LABORATORY STRENGTH-TESTS OF MOTOR-TRUCK WHEELS

In this investigation to determine strength and physical properties 12 motor-truck rear-wheels were tested, comprising two each of the following types: Class-B trucks, standard wood; Class-B truck, cast-steel; I-beam type; steel disc; aluminum; and rubber-cushion, each having a 34-in. diameter and a 12-in. tread. The wood, the I-beam and the cushion wheels each had 14 spokes; the aluminum and the steel-disc wheels had a solid web between the hub and the rim. All the wheels were tested without tires or brake-bands, were bushed to fit a 4-in. axle and the area of contact between the hub and the bushing was the same as that in service. Illustrations show the construction of the wheels.

Requirements considered essential in a wheel were listed, and the tests were conducted to obtain data concerning them. One wheel of each type was subjected to a radial-compression test. Other tests were for determining the limit of proportionality of deformation to load, for ascertaining the elastic resiliency or ability to absorb shock and for measuring the amount of side-thrust. Photographs illustrate the character of failure of each wheel, a comparison of the important mechanical properties of the different types is shown graphically and seven specific conclusions resulting from the tests are stated.