Right-sizing vehicles

More model choices are leading fleets to smarter vehicle size decisions


Fleets saw a rapid increase in operating costs through the late 1990s and into this century and started looking for ways to reduce costs. They realized that many of their vehicles were oversized and started working with body manufactures to find ways to "right size" their vehicles.

The body companies developed new designs to fit the few Class 4 and 5 chassis available, and this created a tremendous pull-through effect that lead to the development of the more and more Class 4/5 units.

FM: Obviously, if a truck is used for purposes it was not intended for, constantly overloaded or improperly spec'd, the result would be higher maintenance costs for fleets. Correct?
RJ: Absolutely. Overloaded vehicles and/or misused mounted equipment will definitely suffer from high maintenance and operating costs.

FM: Even with more truck model choices, don't fleets still face the challenge of not spec'ing a vehicle that will be too much or too little for the job?
RJ: One of the biggest mistakes fleet make when designing/spec'ing new trucks is to make an arbitrary decision as to what size truck they need and then try to figure out how to make it work for a given application.

When designing a new truck, you first need to define the end application and identify the critical functional requirements. You can then design the second unit/body and have a valid basis for selecting the correct chassis for your application.

The other issue is that fleets frequently fail to define their desired vehicle performance criteria and use this information as a basis for selecting the appropriate engine, transmission and rear end gear ratios. This can result in a truck with either too much, or not enough torque and/or horsepower.

In the past, OEM truck data provided guidance on designing powertrains. As the OEMs shifted to electronic media, a lot of this information was no longer available.

This means that many young fleet managers do not understand the powertrain design process. In fact, that is one of the reasons that the NTEA has started offering training seminars on vocational vehicle design

FM: For fleets that use light and medium duty trucks, hasn't size and cargo-carrying capabilities become more critical key purchasing considerations with the expanded model offerings?
RJ: The expanded availability of chassis ratings has allowed fleets to better match their trucks to their requirements in terms of payload weights and cube requirements. Other factors that need to be considered include individual axle ratings, trailer towing requirements (gcwr), vehicle drive/duty cycles and mounted equipment requirements which can drive factors such as frame and suspension requirements.

FM: Have you seen any trends in the choice of a light and medium duty truck cab configuration between cabover and conventional models?
RJ: There are a number of factors that influence the choice between conventional and low cab forward chassis.

The most obvious factor is operating environment. The shorter overall wheelbase, shorter turning radius and improved forward visibility makes cab forward models the obvious choice for inner city applications.

Conventional chassis, on the other hand, typically have better cab ergonomics and ride characteristics that make them the preferred choice for suburban and rural applications

Other factors include purchasing policies (most cab forwards are offshore sourced), powertrain requirements (limited options for cab forwards) and frame requirements (here again, options are limited for most cab forwards).

FM: Is there anything maintenance shops can be doing to help fleets choose the right vehicle for their operation?
RJ: The maintenance shop is ideally situated to identify chassis maintenance/failure trends associated with overloading and application mismatches. By documenting these trends and calling them to the attention of the people who spec/order new trucks, they can help to insure that future purchases are properly spec'd.

The important thing here is to be sure that you accurately identify the root problem and not just the symptom.

FM: What can maintenance shops do to help fleets keep their vehicles running efficiently - whether or not they are using the right vehicle for their operation?
RJ: First, you need to accurately determine the optimum PM interval for each group of trucks. Too many fleets make the mistake of trying to make one set of criteria work for every truck in the fleet.

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