Wheel Alignment

If we have a precise look on our shoes, we can find that our heel is designed always higher than toe. Why ?  Why the heel should be always higher than ? The answer is because we walk forward, not backward. Like this simple difference in shoe design, we can design the shoe of a vehicle in this way also to give a better driving behavior by giving a small asymmetrical difference in suspension linkages and wheel supporting structures. This specific geometric design, we call “Wheel Alignment”. This alignment, a special geometry of wheels and its linkage, can provide safe, stable and reliable handling. The followings are the components of the alignment. If any of these alignment component is not optimally adjusted, there can be excessive wear of tires, damages in steering and suspension components, not stable handling.

 

Caster

When we have a shopping in a moll, we push a shopping cart. If we look on the wheel of the shopping cart, we see that the wheel center is different from the shaft center. By having this eccentric structure, we can drive the cart much easier than a fixed wheel structure. This is called as “Caster”, which is one important component of wheel alignment.

One more example of the caster, we can find in the front wheel of bicycles. The effect of caster is easier keeping of the current moving direction and at the same time to give handling stability. For example, the lead which is the distance from the vertical line of wheel center and the cross point between wheel support and road surface give easier handling of the front wheel.

 

 

Camber

Camber is the angle represented by the tilt of either the front or rear wheels inward or outward from the vertical as viewd from the front of the car. If we see the vehicle front wheel from the vehicle front, we can find that the lower part of the wheel positioned a little bit closer than the upper part of the wheel as described in the picture. By aligning the front wheel in this way, we can compensate the weight of passenger and vehicle as well as compensating the road crown.

Toe

Toe is the distance comparison between the leading edge and trailing edge of the front tires. If the leading edge distance is shorter than that of trailing edge, there is positive toe or toe-in. If it is bigger, there is negative toe or toe-out.  If we see the vehicle front wheel from the top, we can see that the distance of the front part of the wheel is a little bit shorter than the distance between rear part of the wheel. The effect of the “Toe-In” is keeping the vehicle moving forward.

Turning Radius

When a vehicle turns, the turning radius of outer wheel and inner wheel are different, therefore the steering angle of outer wheel and inner wheel should be different. Of course, the steering angle of outer wheel should be smaller than that of inner wheel to make a bigger turning radius. Because this radius is a result of steering linkage, it is not adjustable.

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