IMPROVE- MENTS IN STEAM ENGINES
Year: 1871

page_text: LETTERS PATENT to James Weir, of Glasgow, in the County of
Lanark, North Britain, Engineer, for the Invention of "IMPROVE-
MENTS IN STEAM ENGINES."
Sealed the 10th May 1872, and dated the 16th November 1871.
PROVISIONAL SPECIFICATION left by the said James Weir at the
Office of the Commissioners of Patents, with his Petition, on the
16th November 1871.
I, JAMES WEIR, of Glasgow, in the County of Lanark, North Britain,
Engineer, do hereby declare the nature of the said Invention for "Im-
PROVEMENTS IN STEAM ENGINES,” to be as follows, that is to say:-
This Invention has principally for its objects to provide for the more
easy and convenient starting and controlling of compound engines, and
to avoid severe strains, being also in part applicable with common or non-
compound engines.

page_text: Existing compound engines vary much in their cut-off arrangements
and in the mode of combining their different cylinders. In some cases
the engines are difficult to control at starting from deficiency of steam
pressure in the casings leading to the low-pressure cylinders, which
difficulty can be completely and satisfactorily overcome by means
described in the Provisional Specification lodged for the present appli-
cant on 22 July 1871 (No. 1936). In other cases however the difficulty
arises from the condenser vacuum not being low enough, or from there
being too great a back pressure; and this condition, which causes the
severest kinds of strain on the engines, generally occurs where the
steam is cut off at a comparatively early period of the stroke in the
cylinders.
By the present Invention the difficulty is overcome, according to one
modification, by introducing a valved communication between the valve
casing and the condenser, or between the valve casing of one low
pressure cylinder and that of the next lower cylinder when there are
more than two. The correcting valve is acted upon by a spring or
weight, or by a disc, diaphragm, or piston exposed to the atmosphere
externally, and suitably proportioned relatively to the valve according to
the arrangement of the engine; and on the back pressure increasing
above its proper limit, it opens the valve and allows the surplus pressure
to pass. With more than two cylinders the discs of the correcting
valves of the intermediate cylinder casings may be arranged to be acted
on by the steam from the casing of an antecedent cylinder.
It is in some cases desirable to apply to the correcting valve a piston
acted upon by steam from the casing of another cylinder in addition to
the disc exposed to the atmosphere, and it is also in some cases desirable
to apply in addition certain fixed pressures, which is done by means of
adjustable springs or weights.
By a second modification the excessive back pressure is neutralised by
placing common check or clack valves in passages between the cylinder
ends and the exhaust passage, and opening towards the cylinder when
the pressure in the exhaust passage, that is, the back pressure, is greater
than what should be the propelling pressure, but closing when the state
of the pressures is reversed.
When the engines are fitted with surface condensers, the difficulty of
starting arising from pressure in the condenser is by this Invention

page_text: overcome or reduced by the temporary use of a three-way eductor. This
eductor is a conical passage connected to the condenser steam space by a
pipe, and having within it two concentric conical nozzles, to the central
one of which a jet of steam is led direct from the boiler, whilst the inter-
mediate nozzle communicates by a pipe with the outlet of the circulating
water from the condenser. This eductor when put into action by
turning a cock on the steam jet pipe both sets the circulating water in
motion and sucks air out of the condenser.
Where this eductor cannot be conveniently applied a similar result
may be obtained by connecting pipes from the steam and water spaces of
the condenser to an auxiliary engine or donkey pump, the conjoint
pumping of the water with the air greatly facilitating the extraction of
the latter.
In both cases a check valve must be put in the pipe leading from the
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Weir in the Great Seal Patent Office on
the 15th May 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
WEIR, of Glasgow, in the County of Lanark, North Britain, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of November, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said James Weir, Her special licence that
I, the said James Weir, my executors, administrators, and assigns,
or such others as I, the said James Weir, my executors, adminis-
trators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN STEAM

