It has been well known to provide plastic wear members for railway vehicles. For example, U.S. Pat. Nos. 4,188,888; 4,237,792 and 4,289,077 show wear members in the form of liners for center bearings of trucks. Wear members of plastic have also been widely used at the sliding surfaces of coupler members, as disclosed in U.S. Pat. Nos. 4,238,039; 4,249,665; 4,261,472, and 4,264,015. Plastic wear members have further been used for pedestals of a railway truck, as disclosed in U.S. Pat. Nos. 4,237,793 and 4,239,007; and for brake rods, as disclosed in U.S. Pat. Nos. 4,079,818 and 4,452,345. It has also been known to provide wear plates having a plastic material for sliding sill supports, as disclosed in U.S. Pat. Nos. 4,348,964 and 4,784,068.
These wear members have been developed following the availability of suitable plastic resins and particularly certain polyethylenes, such as a linear high-density polyethylene which is usually referred to as an ultra-high molecular weight polyethylene. As disclosed in some of the above patents, these plastic materials have been bonded to metal supporting members which are then mounted on supporting parts of a railway vehicle, or used in sheets and secured in place.
It has only been within the last ten or so years that auto rack cars of the bilevel and trilevel type have included the use of doors at the ends of the cars so as to provide security for the automobiles and vehicles being transported by the rail cars and preventing damage by unauthorized persons. One of the problems encountered with respect to the use of doors has been maintaining the integrity of the door suspension and mounting components to assure proper closing of the doors to maintain the security of the interior of the cars. The suspension system for the doors includes a lower track supporting the doors at the lower ends and guiding them during opening and closing operations, an intermediate arm connected to the doors and the frame of the car, and a guide system at the upper ends of the doors including a track secured to the cars and door finger guides mounted on the doors coacting with the tracks for guiding the upper ends during opening and closing operations. Further, locking devices are used for locking the doors in open and closed positions. Excessive wear of the guides, as well as sometimes complete failure of the guides, results in excessive wear of the other suspension and locking components of the doors, all of which lead to breach of the integrity of the security intended by the doors. Not only are the doors subjected to the normal vibration and oscillations generated by a car during travel over rails, but they are also subjected to the twisting of the entire car structure during car movement, all of which result in a very severe wearing problem for the door finger guides which have heretofore been made of metal such as steel. Also, the tracks are made of steel, as it is necessary to utilize the strength of steel in construction of the components for these cars.
While it is possible to replace the steel door finger guides, it has been found that maintenance is not always conducted at the times where a replacement is first needed. Further, the impact of steel guides on a steel track causes wear of the track and sometimes complete destruction of the track. This impact is transmitted through the other parts of the door components leading to adverse wear conditions of those components.
Thus, the heretofore known metal wear guides have resulted in breaching the integrity of the security of these cars which leads to easy entry of the cars and damage to or loss of the vehicles being transported.
USPTO Backgrounds
USPTO Backgrounds