British Wreck Commissioner's Inquiry
Description. - The propelling machinery was of the combination type, having two sets of reciprocating engines driving the wing propellers, and a low-pressure turbine working the centre propeller. Steam was supplied by 24 double-ended boilers, and 5 single-ended boilers, arranged for a working pressure of 215 lbs. per square inch. The turbine was placed in a separate compartment aft of the reciprocating engine room and divided from it by a watertight bulkhead. The main condensers, with their circulating pumps and air pumps, were placed in the turbine room. The boilers were arranged in six watertight compartments, the single-ended boilers being placed in the one nearest the main engines, the whole being built under Board of Trade survey for passenger certificate.
Reciprocating Engines. - The reciprocating engines were of the four-crank triple expansion type. Each set had four inverted, direct-acting cylinders, the high-pressure having a diameter of 54 in., the intermediate pressure of 84 in., and each of the two low-pressure cylinders of 97 in., all with a stroke of 6 ft. 3 in. The valves of the high pressure and intermediate cylinders were of the piston type, and the low-pressure cylinder had double-ported slide valves, fitted with Stephenson link motion. Each engine was reversed by a Brown's type of direct-acting steam and hydraulic engine. There was also a separate steam-driven high-pressure pump fitted for operating either or both of the reversing engines. This alternative arrangement was a stand-by in case of breakdown of the steam pipes to these engines.
Turbine. - The low-pressure turbine was of the Parson's reaction type, direct coupled to the centre line of shafting and arranged for driving in the ahead direction only. It exhausted to the two condensers, placed one on each side of it. A shut-off valve was fitted in each of the eduction pipes leading to the condensers. An emergency governor was fitted and arranged to shut off steam to the turbine and simultaneously change over the exhaust from the reciprocating engines to the condensers, should the speed of the turbine become excessive through the breaking of a shaft or other accident.
Boilers. - All the boilers were 15 ft. 9 in. in diameter, the 24 double-ended boilers being 20 ft. long, and the single-ended 11 ft. 9 in. long. Each double-ended boiler had six, and each single-ended boiler three furnaces, with a total heating surface of 144,142 sq. ft. and a grate surface of 3,466 sq. ft. The boilers were constructed in accordance with the rules of the Board of Trade for a working pressure of 215 lbs. per square inch. They were arranged for working under natural draught, assisted by fans, which blew air into the open stokehold.
Auxiliary Steam Pipes. - The five single-ended boilers and those in boiler rooms Nos. 2 and 4 had separate steam connections to the pipe supplying steam for working the auxiliary machinery, and the five single-ended boilers and the two port boilers in boiler room No. 2 had separate steam connections to the pipe supplying steam for working the electric light engines. A cross connection was also made between the main and auxiliary pipes in the reciprocating engine room, so that the auxiliaries could be worked from any boiler in the ship. Steam pipes also were led separately from three of the boiler rooms (Nos. 2, 3, 5) above the watertight bulkheads and along the working passage to the emergency electric light engines placed above the loadline in the turbine room. Pipes were also led from this steam supply to the pumps in the engine room, which were connected to the bilges throughout the ship.
Main Steam Pipes. - There were two main lines of steam pipes led to the engine room, with shut-off valves at three of the bulkheads. Besides the shut-off valves at the engine room bulkhead, a quick-acting emergency valve was fitted on each main steam pipe, so that the steam could at once be shut-off in case of rupture of the main pipe.
Condensing Plant and Pumps. - There were two main condensers, having a combined cooling surface of 50,550 square feet, designed to work under a vacuum of 28 ins. with cooling water at 60 deg. Fahr. The condensers were pear-shaped in section, and built of mild steel plates.
Four gunmetal centrifugal pumps were fitted for circulating water through the condensers. Each pump had suction and discharge pipes of 29 in. bore, and was driven by a compound engine. Besides the main sea suctions, two of the pumps had direct bilge suctions from the turbine room and the other two from the reciprocating engine room. The bilge suctions were 18 in. diameter. Four of Weir's "Dual" air pumps were fitted, two to each condenser, and discharged to two feed-tanks placed in the turbine engine room.
Bilge and Ballast Pumps. - The ship was also fitted with the following pumps: Five ballast and bilge pumps, each capable of discharging 250 tons of water per hour; three bilge pumps, each of 150 tons per hour capacity.
One ash ejector was placed in each of the large boiler compartments to work the ash ejectors, and to circulate or feed the boilers as required. This pump was also connected to the bilges, except in the case of three of the boiler rooms, where three of the ballast and bilge pumps were placed. The pumps in each case had direct bilge suctions as well as a connection to the main bilge pipe, so that each boiler room might be independent. The remainder of the auxiliary pumps were placed in the reciprocating and turbine engine rooms. Two ballast pumps were placed in the reciprocating engine room, with large suctions from the bilges direct and from the bilge main. Two bilge pumps were also arranged to draw from bilges. One bilge pump was placed in the turbine room and one of the hot salt-water pumps had a connection from the bilge main pipe for use in emergency. A 10 in. main ballast pipe was carried fore and aft through the ship with separate connections to each tank, and with filling pipes from the sea connected at intervals for trimming purposes. The five ballast pumps were arranged to draw from this pipe. A double line of bilge main pipe was fitted forward of No. 5 boiler room and aft of No. 1.