edge of the tires. Steer axle toe is adjustable to reduce wear to the

leading edge of the tire and also to avoid road wander. Toe is adjusted in

a static, unloaded condition so that the tires will run in a straight line under

a dynamic, loaded condition.

TOE-OUT

TOE-IN

KINGPIN

OFFSET

KINGPIN

INCLINATION

IN DEGREES

SERVICE MANUAL

FRONT AXLE & SUSPENSION

APPENDIX