The present invention relates to fittings for securing articles in a desired position and, more particularly, to a tie-down connector fitting for securing automobiles and the like to the bed of a transporter, such as a railroad car or truck.
Automobiles and other vehicles are normally transported from the factory to a location near the point of purchase by transporters, including trucks and railroad cars. In the past, various means of securing vehicles to such transporters have been used, the most popular method being a tie-down assembly attaching the undercarriage of the vehicle to the bed of the transporter. Generally, prior tie-down assemblies consist of a hook section and a single chain extending therefrom to an idler assembly movable along a track formed in the floor or bed of the transporter to accommodate vehicles of different lengths. In securing a vehicle, the idler assembly is moved along the track to a position beneath the vehicle, where the hook is attached to an opening or slot in the undercarriage of the vehicle. The chain is attached at its free end to a conventional ratchet, movable within the track, which tightens the chain for securing the vehicle to the bed of the transporter for shipment. This procedure was often repeated at each of the four corners of the vehicle as a safety precaution to avoid potentially dangerous and damaging movement of the vehicles should one of the chains break.
In an effort to reduce material and labor costs in tying down vehicles for shipment, shippers have begun to use single tie-down assemblies at the front and rear of the vehicles. Such an arrangement, however, introduces the danger of a loose vehicle on the transporter should one of the chains break. Accordingly, improved vehicle tie-down systems have been developed to safeguard against the possibility of chain failure, such as that disclosed in U.S. Pat. No. 4,022,134 to Krokos, issued May 10, 1977, which shows multiple chains attached to a clevis 41, pivotally pinned to the center of a connector fitting formed in various configurations. A further improvement is shown in patent application Ser. No. 703,594, filed July 8, 1976, now U.S. Pat. No. 4,044,691, issued Aug. 30, 1977, by Donald C. Kilgus and entitled "Vehicle Tie-Down System for Rail Cars".
These improved tie-down systems generally provide a connector fitting which attaches to a pair of chains or at a point along the length of a single chain in a triangular configuration. In such systems, each separate chain or the ends of a single chain are secured to the transporter so that one will hold the vehicle alone, should the other break. It has been discovered in using such tie-down systems, however, that a great deal of stress and strain is placed on the fitting itself, and particularly on the end link of the chain which attaches to the fitting. The tensile and torsion stresses applied to the chains and fitting by the motion of the vehicle on the transporter, especially in starting and stopping, have caused failures in both after relatively short periods of use.
Accordingly, it is desirable to provide a tie-down system wherein the chains may be separated from the fitting should one fail before the other. However, in many prior art designs, such as that disclosed in U.S. Pat. No. 4,049,229 to Peisner, issued Sept. 20, 1977, the chains are integral with the fitting and may not be separated therefrom. In such designs, if either one of the fitting or chains prematurely fail, the entire connector fitting, including the chains, must be replaced.