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[Page 38]
Shafting & Bearings The crank shafts are of forged steel, and for each engine are made in three interchangeable and reversible sections, the cranks being 120º apart, and for the ahead motion follow in the order H.P., I.P., & L.P. There is a 7-1/2” axial hole through crankshaft and pin. The line, thrust & propeller shafting is hollow and of forged nickle steel. The propeller shafts are fitted with a composition casing from inboard of the stern tube stuffing box to the propeller hub. The propeller shaft is in two sections connected by an outboard sleeve coupling fitted near the after end of the stern tube, and protected by a watertight covering. The thrust bearings are of the horseshoe pattern; the pedestals are of cast iron, the ends and side walls forming an oil trough; at each end there is a bearing, lined with white metal for taking the weight of the shaft. The horseshoes are eleven in number and are of cast steel, faced with white metal, and fitted with oil cups & holes for the distribution of oil to the bearings. At each end of the bearing there is a divided stuffing box and gland to prevent the escape of oil. The pedestal is bolted to a cast-iron sole plate, fitted with wrought iron wedges at each end of the pedestal for adjusting the bearing fore & aft.
Main condenser Shells of wrought steel plate, with angle iron riveted around each end forming a flange for securing the water chests. Water chests & tube sheets of composition. The circulating water passes through the tubes. Baffle, circulating and tube-supporting plates are fitted. There are by-pass valves in the after water chests to allow the water to pass directly overboard from the circulating pumps.
Shell: dia. 5’8-1/2”; thickness 5/16”; length 13’4”
Tubes: dia (outside) 5/8”; length 11’6”; thickness .049”
No. of tubes 3,749; cooling surface 7,050 sq.ft.
Ratio total cooling to total heating surface 1 to 1.56
[Page 39]
Main air pumps Two Worthington, twin cylinder, vertical, single acting air pumps. Steam cylinders directly over pump cylinders, pump and piston rods are in one. The pumps are connected by means of a beam, which is pivoted at its center, and from which beam the valve motion is actuated. The beam receives its motion through links swinging from crossheads on the pump & piston rods. The pump valves are each made of three flat discs of rolled manganese-bronze.
Cylinders, dia. Steam 12”. Pump 25”. Stroke 18”
Piston rods, dia. 2-7/16”, pump rods 2-3/4”
Diameter of pump valves, 3”, 4”, 4-1/8”
Main circulating pumps
For each condenser a centrifugal, double inlet circulating pump, which is arranged to draw from the sea, bilge & main drain pipe, and to discharge either into condenser or directly overboard. The sea and bilge injection valves are fitted with a self-locking arrangement so that both cannot be operated at the same time. One of these was tested under conditions assimilated to that of drawing water from the bilge and discharging directly overboard, the length & size of the piping and the head at discharge being the same as would occur in actual service. The velocity at discharge was measured by a small propeller, and the results were well over their rated capacity of 10,000 gallons per minute.
Dia. Steam cylinders 11”. Stroke 8”.
Dia. Pump runner 42”, width 8-1/4”
Dia. Inlet & outlet nozzles 15-1/2”
Auxiliary condensers One in each engine room, connected with auxiliary exhaust pipes. The heads & shell are of composition and the tube sheets of rolled brass. Each has a Worthington horizontal, duplex, combined air & circulating pump; the steam cylinders being between the water cylinders, and all the pistons being on one rod. The tubes are arranged and packed as in the main condensers.
Cooling surface 801 sq.ft., Stroke 10”
Dia. Steam cylinders 7-1/2”; circulating pump cylinders & air pump cylinders 8-1/2”