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 five single-ended boilers, arranged
for a working pressure of 215 lb 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 lb. per sq. in. 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 connetions
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 load-line 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 pie, 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
20 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” main ballest 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.