This article was published in the April 2013 edition of NTEA
News
Question: We’re a truck equipment distributor that
installs various types of truck bodies and accessories for the commercial
vehicle market. On many occasions, a customer will ask us to supply and install
a new body with accessories on an existing truck. As such, we need to make sure
the body, equipment and desired payload are appropriate for the given chassis.
How can we do so?
Answer: A thorough understanding of the customer’s
application and requirements is essential. Advise the customer that a payload
and weight distribution analysis is needed in order to verify that you can
install the desired body and accessories while satisfying their payload
requirements. Explain to your customer that, as a distributor, your company is
responsible for ensuring that their trucks meet all applicable federal and state
safety standards and regulations. This also includes making sure the completed
vehicle, when fully loaded, will comply with the weight restrictions for vehicle
and axle loading.
Whether dealing with an existing truck or designing a new unit, a
payload analysis is a necessary first step. On an existing vehicle, compromises
are often required because of the truck’s gross vehicle weight rating (GVWR) and
gross axle weight rating (GAWR). This often limits or restricts choices for the
body, accessories and payload. When designing a new unit, all of these factors
are taken into account, ensuring the truck has the proper GVWR, GAWR and
wheelbase that can be certified to meet all applicable Federal Motor Vehicle
Safety Standard (FMVSS) regulations and state/federal axle
loading limits.
The next step is the weight distribution analysis, which provides the
information needed to select and confirm the
proper wheelbase for the chassis, placement of body,
location of accessories and payload. The results show axle loading and confirm
if the completed truck will comply with the manufacturer’s axle ratings, any
possible center of gravity restrictions and weight laws.
An accurate payload and weight distribution analysis offers you
the best opportunity to provide your customer with the right-sized truck
that has the proper body and meets the payload requirements.
Matching the chassis and body, calculating/selecting the proper wheelbase
and meeting payload requirements help prevent overloading of the truck
and front and rear axles. This also helps ensure that the resulting vehicle
meets both federal and state highway and bridge weight limits. In the end, a
properly designed truck provides the user with a safe vehicle that performs as
intended and optimizes durability and useful life.
This analysis will also supply customers with the information they will
need to make informed decisions on their body, equipment and payload choices. In
addition, it reflects your commitment to providing an upfitted truck that will
meet customer expectations for vehicle performance and durability.
Before you can get started on the analysis, though, there is specific
information that must be compiled from the manufacturers of the truck chassis,
body, parts and accessories. Truck chassis manufacturers typically offer this
information on their websites for dealers and body builders. Additionally, an
OEM’s sales order guide contains weight information for the base model and
optional equipment used in determining the vehicle’s curb
weight. Chassis manufacturers also publish a body builder
manual/layout book which includes drawings, charts, diagrams and guidelines for
upfitters. In addition, OEMs are required to provide an incomplete vehicle
document, which gives second-stage manufacturers instructions and
requirements for completing a vehicle that will comply with applicable FMVSS.
Weights and center of gravity locations are needed for bodies, parts and
accessories from each respective manufacturer to complete your analysis.
Helpful Resources
If you have
any questions or concerns about performing a weight distribution
calculation, the NTEA’s Technical Services Department can help.
Members can request a weight distribution analysis from the Association’s
staff engineers by taking the following easy steps:
- Complete a Weight Distribution Input Form
- Fax the completed form to (248)
489-9766 or email to Jennifer Poore, NTEA technical services administrative
assistant, at jennifer@ntea.com.
The NTEA offers additional resources, tools and training to help you
understand, compile and prepare your analysis:
Chassis
Manufacturer Directory
The Chassis
Manufacturer Directory lists OEM sales and technical contact information as
well as links to additional documents and resources. Note: login information is
required to access technical contacts.
For personalized login assistance, contact Emily Hooks,
NTEA membership coordinator, at 1-800-441-6832, ext. 134, or emily@ntea.com.
Shop
NTEA
The “Shop NTEA” section of NTEA.com
offers forms, programs and publications available for purchase from the NTEA,
including:
- Weight Distribution & Center of Gravity Calculation Software — These PC-based
spreadsheets calculate and print information such as axle loads and horizontal
and vertical centers of gravity.
- Truck Equipment Handbook
— A comprehensive guide that features in-depth technical
information on the selection of commercial vehicle components and
equipment. Contents include: Matching Chassis and Body; Maximum Net
Payload; Weight Distribution; Center of Gravity; Bridge Gross
Weight Formula; and more.
Education and Training
The NTEA is a
leading provider of education and training for the work truck
industry. Opportunities specific to this article topic include:
- The Work Truck
Show — North America’s largest work truck event offers
more than 60 world-class educational programs, including topics such as
performing accurate weight distribution and payload calculations.
- Weight Distribution
Fundamentals — A convenient online course that offers 10
sections designed to provide insights, strategies and tactics to advance your
knowledge of all aspects of weight distribution. Learn more at www.ntea.com/eventsandtraining.
As always, if you have any questions, please don’t hesitate to call the
NTEA’s Technical Services Department at 1-800-441-6832,
Monday–Friday, 8 a.m.–5 p.m. EST. We’re happy to
help!