Weight distribution and analysis: Choosing the proper work truck

From an NTEA member With electric vehicles and supply chain disruptions continuing to dominate news headlines, our customers have been asking how to choose the correct commercial vehicles to meet their needs. Many work truck customers are interested in right-sizing their vehicles for their applications. Some order a specific vehicle and equipment combination only to find it’s either too large or too small for their needs. Sometimes, the specified vehicle will not carry all the desired payload the customer needs or they find the vehicle chosen is too big for the job. The customer is looking for an efficient vehicle to do the desired job. Performing a payload analysis and weight distribution are key starting points in determining the correct chassis size for the application. When performing a payload analysis, key elements and accurate weights must be determined. Key elements will include desired chassis curb weight, including all options (not just the base vehicle weight); body weight including all options (bumper, hitch, etc.); and equipment weight (cranes, compressors, shelving, ladder racks, etc.). It’s also important to gather the weight information on additional items like radios, GPS systems, computer racks and other systems as well as the customer’s true payload expectations as these factors are often underestimated, leaving the vehicle overloa the customer is towing a trailer, and if yes, then subtract 10–15% of the trailer gross vehicle weight rating (GVWR) from the available payload. To begin the payload analysis, start with the customer’s desired chassis GVWR and then subtract the selected chassis weight with all options, including a full tank of fuel. Then subtract the weight of the driver and passengers (minimum 150 pounds for each belted seating position). Next, subtract the body weight (if needed) and all the permanently attached equipment. Example 1: 9,500-pound GVWR battery electric chassis cab with 14-foot van body, bumper, interior shelving, and driver and passenger. GVWR 9,500 pounds – chassis weight 5,110 pounds – body weight 1,750 pounds – bumper weight 100 pounds – shelving weight 350 pounds – minimum driver and passenger weight (two seats) 300 pounds = 1,890 pounds payload Example 2: 9,950-pound GVWR gas engine chassis cab with 14-foot van body, bumper, fuel, interior shelving, and driver and passenger. GVWR 9,950 pounds – chassis weight 4,649 pounds – body weight 1,750 pounds – bumper weight 100 pounds – fuel weight (25 gallons) 150 pounds – shelving weight 350 pounds – minimum driver and passenger weight (two seats) 300 pounds = 2,651 pounds payload The two examples show the weight difference between the battery-powered versus gas-powered — including fuel of over 300 pounds, plus the available GVWR difference of 450 pounds — made a significant difference in payload availability. This may help the customer determine if the battery electric vehicle will meet their payload needs before reviewing their drive and duty cycle needs. If the payload meets the customer’s needs, you would next proceed to performing a weight distribution analysis to ensure the vehicle’s front or rear axle ratings are not overloaded based on equipment location or excess payload. Planning vehicle upfits to remain within curb weight limitations, gross vehicle and axle weight ratings, and OEM center of gravity limitations, are critical for a number of Federal/Canadian Motor Vehicle Safety Standards and chassis-based emission requirements. In particular, braking and electronic stability control systems can be affected by a vehicle’s weight and overall center of gravity. Towing adds another dimension to these considerations, and heavier vehicles with federal bridge or other roadway weight limitations require weight evaluations across different groupings of axles. Weight distribution calculations help ensure the vehicle will comply with OEM weight-based limitations and certification limitations. There are tools that can help. For vehicle center of gravity position, axle weights and federal bridge weight calculations, NTEA’s Vehicle Center of Gravity and Axle Weight Calculator is available to members as a free web-based resource. NTEA has also partnered with TruckScience to offer their cloud-based Axle Weight Calculator app to members at a discounted annual subscription rate (member $550/nonmember $600). Learn more at ntea.com/weightcalculatortools. The weight calculator can help perform certain compliance calculations needed to properly certify incomplete vehicles for braking standards (air and hydraulic), electronic roll stability systems standards and center of gravity limitations, in addition to general vehicle balance for proper control. Helping customers specify their next new work trucks will take planning that begins with an accurate payload analysis and weight distribution calculation, which is critical to choosing the correct vehicle for their application.

Weight distribution and analysis: Choosing the proper work truck

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