RIGID six-wheel vehicles and semi-trailer combinations are classified and described as to load distribution, application of power, arrangement of spring suspension and of tires.
Consideration is given to the desirability of a conventional differential between the two driving axles, and the advantages to be gained by substituting a differential in which the action is limited.
The semi-trailer is said to be useful for specialized services and to compete rarely with the rigid six-wheeler. The automotive industry is said to be following in the steps of railway engineers in providing more wheels for greater loads.
At the close of the paper is given a bibliography of S.A.E papers and general periodical literature referring to six-wheel vehicles.