The ARTSA-i Coupling Project was instigated to ensure the dynamic loads being put on the couplings on multiple combinations were quantified and rated correctly, verifying coupling strength was adequate to meet safety standards. Bob Woodward reports on the findings.
Australia has been a leader in high productivity freight vehicles (HPFV) for a long period, the original 1934 Government Road Train is now on display at the Transport Hall of Fame in Alice Springs, operating some of the longest and heaviest freight vehicles in the world, often unsealed corrugated roads. With the development of these world class heavy vehicle many in conjunction with the PBS Scheme and also the development of modular HPFV’s, combinations with ever increasing mass are being introduced.
The history of the strength requirements for fifth wheel couplings and pin type couplings dates back to findings by the Australian Road Research Board, this research developed formula, later to be included in Australian Standards but was typically limited to a gross combination mass (GCM) of 125 tonnes.
The minimum coupling strength required in a multi vehicle combination is known as the D-rating, the relevant coupling component required strength is identified as D-value. For vehicle combinations with more than one fifth wheel/kingpin coupling and/or more than one pin type coupling, by identifying the critical coupling/s the maximum D-value may be ascertained.
Whilst reported coupling failures are very rare, there was growing concern by technicians that the formula developed several decades ago may not be representative of today’s combinations and potentially not appropriate to the newer HPFV configurations with GCM’s of around 160 tonnes and more.
Following discussions among various industry sectors, representatives of several industry associations ARTSA Institute (ARTSA-i), Australian Trucking Association (ATA), Truck Industry Council (TIC) and Heavy Vehicle Industry Australia (HVIA) met and discussed the need to industry and the public assurance of ongoing coupling safety. The initial aim of the project was to ensure the continued safe operation of couplings on large and innovative vehicle combinations by developing a broad scope of what would be required and the options to achieve the technical research and how such a project would be funded. The initial meeting of the minds agreed that ARTSA-i provided the appropriate platform for management of such a technical project.
The group then agreed that with ARTSA-i as the project manager, the Heavy Vehicle Safety Initiative (HVSI) project funding grants should be explored subsequently the appropriate application was completed and submitted.
The proposal for the project ‘Safety of Couplings on High Productivity Vehicles’ HVSI Round 6 funding 2021-22 was successful the project to bring together industry expertise to investigate dynamic loads on the couplings on heavy HPFV and PBS combinations vehicles and fill a gap in knowledge and provide evidence to update relevant standards and rules.
There were many logistical hurdles identified and encountered through the project. Real vehicle combinations were needed to provide realistic in-service operating conditions, varying road conditions/services, at varying speeds, instrumenting fifth wheels and pin couplings, accessing equipment combinations.
Following preliminary discussions with Direct Haul (Darwin) the project had an operator who was willing to assist with the equipment, assist with flexible operations and provide access to personnel and workshop facilities, AAB Quad and BAA Quad with the instrumented triaxle converter dolly in various combination positions whilst maintaining fuel deliveries to their many remote customers.
Howard Porter assisted in providing a triaxle converter dolly and CIMC assisted with the specially designed drawbar manufactured to accommodate strain gauges etc. The diversity of the project group was demonstrated through several Zoom discussions that involved European technical resources from coupling suppliers in Europe who have experience in coupling force research in larger European combinations (up to 84 tonnes GCM).
Smedleys Engineers developed a schedule and test program. The operations team at Direct Haul assisted with route options to ensure that appropriate road surfaced were accessible.
Gigabytes of data has been collected through instrumented logging and the Smedleys project team are well advanced in interpreting the data and building the relevant computer models to simulate the forces at the couplings. The NHVR has provided technical assistance to this significant research project and will be involved in the validation of the results that should be finalised by the end of August 2023.
The collaboration and cooperation of these industry associations (ARTSA-i, ATA, TIC and HVIA) should not be under estimated now or into the future. The final report will provide assurance of appropriate coupling requirements to Road Managers, Legislators and Regulators for innovative high productivity combinations into the future. The finalisation of this project will provide a benchmark for future industry joint technical research.
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