In New Zealand a trailer over 2500kg is required to be fitted with a breakaway system.

Overview

Breakaway brake units are essential for electric braked and electric over hydraulic braked trailers, as they activate the trailer brakes automatically if the trailer detaches from the tow vehicle.

The breakaway unit consists of a switch box with a removable pin that is connected to a cable. The box is attached to the trailer drawbar and the cable is secured to the tow vehicle with a shackle or hook.

Battery

A small rechargeable battery (or the system can be connected to the house battery on caravan) on the trailer provides power to the breakaway unit and when the pin is removed from the box (when the trailer disconnects from the tow vehicle) full power is applied to the brakes immediately.

The brakes will remain on until the battery runs out of power or the pin is reinserted into the box.

It is important to check the battery charge regularly, especially if the trailer is not used often. If so, remove the battery and charge it on a mains charger before any trips. You can also configure the system to have the tow vehicle charging the battery when connected to the trailer.

Testing

To test if the breakaway unit and battery are functioning properly, immobilize the trailer and lift the wheels up. Pull the breakaway pin while someone spins the wheels. They should stop instantly. Also, the cable should be in good condition and replaced if it is kinked, frayed or damaged. If the damaged part fails before the breakaway pin can be pulled, the brakes will not work.