The desire for greater speed, higher payloads, and bigger machines in off-highway trucks was met with the advent of the LeTourneau-Westinghouse “Haulpak” truck line, which was made possible by the introduction of the variable rate “Hydrair” Suspension. This paper discusses the general construction and application of this suspension and also compares the “Hydrair” characteristics with the conventional heavy duty leaf springs when operating at different speeds with varying payloads.
