Wheel alignment
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Wheel alignment is part of standard automobile maintenance that consists of adjusting the angles of the wheels so that they are set to the car maker's specification. The purpose of these adjustments is to reduce tire wear, and to ensure that vehicle-travel is straight and true (without "pulling" to one side). Alignment angles can also be altered beyond the maker's specifications to obtain a specific handling characteristic. Motorsport and off-road applications may call for angles to be adjusted well beyond 'normal' for a variety of reasons. [1]
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[edit] Angles
There are two types of angles that should be adjusted regularly during the life of an automobile. The first type is called the 'primary angles' and second type is called 'secondary angles'.
Within primary angles, there are three adjustment parameters involved on each axle in order to properly align a vehicle. These adjustments are camber, caster and toe. On some cars, there may only be the ability to adjust for one or two of the parameters.
These three parameters can be further categorized into front and rear, so summarily the parameters are:
- Front: Caster (left & right)
- Front: Camber (left & right)
- Front: Toe (left, right & total)
- Rear: Camber (left & right)
- Rear: Toe (left, right & total)
- Rear: Thrust angle
As for the Secondary Angles, the adjustment parameters are quite numerous. They are:
- SAI (left & right)
- Included angle (left & right)
- Toe out on turns (left & right)
- Maximum Turns (left & right)
- Toe curve change (left & right)
- Track width difference
- Wheel base difference
- Front ride height (left & right)
- Rear ride height (left & right)
- Frame angle
Setback (front & rear) is often referred as a wheel alignment angle. However setback simply exists because of the measuring system and does not have any specification from car manufacturers.
A camera unit (sometimes called a "head") is attached to a specially designed clamp which holds on to a wheel. There are usually four camera units in a wheel alignment system (a camera unit for each wheel). The camera units communicate their physical positioning with respect to other camera units to a central computer which calculates and displays how much the camber, toe and caster are misaligned.
Often with alignment equipment, these "heads" can be a large precision reflector. In this case, the alignment "tower" contains the cameras as well as arrays of LEDs. This system flashes one array of LEDs for each reflector whilst a camera centrally located in the LED array "looks for" an image of the reflectors patterned face. These cameras perform the same function as the other style of alignment equipment, yet alleviate numerous issues prone to relocating a heavy precision camera assembly on each vehicle serviced.
[edit] See also
- Car handling
- Car maintenance
- Auto mechanic
- Tire rotation
- ASE
- Hunter Engineering (Leading Manufacturer of Alignment Equipment)
[edit] External links
- Bee Line Company Leading Manufacturer of Heavy Duty Alignment Equipment
- Tire Rack Article: Alignment
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Wikibooks has a book on the topic of |
- A short course on alignment
- Tire / Wheel Size Calculator
- Car database and calculator for Tire & Wheel Sizes
- How Truck Alignments Affect Fuel Mileage
[edit] Notes
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