Engines: Two Reciprocating Engines driving the wing
propellers were of the four-crank triple expansion
type. Each weighed approximately 990 tons each. Each
set had four inverted, direct-acting cylinders and
high pressure having a diameter of 54 inches, the
intermediate pressure of 84 inches, and each of the
two low pressure cylinders of 97 inches., all with
a stroke of 6 feet 3 inches.
The valves of the
high pressure and intermediate cylinders were of the
piston type, and thoe low-pressue 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 were also a separate
steam-driven high pressure pump fitted for operating
either or both of the reversing engines. This alternative
arrange was a stand-by in case of breakdown of the
steam pipes to the engines.
A low pressure
turbine was of the Parson’s reaction type, directly
coupled to the center line of shafting and arranged
for driving in ahead direction only. It was exhausted
by two condensers, placed one on each side of it.
A shut off valve was fitted in each of the eduction
pipes leading off to the condensers. An emergency
governor was fitted to shut down steam to the turbine,
and simultaneously change over the exhaust from the
reciprocating engines to the condensers, should the
turbine speed become excessive through the breaking
of a shaft or some other form of accident.
Boilers: All the
boilers were 15 feet 9 inches in diameter, the 24
double ended boilers being 20 feet long and the single
ended 11 feet 9 inches long. Each double ended boiler
had six and each single ended boiler had 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 to the Board of Trade regulations and
had a working draught of 215 lb. Per square inch.