Specifications should be defined by the application and mission requirements. With this in mind, trucks must be spec’ed to handle very specific fleet applications, which requires correctly specifying a multitude of components such as the right drivetrain, suspension, and body. It is critical to understand day-to-day fleet applications when spec’ing a truck. Without fully understanding the fleet application requirements and operating parameters, it is impossible to spec the best chassis, powertrain, and body necessary to optimize productivity. But, most importantly, determining the fleet application determines the payload requirements.
Properly identifying payload parameters is the foremost consideration to properly spec’ing a truck. To illustrate this fact, the weight of the payload will determine the engine, transmission, size of tire, frame, and just about everything else. The first step in calculating payload is to determine how much weight a truck will need to carry in its daily work application. It is important to determine the maximum need here, not an average. The vehicle must be able to do the job every day with the maximum load at any given time. In addition, you need to make sure that the truck can carry not only the payload, but also any additional equipment you put on the truck. It is important to factor in the body and equipment weight, as well as, any tools or other material that may be stored or transported by the chassis.
Determining Payload Requirements
There are three components to determining payload requirement. The first is payload weight. How much weight will the truck need to carry in its daily workload? As mentioned earlier, you need to determine the maximum payload need, not an average.
Another determinant is the volume or size of the payload. The truck needs to be large enough to handle the volume. Payload weight will also help determine if the cargo can be loaded and unloaded by hand, or whether you will need a power liftgate or some other type of assist to get it up in the body or bed. And, you need to know how the payload will be loaded. Is it stackable? Can you stack it right to the ceiling? Or, can only the floor space be used? How do you secure the product? Getting any of these factors wrong can mean the vehicle will be spec’ed incorrectly.
The third component is the type of payload. Are you hauling loose gravel, pallets, or boxes of merchandise? This will determine the type of truck and body combination you need to choose.
Over-Spec’ing vs. Under-Spec’ing
Overextending a truck’s payload capacity beyond the chassis’ weight specifications is a good way to shorten the truck’s service life. Overloaded trucks will cause premature tire wear, decreased fuel economy, and downtime due to engine or transmission repair. In addition, overloading results in fines and possible impoundment of the vehicle by the authorities.
Determining the correct vehicle size for the intended payload often requires a judgment call as to how much over-capacity to build into the payload capacity of the vehicle when spec’ing its requirements. Spec’ing the truck to the minimum necessary payload rating (by basing it on an average load or looking at only today’s business needs instead of trying to anticipate future needs) means that the vehicle will be operating at peak capacity most of the time, which may compromise safety and the length of its service life. Using average payload for specs means that the vehicle will sometimes be overloaded – and that means excessive wear-and-tear, higher maintenance costs, and poor fuel economy.
It can’t be emphasized enough – to properly spec a truck you need to talk with the people in the field to understand what type of service the truck is expected to perform and how it will be used. You should solicit input from field personnel to ensure that local issues affecting the vehicle’s operation are taken into account.
In the final analysis, you need to view work trucks as revenue earning assets. To maximize the productivity of this working asset, it is necessary to optimize specs to fulfill the fleet application.
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Originally posted on Automotive Fleet