For years, a key criteria for spec'ing medium duty trucks has been the grossvehicle weight rating (GVWR).

For years, a key criteria for spec'ing medium duty trucks has been the grossvehicle weight rating (GVWR). Users select trucks primarily on the basis of their class. So a Class 6 vehicle may be suitable for one application and a Class 7 may work better _for another.

While the vehicle's GVWR is still important, many dairy truck buyers are increasingly focusing on other factors when making their selection, says Mike Parrish, medium duty product marketing manager for Kenworth Truck Company.

"The expectations that dairy people have of medium duty trucks has continued to increase in recent years," Parrish notes. "Many of these truck users are looking for a business solution rather than just a vehicle. Dependability is high on their list because they are hauling perishable goods and they can't afford breakdowns.

"Buying the least expensive truck available off a dealer lot may seem like a good deal at the time, but in the long run it may be more expensive than one that was carefully spec'd. Their key concern should be minimizing life cycle cost and sometimes they lose sight of that," Parrish says.

Some of the first things to consider are the type of load, annual mileage and operating environment. Buyers can choose from a wide range of bodies that can be mounted differently depending on the truck's wheelbase and local weight regulations.

"Bodies can be mounted flush with the cab or with a space in between," Parrish explains. "They can also be on top of the frame or extend below it.

"In order to calculate the correct frame strength, we first need to know the type of body selected. Typically, the big issue with a frame isn't just the kind of load, but also the body type and _vehicle application.

With dairies finding it harder to _recruit drivers, a truck's driveability has become a priority for many buyers. A truck that is easy to drive and comfortable to operate is desirable. "The person driving is a retail salesperson first and foremost and usually isn't being hired for driving skills," Paish says.

"That's why automatic transmissions have become very popular in dairy. About 50% of our dairy truck buyers are choosing Allison automatic transmissions because they are easier to drive and require less maintenance."

Other important driver factors are "startability", maneuverability, visibility, and ease of entrance and exit into and from the truck. "If your truck is going to be operated on busy roads, or there's a lot of loading and unloading in tight quarters, these factors become crucial," says Parrish.

Numerous items factor into the vehicle's actual performance. Take, for example, turning radius. "Our Kenworth T300 model comes standard with a 50-degree wheelcut to give you a tight turning circle. But if you need to carry more weight for a driver who is out making deliveries all day, you may need a heavier axle and larger tires and that could affect your turning radius," Parrish notes.

Visibility and cab access are more a function of truck design, but there are still choices. "The wider the steps and the less climbing drivers have to do to get in and out, the better," says Parrish. "Going to low-profile 19.5-inch tires can make life easier for a driver in an application with a lot of stop-and-go by helping to reduce fatigue."

A final driveability issue is ride quality. Parrish says rear air ride suspensions are currently being spec'd on around 30% of all Kenworth medium duty vehicles.

A carefully spec'd drivetrain can lower your total operating costs over the truck's life. Be careful not to over-spec the engine, says Parrish. "In a dairy application, for a 20-22-foot truck on a single axle making a lot of stops in-town, you're spec'ing a 230-horsepower engine. For a 26-footer carrying greater loads with fewer stops, you're spec'ing 300 horsepower."