|I have just read the Australian Design Rules regarding trailer brakes and wonder whether some of us are being tricked into upgrading trailers when it is not needed. Also, it is clear manufacturers are not rating new trailers at their full capacity because they donot understand the ADRs |
Having just bought a new single axle trailer for my RL24 and found its ATM is 140kg less than what it should be, I am less than impressed with the manufacturer.
First an explanation of terms. Gross Trailer Mass is the axle load (measured at the wheels). Aggregate Trailer Mass is the mass of the trailer uncoupled (the GTM plus the drawbar mass).
The ADR requires brakes on trailers with a GTM greater than 750kg and breakaway brakes on trailers with GTM greater than 2000kg.
Explanation 1. If you have a trailer with a drawbar mass of 100kg and a GTM of 750kg, it does not need brakes providing the car is rated to tow a trailer with GTM of 750kg without brakes.
Explanation 2. . If you have a trailer with a drawbar mass of 150kg and a GTM of 2000kg, it needs brakes but does not need breakaway brakes providing the car is rated to tow a trailer with GTM of 2000kg with brakes.
Trailer manufacturers are rating trailers ATM to the axle capacity, which means you are loosing the ability to carry the extra weight taken on the drawbar. In fact the ADR acknowledges the car carries and stops the drawbar load.
With old trailers that are not plated, transport officials should not down rate the ATM to the GTM. There is no technical merits in uncoupling an old trailer to weight its ATM if it is not plated to a ATM. They can only check the axle loads of the car and trailer because when it is coupled up the combination becomes the vehicle. If the trailer axle load is less than its rating then you are ok.
As for my new trailer, I asked the manufacturer "Why they de-rated it to 1400kg when that is simply the axle rating? If they plate it properly, it should be plated for an ATM of 1540kg that is the coupling capacity plus the axle capacity." I was less than impressed with their lack of understanding of very basic vehicle engineering.
The trailer was $3700.
I hope this helps