page_text: to, and representing modifications of my improved arrangements. In
these Drawings the same reference numerals are used to mark the same
or like parts wherever they are repeated.
Figure 1, on Sheet 1, is a plan, and Figure 2 is a vertical section of a
set of compound engines with two inverted cylinders 1, 2, and the valved
communication or pipe 3 herein-before referred to is shown as applied
between the passage 4 by which the exhaust from the low-pressure
cylinder 2 passes to the condenser 5 and the receiver 6 which surrounds
the high-pressure cylinder 1, and is practically part of the low-pressure
valve casing 7. The correcting valve 8 in the pipe 3 is acted upon by a
spring 9 or weight, and by a disc or diaphragm 10, or a piston exposed
to the atmosphere externally, and suitably proportioned relatively to the
valve 8 according to the arrangement of the engines; and on the back
pressure (in this instance in the high pressure cylinder 1) increasing
above its proper limit, the valve 8 opens and allows the surplus pressure
to pass.
With more than two cylinders the discs (10) of the correcting
valves of the intermediate cylinder casings may be arranged to be acted
on by the steam from the casing of an antecedent cylinder.
It is in some cases desirable to apply to the correcting valve 8 a piston
acted upon by steam from the casing of another cylinder in addition to
the disc 10 exposed to the atmosphere, and it is also in some cases
desirable to apply in addition certain fixed pressures, which is done by
means of adjustable springs or weights.
By a second modification, shown in Figures 1 and 2 as applied to the
low-pressure cylinder 2, the excessive back pressure is neutralised by
placing common check or clack valves 11, 12, in passages 13 between
the cylinder ends and the exhaust passage 4, and opening towards the
cylinder when the pressure in the exhaust passage, that is, the back
pressure, is from any cause greater than what should be the propelling
pressure, but of course closing when the state of the pressures is
reversed.
When the engines are fitted with surface condensers (5) the difficulty
of starting arising from pressure in the condenser is by this Invention
overcome or reduced by the temporary use of a three-way eductor,
such as is shown in section in Figure 3, and as applied at 14 in Figure 1.
This eductor when put into action by turning a cock on the steam jet
pipe sets the circulating water in motion and sucks air out of the

page_text: condenser, discharging the whole by the outlet pipe 20, which in the
case of a steamship is led over or through the vessel's side. This eductor
comprises a conical passage 15 connected to the condenser steam space
by a pipe 16, and having within it two concentric conical nozzles
17, 18, to the central one (18) of which a jet of steam is led directly
from the boiler or steam pipe, whilst the intermediate nozzle 17
communicates by a pipe 19 with the outlet of the circulating water from
the condenser.
Where the eductor herein-before described cannot be conveniently
applied, a similar result may be obtained by connecting pipes 21, 22, as
shown in Figures 1 and 2, from the steam and water spaces of the con-
denser 5 to an auxilliary engine or donkey pump 23, the conjoint
pumping of the water with the air greatly facilitating the extraction of
the latter.
In both cases a check valve 24 must be put in the pipe 16, 21, leading
from the steam space of the condenser to prevent water going back
thereby.
Instead of the water passing from the condenser 5 through the
eductor 14 or pump 23, it may in some cases be preferable for the
eductor or pump to draw the water directly from the sea and force it
onwards to the water space of the surface condenser.
The application of my herein-before described arrangements for pre-
venting excessive back pressure is not confined to compound condensing
engines, but will also be of great advantage in the case of compound
engines without condensers. It is indeed the want of such arrangements
which has hitherto prevented the extended use of this class of engine.
Figure 4, on Sheet 2 of the Drawings, is a sectional plan, and Figure 5
is a transverse vertical section of an arrangement well adapted for a
locomotive steam engine, and comprising three cylinders 1, 2, 2. The
steam works first in the central or high-pressure cylinder 1, and then
equally in the two outside cylinders 2, 2, and the latter act on crank pins
at right angles to a crank on which the middle one 1 acts.
Figure 6 is an enlarged section showing the correcting valve 8, which
I employ in this case in a pipe 3 communicating from the intermediate
receiver 6 to one of the exhaust pipes 4. This valve 8 is controlled by
a suitably proportioned piston 10, to which the high-pressure steam has
access by a pipe 30, and opens when the back pressure in the high-

page_text: pressure cylinder 1, or what is the same thing the pressure in the
receiver 6, becomes from any cause greater than that for which the
valve is proportioned.
Having thus particularly described my said Invention, and the manner
in which the same is to be performed, I have to state that I do not
restrict myself to the precise details herein described or delineated; but
that what I believe to be novel and original, and claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,―
1. The applying of valves in connection with the intermediate casings
of compound engines, such valves allowing of the escape of steam when
the pressure becomes excessive, and being arranged and working sub-
stantially as herein described.
2. The preventing of an excess of back pressure in a steam cylinder
by placing valves in passages between the cylinder ends and the exhaust
passage, such valves opening towards the cylinder, substantially as
herein-before described.
3. The applying of a three-way eductor for removing air from the
condenser when about to start the engines, such eductor simultaneously
passing water through it to aid its action, substantially as herein-before
described.
4. The applying of an auxilliary or donkey pump to remove air from
the condenser when about to start the engines, water being allowed to
pass through such pump at the same time to facilitate its action, sub-
stantially as herein-before described.
In witness whereof, I, the said James Weir, have hereunto set my
hand and seal, this Seventh day of May, in the year of our Lord
One thousand eight hundred and seventy-two.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JAMES WEIR. (L.S.)