IMPROVEMENTS IN MARINE STEAM ENGINES
Year: 1857

page_text: PROVISIONAL SPECIFICATION left by James Alfred Limbert at the Office
of the Commissioners of Patents, with his Petition, on the 7th February
1857..
I, JAMES ALFRED LIMBERT, Engineer, Royal Navy, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN MARINE STEAM ENGINES,"
to be as follows:-
This Invention relates to a novel combination of the parts of marine
steam engines, by which such engines may be made of a given power, requiring
considerable less room in the ship, having less dead weight, being simpler in
construction, and less costly to manufacture, whilst the advantages of long
connecting rods, fewness of parts, and simplicity of construction, and ready
access to every working part or surface for facility of examination or repair
are retained.
The form of engine to which these improvements relate is that known as
the horizontal direct acting marine engine for driving the screw propeller, the
cylinders being on one side of the crank shaft, whilst the air pumps, con-
densers, hot well, bilge, feed, and other pumps are on the opposite side, and
thereby balance, the working of the engine, and the dead weight of the
materials; and assuming the size of an engine to be of .400 horse power,
comparative area or space required for the engine room of an engine con-
the

page_text: structed according to this Invention, and the most compact direct action screw
engines by the two most celebrated Government contractors, taking as an
example the engines of H.M. ship Princess Royal and H.M. ship Cæsar,
would respectively be represented by Princess Royal, 553-5 sq feet, the
Cæsar, 514.5 sq ft, whilst the improved engine would require only 355.2
sq ft, which would, assuming the height of the bunkers to be 20 ft, give
an additional space sufficient to store, in the one case, 82-6 tons, and in the
other, 66-3 tons more coals.
I obtain the advantages which belong to this Invention by adopting the
ordinary form of horizontal cylinder and piston, instead of the trunk arrange-
ments; and I employ two piston rods, but instead of placing them vertically
one above the other over the crank, or as heretofore constructed, I place the
two piston rods diagonally one on each side of the crank, one above and the
other below the crank shaft; I connect or secure the outer ends of these rods
by means of a cross head, which, working horizontally, has a journal for the
connecting rod end in the centre of its length; on each side of which centre
bearing there is a guide block which works in a suitable flat or V guide over
the condensers and air pump, and the ends of the cross heads are so formed or
constructed that the one is turned upward, and the other downward, forming
lugs or bosses, through which the ends of the piston rods pass, and wherein
they are secured.
Thus, instead of forming the guide bearings at the outside or extreme ends,
or having only one bearing or guide in the centre of the cross head, I have
two bearings, and bring them within the extreme ends, and so divide the
strain, equalize the wear, and economize space, whilst each part can be readily
got at.
I am enabled by this arrangement, and the novel construction of condenser
apparatus arranged on the opposite side of the crank shaft to that upon which
the steam cylinders are, to bring the steam cylinders close together side by
side, and thus to give greater stability as well as compactness to the engine.
I work the air pump belonging to each cylinder direct from the steami
piston by means of a rod working through a stuffing box in the cylinder
cover, and I use a double acting pump with valves suitable to such form of
pump, but I arrange the foot valves on the one side of the pump, whilst the
delivery valves are placed on the other side of the condenser, and these
delivery valves are connected with the corresponding sides of the air pump
by means of a passage across the condenser.
I work each of the slide valves of the steam cylinders which are double
ported by means of a weigh shaft supported in a single long bearing formed

page_text: by a pedestal cast on the front part of the air pump jacket or frame, the slides
being worked by the eccentric gearing in the ordinary way.
The expansion valve gearing is placed in the centre or between the engines,
instead of on the outsides.
.
I work the starting gear by means of a horizontal instead of a vertical
wheel; I combine the throttle, blow-through, expansion valves, and injection
cock handles, together with the starting gear levers, and the pressure and
vacuum guages, and other indicating or recording instruments or apparatus
may be fixed on the same standard or pedestal.
I require only three bearings for the crank shaft constructed according to
my Invention.
By the arrangement of a high hot well in the centre or between the two
condensers and air pump, and by the arrangement of passages across the
condenser connecting the air pumps with the delivery valves, as before
described, I am enabled to give larger cubical contents to the hot well, thus
forming a kind of air vessel, by which the strain upon the air pumps will be
reduced.
By this arrangement the delivery valves at the bottom of the hot well are
at the lowest level of the condenser, which is of great advantage in working,
and enables a better vacuum to be maintained than where they are above the
condenser space, and above the level of the air pumps.
In consequence of placing the air pumps on each side of the hot well, and
condensers on the outside of the engine, greater freedom of access is obtained
to every part of the air pump, as also to the foot valves and passages, the
doors or covers of which being at the bottom of the frame and unincumbered,
may be removed without disturbing any other part of the engine.
I convey the steam from the boilers by means of a single steam pipe,
having a double bend, connecting by a T-piece or pipe the two cylinders, and
within the T-piece I. arrange the valves by which the admission of steam is
regulated, and may be admitted to both or only one of the cylinders.
I connect the exhaust passages of the two cylinders by means of a large
exhaust pipe connecting them with the condenser, and within the exhaust
pipe I provide, by means of a semicircular disc or plate for closing or shutting
off communication with either engine, in case of accident or when from any
cause only one engine is in use.