The right braking system for your trailer

In Australia, it’s law that trailers over 750KG gross mass are fitted with brakes that comply with the Australian Design rules. There are two types of brakes as standard – mechanical override brakes or electric/hydraulic brakes, and the right type for your trailer is determined by the trailer’s gross weight.

Mechanical Override Brakes – Trailers 751kg to 2200kg

Override brakes are relatively simple to use and to maintain. When your vehicle brakes, the override coupling has an internal spring that compresses and activates the brake lever fitted to the back of the coupling. This in turn pulls the brake cable connected to the calipers and the brakes are applied. The harder you brake your vehicle, the more the coupling moves and the more brakes are applied.

A hydraulic caliper upgrade option is available with over-ride systems. This improves brake performance and smoothness of operation. Consult your local Dunbier dealer for more information.

Electric/Hydraulic Brake Systems – Trailers over 2200kg

These systems are used on larger heavier trailers, over 2200KG. Although highly advanced in their designs they are relatively simple in their operation.

The brake controller fitted to the vehicle sends a signal to the “pump”, the pump then converts this signal to hydraulic brake pressure that operates the hydraulic brake calipers. The system is powered from the vehicle and must be connected to operate.

These systems create a huge amount of braking force (up to 1200PSI) and it is very important that you do not ‘over-brake’ the trailer, causing premature failure of the brake calipers. This is caused when the brake controller is set with too much gain (voltage output too high) and the brakes on the trailer not only attempt to stop the actual trailer mass, but they also brake a portion of the tow vehicle. This is outside the design specification of the calipers and rotors fitted to your trailer and should be avoided at all costs.

Remember that most tow vehicles are already designed to brake up to 750KG (the Australian design rules maximum for a non-braked trailer) so the trailer brakes should only ever be braking their own weight less this amount.

See below example. Assume our tow vehicle and boat weigh the same and our tow vehicle has a 750kg unbraked tow rating.

There are many brake controllers on the market that can safely operate modern brake systems, many vehicles are now equipped with their own systems. It is critical that a proportional brake controller be utilized and that they are compatible with electric hydraulic systems. Please contact your Brake controller supplier to confirm this. Brake controllers should be fitted by an Auto electrician or a suitably qualified business.

NOTE: Some modern controllers e.g. ‘Tow Pro Elite®’ have a manual or ‘User controlled’ function and an proportional ‘automatic’ function. You must only operate these types of systems in automatic to prevent serious damage to your braking system.