ForConstructionPros.com

Want to extend the useful life of your vocational truck fleet without dramatically increasing downtime or maintenance costs? It is possible, but it may require a change in the way you manage and maintain your trucks.

Vocational trucks used in off-road applications are subject to different types of wear and stresses compared to their over-the-road counterparts. "Failure points depend on type of equipment, operating environment, duty and drive cycles and overall quality of maintenance," says Bob Johnson, director of fleet relations at the National Truck Equipment Association (NTEA). "However, electrical system problems seem to top many maintenance analysis studies, followed by brake, suspension and steering issues, which often result when vehicles are overloaded."

Failures can also occur when strict adherence to suggested maintenance intervals is not followed. There are many maintenance items that tend to get neglected on the typical vocational truck. Steve Ginter, vocational truck manager, Mack Trucks, lists tire pressure, suspension components and engine valve clearance as examples. You should re-torque suspension components, grease bronze trunnion bushings and front king pins and adjust valve lash roughly every two years or 250,000 miles.

In addition, you need to tailor your maintenance practices to match how the vehicle is actually used. "For those that do a lot of idling, one of the most neglected area's that we see is with oil changes," says Jim Michon, truck fleet marketing manager, Ford Motor Co. "For vocations that do a significant amount of idling, they should base the frequency of oil changes on engine hours instead of miles. In general, one hour of idling is equivalent to 30 to 50 miles of driving."

Yet, failure points on these vehicles commonly have little to do with the chassis. "Buy a Mack chassis and most of the failures will be on the tarp system or tailgate," notes Ginter. "All OEMs work to reduce component failures and extend service intervals."