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A STUDY OF DYNAMIC WHEEL FORCES IN AXLE GROUP SUSPENSIONS OF HEAVY VEHICLES
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1983
Year
Unknown Venue
Geotechnical EngineeringSuspension StructureHighway PavementEngineeringLoad Sharing SuspensionsMechanicsTrailer SuspensionsMechanical EngineeringCivil EngineeringMechanical SystemsStructural EngineeringVehicle DynamicLower DlcLoad-bearing CapacityStructural MechanicsTransportation EngineeringVehicle Dynamics (Mechanical Engineering)
A wheel force transducer measured dynamic wheel loads at 40–80 km/h on various road roughness levels, accounting for tyre pressure and axle load, and a factorial design derived a dynamic load coefficient (dlc) as a function of speed and roughness for each suspension type. The dlc was found to depend on the product of speed and the square root of NAASRA roughness, with centrally‑pivoted drive suspensions showing higher dlc with stiffer springs; although trailer and torsion‑bar suspensions had lower dlc, all suspensions generated large dynamic loading, with three of five drive axles causing severe pavement loading and at least one non‑compliant with Australian regulations, prompting a quantitative test and a proposed 10 % load‑sharing criterion. Author: TRRL.
A wheel force transducer was used to measure dynamic wheel loads for speeds ranging between 40 km/h and 80 km/h over road surfaces ranging from as-new construction to the maximum tolerable roughness as measured using the NAASRA roughness meter. The effects of tyre inflation pressure and axle group load were taken into account and a factorial experimental design was used to determine dynamic loading, expressed as a form of coefficient of variation termed the dynamic load coefficient (dlc), as a function of speed and roughness for each suspension type. It was found that, for practical purposes, the dlc for each suspension type is a function of the product of the speed and the square root of the NAASRA roughness value. The centrally-pivoted drive axle suspensions (walking beam and single point types) show a dlc increasing with spring stiffness. Although the trailer suspensions and the torsion bar drive axle suspension showed, in general, lower dlc's than the centrally-pivoted drive suspensions, it was concluded that the level of dynamic loading generated by all suspensions is large. Three out of five drive axle suspensions were found to cause severe dynamic pavement loading. At least one of these does not comply with current Australian regulations for load sharing suspensions, and a quantitative test of dynamic loading is suggested. Most suspensions were found to share the load between the wheels to within 10 per cent of an equal share and this level is proposed as a quantitative criterion of load sharing ability. One currently accepted type did not load-share adequately and it is concluded that a test is needed and in some cases proper fitment of the suspension to the chassis needs to be ensured. (Author/TRRL)