(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.

1. (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. (2) Weight carrying hitch.

   1. (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.

   2. (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.

3. (1) Class 1—Trailers with a gross weight (trailer weight including load) not exceeding 2,000 pounds.
4. (2) Class 2—Trailers, with a gross weight (trailer weight including load) over 2,000 pounds but not exceeding 3,500 pounds.
5. (3) Class 3—Trailers, with a gross weight (trailer weight including load) over 3,500 pounds but not exceeding 5,000 pounds.

6. (4) Class 4—Trailers, with a gross weight (trailer weight including load) over 5,000 pounds but not exceeding 10,000 pounds.

   (d) Couplings.

7. (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.

8. (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.
9. (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.

10. (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.

11. (1) Hitch rating. Hitches shall be rated by the maximum gross trailer weight and the vertica l tongue weight each is qualified to tow.
12. (2) Hitch strength requirements. Each hitch, when subjected to a static bench test, shall conform to the minimum strength requirements contained in table 2.
13. (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.

14. (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.

15. (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.

16. (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.

17. (1) Marking. Each coupling and each hitch shall be legibly and permanently marked to show:

    1. (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.)
    2. (ii) Model number, part number, or style and, for couplings only, the class.
    3. (iii) Maximum gross trailer weight to be drawn.
    4. (iv) Maximum vertical tongue weight to be imposed on the ball or other points of connection.

18. (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:

19. (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”.

20. (2) Hitches for full trailers,

    1. (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”.
    2. (ii) A weight carrying hitch may be used in lieu of a weight distributing hitch.

(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: