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Page 58
Suggested Citation:"Definition of Terms." National Academies of Sciences, Engineering, and Medicine. 2010. Review of Canadian Experience with the Regulation of Large Commercial Motor Vehicles. Washington, DC: The National Academies Press. doi: 10.17226/14458.
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Page 58
Page 59
Suggested Citation:"Definition of Terms." National Academies of Sciences, Engineering, and Medicine. 2010. Review of Canadian Experience with the Regulation of Large Commercial Motor Vehicles. Washington, DC: The National Academies Press. doi: 10.17226/14458.
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Page 59
Page 60
Suggested Citation:"Definition of Terms." National Academies of Sciences, Engineering, and Medicine. 2010. Review of Canadian Experience with the Regulation of Large Commercial Motor Vehicles. Washington, DC: The National Academies Press. doi: 10.17226/14458.
×
Page 60
Page 61
Suggested Citation:"Definition of Terms." National Academies of Sciences, Engineering, and Medicine. 2010. Review of Canadian Experience with the Regulation of Large Commercial Motor Vehicles. Washington, DC: The National Academies Press. doi: 10.17226/14458.
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Page 61

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58 D E F I N I T I O N O F T E R M S This section contains a list of definitions of terms used to identify or describe vehicle configura- tion, components, axle groups, dimensions, and other aspects of heavy trucks. A Dolly A-Train Double Axle Axle Spread Axle Group Axle Weight B-Train Double Base Length Belly Axle Box Length C Dolly Means a trailer converter dolly that is towed from a single hitch located on the center line of the towing unit (34) Means a combination of vehicles composed of a tractor, a semitrailer, and either an A Dolly and a semitrailer or a full trailer attached to the lead semitrailer in a like manner as if an A Dolly were used (34) Means an assembly of two or more wheels whose centers are in one transverse vertical plane that transmits weight to the highway (34) Means the longitudinal distance between the extreme axle centers of the axle group (34) Any number of axles, within a single vehicle unit, that equal- ize loads on adjacent axles within 1,000 kg (34) Means the total weight transmitted to the highway by the axle or axle group (34) Means a combination of vehicles composed of a tractor, a semitrailer, followed by another semitrailer attached to the first semitrailer by the means of a fifth wheel mounted on the rear of the first semitrailer (34) Means the distance measured between the centers of the first axle of the front axle of a vehicle or combination of vehicles an the last axle of a vehicle or combination of vehicles (12) Means an axle located ahead of the rear fixed axle group on a trailer that is usually a liftable axle Means the longitudinal dimension from the forward most part of the cargo carrying unit(s) or load(s) to the rearmost part of the cargo carrying unit(s) or load(s), exclusive of any extension(s) in the dimension caused by auxiliary equip- ment or machinery at the front that is not designed for the transportation of goods (34) Means a trailer converter dolly, with a rigid frame in the horizontal plane that is towed from two hitches located in a horizontal transverse line on the towing unit, that precludes any rotation in the horizontal plane about the hitch points, and which satisfies all requirements of the Canadian Motor Vehicle Safety Standards applicable to such devices (34)

59 C-Train Double Drawbar Drawbar Length Drive Axle Effective Rear Overhang Fifth Wheel Fifth Wheel Offset Full Trailer Gross Vehicle Weight Height Hitch Offset Inter-axle Spacing Inter-vehicle-unit-distance Intercity bus Lift Axle Liftable Axle Means a combination of vehicles composed of a tractor, a semitrailer, and followed by another semitrailer attached to the first semitrailer by the means of a C Dolly (34) Means a structural member of a full trailer, pony trailer or trailer converter dolly that includes a device for the purpose of coupling with a trailer hitch or fifth wheel (34) Means the longitudinal distance from the center of the hole in the fifth wheel of a converter dolly to the center of the hitching device on the towing vehicle (34) Means the axle or axle group that is or may be connected to the power source of a motor vehicle and that transmits power to the wheels (34) Means the longitudinal distance calculated from the trailer turn center to the rearmost point including load on the trailer or semitrailer (34) Means a coupling device that is mounted on the vehicle chas- sis and that consists of a skid plate, associated mounting brackets and latching mechanism that couples or connects to a kingpin located on the other vehicle or component, for the purpose of supporting and towing a semitrailer (34) Means the longitudinal distance calculated from the center of the hole for the kingpin in the fifth wheel/kingpin assem- bly to the center of the drive axle unit (34) Means a vehicle that is designed to be towed by another vehi- cle and is designed and used so that the whole of its weight and load is carried on its own axles and includes a combination consisting of a semitrailer and a trailer converter dolly (34) Means the total weight transmitted to the highway by a vehicle or combination of vehicles (34) Means the vertical distance from the highest point on the vehicle to the ground (34) Means the longitudinal distance from the towing-vehicle turn center to the articulation point of the hitch or fifth wheel used to tow the trailing unit (34) Means the longitudinal distance separating two axle or axle groups calculated from the centers of the two adjacent axles (34) Means, for a combination of vehicles, the distance between the centers of the last axle of the motor vehicle . . . and the first axle of the towed vehicle, and the distance between the centers of the last axle of the towed vehicle and the first axle of the second towed vehicle (12) Means a vehicle designed to carry more than fifteen passen- gers and equipped with facilities to allow extended travel without stopping. (34) See Liftable Axle Means an assembly of two or more wheels whose centers are in one transverse plane that is equipped with a device for al- tering (other than by longitudinal movement of the assembly only) the weight transmitted to the highway surface and that may be able to lift its tires from contact with that surface (34)

