AN IMPROVED THREE CYLINDER RADIAL DOUBLE-ACTING COMPOUND CONDENSING OR NON-CONDENSING STEAM ENGINE
Year: 1877

page_text: LETTERS PATENT to William Cooper, Chief Engineer, Peninsular & Oriental
Steam Navigation Company, and of No. 7, The Green, Romford Road, Stratford,
in the County of Essex, for the Invention of " AN IMPROVED THREE CYLINDER
RADIAL DOUBLE-ACTING COMPOUND CONDENSING OR NON-CONDENSING STEAM
ENGINE"
Sealed the 15th February 1878, and dated the 24th September 1877.
PROVISIONAL SPECIFICATION left by the said William Cooper at the
Office of the Commissioners of Patents on the 24th September 1877.
WILLIAM COOPER, Chief Engineer, Peninsular & Oriental Steam Navigation
Company, and of No. 7, The Green, Romford Road, Stratford, in the County of
Essex. "AN IMPROVED THREE CYLINDER RADIAL DOUBLE-ACTING COMPOUND
CONDENSING OR NON-CONDENSING STEAM ENGINE."
The Invention or improvements claimed are in the special arrangements of the
three cylenders, the connections of piston rods to crank or disc, and the slide valve
gear of engines generally known as the inverted cylinder type.
I place two high-pressure cylenders, of proportionately small diameters, radially
from centre of engines, on each side of the low-pressure cylender. Each
high-pressure cylender to be from 20 to 40 degrees from centre of low-pressure
cylender, but I specially recommend them to be placed at 30 degrees from centre of
low-pressure cylender, as this enables the leading engine to exhaust its steam direct
into the slide casing of L. P. cylender in time to supply steam for cushioning the piston,
and follow it up, thus giving a free and direct exhaust from the eduction side
of H. P. cylender to steam side of L. P. piston throughout the stroke, whilst the
exhaust from the following H. P. has a free and direct passage to the steam side of
the L. P. piston immediately the exhaust opens, thus enabling the L. P. cylender to
get the exhaust steam of both H. P. cylenders at each end of the stroke; and the
two H. P. cylenders being 60 degrees apart, and all connections to one crank pin,
does away with all dead points either going ahead or astern, and thus dispensing

page_text: with the use of auxillary starting valves on the L. P. cylenders, whilst reversing or
starting at any point of the stroke is made certain by the full pressure of steam
acting on one of the H. P. pistons when the other is at the end of its stroke.
The centre or low-pressure connecting rod is formed with the usual gudgeon
bearing on the top, and at the bottom is a butt end in which fits the crank pin brasses,
and on each side of the butt, squared off to the angle of H. P. cylenders, is fitted
a cap which is bolted to the butt, and these parts being then bored out and lined up
with a suitable metal bush forms the joints for the two H. P. connecting rods to the
centre rod at the bottom ends, so that the H. P. rods are attached to the bottom of
L. P. connecting rod, and not to the crank pin direct, there being only one pair of
crank pin brasses for all three cylinders.
The cylenders being set radially from centre of crank shaft requires only two
eccentrics to work the reversing link motion, one rod being rigidly fixed to each
eccentric strap, the others all jointed on each side at their respective angles; or for
small engines of, say, below 10 H. P., I would recommend only one eccentric of the
type known as the sleeve shifting eccentric for reversing engines; but when
these compound engines are required to go only one way, one eccentric is sufficient
to work all three slide valves; if for condensing engines, the usual ordinary lever
gear can be attached, or separate motive power supplied to work the air & circulating
pumps.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Cooper in the Great Seal Patent Office on the 23rd March
1878.
WILLIAM COOPER, Chief Engineer, Peninsular and Oriental Steam Navigation
Company, and of 7, The Green, Romford Road, Stratford, in the County of Essex.
"AN IMPROVED THREE CYLINDER RADIAL DOUBLE-ACTING COMPOUND CON-
DENSING OR NON-CONDENSING STEAM ENGINE."
My said Invention relates to three cylinder radial double-acting compound
condensing or non-condensing steam engines, and consists,--
First. Of an improved arrangement or disposition of the three cylinders.
Secondly. Of a peculiar arrangement of the slide valve gear.
And, Thirdly. Of a peculiar arrangement of the connections of the several piston
and connecting rods with the crank pin.
By my improvements I dispense with the necessity for steam receivers and
auxiliary starting valves on the low-pressure cylinder, and I entirely obviate all
dead points of the crank, whether going ahead or astern, whilst at the same time I
am enabled to utilize completely the full power of the exhaust steam from the
eduction ports of the two high-pressure cylinders throughout the stroke of the low-
pressure piston. I obtain moreover all the advantages of triple-connected engines,
whilst occupying only the fore-and-aft space of a single-cylinder engine.
And in order that my said Invention may be fully understood, I shall now proceed
more particularly to describe the same, and for that purpose shall refer to the several

