More than 200 independent service professionals gathered earlier this year to learn more about commercial vehicle axle alignment.
Hosted by training veterans from Meritor and Hendrickson, the hands-on teaching session “hit home” with the pros, as they learned significant new information and strongly recommended a technical session be repeated in 2014 during Heavy Duty Aftermarket Week.
The single most important element of alignment is proper wheel bearing adjustment, according to Rick Martin, training manager at Meritor. It’s often said that if you asked 10 technicians about wheel bearing adjustment, you could hear 10 different opinions. One telltale sign of unattended wheel bearing adjustment is dust on the torque wrench and the dial indicatortwo important tools that must be used every time to operate properly adjust wheel end bearings, according to Martin.
“Technicians are deserving of more training and attention on the proper wheel-end procedures, and in many cases, they’re simply not measuring anything and relying on feel,” said Martin. With a recommended wheel bearing end-play of 0.001-in. to 0.005-in., technicians should follow the TMC RP-618 procedure to the letter, he added.
As for tire wear diagnostics, most technicians automatically blame the front axle when a complete diagnosis is called for. Look at the tire wear patternsome are very normal wear patterns, while other patterns are clear indicators of a problem. It’s strongly recommended that fleet asset managers pay close attention to TMC’s Radial Tire Conditions Analysis Guide and the soon-to-be-released Recommended Practice, as produced by Study Group 6.
Pre-alignment maintenance inspection checks for condition and wear should include: cold tire pressure, Pitman arm, draglink, steering arm, tie rod ends, cross tube, kingpin bushing, wheel bearing end-play, tire and wheel runoutlateral and radial, and suspension torque roads and bushings.
Axle alignment is necessary to set the wheels/tires in the optimum position for maximum tire performance. The axle should be aligned in a static position so that at vehicle operation, the wheels and tires are in an optimum position with the road surface. Martin emphasized the importance of adjusting steer axle toe to compensate for steering component deflection, to reduce wear to the leading tire edge and to avoid road wander.
The session covered the importance of also checking trailer axle alignment, since in many cases, the trailer is a “forgotten member of the family.” Its alignment is a function of three parameters: axle orientation (adjustable), axle camber (non-adjustable), and axle toe (non-adjustable).
As the technicians heard at the HDAW session, trailer axle orientation is the positioning of the axle assembly relative to the vehicle on which it is installed (and to the kingpin). On a single-axle vehicle, the axle is positioned relative to the vehicle. On a multiple-axle vehicle, the front axle is positioned relative to the vehicle, and then the remaining axles are positioned so they are parallel to this axle.
One overriding tip on attending all equipment training sessions: take notes and use and reference the maintenance manuals, which detail proper procedures to ensure uptime and component performance.
“It’s hard to remember all the instructors’ tips and pointers in a training session, especially since a typical technician might have 8-10 different jobs in-process at any one time,” Martin said.
Both of the sessions’ instructors recommended that fleet technicians make full use of the component manufacturers’ maintenance manuals (all are online) and TMC Guidelines for Total Vehicle Alignment and Troubleshooting Ride Complaints (both at http://atabusinesssolutions.com).