[Code of Federal Regulations]

[Title 49, Volume 5]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 49CFR393.5]



[Page 362-367]

 

                        TITLE 49--TRANSPORTATION

 

                      DEPARTMENT OF TRANSPORTATION

 

PART 393_PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION--Table of 

Contents

 

                            Subpart A_General

 

Sec. 393.5  Definitions.



    As used in this part, the following words and terms are construed to 

mean:

    Aggregate working load limit. The summation of the working load 

limits or restraining capacity of all devices used to secure an article 

of cargo on a vehicle.

    Agricultural commodity trailer. A trailer that is designed to 

transport bulk agricultural commodities in off-road harvesting sites and 

to a processing plant or storage location, as evidenced by skeletal 

construction that accommodates harvest containers, a maximum length of 

28 feet, and an arrangement of air control lines and reservoirs that 

minimizes damage in field operations.

    Air brake system. A system, including an air-over-hydraulic brake 

subsystem, that uses air as a medium for transmitting pressure or force 

from the driver



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control to the service brake, but does not include a system that uses 

compressed air or vacuum only to assist the driver in applying muscular 

force to hydraulic or mechanical components.

    Air-over-hydraulic brake subsystem. A subsystem of the air brake 

system that uses compressed air to transmit a force from the driver 

control to a hydraulic brake system to actuate the service brakes.

    Anchor point. Part of the structure, fitting or attachment on a 

vehicle or article of cargo to which a tiedown is attached.

    Antilock Brake System or ABS means a portion of a service brake 

system that automatically controls the degree of rotational wheel slip 

during braking by:

    (1) Sensing the rate of angular rotation of the wheels;

    (2) Transmitting signals regarding the rate of wheel angular 

rotation to one or more controlling devices which interpret those 

signals and generate responsive controlling output signals; and

    (3) Transmitting those controlling signals to one or more modulators 

which adjust brake actuating forces in response to those signals.

    Article of cargo. A unit of cargo, other than a liquid, gas, or 

aggregate that lacks physical structure (e.g., grain, gravel, etc.) 

including articles grouped together so that they can be handled as a 

single unit or unitized by wrapping, strapping, banding or edge 

protection device(s).

    Auxiliary driving lamp. A lighting device mounted to provide 

illumination forward of the vehicle which supplements the upper beam of 

a standard headlighting system. It is not intended for use alone or with 

the lower beam of a standard headlamp system.

    Bell pipe concrete. Pipe whose flanged end is of larger diameter 

than its barrel.

    Blocking. A structure, device or another substantial article placed 

against or around an article of cargo to prevent horizontal movement of 

the article of cargo.

    Boat trailer. A trailer designed with cradle-type mountings to 

transport a boat and configured to permit launching of the boat from the 

rear of the trailer.

    Bracing. A structure, device, or another substantial article placed 

against an article of cargo to prevent it from tipping, that may also 

prevent it from shifting.

    Brake. An energy conversion mechanism used to stop, or hold a 

vehicle stationary.

    Brake power assist unit. A device installed in a hydraulic brake 

system that reduces the operator effort required to actuate the system, 

but which if inoperative does not prevent the operator from braking the 

vehicle by a continued application of muscular force on the service 

brake control.

    Brake power unit. A device installed in a brake system that provides 

the energy required to actuate the brakes, either directly or indirectly 

through an auxiliary device, with the operator action consisting only of 

modulating the energy application level.

    Brake tubing/hose. Metallic brake tubing, nonmetallic brake tubing 

and brake hose are conduits or lines used in a brake system to transmit 

or contain the medium (fluid or vacuum) used to apply the motor 

vehicle's brakes.

    Chassis. The load-supporting frame of a commercial motor vehicle, 

exclusive of any appurtenances which might be added to accommodate 

cargo.

    Clearance Lamps. Lamps that provide light to the front or rear, 

mounted on the permanent structure of the vehicle, such that they 

indicate the overall width of the vehicle.

