Issue link: https://read.dmtmag.com/i/34500
ALIGNMENT AND VIBRATION INTRODUCTION In order to maximize tire life, the MICHELIN X One ® ® tire-equipped truck needs to be maintained just like its dual equipped counterpart. Due to the complexity of today’s trucks, this can be an overwhelming task. By addressing the primary causes of the most common tire wear issues, we can simplify this process. The following 4-step approach attacks the major sources of tire wear, alignment wear, and vibration. 1. Air Pressure: #1 cause of irregular wear issues (Pages 45-46). 2. Toe: #1 cause of alignment-related wear issues. 3. Axle Skew: #2 cause of alignment-related wear issues. 4. Radial and Lateral Runout: #1 cause of vibration-related issues. All 4 steps can be performed at the fleet level and require a minimal investment for tools and training. For more detailed information on alignment, refer to TMC RP 642A, Total Vehicle Alignment: Recommendations for Maximizing Tire and Alignment-Related Component Life. For more detailed information on runout and balance, refer to TMC RP 214C, Tire/Wheel End Balance and Runout. TOE Toe is the #1 cause of alignment-related tire wear generally affecting the steer position. It is also a parameter that can be checked and adjusted easily Toe-In in a shop environment. With the vehicle jacked up and using a toe scribe, you can mark a line around the circumference of the left steer tire and repeat the procedure to the right steer tire. Then letting the truck down on a frictionless surface (a folded plastic bag), you can then measure between those two lines at the same height on both sides. You can use two equal-sized objects as a reference. The closer you are to hub height, the more accurate your measurement will be. Ideally, you want the rear measurement to be bigger by 1⁄16" or 1.5 mm. If it is not, you should adjust the toe by loosening the cross tube clamps and turning the cross tube to either lengthen or shorten the overall assembly. Remember to re-tighten the clamps and recheck your measurement following the adjustment. Specification: 1⁄16" Toe In or “Positive Toe.” Note that there is no tolerance or “slop” for this setting. Tools Required: Toe scribe, tape measure, spray paint, and plastic trash bags. AXLE SKEW Axle skew is the #2 cause of alignment-related wear and affects steer, drive, and trailer tires. It is sometimes referred to as scrub or axle parallelism. When drive axles are not parallel to each other, it has a negative effect on all tractor tires. This is due to the vehicle wanting to pull in the direction where the axle ends are closest together. This forces the driver to counter-steer in the opposite direction. This usually results in feathering of the steer tires in opposite directions. In other words, one exhibits toe in and the other exhibits toe out. If this condition is felt on your steer tires, it is usually a classic symptom of your rear drive axles not being parallel with each other. By using a trammel bar, you can quickly and easily determine if your tractor has a skew problem. A (Distance Between Rear of Tires) – (Distance Between Front of Tires) = Total Toe If the value is a negative number (rear measurement less than the front), then you have Toe Out. If the value is a positive number (front measurement less than rear), then you have Toe In. B MICHELIN X One Tire Maintenance 47 ® ®