The present invention relates generally to automobile and cargo transport, and more particularly, to method for retrofitting a chain tie down system to a strap tie down system.
FIG. 1 illustrates a prior art vehicle transport trailer 100. Several vehicles 105 can be transported on the trailer. Each of the vehicles typically has its own platform 110 onto which each vehicle 105 is secured. Many vehicle manufacturers have specified chains as the allowable securement device when transporting their vehicles. Consequently, many vehicle transport trailers in active service are designed for and equipped with chain tie downs as illustrated in FIG. 2 that illustrates a side view of a prior art vehicle trailer tie down system 101. As previously described, each vehicle 105 is secured to its platform 110. FIG. 2 illustrates the vehicle 105 tied to its platform 110 by chains 115 in a “V” arrangement. Those skilled in the art understand that the chains 115 can be tied in other arrangements such as an “A” arrangement. The vehicle 105 is typically restrained to the platform 110, and therefore the trailer, by connecting the chains 115 to the frame of the vehicle 105 and the platform 110 or other part of the trailer. The chains 115 are placed in tension to prevent movement and are tightened in opposite directions to prevent the vehicle 105 from shifting front to back or vice versa. Currently, locking mechanisms 120 are used to keep the chain 115 from loosening due to forces acting upon the vehicle 105 (e.g. gravity, centripetal and other forces asserted on the vehicle 105 from the trailer or otherwise). There are many types of mechanisms 120 such as ratchet and clamping devices that are typically manually tightened by the driver of the trailer. The chains 115 may have to be routed around the idlers 125 in order to achieve the proper chain angle and chain direction.
Many vehicle manufacturers are now allowing their vehicles to be shipped secured by either chain or strap tie downs. Still other vehicle manufacturers have gone to wheel strap tie down as the only approved vehicle securement method.
In light of the trend toward strap tie down equipment combined with the majority of fleet equipment in service being configured for chain, it would be desirable to have an economical way of converting a chain tie down transport trailer to a wheel strap tie down transport trailer. This would allow vehicle transportation companies to use existing transport trailers and possibly not have to purchase new transport trailers.
FIG. 3A illustrates a typical “open” chain tie down shaft system showing a chain 115 secured to a vehicle 105 (with one wheel 102 shown). FIG. 3B illustrates a typical “enclosed” chain tie down a chain 115 secured to a vehicle 105 (with one wheel 102 shown). A shaft enclosure 106 is also shown.
Previous procedures for retrofitting the chain tie down mechanism to strap tie down included connecting a wheel strap to the end of an existing chain, routing the chain 115 around a deck idler 107 and back to the strap 150 as illustrated in FIG. 3C. Previous procedures for retrofitting the chain tie down mechanism to strap tie down have further included welding a rigid rod 140 parallel to the original shaft 116, spaced away from the original shaft 116 as illustrated in FIGS. 3D and 3E. This arrangement results in a fixed gap through which a strap can be passed. The rigid rod 140 can be prone to permanently deflect, so intermediate spacers are added 141, which results in an incrementally adjustable strap as opposed to an infinitely adjustable strap.