Section 308.14. Safety chain or cable for full trailers or trailer converter dollies connected by means of a pintle and tow bar eye.

 

(1)   Definitions.

(a) Full trailer means a truck trailer whose weight is carried entirely on its own wheels.

(b) Trailer converter dolly means a truck trailer with one or more axles equipped with a fifth wheel, a drawbar and other parts necessary to convert a semitrailer to a full trailer.

(c) Truck trailer means a vehicle without auxiliary motive power designed to be drawn by a motor truck or truck tractor, but does not include a mobile home.

(d) Safety chain means the chain or cable from the front of a full trailer or a trailer converter dolly to the rear of the towing vehicle for the purpose of retaining the connection between the towing and the towed vehicles and of controlling the direction of travel of the towed vehicle in the event of failure of the drawbar or the connection on the rear of the towing vehicle.

(e) Pintle means a connection meeting the requirements of SAE J849b. See Fig. 1 following this section.

(f) Tow bar eye means a device attached to the tow bar of the full trailer or trailer converter dolly meeting the requirements of SAE J847. See Fig. 2 following this section.

(2)   Use of a single length of safety chain or cable. A single length of chain or of cable or a bridle arrangement of a single chain or cable may be used between a towing vehicle and a full trailer or between a towing vehicle and a trailer converter dolly when the towing vehicle is connected to the towed vehicle by means of a pintle and tow bar eye if all the installation and capacity requirements of this section are met.

(3)   Installation.

(a) The safety chain shall be attached by suitable means to the frame of the full trailer or of the trailer converter dolly to which full trailer or trailer converter dolly a hinged drawbar is attached and to the frame of the towing vehicle. Trailer converter dollies with solid tongues and without hinged tow bars may have the safety chain attached to the solid tongue. The connection or coupling device shall not be used as a means of attaching the safety chain to the towing vehicle frame. The safety chain shall be attached to both the towing and the towed vehicles in such a manner so as to be capable of developing the full capacity of the chain into the frame members of the towing and towed vehicles. The safety chain shall be so installed as to support the drawbar and prevent it from dropping to the ground in the event of failure of the drawbar or connection on the rear of the towing vehicle. The safety chain shall be attached and installed so as to keep the trailer in a straight line back of the towing vehicle insofar as practicable in the event of failure of the drawbar, connection or coupling device. The safety chain shall have no more slack, when in use, than is necessary to permit proper turning of the vehicle.

(b) Two safety chains or 2 cables, when used, may be attached to the full trailer front axle or to the trailer converter dolly axle near the wheels in lieu of the requirements set forth in par. (a) . The means of attachment shall be capable of developing the full capacity of the safety chains or cables into the axle and shall meet all the requirements set forth in s. Trans 308.12 (3) .

(4)   Capacity.

(a) The safety chain capacity shall be equal to the gross weight of the vehicle or vehicles being towed. For the purpose of this section, the safety chain capacity shall be the published breaking strength. The safety cable capacity shall be the published breaking strength. In the absence of a published breaking strength, the safety chain or cable capacity shall be the ultimate strength by actual test performed by the manufacturer.

(b) When 2 chains or 2 cables are used, each chain or cable shall have a capacity equal to the gross vehicle weight of the vehicle or vehicles being towed.

(c) Breaking strengths are given as follows: - See PDF for table

(5)  The following figures are Society of Automotive Engineers' (SAE) recommended practices found in the 1980 SAE Handbook. These recommended practices are on file in the offices of the department of transportation, the secretary of state and the legislative reference bureau, or may be obtained from the Society of Automotive Engineers, Inc., 400 Commonwealth Drive, Warrendale, Pennsylvania 15096.

History: Emerg. cr. eff., 4-14-80; cr. Register, September, 1980, No. 279 , eff. 10-1-80; correction in (5) made under s. 13.92 (4) (b) 6. , Stats., Register March 2012 No. 675 . - See PDF for diagram - See PDF for diagram - See PDF for diagram