Plan for the Long Haul

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."

"In general, the most neglected items on vocational trucks are the work equipment installed to adapt the vehicle for a specific job," agrees Johnson. "In far too many cases, equipment maintenance, if performed at all, is limited to servicing easily visible or accessible grease fittings."

Such equipment should be regularly inspected and tested for proper operation. "In many cases, such as cranes and aerial devices, these inspections are mandated by OSHA," notes Johnson. "Failure to inspect the unit and document inspection results may place the owner in violation of federal regulations."

Cost control
Extending useful vehicle service life doesn't have to be complicated. According to Ginter, reducing owning and operating costs can be as simple as proper cleaning and comprehensive daily driver inspection reporting using a checklist.

In the case of Mack Trucks, the driver can take note of any error codes on a regular basis. "Utilize On-board Diagnostics (OBD)," says Ginter, "and monitor both active and in-active fault recording on a regular basis available from the VMAC IV software system."

It doesn't hurt to give drivers a vested interest in cost control. "Operating costs can be reduced by giving incentives [such as providing] drivers with fuel economy targets and rewarding success," says Ginter. "Driving for maximum fuel economy saves fuel and reduces wear and tear, as the truck is being driven well below the extreme capabilities built into it."

But you can't truly control costs until they are first understood. "When seeking ways to reduce operating costs, first perform a detailed analysis of these costs and identify the top two or three items to focus on," says Johnson. He notes it's likely that labor, fuel or both will make the list. "This analysis should be very detailed in order to be effective. For example, don't list maintenance as a single item - break it down into specific categories, such as electrical repair, brakes and tires."