. American engineer and railroad journal . ed quite close together on both sides of the fire box atthe crown sheet and two 6-inch hand holes are located in thewaist of the boiler in addition to the openings at the mud ring. The superheater elements are contained in thirty-two sJ/J-inchboiler tubes. These tubes replace about 96 of the regular 2^4-inchtubes, but the total fire heating surface is reduced only about 220square feet by this substitution. All tubes are 21 feet long andthe superheater has a heating surface of 641 square feet. Because of the reduced boiler pressure the cylinders are en
. American engineer and railroad journal . ed quite close together on both sides of the fire box atthe crown sheet and two 6-inch hand holes are located in thewaist of the boiler in addition to the openings at the mud ring. The superheater elements are contained in thirty-two sJ/J-inchboiler tubes. These tubes replace about 96 of the regular 2^4-inchtubes, but the total fire heating surface is reduced only about 220square feet by this substitution. All tubes are 21 feet long andthe superheater has a heating surface of 641 square feet. Because of the reduced boiler pressure the cylinders are en-larged to 26 inches in diameter and are provided with walls suf-ficiently thick to enable them to be subsequently bored to 27inches diameter if desired. The stroke is 30-inch. The pistonsare of cast iron and provided with a front extension piston rod,which carries the greater weight of this part. The steam distri-bution is controlled by 12-inch piston valves, each valve beingcomposed of a body casting with two heads, or followers, of the. PISTON VALVE PACKING. usual type. The packing rings, a section of which is shown inone of the illustrations, are parted at the bottom and are carriedin bull rings, which slip over the followers. The valve rod alsohas a front extension and the weight of the valve is carried by it,the bull rings being arranged to float on the followers. Thevalve setting is shown in the table at the end of this article. Theby-pass valves are somewhat similar to those used on the Penn-sylvania Railroad, the live steam ports being extended upwardabove the steam chest and the ports at that point beingcpvered by a flat plate held down by steam pressure acting on itsupper surface. This plate has a limited amount of rise and isguided by a central spindle and excess pressure within the cyl-inders will readily lift it from its seat. The steam chests are setout sufficiently to avoid the use of rockers in the valve gearand the width over the outside of the cylinders is 12
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