    Container chassis trailer. A semitrailer of skeleton construction 

limited to a bottom frame, one or more axles, specially built and fitted 

with locking devices for the transport of intermodal cargo containers, 

so that when the chassis and container are assembled, the units serve 

the same function as an over the road trailer.

    Converter dolly. A motor vehicle consisting of a chassis equipped 

with one or more axles, a fifth wheel and/or equivalent mechanism, and 

drawbar, the attachment of which converts a semitrailer to a full 

trailer.

    Curb weight. The weight of a motor vehicle with standard equipment, 

maximum capacity of fuel, oil, and coolant; and, if so equipped, air 

conditioning



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and additional weight of optional engine. Curb weight does not include 

the driver.

    Dunnage. All loose materials used to support and protect cargo.

    Dunnage bag. An inflatable bag intended to fill otherwise empty 

space between articles of cargo, or between articles of cargo and the 

wall of the vehicle.

    Edge protector. A device placed on the exposed edge of an article to 

distribute tiedown forces over a larger area of cargo than the tiedown 

itself, to protect the tie-down and/or cargo from damage, and to allow 

the tiedown to slide freely when being tensioned.

    Electric brake system. A system that uses electric current to 

actuate the service brake.

    Emergency brake. A mechanism designed to stop a motor vehicle after 

a failure of the service brake system.

    Emergency brake system. A mechanism designed to stop a vehicle after 

a single failure occurs in the service brake system of a part designed 

to contain compressed air or brake fluid or vacuum (except failure of a 

common valve, manifold brake fluid housing or brake chamber housing).

    Fifth wheel. A device mounted on a truck tractor or similar towing 

vehicle (e.g., converter dolly) which interfaces with and couples to the 

upper coupler assembly of a semitrailer.

    Frame vehicle. A vehicle with skeletal structure fitted with one or 

more bunk units for transporting logs. A bunk unit consists of U-shaped 

front and rear bunks that together cradle logs. The bunks are welded, 

gusseted or otherwise firmly fastened to the vehicle's main beams, and 

are an integral part of the vehicle.

    Friction mat. A device placed between the deck of a vehicle and 

article of cargo, or between articles of cargo, intended to provide 

greater friction than exists naturally between these surfaces.

    Front fog lamp. A lighting device whose beam provides downward 

illumination forward of the vehicle and close to the ground, and is to 

be used only under conditions of rain, snow, dust, smoke or fog. A pair 

of fog lamps may be used alone, with parking, tail, side, marker, 

clearance and identification lamps, or with a lower beam headlamp at the 

driver's discretion in accordance with state and local use law.

    Fuel tank fitting. Any removable device affixed to an opening in the 

fuel tank with the exception of the filler cap.

    g. The acceleration due to gravity, 32.2 ft/sec\2\ (9.81 m/sec\2\).

    Grommet. A device that serves as a support and protection to that 

which passes through it.

    Hazard warning signal. Lamps that flash simultaneously to the front 

and rear, on both the right and left sides of a commercial motor 

vehicle, to indicate to an approaching driver the presence of a 

vehicular hazard.

    Head lamps. Lamps used to provide general illumination ahead of a 

motor vehicle.

    Heater. Any device or assembly of devices or appliances used to heat 

the interior of any motor vehicle. This includes a catalytic heater 

which must meet the requirements of Sec. 177.834(l)(2) of this title 

when Class 3 (flammable liquid) or Division 2.1 (flammable gas) is 

transported.

    Heavy hauler trailer. A trailer which has one or more of the 

following characteristics, but which is not a container chassis trailer:

    (1) Its brake lines are designed to adapt to separation or extension 

of the vehicle frame; or

    (2) Its body consists only of a platform whose primary cargo-

carrying surface is not more than 1,016 mm (40 inches) above the ground 

in an unloaded condition, except that it may include sides that are 

designed to be easily removable and a permanent ``front-end structure'' 

as that term is used in Sec. 393.106 of this title.

