Current through Register Vol. 46, No. 12, March 20, 2024
(a) These are for use with trailers not
exceeding 10,000 pounds gross weight. This includes but is not limited to such
types as the utility, boat, camping, travel and other trailers which are
normally towed by the conventional passenger car, or similarly constructed
vehicle or light-duty truck. This section is intended basically for the
ball-and-socket type of primary connecting system. It is not limited to this
type alone.
(b) Light service hitch
nomenclature. The following nomenclature has been adopted for uniformity in the
terms used for this portion of the primary connecting system:
(1) Weight distributing hitch means a
mechanical device that connects the trailer to the towing vehicle, and by means
of leverage applied on both trailer and car structures or axles, when properly
adjusted, distributes the imposed vertical load at the hitch and coupling
connection between the structures or axles of towing vehicle and trailer. The
towing vehicle thus loaded tends to retain a level position with respect to the
road.
(2) Weight carrying hitch.
(i) Bumper hitch means a mechanical or
structural device that bolts or is otherwise fastened to the bumper of the
towing vehicle. No connection is made to other structural members of the towing
vehicle.
(ii) Frame hitch means a
mechanical and/or structural device that bolts or is otherwise fastened to at
least two of the towing vehicle structural members which can include frame,
unitized body, and bumper.
(c) Trailer classification.
(1) Class 1--Trailers with a gross weight
(trailer weight including load) not exceeding 2,000 pounds.
(2) Class 2--Trailers, with a gross weight
(trailer weight including load) over 2,000 pounds but not exceeding 3,500
pounds.
(3) Class 3--Trailers, with
a gross weight (trailer weight including load) over 3,500 pounds but not
exceeding 5,000 pounds.
(4) Class
4--Trailers, with a gross weight (trailer weight including load) over 5,000
pounds but not exceeding 10,000 pounds.
(d) Couplings.
(1) Coupling classification.
There shall be four major strength classifications, or
designations, of couplings. The designation shall be based on the maximum gross
trailer weight the coupling is qualified to tow. The No. 1 couplings shall be
used for towing class 1 trailers; No. 2 couplings for class 2 or smaller
trailers; No. 3 couplings for class 3 or smaller trailers; and No. 4 couplings
for class 4 or smaller trailers. This is not intended to limit the number or
variety of couplings in a given class, or designation.
(2) Coupling ultimate strength. Each
coupling, when subjected to static bench tests, shall exhibit the minimum
breaking strengths required in table 1 for its strength classification, or
designation. Each type of test load shall be applied independently.
(3) Attachment of couplings. Each coupling is
to be mounted to the trailer attaching member by bolting, welding or riveting
in such manner that the maximum loading specified for the coupling designation
in table 1 is safely and adequately transferred to that member.
(4) Provisions for safety. Each coupling,
regardless of classification, or designation must be equipped with a manually
operated mechanism so adapted as to prevent disengagement of the unit while in
operation. In addition to this positive locking mechanism, the coupling shall
be so designed that the trailer can be disconnected from the towing vehicle
regardless of the angle of the trailer to the towing vehicle.
(e) Hitches.
(1) Hitch rating. Hitches shall be rated by
the maximum gross trailer weight and the vertica l tongue weight each is
qualified to tow.
(2) Hitch
strength requirements. Each hitch, when subjected to a static bench test, shall
conform to the minimum strength requirements contained in table 2.
(3) Attachment of hitch. Each hitch shall be
attached to the structural member or members of the towing vehicle in such a
manner that the tension, compression and transverse thrust loads shown in table
2 are transferred to the towing vehicle without residual distortion or failure
of either the attachment or the vehicle structure which would affect the safe
towing of trailers, as defined in table 2.
(4) Vertical load on hitch. The weight load
carried by the hitch at its connection with the trailer coupling shall not,
when on a level surface, exceed the maximum tongue weight load recommended by
the manufacturer for the hitch but in no case shall the tongue weight load
exceed that specified in table 3 for the class of trailers and type of hitch
used.
(f) Safety chains
and attaching means. Each towing system shall include safety chains.
(1) Strength requirements. Each safety chain
and each attaching means shall meet strength requirements as shown in table 4
and defined in section
57.2.
(2) Installation and connections. The means
of attachment of safety chains shall be located equally distant from and on
opposite sides of the longitudinal centerline of the towing vehicle and of the
trailer, except that where a single length of safety chain is connected to one
single means of attachment of a trailer such single attachment shall be on the
trailer longitudinal centerline. Each means of attachment shall not be common
with or utilize fasteners common with a ball or coupling. No welding operation
shall be performed on a safety chain subsequent to its manufacture. Safety
chains shall be so connected that the slack for each length of chain between
trailer and towing vehicle is the same and is not more than necessary to permit
the proper turning of the vehicles. When passing forward to the towing vehicle,
safety chains must be crossed under the tongue and oriented in such a manner as
to prevent the tongue from dropping to the ground and to maintain connection in
the event of failure of the primary connecting system. (See figures 2 and 3,
section
57.5.)
(g) Identification.
(1) Marking. Each coupling and each hitch
shall be legibly and permanently marked to show:
(i) Manufacturer's or distributor's name,
initials, or trademark, trade name or code symbol. (Code symbol shall mean one
assigned and approved by appropriate regulatory authority.)
(ii) Model number, part number, or style and,
for couplings only, the class.
(iii) Maximum gross trailer weight to be
drawn.
(iv) Maximum vertical tongue
weight to be imposed on the ball or other points of connection.
(2) Labeling. Each crate, box or
other container in which a coupling or hitch is packed shall be imprinted or
labeled to display at least the same information required in paragraph (1) of
this subdivision for marking, except that the maximum gross weight to be drawn
must be shown for each coupling regardless of class. Also, the year, make, and
model of each vehicle on which a hitch may be installed and meet the
requirements of this Part shall be shown but may be shown on an enclosed sheet,
or sheets, separate from the imprintation, or labeling, or on hitch
manufacturer's application tables which are kept available at the locations
where the device or system is sold, either for resale or for use. However, this
provision shall not apply to hitches adaptable to a large number of vehicles
and designated to be a universal type.
(h) Full trailers. Light service connecting
devices or systems used with full trailers not exceeding 10,000 pounds gross
weight shall meet all requirements of this section except as shown below:
(1) Couplings for full trailers. The vertical
strengths shown in table 1 shall not be required. Such couplings shall be
legibly and permanently marked "For Full Trailers Only".
(2) Hitches for full trailers,
(i) The vertical strengths shown in table 2
shall not be required. However, the hitch must be capable of supporting the
entire weight of the tow bar, drawbar or tongue and when undergoing the other
tests shown in table 2 must not exhibit any vertical residual distortion which
would affect safe towing, as defined in table 2. Such hitches shall be legibly
and permanently marked "For Full Trailers Only".
(ii) A weight carrying hitch may be used in
lieu of a weight distributing hitch.