[Code of Federal Regulations]
[Title 49, Volume 4]
[Revised as of October 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR393.5]

[Page 1034-1038]
 
                        TITLE 49--TRANSPORTATION
 
        CHAPTER III--FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION,
                      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:
    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.
    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.
    Brake. An energy conversion mechanism used to stop, or hold a 
vehicle stationary.
    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.
    Bus. A vehicle designed to carry more than 15 passengers, including 
the driver.
    Chassis. The load-supporting frame in a truck or trailer, exclusive 
of any appurtenances which might be added to accommodate cargo.
    Clearance lamp. A lamp used on the front and the rear of a motor 
vehicle to indicate its overall width and height.
    Container chassis. 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 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 and additional weight of optional engine. Curb weight does 
not include the driver.
    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.
    Fuel tank fitting. Any removable device affixed to an opening in the 
fuel tank with the exception of the filler cap.
    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.

[[Page 1035]]

    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(1) of this title when 
flammable liquid or gas is transported.
    Heavy hauler trailer. A trailer with one or more of the following 
characteristics:
    (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 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 Section 393.106 of this title.
    Identification lamps. Lamps used to identify certain types of 
commercial motor vehicles.
    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.
    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.
    Parking brake system. A brake system used to hold a vehicle 
stationary.
    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.
    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.

[[Page 1036]]

    Reflective material. A material conforming to Federal Specification 
L-S-300, ``Sheeting and Tape, Reflective; Non-exposed Lens, Adhesive 
Backing,'' (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.
    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 shown to the side of a 
trailer to indicate the approximate middle of a trailer 30 feet or more 
in length.
    Side marker lamps. Lamps used on each side of a trailer to indicate 
its overall length.
    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).
    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.
    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.
    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

[[Page 1037]]

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.

[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]

    Effective Date Note: At 67 FR 61224, Sept. 27, 2002, 24 definitions 
were added to Sec. 393.5 effective December 26, 2002. For the 
convenience of the user, the added definitions are set forth as follows.

Sec. 393.5  Definitions.

                                * * * * *

    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.

                                * * * * *

    Anchor point. Part of the structure, fitting or attachment on a 
vehicle or article of cargo to which a tiedown is attached.

                                * * * * *

    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).

                                * * * * *

    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.
    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.

                                * * * * *

    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.

                                * * * * *

    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.

                                * * * * *

    g. The acceleration due to gravity, 32.2 ft/sec\2\ (9.823 m/sec\2\).

                                * * * * *

    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.

                                * * * * *

    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

[[Page 1038]]

down devices are mated to provide securement of the complete vehicle and 
its articles of cargo.

                                * * * * *

    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.

                                * * * * *

    Rail vehicle. A vehicle whose skeletal structure is fitted with 
stakes at the front and rear to contain logs loaded crosswise.

                                * * * * *

    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.

                                * * * * *

    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).
    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.

                                * * * * *

    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.

                                * * * * *

    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.