The connection between any two vehicles, one of which is towing or drawing the other on a highway, shall consist of a fifth wheel, drawbar, trailer hitch, or other similar device not to exceed 15 feet in length from one vehicle to the other. Any such two vehicles shall, in addition to such drawbar or other similar device, be equipped at all times when so operated on the highway with an emergency chain or cable that is structurally adequate to securely stop and hold the trailer being towed. The fifth wheel, drawbar, trailer hitch, or similar device must (i) be structurally adequate for the weight being drawn, (ii) be properly and securely mounted, (iii) provide for adequate articulation at the connection without excessive slack at that location, and (iv) be provided with a locking device that prevents accidental separation of the towed and towing vehicles. The mounting of the fifth wheel, drawbar, trailer hitch, or similar device on the towing vehicle must include reinforcement or bracing of the frame sufficient to produce strength and rigidity of the frame to prevent its undue distortion. The foregoing provisions of this section shall not apply to (i) any farm tractor, as defined in § 46.2-100, when such farm tractor is towing any farm implement or farm machinery by means of a drawbar coupled with a safety hitch pin or manufacturer’s coupling device or (ii) any tow truck towing a vehicle by means of a wheel lift apparatus that employs a safety strap to hold two of the towed vehicle’s wheels within a wheel lift cradle in a manner consistent with instructions of the manufacturer of such wheel lift apparatus. For the purposes of this section, “tow truck” means any motor vehicle that is constructed and used primarily for towing, lifting, or otherwise moving illegally parked or disabled vehicles.