(How they work)
Override couplings are a mechanical braking system designed to apply the brakes on a trailer when the towing vehicle begins to slow or come to a stop. Whilst being a very useful braking system, there are certain aspects that should be covered prior to use to ensure you achieve the best performance from the system.
Override couplings can be used with different brake components including hydraulic, drum and disk brakes. The brakes on the trailer are engaged via a cable system from the override coupling to the brake hubs behind the wheels of the trailer. When a towing vehicle brakes, the forward force of the trailer applies pressure against a cylinder within the coupling. This pressure forces the cylinder rearward causing the cable to apply the brakes.
When reversing you must to ensure that the lock out latch is in the closed position to ensure the brakes do not engage, making it difficult to reverse. If the latch is left open, as you reverse the trailer will think you are slowing down rapidly and apply the brakes. The same may apply if you are parked on a steep hill or driveway.
The brakes can be adjusted as required by using the cable tension coil. Remember: over tightening of the braking cable will cause smoke and may burn out the brakes. Not having the cable tight enough will cause the brakes not to engage and you will lose your rating. It is a good idea to check the tension of the brake cable before use as factors such as heat and excessive use can cause slight movment in the cable.
The tension of the cable can be tested by applying the handbrake and ensuring the brakes apply, preventing the trailer from moving or rolling. If the trailer can roll with the hand brake applied, the cable needs to be tightened via the tensioner coil. If the trailer still fails to move or roll once the handbrake has been removed, you can loosen off the brake cables tension slightly untill both handbrake functions are performing correctly.
For more safety related tips and guidelines, please visit Adelaide Trailer Hire's Safe Towing Guide.