Railroad rolling stock

Large numbers of railroad electric and diesel engines, passenger cars, and freight cars are in service. They are designed to function for at least 30 years with minimum maintenance of their coatings. 

Anticorrosive primers are followed by a 40- 50 pm intermediate coat, based on two-pack polyurethane resins. This coat is sanded to yield a smooth surface. 

Sometimes, the intermediate coat is overcoated with the topcoat in a wet-in-wet system. Normally, however, two-pack polyurethane topcoats are applied to the dried filler. These topcoats with aliphatic isocyanate hardeners have excellent gloss and color retention. The DFT of topcoats is 40 - 80 pm, depending on the hiding power of the topcoat. 

orange, and yellow pigments used in topcoats are now free of toxic lead and heavy metals to protect workers and the environment. Railroad companies expect a service life of 15 years before the topcoat has to be replaced (provided that spot repair is carried out when necessary). The whole coating system should not need to be renewed before a minimum service life of 30 years. 

Although two-pack epoxy primers and polyurethane intermediate coats have high solids contents, they still contain significant amounts (20-30 wt%) of organic solvents. In polyurethane topcoats, the VOC is even higher. Anticorrosive, waterborne primers based on aqueous dispersions of two-pack epoxy resins and one-pack acrylic resins have been developed to decrease solvent emission. Waterborne, one-pack acrylic topcoats are also used. All of these waterborne paints contain 2 - 5 % organic cosolvents that are required for film formation. 

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Influence of Thickness of Oil Layer on Adhesion. Atmospheric dust generally contains not only solid particles, but also oily contaminants, which settle on surfaces and make the surfaces oily. Also, the surfaces of some objects such as motor vehicles may become oily in the operating process. It has been found that 17% of the adherent particles on the surfaces of motor vehicles operating in Moscow do have such a layer of oil. Roughly the same results were obtained in an analysis reported in [234] on the contaminants appearing on exterior surfaces of railroad rolling stock. On a locomotive, for example, 23% of the adherent particles were in contact with oily surfaces, and on the railroad cars the figure was 19%. The presence of oily contaminants on surfaces tends to increase particle adhesion because of tackiness this is illustrated by data shown in Table VIII.8 [11]. 

Adhesion of Particles to an Oily Surface. Usually, atmospheric dust contains not only solid particles but also oil contaminations [166] which settle on surfaces, making them oily. In addition to this the surface of objects such as motor vehicles may become oily in the course of use. Thus it is found that 17% of the particles adhering to the motor vehicles of Moscow contain such oil layers. Similar results are obtained on analyzing the contaminations [226] adhering to the outer surfaces of railroad rolling stock. For example, on locomotives, 23% of the surfaces in contact are oily, and in trucks, 19%. 

Material hardness of the produced springs corresponded to the standard requirements for springs of railroad rolling stock of42. .. 46 HRC. 

Much discussion has evolved about the regrettable condition of the railbeds of our country. Derailments occur daily. Much of the rolling stock is also seriously in need of repair. Essentially all tank cars are owned or leased by shippers hence, can be improved at industry expense. Boxcars, gondolas, etc., are usually owned by the railroads (or Conrail) and a broken axle, hotbox or other failure of any car can cause a pile-up, possibly involving tank equipment or trackside hazards. 

Association of American Railroads (AAR) http //www.aar.org/ (accessed September 13, 2010). AAR represents the major freight railroads in North America and Amtrak. It publishes manuals, handbooks, recommended practices, and technical standards. A subsidiary, Transportation Technology Center, Inc., conducts research on rolling-stock, track components, strnctnres, signals, and safety devices it also provides training. 

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