September 2008, Work Truck - Feature
Avoiding the Pitfalls in Spec'ing Powertrains & Transmissions
By Joe Bohn
High fuel prices and dramatic change in the cost of diesel versus gasoline, the expense of diesel engines themselves, and more powertrain-related choices have all contributed to changing the landscape of powertrain spec’ing. Optimizing engine, transmission, and axle ratio combinations for a given application is more difficult today.
Fleets must be open to considering alternatives to traditional methods in spec’ing powertrains, according to experts at major fleet management companies.
Detailed in the following are changes that have impacted powertrain spec’ing for light- and medium-duty trucks and the potential pitfalls they create.
Relying on Experts
Assistance from qualified professionals, such as knowledgeable fleet management companies and dealership salespeople, is helpful to making good spec’ing decisions. At the dealership level, fleet managers should temper a salesperson’s advice with their own good judgment.
"Salespeople in dealerships will do factory orders when they have to," notes Lou Mathai, truck specification engineer for PHH Arval, headquartered in Sparks, Md. "But first they’ll make every effort to sell what’s on the lot, getting as close as they can to what the customer needs."
Mathai
Mathai adds that it’s important to know whether the salesperson has expert knowledge about a fleet’s desired vehicle class. Even in seemingly minor items such as axle ratios, expert advice can make a big difference ultimately in the truck’s operating efficiency.
Right-Sizing the Engine
Many fleets are turning to smaller, more fuel-efficient engines to cut costs.
"Reducing horsepower, if you don’t need it, is the way to go, but just don’t cut yourself short," advises Dave Duford, senior specifications analyst for Automotive Resources International (ARI), in Mt. Laurel, N.J.
Duford
In spec’ing the engine, a fleet should consider extra load-carrying or trailering contingencies that may occur.
If the truck will operate at maximum or near maximum capacity, it may require a larger/heavier engine. It can be a mistake for a company with multiple locations to use common or standardized specs for trucks operating in diverse areas where terrain variations might require different engines.
If a truck is underpowered for its specific duty requirements or location, vehicle operators are forced to run the truck at high throttle/rpms more often. This practice reduces powertrain life and leads to costlier servicing/repair bills, such as premature brake wear. In the end, the fleet may incur more extra expenses than it saves in fuel costs.