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. They are a very useful braking system and are used on most commercial trailers GTM 2000kg or under.
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 you apply your tow vehicle brakes, the equipment trailers or caravan tries to continue at the same speed (inertia) and travels forward in relation to the towing vehicle this forward momentum of the trailer applies pressure against the cylinder and spring within the override coupling therefore activating the trailer brakes.
The override system is very simple and effective, the harder you brake, the more force that is transferred to the coupling and drawbar, therefore the system applies more braking effort. So when you ease off the brakes the force being transferred is less therefore releasing some of the braking pressure applied.
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