BRIDGESTONE | WHEEL ALIGNMENT
CAN YOU EXPLAIN THE DIFFERENT WHEEL ALIGNMENT TERMINOLOGY AND DEFINITIONS? When we talk about wheel alignment issues you will often hear the words “camber”, “caster” and “toe” mentioned. These relate to the angle of the wheels/ tyres measured against fixed points. They need to be set up correctly to ensure good and even tyre wear and road safety. Camber is the angle of the wheel from the
true vertical to the center line of the wheel. Standing in front of the vehicle, if the top of the wheel is tilted (leaning) outwards then the camber is positive and if it's tilted in, then the camber is negative. If the camber is out of adjustment, it will cause premature tyre wear on one side of the tyre's tread. When the camber is out of adjustment it can also cause the vehicle to pull to one side. This usually happens when the
WHAT IS AXLE PARALLELISM AND HOW DOES IT RELATE TO WHEEL ALIGNMENT?
Closely related to wheel alignment, Axle Parallelism only comes into play when dealing with articulated vehicles with multiple axles. Improper Axle Parallelism will have much of the same negative effects on tyre wear and road safety as wheel alignment will have. Proper Axle Parallelism aims to have all axles perpendicular to the center line of the chassis and all axles parallel to each other. Typically there are three sets of axles on
an articulated vehicle – they are the Steer Axle, Drive Axle and Trailer Axle. When one or more of these axle sets are not parallel or perpendicular to the chassis, this will cause excessive and uneven wear to tyres and also give the driver the sensation that the vehicle is pulling to one side. Axle Parallelism problems can be
corrected and is usually caused by one or more of the following: uneven axle springs, broken leaf spring, worn springs, broken U-bolt, bent frame, adjustment of torque rods or worn torque rod bushings.
Parallel Axles
UNPARALLEL AXLES RESULTS IN IRREGULAR WEAR Unparallel Axles
Direction of Motion Direction of tyres rotation Thrust Angle
+ve
-ve
Camber
vehicle has been involved in an accident which has caused structural damage to the suspension. Camber also goes out of adjustment when the springs sag and causes ride height to change, or when ball joints and or other attached parts are worn or defective. Camber also varies depending on the load that the vehicle is carrying. Caster is the angle of the steering pivot
from true vertical to the steering axis. Viewed from the side, the caster is the tilt
AXLE PARALLELISM
of the steering axis. When the wheel is in front of the load the caster is positive. Toe is the most critical alignment setting of a vehicle relative to tyre wear. The toe angle identifies the direction of the tyres compared to the centerline of the vehicle. Increased toe-in will reduce “oversteer”, steady the vehicle and enhance high-speed stability. Increased toe-out will reduce “understeer”, free up the vehicle, especially during initial turn-in while entering a corner.
Toe Angle
26 JANUARY 2012 real QUESTIONS real ANSWERS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28