In order to ensure the stability and easy operation during straight line travel of the vehicle and to reduce the abrasion between the tyres and other parts, many factors should be taken into consideration to determine the angle between the wheel and the ground surface and the mounting between the steering wheel, steering knuckle, front axle and the bracket. This should retain certain relative position, and such mounting with the relative position is referred to as steering wheel alignment, namely, front wheel alignment.
Previously, wheel alignment refers to front wheel alignment, while the modern vehicles also need rear wheel alignment that is four-wheel alignment. The complete four-wheel alignment is to test the angular position relations between bracket, suspension components and wheels as well as relation between four wheels at the directions of X, Y and Z shafts. Via precise measurement of the vehicle with special instruments, adjust to standard scope based on measurement results and the parameter comparison with original design so as to make the vehicle restore the original standard and reach the optimum operating and travel performance.