Issue link: http://read.dmtmag.com/i/34501
ALIGNMENT EQUIPMENT Alignment equipment exists that ranges from simple and inexpensive to sophisticated and costly. One factor that is common to all types of alignment equipment is that the person using it is extremely important to the resulting tire and vehicle performance! Calibration is another critical factor in maintaining the accuracy of the system – follow manufacturers’ recommendations. Some fleets have obtained excellent results with a good “scribe and trammel bar” and paying strict attention to toe and axle parallelism. Other fleets establish permanent records, make adjustments more easily, have more information for trouble-shooting, and obtain excellent results with the more expensive equipment. The common ground is that the person using the equipment understands it, uses it properly, and follows the procedures consistently. Michelin ® remember when analyzing steering tire wear is “Smooth In” means Toe-In; “Smooth Out” means Toe-Out. A quick field check procedure is done on elevated, dry tires, and with a can of spray paint or marker, highlight a section of the tread area around the tire. With a sharp pointed scribe, mark a thin line in the highlighted area while rotating the tire. Repeat this process on the other steer tire. Lower the vehicle on folded plastic bags. Once the steer tires are down, bounce the truck to make sure the suspension is relaxed, and verify that the wheels are pointing straight ahead. Then measure from side to side between the scribed lines, first rear, then front, with a tape measure or a fine-lined toe gauge to determine relative toe. Subtract front from rear: positive result indicates toe-in, negative is toe-out. See Section Nine, Appendix under Alignment – Field Method (Pages 118- 119) for complete procedures. developed the BibAlignment System as a very simple, accurate, and repeatable method of establishing the position of a vehicle’s axles relative to each other. Through the use of a computer program, the highly portable and cost-effective BibAlignment System calculates the corrections necessary to improve the vehicle’s axle parallelism. It locates the centerline of drive and trailer axles and projects this centerline to the ground. These points are measured, recorded, and entered into the computer program. The resulting data concerning the axle alignment and recommended corrections may be printed for historical reference. Contact your local MICHELIN Representative for ordering information. Heavy truck alignment has evolved to a precise science. The “field check” techniques below may be used to detect a problem condition but are not recommended for making adjustments/corrections. Proper alignment equipment should be used if a decision is made to complete this service. FIELD CHECK TECHNIQUES TOE: This wear on the tread occurs due to the shearing action created by side forces resulting from excessive toe-in or toe-out. If the toe is properly set, the steer tires will feel even and smooth when you move your hand across the tread surface. If the front tires have excessive toe-in, a feathering wear will be created. This can be felt very easily with your hand. The tread will feel smooth when you move your hand in across the tire, but you will feel a drag or resistance when you move your hand back out across the tread. If the front tires have excessive toe- out, the opposite will be evidenced. The resistance will be felt going across the tread, with no resistance felt while being withdrawn. A simple Rule of Thumb to 50 Section Three: Extending Tire Life Toe-in