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GENERAL DISCUSSION HOW BIG IS A TRUCK? - HOW SHARP DOES IT TURN? A question confronting anyone attempting to design or build a facility which will handle commercial motor vehicles (trucks) and a question to which, unfortunately, there is no quick, easy answer is, "How big is a truck and how sharp does it turn?" There are almost as many different sizes of trucks as there are jobs for them to do. Size is so variable, in fact, that some manufacturers do not even list standard wheelbase dimensions in their catalogs. TERMS Before dealing with the size and maneuverability of trucks, it is necessary to define, generally, the equipment used in truck operations today. Following is a glossary which suppli~s deiinitions of the terms used for equip- ment in this discussion. Cab-Behind-Engine (Conventional) Chassis - This is a straight truck or tractor in which the driver's compart- ment and controls are located at the rear of a hood- enclosed power plant. See Appendix I, page II. Cab-Over-Engine (CaE) Chassis - This is a straight truck or tractor in which all, or a substantial part of, its engine is located under the cab. See Appendix I, page 12. Converter doUy (DoUy converter) (DoIly) - A con- verter dolly is a vehicle designed to convert a semitrailer to a full trailer. It is equipped with the lower half of a fifth wheel, a drawbar, one or more axles, and other parts necessary for the conversion. See Appendix I, page 13. Doubles - Doubles consist of a double trailer com- bination made up of a tractor, a semitrailer, a converter dolly, and another semitrailer coupled together. See Appendix I, page 12. Fifth Wheel - A device which connects a tractor or converter dolly to a semitrailer and permits articulation between the vehicles. It is generally composed of (l) a lower half, mounted on the tractor or dolly, consisting of a trunion, plate and latching mechanism, and (2) an upper half consisting of a kingpin mounted on the semi- trailer. Full Trailer - A full trailer is a truck trailer con- structed so that all its own weight and that of its load rests upon its own wheels. See Appendix I, page 23. Off-track - Off-track is the difference in turning' radius between the path a vehicle's front axle center- point follows during a tUfn and the path its rear axle centerpoint follows during the turn. See Fig. 2 page 9. Semitrailer - A semitrailer is a truck trailer equipped with one or more axles, and so constructed that the front end and a substantial part of its own weight and that of its load rests upon a truck tractor. See Appendix I, page 13. Straight truck (motor truck) - A straight truck is a single self-propelled vehicle carrying its load on its own wheels and pnmarily designed f(lf the transportation of property. See Appendix I, page II. Tractor (truck tractor) - A tractol is a motor vehicle designed primarily for drawing semitrailers and, con- structed. so as to carry part of the weight and load of a semitrailer. See Appendix I, page II. Tractor-semitrailer - A tractor-semitrailer is a vehicle consisting of a tractor towing a semitrailer. See Appen- dix I, page II. Trailer (truck trailer) - A truck trailer is a vehicle with or without auxiliary motive power designed to be drawn by a straight truck or a tractor. Truck-full trailer - A truck-full trailer is a vehicle consisting of a straight truck towing a full trailer. See Appendix I, page 23. Vehicle - This is any conveyance on wheels consist- ing of either a single unit, a single self-propelled unit or combination of units consisting of a self-propelled unit and one or more towed single units designed primarily for the transportation of property. VEHICLE SELECTION With such a great variety in types, sizes and shapes, how is one to know just how large a vehicle might be encountered in any particular facility? There is no sure way to know; however, there are two general approaches which can be made. Some docking and loading facilities will be used only by a certain type of vehicle. It will probably be operated by the owner of the facility himself. In this case its dimensions can be obtained and the facility designed using them. When, as is the usual case, there will be a variety of vehicles operating from the facility, its design should be based on the vehicle which requires the most space for maneuvering. The vehicle requiring the most space for maneuvering is usually a tractor-semitrailer. Although doubles are longer than the tractor-semitrailer, doubles have several pivot points and, consequently, actually require less space to make a turn. (See Fig. I, page 8).