60 Kingpin Setback Length (Full Trailer) Length (Pony Trailer) Length (Semitrailer) Overall Height Overall Length Pony Trailer Pusher Axle Rear Overhang Semitrailer Single Axle Steering Axle Self Steering Axle Tag Axle Tandem Axle Group Tractor Track Width Means the horizontal distance from the vertical axis through the center of the kingpin to any point on the semitrailer ahead of the kingpin, including load but exclusive of any extension to the length caused by auxiliary equipment or machinery that is not designed for the transportation of goods (34) Means the longitudinal dimension from the front of the cargo carrying section of the full trailer to its rearmost point (34) Means the longitudinal dimension from the front of the drawbar of the pony trailer to its rearmost point (34) Means the longitudinal dimension from the front of the cargo carrying section of the semitrailer to its rear, exclusive of any extension in length caused by equipment or machin- ery at the front that is not designed for the transportation of goods (34) Means the greatest overall vertical distance from the highest point on the vehicle or load to the ground (34) Means the greatest overall longitudinal dimension of a vehicle or combination of vehicles including load (34) Means a vehicle that is designed to be towed by another vehicle and is equipped with a drawbar that is rigidly attached to the structure of the trailer, and is so designed and used that the preponderance of its weight and load is carried on its own axles (34) Means an axle located ahead of the drive axle group on a power unit that is usually a liftable axle. Means the longitudinal distance calculated from the center of the last axle to the rearmost point, including load, on the trailer or semitrailer (34) Means a vehicle that is designed to be towed by another ve- hicle and is so designed and used that a substantial part of its weight and load rests on or is carried by the other vehicle or a trailer converter dolly through a fifth wheel and king- pin combination (34) Means one or more axles whose centers are included between two parallel transverse vertical planes 1.2 meters apart (34) Means the articulated lead axle or axles of a motor vehicle which govern the direction travelled by the vehicle (34) Means an axle which articulates in response to forces gener- ated between the tire and the road or through mechanisms or linkages operating independently of the driver of the vehicle (34) Means an axle located to the rear of the rear fixed axle group on a power unit or trailer that is usually a liftable axle. Means an axle group containing two consecutive axles whose centers are not less than 1.2 meters apart and are at- tached to the vehicle in a manner which achieves equalized loading between the axles (34) Means a motor vehicle designed to and normally used to pull a semitrailer or a semitrailer and a full trailer or a semi- trailer and a semitrailer (34) Means the overall width of an axle across the outside edges of the tires (34)

61 Tractor Wheelbase Trailer Converter Dolly Trailer Wheelbase Tri-Axle Group Tridem Axle Group Truck Turn Center Width of Tire Means the longitudinal distance from the center of the steer- ing axle to the geometric center of the drive axle unit (34) Means a vehicle unit consisting of one or more axles, a fifth wheel and a drawbar used to convert a semitrailer to a full trailer (34) Means the longitudinal distance from the center of the king- pin of a semitrailer, or the center of the turntable of a full trailer, or the center of the hitching device on a pony trailer, to the trailer turn center (34) Means an axle group containing three consecutive axles whose extreme centers are not less than 2.4 meters apart, are not equally spaced, and may be attached to the vehicle in a manner which does not achieve equalized loading among the three axles Means an axle group containing three consecutive axles whose extreme centers are not less than 2.4 meters apart, are equally spaced and are attached to the vehicle in a manner which achieves equalized loading among the three axles (34) Means a motor vehicle, other than a bus, that is either per- manently fitted with a special purpose device, or is designed to and normally used to carry a load, that may operate as a single unit or may pull a trailer other than a semitrailer (34) Means the geometric center of the axle group on a semitrailer or pony trailer or the rear axle group on a truck, tractor or full trailer (34) Means the width of the tire as customarily measured and rated by manufacturers of motor vehicles and tires (34)

Next: Appendix A - Heavy Truck Weight and Dimension Limits for Interprovincial Operations in Canada »
Review of Canadian Experience with the Regulation of Large Commercial Motor Vehicles Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Report 671: Review of Canadian Experience with the Regulation of Large Commercial Motor Vehicles examines the process used in Canada to harmonize heavy truck size and weight regulations across the country. The report provides insights on how lessons learned from the Canadian experience might be applied in the United States.

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