page_text: Figures on the explanatory Sheets of Drawings hereunto annexed, the same letters.
of reference indicating corresponding parts in all the Figures.
Figures 1 and 2 (Sheet 1) represent respectively a back and front elevation of my
improved engine; Figures 3 and 4 (Sheet 2) represent respectively a plan and end
elevation of the same; and Figure 5 (Nos. 1, 2, 3, 4, and 5) illustrates in detail the
arrangements of the three connecting rods attached to one crank journal.
On referring to Figures 1, 2, 3, and 4, it will be seen that I place two high-pressure
cylinders A, A, of proportionately small diameters, on each side of the low-pressure
cylinder B, and dispose them radially from the centre of the crank shaft, such high-
pressure cylinders A, A, being from 20 to 40 degrees from the centre line of the low-
pressure cylinder B, this being the margin on which I base my claim for the
disposition or arrangement of my high-pressure cylinders in regard to the low-
pressure cylinders, but I specially recommend them to be placed at 30 degrees from
the longitudinal centre line of each high-pressure cylinder to the axial centre line of
the low-pressure cylinder, as shown in Figures 1 and 2, as this enables the leading
engine, whether going ahead or astern, to exhaust its steam direct into the slide
valve chest of the low-pressure cylinder just in time to supply steam for cushioning
the low-pressure piston on its centre, and then following up the piston throughout
the stroke, thereby dispensing with the necessity for a receiver, giving a free and
direct exhaust from the eduction side of the high-pressure cylinder to the steam side
of the low-pressure cylinder, and obtaining the full force of action of the expanded
steam on the low-pressure piston, whilst the exhaust steam of the following high-
pressure cylinder has a free and direct passage to the steam side of the low-pressure
piston, thus enabling the low-pressure piston to receive the full force of the exhaust
and partially expanded steam of both the high-pressure cylinders at each end of
the stroke.
The two high-pressure cylinders A, A, being placed at 30 degrees from the centre
of the low-pressure cylinder B, their centre lines will form an angle of 60 degrees;
consequently when one is on the centre the other has nearly its full power, and has
completely its full pressure of steam, and since all the piston rod connections are
attached to one crank journal, and the three cylinders are radially disposed from the
centre of the crank shaft, it follows that all dead centres are obviated and the use of
auxiliary starting valves on the low-pressure cylinder dispensed with, whilst the
operations of starting and reversing the engines are made certain by reason of the
full pressure of steam being on one or other of the high-pressure pistons at its most
effective part of the stroke should the other one be on the centre, thus dividing the
power of the three cylinders at such points of the crank radius that they help each
other over their respective centres, and obviate the difficulty of starting or reversing
so often experienced with two-cylinder compound engines of the ordinary type, or
even with a pair of double-cylinder engines, where the high-pressure cylinder is
fitted on to the top of the low-pressure cylinder.
As the cylinders are set radially from the centre of the crank shaft only two
eccentrics C, C, are required to work the reversing link motion (see Figures 2 and 4),
the two rods of the low-pressure link being rigidly fixed to their respective eccentric
straps, whilst the high-pressure rods are jointed at their respective angles to their
corresponding straps; or, for small launch engines, the reversing can be effected by a
single sleeve eccentric. For larger engines however of over 20 horse-power, I prefer
to employ a separate pair of eccentrics to work the low-pressure slide valves, as this
would allow the valve casings of the high-pressure cylinders as well as the travel of
their valves to be shortened.
The peculiar arrangement of the three connecting rods will be clearly seen on
referring to Figure 5, wherein Nos. 1, 2, and 3 are the top joints; No. 4, a front
view in half section, showing my new arrangement, wherein I attach both of the
high-pressure connecting rods to the butt of the low-pressure or centre rod; and No.
5 is an end sectional view of the butt end of the centre or low-pressure connecting
rod and brasses; H, H, are the crank pin brasses; E, E, the gudgeon bearings of the