    Hook-lift container. A specialized container, primarily used to 

contain and transport materials in the waste, recycling, construction/

demolition and scrap industries, which is used in conjunction with 

specialized vehicles, in which the container is loaded and unloaded onto 

a tilt frame body by an articulating hook-arm.

    Hydraulic brake system. A system that uses hydraulic fluid as a 

medium for transmitting force from a service brake control to the 

service brake, and



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that may incorporate a brake power assist unit, or a brake power unit.

    Identification lamps. Lamps used to identify certain types of 

commercial motor vehicles.

    Integral securement system. A system on certain roll-on/roll-off 

containers and hook-lift containers and their related transport vehicles 

in which compatible front and rear hold down devices are mated to 

provide securement of the complete vehicle and its articles of cargo.

    Lamp. A device used to produce artificial light.

    Length of a manufactured home. The largest exterior length in the 

traveling mode, including any projections which contain interior space. 

Length does not include bay windows, roof projections, overhangs, or 

eaves under which there is no interior space, nor does it include 

drawbars, couplings or hitches.

    License plate lamp. A lamp used to illuminate the license plate on 

the rear of a motor vehicle.

    Longwood. All logs that are not shortwood, i.e., are over 4.9 m (16 

feet) long. Such logs are usually described as long logs or treelength.

    Low chassis vehicle. (1) A trailer or semitrailer manufactured on or 

after January 26, 1998, having a chassis which extends behind the 

rearmost point of the rearmost tires and which has a lower rear surface 

that meets the guard width, height, and rear surface requirements of 

Sec. 571.224 in effect on the date of manufacture, or a subsequent 

edition.

    (2) A motor vehicle, not described by paragraph (1) of this 

definition, having a chassis which extends behind the rearmost point of 

the rearmost tires and which has a lower rear surface that meets the 

guard configuration requirements of Sec. 393.86(b)(1).

    Manufactured home means a structure, transportable in one or more 

sections, which in the traveling mode, is eight body feet or more in 

width or forty body feet or more in length, or, when erected on site, is 

three hundred twenty or more square feet, and which is built on a 

permanent chassis and designed to be used as a dwelling with or without 

a permanent foundation when connected to the required utilities, and 

includes the plumbing, heating, air-conditioning, and electrical systems 

contained therein. Calculations used to determine the number of square 

feet in a structure will be based on the structure's exterior dimensions 

measured at the largest horizontal projections when erected on site. 

These dimensions will include all expandable rooms, cabinets, and other 

projections containing interior space, but do not include bay windows. 

This term includes all structures which meet the above requirements 

except the size requirements and with respect to which the manufacturer 

voluntarily files a certification pursuant to 24 CFR 3282.13 and 

complies with the standards set forth in 24 CFR part 3280.

    Multi-piece windshield. A windshield consisting of two or more 

windshield glazing surface areas.

    Parking brake system. A mechanism designed to prevent the movement 

of a stationary motor vehicle.

    Play. Any free movement of components.

    Pulpwood trailer. A trailer or semitrailer that is designed 

exclusively for harvesting logs or pulpwood and constructed with a 

skeletal frame with no means for attachment of a solid bed, body, or 

container.

    Rail vehicle. A vehicle whose skeletal structure is fitted with 

stakes at the front and rear to contain logs loaded crosswise.

    Rear extremity. The rearmost point on a motor vehicle that falls 

above a horizontal plane located 560 mm (22 inches) above the ground and 

below a horizontal plane located 1,900 mm (75 inches) above the ground 

when the motor vehicle is stopped on level ground; unloaded; its fuel 

tanks are full; the tires (and air suspension, if so equipped) are 

inflated in accordance with the manufacturer's recommendations; and the 

motor vehicle's cargo doors, tailgate, or other permanent structures are 

positioned as they normally are when the vehicle is in motion. 

