Characterising heavy vehicle suspensions – impulse testing results and analysis

One response to requests from the transport industry to allow more “freight efficient” heavy vehicles (HVs) onto the road network has been that road authorities have allowed higher axle loads in return for HVs being equipped with “road-friendly” suspensions. These suspensions (particularly those with air springs) are critically dependant on shock absorber health for proper operation. They are only certified, however, as “road-friendly” at the time of manufacture and this via a type-test. Once in service, the “road-friendliness” is determined solely by the maintenance regime of the transport operator. There is no in-service test for HV suspensions in Australia yet. Over 50% of HVs do not meet at least one of the criteria for Australian requirements of “road-friendly” suspensions (Blanksby, George, Germanchev, Patrick, & Marsh, 2006). The Australian Government and the States of New South Wales and Queensland are funding a programme to develop an in-service suspension test for HVs (Australia Department of Transport and Regional Services, 2005a, 2005b). This report examines some possible low-cost test methodologies for an in-service HV suspension test and their results within the context of a “proof-of-concept” test programme. The results show that low-cost testing is possible and is comparable in accuracy to the high-cost methods used for the original “road-friendly” certification