Industry collaboration develops safer converter dolly

A trial to measure the performance of an industry converter dolly prototype has showcased industry innovation, demonstrating the superior capabilities of a rigid converter dolly when compared to other hinged units.

The prototype was developed following concerns raised regarding dynamic issues with hinged drawbar converter dollies, in particular brake reactivity and tyre wear. The innovative new unit removed the pivot point of a hinged drawbar, making a dramatic difference in the brake system control.

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The Australian Trucking Association’s rigid drawbar converter dolly was developed in partnership with industry suppliers and manufacturers MaxiTRANS, Bridgestone, Hendrickson, JOST, Wabco and Alcoa, and has since undergone informal trials with operators across the country.

Delivered by members of the ATA’s Industry Technical Council and Toll Group, a formal trial has taken place to evaluate the converter dolly’s performance and acquire measurable data using Inertial Measurement Units (IMUs), strain gauges and GPS.

“We were looking to complete back-to-back testing of the rigid drawbar dolly and a standard hinged drawbar dolly when used in an A-double combination, comparing the lateral force accelerations seen in each of the vehicle units to determine which is better,” said ITC Member and Managing Director of Smedley’s Engineers, Rob Smedley.

The IMUs were placed above the axle group in the lead trailer, the converter dolly and the trailing trailer to measure roll, pitch and yaw, and lateral, longitudinal and vertical acceleration. Strain gauges were fitted on the converter dolly fifth wheel pedestals and towing eyes to measure correlation of forces and comparative stresses, while GPS recorded positioning and speed.

“Initial observations left me really surprised at how severely the hinge drawbar pitched and danced around on the road in comparison to the rigid drawbar. It will be very interesting to examine the final data of the difference in performances between the two,” Mr Smedley said.

Toll Group National Equipment Manager Ian Lipplegoes said improving safety for all road users is a very high priority for Toll, who were proud to support the trial.

“The trial has been valuable and early outcomes are encouraging. We eagerly await the final results which will help demonstrate the safety benefits of making the dollies accessible to all,” Mr Lipplegoes said.

With the data gathered during the trial now being evaluated, MaxiTRANS Engineering Support Manager Greg Brown said the project was about building a safer, better performing dolly than those already on the market.

“With the support of the project partners, we have seen this project evolve from concept to reality, and based on the success of the prototype, MaxiTRANS has since manufactured and sold a number of these dollies,” Mr Brown said.

“It performs and handles better than other dollies and this trial has proven it, providing a direct comparison between the rigid drawbar and a hinged drawbar dolly to see the performance differences on the same route,” he said.

ITC Chair and Managing Director of Kel Baxter Transport, Kel Baxter, has had the opportunity to trial the dolly as it made its way around the country, and said he was immediately convinced it was a superior piece of equipment.

“I was immediately sold on the idea and have since had a dolly manufactured with another one on the way,” Mr Baxter said.

“Our drivers have been very impressed as the whole setup makes the combination feel like a single unit, with no pitching. This dolly has better handling than both airbag and spring hinged drawbar dollies,” he said.

ATA Chief Engineer Bob Woodward said the difference in the vehicle’s stability when using the converter dolly during the trial was incredible.

“Visually, the trial demonstrated how much more settled the combination with the rigid drawbar converter dolly was on the road, tracking and in corners,” Mr Woodward said.

“It's amazing to see what can be achieved in our industry when the talent and expertise can be brought together to deliver real outcomes. The team is excited to see what the data produces,” he said.

The prototype dolly will be trialled by one final operator in South Australia for further analysis before being sold.