Nonstructural protrusions such as taillamps, rubber bumpers, hinges and 

latches are excluded from the determination of the rearmost point.

    Reflective material. A material conforming to Federal Specification 

L-S-300, ``Sheeting and Tape, Reflective; Non-exposed Lens, Adhesive 

Backing,''



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(September 7, 1965) meeting the performance standard in either Table 1 

or Table 1A of SAE Standard J594f, ``Reflex Reflectors'' (January, 

1977).

    Reflex reflector. A device which is used on a vehicle to give an 

indication to an approaching driver by reflected lighted from the lamps 

on the approaching vehicle.

    Saddle-mount. A device, designed and constructed as to be readily 

demountable, used in driveaway-towaway operations to perform the 

functions of a conventional fifth wheel:

    (1) Upper-half. Upper-half of a ``saddle-mount'' means that part of 

the device which is securely attached to the towed vehicle and maintains 

a fixed position relative thereto, but does not include the ``king-

pin;''

    (2) Lower-half. Lower-half of a ``saddle-mount'' means that part of 

the device which is securely attached to the towing vehicle and 

maintains a fixed position relative thereto but does not include the 

``king-pin;'' and

    (3) King-pin. King-pin means that device which is used to connect 

the ``upper-half'' to the ``lower-half'' in such manner as to permit 

relative movement in a horizontal plane between the towed and towing 

vehicles.

    Service brake system. A primary brake system used for slowing and 

stopping a vehicle.

    Shoring bar. A device placed transversely between the walls of a 

vehicle and cargo to prevent cargo from tipping or shifting.

    Shortwood. All logs typically up to 4.9 m (16 feet) long. Such logs 

are often described as cut-up logs, cut-to-length logs, bolts or 

pulpwood. Shortwood may be loaded lengthwise or crosswise, though that 

loaded crosswise is usually no more than 2.6 m (102 inches) long.

    Sided vehicle. A vehicle whose cargo compartment is enclosed on all 

four sides by walls of sufficient strength to contain articles of cargo, 

where the walls may include latched openings for loading and unloading, 

and includes vans, dump bodies, and a sided intermodal container carried 

by a vehicle.

    Side extremity. The outermost point on a side of the motor vehicle 

that is above a horizontal plane located 560 mm (22 inches) above the 

ground, below a horizontal plane located 1,900 mm (75 inches) above the 

ground, and between a transverse vertical plane tangent to the rear 

extremity of the vehicle and a transverse vertical plane located 305 mm 

(12 inches) forward of that plane when the vehicle is unloaded; its fuel 

tanks are full; and the tires (and air suspension, if so equipped) are 

inflated in accordance with the manufacturer's recommendations. Non-

structural protrusions such as taillights, hinges and latches are 

excluded from the determination of the outermost point.

    Side marker lamp (Intermediate). A lamp mounted on the side, on the 

permanent structure of the motor vehicle that provides light to the side 

to indicate the approximate middle of the vehicle, when the motor 

vehicle is 9.14 meters (30 feet) or more in length.

    Side Marker Lamps. Lamps mounted on the side, on the permanent 

structure of the motor vehicle as near as practicable to the front and 

rear of the vehicle, that provide light to the side to indicate the 

overall length of the motor vehicle.

    Special purpose vehicle. (1) A trailer or semitrailer manufactured 

on or after January 26, 1998, having work-performing equipment that, 

while the motor vehicle is in transit, resides in or moves through the 

area that could be occupied by the horizontal member of the rear impact 

guard, as defined by the guard width, height and rear surface 

requirements of Sec. 571.224 (paragraphs S5.1.1 through S5.1.3), in 

effect on the date of manufacture, or a subsequent edition.

    (2) A motor vehicle, not described by paragraph (1) of this 

definition, having work-performing equipment that, while the motor 

vehicle is in transit, resides in or moves through the area that could 

be occupied by the horizontal member of the rear impact guard, as 

defined by the guard width, height and rear surface requirements of 

Sec. 393.86(b)(1).

