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A little test. What is different about one of the three truck bolsters shown? Only two have transverse truss rods. Why? The third bolster is evidently a replacement, made of cast STEEL instead of cast IRON. When Climax CN 1551 was made, in 1919, almost all castings were made of relatively brittle cast iron, hence the reinforcing truss rods on the older two of our bolsters. About 1921, Climax saw the light and abandoned cast iron (cheap) and began to make their castings of steel (more expensive, yet much stronger and not as brittle) as their material-of -choice for castings. During this change, the foundry patterns were altered, or made new, to eliminate many bosses and lugs needed to apply the no-longer-needed truss rods. No doubt the less complicated foundry molds reduced the cost of the castings somewhat.
Photo by Bill Liebman |