#503 Arch Bar Trucks with Ready-to-Mount Whisker® Couplers, 33" Ribbed Back Wheels - HO ScaleMetal Fully Sprung Equalized Trucks The Whisker® couplers will need to be assembled on to the trucks coupler bottom plate. Mounts with a #2 or 2-56 screw.Mounting Screws not Included. Commonly used 1890’s and early 1900’s - Allowed in interchange service until about 1941. The Arch Bar Truck is typical of these trucks from around the turn of the century. Despite the age of these trucks, they saw more than seventy years of service in some applications. The arch bar was allowed in interchange service until about 1941. On railroads that were not common carriers such as logging or other industrial lines, this restriction of the trucks did not apply since the trucks did not operate on rails other than the owner's. The Northern Pacific, for example, used truss rod frame maintenance of way cars fitted with arch bar trucks well into the early 1970's. Many logging railroads also used them at least until then.