    Split service brake system. A brake system consisting of two or more 

subsystems actuated by a single control designed so that a leakage-type 

failure of a pressure component in a single subsystem (except structural 

failure of a housing that is common to two or more subsystems) shall not 

impair the operation of any other subsystem.



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    Steering wheel lash. The condition in which the steering wheel may 

be turned through some part of a revolution without associated movement 

of the front wheels.

    Stop lamps. Lamps shown to the rear of a motor vehicle to indicate 

that the service brake system is engaged.

    Tail lamps. Lamps used to designate the rear of a motor vehicle.

    Tiedown. A combination of securing devices which forms an assembly 

that attaches articles of cargo to, or restrains articles of cargo on, a 

vehicle or trailer, and is attached to anchor point(s).

    Tow bar. A strut or column-like device temporarily attached between 

the rear of a towing vehicle and the front of the vehicle being towed.

    Tractor-pole trailer. A combination vehicle that carries logs 

lengthwise so that they form the body of the vehicle. The logs are 

supported by a bunk located on the rear of the tractor, and another bunk 

on the skeletal trailer. The tractor bunk may rotate about a vertical 

axis, and the trailer may have a fixed, scoping, or cabled reach, or 

other mechanical freedom, to allow it to turn.

    Trailer kingpin. A pin (with a flange on its lower end) which 

extends vertically from the front of the underside of a semitrailer and 

which locks into a fifth wheel.

    Turn signals. Lamps used to indicate a change in direction by 

emitting a flashing light on the side of a motor vehicle towards which a 

turn will be made.

    Upper coupler assembly. A structure consisting of an upper coupler 

plate, king-pin and supporting framework which interfaces with and 

couples to a fifth wheel.

    Upper coupler plate. A plate structure through which the king-pin 

neck and collar extend. The bottom surface of the plate contacts the 

fifth wheel when coupled.

    Vacuum brake system. A system that uses a vacuum and atmospheric 

pressure for transmitting a force from the driver control to the service 

brake, not including a system that uses vacuum only to assist the driver 

in applying muscular force to hydraulic or mechanical components.

    Void filler. Material used to fill a space between articles of cargo 

and the structure of the vehicle that has sufficient strength to prevent 

movement of the articles of cargo.

    Well. The depression formed between two cylindrical articles of 

cargo when they are laid with their eyes horizontal and parallel against 

each other.

    Wheels back vehicle. (1) A trailer or semitrailer manufactured on or 

after January 26, 1998, whose rearmost axle is permanently fixed and is 

located such that the rearmost surface of the tires (of the size 

recommended by the vehicle manufacturer for the rear axle) is not more 

than 305 mm (12 inches) forward of the transverse vertical plane tangent 

to the rear extremity of the vehicle.

    (2) A motor vehicle, not described by paragraph (1) of this 

definition, whose rearmost axle is permanently fixed and is located such 

that the rearmost surface of the tires (of the size recommended by the 

vehicle manufacturer for the rear axle) is not more than 610 mm (24 

inches) forward of the transverse vertical plane tangent to the rear 

extremity of the vehicle.

    Width of a manufactured home. The largest exterior width in the 

traveling mode, including any projections which contain interior space. 

Width does not include bay windows, roof projections, overhangs, or 

eaves under which there is no interior space.

    Windshield. The principal forward facing glazed surface provided for 

forward vision in operating a motor vehicle.

    Working load limit (WLL). The maximum load that may be applied to a 

component of a cargo securement system during normal service, usually 

assigned by the manufacturer of the component.



[53 FR 49384, Dec. 7, 1988, as amended at 63 FR 8339, Feb. 18, 1998; 63 

FR 24465, May 4, 1998; 64 FR 47707, Sept. 1, 1999; 67 FR 61224, Sept. 

27, 2002; 68 FR 56208, Sept. 30, 2003; 70 FR 48026, Aug. 15, 2005]