The location and operation of instruments and controls herein described are recommended for adoption by manufacturers of trucks and truck-tractors in new or revised designs in order to avoid confusion when drivers shift from one truck to another, to promote safety and convenience, and to simplify design, production, and servicing. This recommended practice shall apply to all on-highway trucks and truck-tractors equipped with power brake systems and having a GVW rating of 26 000 lb or more. Of prime importance in this recommended practice is the basic premise that all controls requiring operation while the vehicle is in motion be located so that the driver can manipulate them with his right hand and keep his left hand on the steering wheel. Controls operated only when the vehicle is not in motion, such as the ignition key, starter switch, and engine shutdown, may be located at the left side of the instrument panel and be manipulated with the driver's left hand.