Opinion

Converter dolly makes waves

From proof of concept to national industry recognition, the ATA’s Industry Technical Council Converter Dolly Project has had a significant impact in the trucking industry, revolutionising the dolly market.

Following concerns raised regarding dynamic issues with hinged drawbar converter dollies, in particular brake reactivity and tyre wear, the Converter Dolly Project was born.

There has been a lot of issues in the past where, particularly under braking when they were lightly laden, weight transfer occurs, and an axle comes off the ground. There have even been instances in which axles have come off the ground to the point where the back of the dolly has hit the underside of the trailer above it.

Led by the ATA’s Industry Technical Council together with technical and component support from MaxiTRANS, Hendrickson, Alcoa Wheels, Bridgestone, JOST and WABCO, the project explored the further development of a rigid drawbar converter dolly and is a collaboration of the resources and knowledge of these manufacturers, suppliers and operators all working towards a common goal.

One of the most versatile components in a combination, the dolly market has been well overdue for a change. While the traditional dolly has been around for a long time, this has been the first significant shift in dolly design for many years.

The project aimed to explore options and opportunities, industry to design, and manufacture a converter dolly based on a rigid drawbar design for use as a further ‘proof of concept’ engineering test bed.

The ITC converter dolly was first on display at the Brisbane Truck Show in 2019, where it received an overwhelming amount of positive feedback. Since then, the dolly has been trialled with several operators across the country, including BAB Quads and ABB quads.

This new type of dolly delivers a range of benefits to improve safety, productivity and reduce maintenance costs, including improved tyre wear, stability, and controllability as well as advantages in vehicle handling, braking performance and dynamic load distribution for more consistent and even tyre wear.

Taking out the pivot point with no hinged drawbar makes a dramatic difference in the way the brake system can control everything.

With such positive response from industry, the ATA has developed a technical bulletin which outlines specification guidelines for Rigid Drawbar Tandem Axle Converter Dollies – allowing operators access to the insight behind the project.

The technical bulletin details the specifications of the project dolly, including fifth wheel positioning, axle group spacing, drawbar length, and suspension and coupling requirements.

A suspension with neutral roll steer at nominal ride height is preferred, as well as a coupling type must be limited to a flanged drawbar eye or a special flanged drawbar eye and the drawbar length is determined by combination and application.

To limit static vertical loading at the tow coupling of a tandem axle converter dolly, the axle spacing range needs to be reduced as the drawbar length reduces, and the fifth wheel positioned on the theoretical centreline of the axle group, and not restricted in fore/aft articulation (just as a fifth wheel would be installed on a prime mover).

In recognition of the innovative design and contribution to industry, the Converter Dolly Project supply partners MaxiTRANS, Hendrickson, Alcoa Wheels, Bridgestone, JOST and WABCO were awarded the 2020 Castrol Vecton Industry Achievement award, in celebration of the development and implementation of modern technologies and design to improve the industry’s safety and productivity.

As the converter dolly gains more recognition throughout industry, it is hoped the design sees an increase in adoption with operators around the country, who are looking to drastically improve their combinations and overall performance.

  To view the technical bulletin or find out more about the Industry Technical Council, head to www.truck.net.au.

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