Trucks, Dogs and Brakes

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Two initiatives from the Australian Trucking Association are looking at truck and dog safety as well as brake component reliability. The ATA has published a revised and updated version of its truck and dog Technical Advisory Procedure (TAP) and also warned against the use of non-identical brake parts across axles with a new Safety Alert. 



The truck and dog TAP provides best practice advice for achieving dynamic stability with these combinations. This is a key safety issue for all trucking operators, but, in the past, little guidance was available for optimising truck and dog combinations.




“Under the Australian Design Rules, the truck and towed dog trailer are assessed as two separate vehicles, which may then be put together into a truck and dog combination,” said Chris Melham, ATA CEO. “While completely legal, this means that operators may not receive guidance on how they can optimise the safety and stability of these combinations.


“This advisory procedure provides step-by-step instructions and formulas to help operators improve the overall performance, dynamic stability and safety of their truck and dog combinations. The formulas cover five different common truck and dog combinations between 42.5 and 50 tonne Gross Combination Mass. In general, the formulas promote longer wheelbases for both the truck and trailer, reducing coupling offset, and lowering the combination’s centre of gravity.”


The TAP was developed by the ATA’s Industry Technical Council, which includes operators and suppliers with leading expertise in truck technology. It is the latest in a number of TAPs, which provide best practice guidance for trucking operators, maintainers and suppliers about key technical issues. The procedures are available for free from the ATA’s online resource library.




The warning against the use of non-identical brake parts across axles responds to multiple reports to the ATA’s Industry Technical Council about replacement brake parts on an axle which may not be identical to the original, causing an imbalance.


“Any variation in componentry from left to right within the axle’s brake groups, even the brand and age of component, will negatively impact brake balance,” the document says.


The alert also cautions workshop staff to identify models which use long stroke brake chambers to avoid the possibility of accidentally pairing a long stroke chamber with a normal chamber.


This is the fourth Safety Alert published by the ATA. Each alert is publicly available from the ATA’s online resource library.  New alerts will be released as issues come to the ATA’s attention.