1802. An Inexpensive Way to Accurately Measure Vehicle Weight and CG Location in Three Axes

Paper

Abstract

This document describes a procedure to accurately measure the weight and center of gravity location of a land vehicle in three axis by using standard portable equipment and constructing a few small but inexpensive fixtures. This procedure combines the suspension method and reaction method of measurement. The six methods of locating the center of gravity of a vehicle are: the reaction method; the balance method; the suspension method; the null point method; the platform support reaction method; and the pendulum method. Of these six methods, the suspension method’ null point method, and the platform support reaction method yield the center of gravity location in the longitudinal, lateral, and vertical directions without tipping the vehicle 90 degrees. The null point and the platform support reaction methods require the construction of a very expensive platform that occupies floor space, is not portable’ and does not have any other uses. The suspension method does not require the use of such a platform. However, it cannot be used to measure vehicle weight. By combining the suspension method with the reaction method, a reliable, accurate, and inexpensive method of measuring vehicle center of gravity and weight is achieved. The reaction method will yield the weight and center of gravity location in the longitudinal and lateral directions. The suspension method will yield the vertical location and also provide a check on the longitudinal location. This combined procedure uses standard portable equipment that car, be rented or is readily available in most plants. It is similar to the hoisting procedure used by the SAE J874 (from the Society of Automotive Engineers, Inc.) except that it is more detailed and utilizes an optical mirror to square the vehicle to its reference axis to obtain greater accuracy.