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Tandem Compound Engines in River Towboats HE tow-boats Parrick J. HuRLEY T and JAmEs W. Goop are equipped with twin tandem compound condens- ing horizontal engines built by the Nordberg Mfg. Co., Milwaukee. These engines are mounted on either side of the boat with the low pressure cylin- ders set forward and the high pressure cylinders aft. In size, the engines have 18 inches high pressure cylinders, 36 inches low’ pressure and a stroke of 9 feet. When operating at their nor- mal speed of 18 revolutions per minute and with approximately 50 per cent cut-off, they develop 1000 horsepower. They are designed for a steam pres- sure of 300 pounds gage although the normal operating pressure is 275 pounds with 150 degrees superheat and a vacuum of 4 inches absolute. Referring to the photograph which is of the port side engine, it will be seen that the cylinders are bolted to the engine beams at the center, thus allowing free expansion of the high and low pressure cylinders, the ends of which rest on free moving guides. The forward head of the high pres- sure cylinder is securely bolted to the aft head of the low pressure cylinder, thus forming a single unit free to ex- pand, and one which is not affected by any weaving of the ship. The steam and exhaust valves are of the Nordberg poppet type so long used on steam engines built by this Port side unit of twin tandem com- pound condensing horizontal Nord- berg engines in- stalled in river towboats Patrick J. Hurley and James W. Good company. They are mounted in re movable cages and made of such mate- rials that will permit the use ot steam of high pressure. The inlet valves on both high and low pressure cylinders are of the re- leasing type. ‘They are operated by the Nordberg patented valve gear, the motion being a combination taken from the crosshead and pitman and thereby making the starboard and port side engines each independent. The cut-off from zero to full-stroke is correctly proportioned between the high and low pressure cylinders, thus securing high economy at all loads oft the engines. Incorporated in the valve gear is a mechanism permitting the opening of all valves simultaneously, thus “putting the engine in irons.” The reversing and valve lift mechanisms are operated by hydraulic thrust cylin- ders instead of the ordinary steam equipment commonly used. A feature in the design of these en- gines is the reheating receivers placed between the high and low pres- sure cylinders. These receivers are located just above the cylinders and enclosed in sheet steel lagging. They contain coils through which steam at boiler pressure is passed, thus reheat- ing the steam before it enters the low pressure cylinders. This not only im- proves the economy but assures of dry steam. The live steam, after passing through the coils of these receivers, reheats the forward low pressure cyl- inder head jacket and is then used for driving the boat auxiliaries. Since they take steam at a lower pressure than the propelling engines, the re. ceivers act as de-superheaters, lower. ing the temperature of the steam to that suitable for these auxiliaries, At the end of the receiver is a reducing valve which lowers the pressure to that on which the auxiliaries operate. This steam for the auxiliaries ig qj. ways available regardless of whether the propelling engines are running, - These engines drive a wheel of 23 feet diameter with a bucket length of 25 feet. The buckets are staggered, there being 16 with a width of 8 feet. Launch Third Liner The liner Exeter, third of a quartet of new combination passenger and freight vessels constructed by the New York Shipbuilding Co. for the Export line’s express service between New York and Mediterranean ports, was launched from the Camden yards of the builders Saturday, April 14. Run Performance Tests The Sun Shipbuilding & Dry Dock Co.’s_ latest production, the diesel- engine propelled tanker “SouTHERN Sun, ran her performance tests re- cently in Upper Delaware Bay. Trial trip engineers and the ship’s officers, upon the return of the huge bulk oil carrier to the Chester shipbuilding plant said the vessel’s performances met all the contract requirements. Each of the five vessels now being rebuilt for the Baltimore Mail Steam- ship Co. will be provided with the fol- lowing Sperry equipment: MK. VIII Gyro-compass with duplicate motor generators, repeaters and course re- corder, as well as a special repeater for use in the R.C.A. direction finder; two-unit gyro-pilot system giving com- plete control at will, directly to the steering engine; A-C rudder indicator system with indicators on the bridge and at emergency steering station aft; engine speed indicator system giving indications on the bridge as well as in the engine room; 18-inch pilot house type 1000 watt incandescent search- light. Bunker Prices At New York At Philadelphia Coal Fuel oil Diesel engine i alongside alongside oil alongside ee Wak ee ade per ton per barrel per gallon per ton per Patrol April 18, 1931.4.85@5.25 1.10 4,32 Apr'1 18, 1931.4.85@5.25 1.00 Mar 18.0 02.- 4.85@5.25 1.10 4.5514 Maria... /85@5.25 1.00 Web 180.0: 4.85@5.25 1.10 4.55% Heb, 18. 27. 4.85@5.25 1.00 Jan. 18. 4.85@5.25 1.10 4.5514 an. 18 4.85@5.25 185 Tee: 8:5. 4.85@5.25 1.10 4.5514 so eee 4.85@5.25 195 Nov 18)... 4.85@5.25 1.10 4.92 Nov. 18.2... 4.85@5.25 1.00 Oe 18... ss 4.85@5.25 1.10 4.92 Oct 18... 4.85@5.25 1.05 Sept. 18 -4.85@5.25 1.10 4.92 Sept. 18...... 4.85@5.25 1.05 Aug 48s. a: 4.85@5.25 1.20 4.92 ug. 18.50. . 4.85@5.25 1.05 July 182,00. 4.75@5.00 1.20 4.92 uly 18... 0... -75@4.50 1.10 June 18, 1930.5.00@5.25 ie 4.92 June 18, 1930.5.00@5.25 1.20 44 MARINE REVIEW——M ay, 1931 Diesel engine oil alongside Other Ports Boston, coal, per ton...$7.36 Boston, oil, f. a. s., per barrel 1.26 Hampton Roads,coal,per per gallon sere ewer ere rene 88 ton, f.o.b.,piers$4.35 to 4.50 88 Jan. 8—Cardiff, coal, 88 Def TONses cencnciewe se 13s 6d 88 London, coal, per ton... —s - Antwerp, coal, per ton..19s 6d Antwerp, Fuel oil, per ton. 67s 6d Antwerp, Diesel oil, per COM he Gee aig eee 82s 6d British ports, Fuel oil...67s 6d British ports, Diesel oil. 82s 6d PP PPP PP co oo