Trailer breakaway safety and overrun brakes

Connect the breakaway device correctly so that accidental uncoupling applies the trailer brake. Rust may reduce brake efficiency after prolonged storage, so inspect and test the system. When parking a trailer, apply its parking brake and use wheel chocks on a slope. During braking, an unsecured load tends to move forwards; during acceleration it tends to move backwards. An overrun brake acts in response to the trailer pressing against the slowing towing vehicle, so its operation is not perfectly simultaneous with the towing vehicle's brake application.