61-9-305. Automatic trailer brake application upon breakaway. Every trailer, semitrailer, and pole trailer equipped with air or vacuum actuated brakes and every trailer, semitrailer, and pole trailer with a gross weight in excess of 3,000 pounds, manufactured or assembled after January 1, 1966, shall be equipped with brakes acting on all wheels and of such character as to be applied automatically and promptly, and remain applied for at least 15 minutes upon breakaway from the towing vehicle.