Technology and opinions change
Suspensions have evolved with needs of vehicles
THE steel spring suspension has been used in transport since the horse and buggy days.
Airbag suspensions came into being in the US in the 1970s and have been in use in Australia from around the same time.
Manufacturers’ “application guidelines” from the 1970s specified that air suspension was an “onhighway” suspension and that it would only be approved for 100% highway use.
Limited approval was possible for off-highway use, but the suspension was not to be used for high centre of gravity loads, the guidelines indicated. Much has changed. Air suspension became more widely used in the 1990s with the introduction of the higher mass limits allowed by the use of “roadfriendly” suspension types.
Indeed the current (extensive) listing of approved “road-friendly” suspensions records more air suspensions than it does spring-based ones.
Air suspensions versus spring suspensions has always been a “hot topic”, with users fervently believing one is better than another. Thank goodness Australia is a democracy.
A report prepared for the NT’s Department of Transport and Works dated September 2000 commented from its operator survey “it was evident that no one combination or ‘set up’ of the combination ‘outshone’ any other. Combinations fit the transport task and what works for one task does not necessarily work for another”.
“Furthermore, what operates in the more metropolitan environment does not necessarily operate successfully in remote areas.”
A study published in 2014 by a major US carrier concluded that “air ride did not guarantee greater ride quality than spring and that it was a myth” that it did.
A spokesperson for Australia’s leading trailer manufacturer and supplier, MaxiTRANS, said: “Along with third-party offerings, MaxiTRANS manufactures and fits a number of popular proprietary suspension solutions including VE50 spring suspension and AirMAX airbag suspension.
“Regardless of make, we follow suspension manufacturers’ guidelines to provide best practice recommendations to our customers based on the proposed trailer application.
“Over time, we have seen an increased uptake of airbag suspension and encourage our customers to specify it where appropriate due to the better ride and reduced damage to roads and infrastructure that it offers.”
Despite now being 17 years old, the words of the NT Transport and Works report hold true; suspension “combinations fit the transport task and what works for one task does not necessarily work for another” but advances in suspension technologies are fast closing that gap.
SMOOTH RIDE: Airbags on an IVECO chassis give a smoother ride for sensitive product and height versatility for loading.
Heavy steel suspensions are still favoured for rugged vocations.
This veteran Leyland steel spring suspension is similar in design to the old Mack Camel back.