page_text: high-pressure connections; and F, F, the caps for setting up the brasses; hence it
will be seen that the low-pressure connecting rod is formed with the usual gudgeon
bearings on the top ends, and is provided at the bottom with a butt end, within
which fit the crank pin brasses, whilst on each side of the butt, squared off to the
angle of the high-pressure cylinders, there is fitted a cap which is bolted to the butt,
and these parts being bored out and lined up with a suitable metal bush form the
jointed connections of the two high-pressure connecting rods to the centre rod at the
lower ends, so that the high-pressure rods are attached to the bottom of the low-
pressure connecting rod, and not to the crank pin direct, by which arrangement only
one pair of crank pin brasses are required for all three cylinders. I also fit changing
valves or three-way cocks at the exhaust pipe joints G, G, of the high-pressure
cylinders (Figures 1, 2, 3, and 4), in order to turn the exhaust steam into the
condenser or into funnel, as the case may be, of a condensing or non-condensing
engine, and adapt a separate steam pipe and stop valve to the low-pressure slide
casing with a view to convert these engines from compound to simple engines in a
few moments, or vice versa, for the especial use of war steamers, gunboats, and the
like, so that when converted into simple engines, the power of each cylinder being
independent of its neighbour, the engines can be started and manoeuvred with a very
low pressure of steam for either condensing or non-condensing engines, thus avoiding
the danger and necessity of using high-pressure steam during an action, whilst, if
required to go full speed again, the engines could be immediately converted into
compound engines possessing all the advantages of highly expanded steam and
saving of fuel.
If a separate condenser and air-circulating pumps be fitted in the gunboats or
war steainers provided with these engines, the said pumps could be kept going
during the whole time the engines were stopped, and so maintain the vacuum in
the condenser, the engines being then capable of working as required in action, with
steam in the boilers below the atmospheric pressure, so that should a shot strike the
boilers a wooden shore and a gunny bag would repair the damage; but should a shot
strike a boiler with high-pressure steam, the bursting of the boiler would most
probably completely disable the ship. By the use of a separate air and circulating
pump these engines could be run with perfect safety at a speed far exceeding that
which would be suitable for the working of the pumps.
For large naval engines as at present in use I substitute two of my improved
engines of suitable power, geared on each side of the propeller shaft, the large spur
wheel being fitted on the screw shaft and the pinions on the engine shafts. By this
arrangement I obtain the same power in about half the space heretofore required,
and with the same proportionate reduction of weight over the ponderous steam
engines now in use, whilst I at the same time effect a greater economy of fuel.
For the merchant service (if these engines be required to be condensing) the usual
side lever attachments could be fitted to the low-pressure piston gudgeon, or, as
before mentioned for the navy, a separate air and circulating pump could be
employed.
Having now described and particularly ascertained the nature of my said Invention,
and the manner in which the same is or may be used or carried into effect, I would
observe in conclusion that what I consider to be novel and original, and therefore
claim as the Invention secured to me by the herein-before in part recited Letters
Patent is,-
First. The peculiar construction and arrangement of triple cylinder engines, sub-
stantially as herein-before described, and illustrated by the Drawings hereunto
annexed.
Secondly. The placing the two high-pressure cylinders one on each side of the low-
pressure cylinder, radially from the centre of the crank shaft and at angles from the
centre of the low-pressure cylinder, ranging from 20 to 40 degrees or thereabouts,
substantially as and for the purpose herein-before described, and illustrated by my
Drawings.

page_text: Thirdly. The peculiar combination and arrangement of the connecting rod,
unions at the lower ends of such rods, substantially as and for the purpose herein-
before described, and illustrated by Figure 5 (Nos. 4 and 5) of my Drawings.
Fourthly. The peculiar arrangement for applying my said improved engines to
ships of war, gunboats, and the like, substantially as herein-before described.
In witness whereof, I, the said William Cooper, have hereunto set my hand
and seal, this 18th day of February, in the year of our Lord One thousand
eight hundred and seventy-eight.
WILLIAM COOPER. (LS.)