IM- PROVEMENTS IN SINGLE EXPANSIVE CONDENSING STEAM ENGINES, PARts of WHICH ARE ALSO APPLICABLE TO OTHER ENGINES.
Year: 1874

page_text: LETTERS PATENT to Henry Percy Holt, of Royal Insurance Buildings,
Leeds, in the County of York, Engineer, for the Invention of “IM-
PROVEMENTS IN SINGLE EXPANSIVE CONDENSING STEAM ENGINES, PARts of
WHICH ARE ALSO APPLICABLE TO OTHER ENGINES.'
77
Sealed the 16th March 1875, and dated the 21st September 1874.
PROVISIONAL SPECIFICATION left by the said Henry Percy Holt
at the Office of the Commissioners of Patents, with his Petition,
on the 21st September 1874.
·I, HENRY PERCY HOLT, of Royal Insurance Buildings, Leeds, in the
County of York, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN SINGLE EXPANSIVE CONDENSING STEAM
ENGINES, PARTS OF WHICH ARE ALSO APPLICABLE TO OTHER ENGINES," to be as
follows:-
This Invention has reference to an improved steam engine, and consists
in the use of,-
Firstly. Short multiple ports, in number from 2 to 10 (in both the
cut-off plate and back of main valve faces), at an incline of about 2 to 1

page_text: with the longitudinal centre line of steam chest, which ports run in the
thickness of valve into ports (on the cylinder face of valve) of the usual
form. Both these main and cut-off valves are worked each by a separate
eccentric as usual. To vary the expansion transverse motion is imparted
to the cut-off plate in some cases direct from the governor thro' the
medium of a lever, which at one end is forked so as to slide freely in the
sliding chase on the governor spindle, and at the other is attached to the
cut-off spindle, so as to allow the necessary reciprocating motion of its
travel, but to communicate the rise or fall of governor balls for twisting
or swivelling on its axis the cut-off spindle. In order to avoid undue
friction a swivel with central points is introduced between the cut-off
spindle and eccentric rod, and also on the governor lever. The governor
has a displacement cataract, usually containing oil, and the balls play or
roll in parabolic slots, and their movements are communicated to the
sliding chase by means of a double cross head, in which are straight
slots, in which the pins passing thro' the centres of the balls engage;
their exact vertical motion is thus communicated to the lever before
named. In other cases the governor has an auxiliary single or combined
steam or hydraulic apparatus to increase its power for moving the cut-off
plate transversely. In some cases the hydraulic apparatus is worked
from the engine force pump air vessel, and the exhaust water carried
into the boiler. To prevent the valve or cut-off plates wearing unevenly
on the overlapping edges sometimes the plate is provided with slips of
metal, toothed either rectangularly or diagonally into each side of it, and
tongued longitudinally into back of valve in such a manner as to be
carried longitudinally by the motion of the plate, sufficient clearance at
the ends of teeth being allowed for the transverse motion of plate
without affecting the longitudinal motion of the slide slips. At other
times the cut-off plate is made of hard metal and wider than the valve,
and the valve of softer metal.
Secondly. The exhaust valves are actuated by steam pistons and con-
trolled by dash pots, or check straps, or chains in the chest. These
valves are double-ported, one being in communication as usual with the
condenser, and the other with an exhaust steam heater for warming feed
water, the atmosphere, or blast pipe for boiler draught. These ports are
so arranged that at the proper time for exhausting momentary com-
munication is made first with the. atmosphere, secondly for a period
nearly to the end of return stroke solely with condenser, thirdly

page_text: momentarily (after condenser is closed) with the exhaust to heater. By
this means the vacuum is destroyed (by return steam from passage),
cylinder reheated, and a partial cushion obtained by compression of this
steam. This piston and dash pot arrangement is also applicable for
working the admission and expansion valves.
Thirdly. The cylinder lining is of steel, and in order to reduce the
thickness as low as possible the side to the jacket space is stiffened by
longitudinal and transverse webs or ribs which form cells. In some
cases, in place of this the web is formed spirally round the lining, but in
either case the lining has a much larger amount of surface for absorbing
heat from its steam jacket than for giving off on the surface of bore of
cylinder.
Fourthly. The waste water valves are kept closed when the engine is
at work by steam pistons (which replace the springs ordinarily used)
proportionately in area a little over that of the valves. These pistons
work in cylinders having passages communicating with the steam chest.
They are thus under the control of the main stop valve of the engine,
and require no separate gear of their own to control them, but are
automatic in their action under all varying pressures. The valves are
consequently open when the engine is standing. This part is applicable
to all engines.
Fifthly. The condenser injection valve for regulating quantity of
injection water is connected with a metallic corrugated diaphragm (of
larger area than the valve) having the vacuum on the under and the
atmosphere on the top side of it. The tendency to give before the
atmospheric pressure due to this difference in area is balanced at a
perfect vacuum by means of springs, so that the injection vaive is then
nearly closed; consequently on the vacuum deteriorating the injection
valve opens, or vice versa, and thus automatically regulates the quantity
of injection water required. A fluid cateract is used to moderate the
action of the diaphragm against sudden changes.
Sixthly. The connecting rod small end bushes are eased off on eacli
side of the joint for a distance subtending arcs of 45° sideways, and the
pin has a flat formed on each side of it rather greater than the chord of
these ares when the crank is on the dead centres. At each stroke the
edges consequently overlap cach other, and the pin cannof wear oval.

page_text: In some cases the pin is expanded by wedges instead of closing the
bushes.
Seventhly. One or more broad fly wheels with the same number of
shrouds round it as the shafts to drive, so as to form chases for one belt
to drive each different shaft radially in any convenient direction, but by
preference diametrically opposite to each other. These shrouds have
grooved cross bars so placed that they can rotate thro' them (the
grooves) without friction, and are placed so as not to interfere with the
belts running on the fly wheel, their object being in case of a belt
breaking to prevent its interfering with the remainder.
All these improvements are likewise annlicable to other ancine
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Percy Holt in the Great Seal Patent Office
on the 20th March 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
PERCY HOLT, of Royal Insurance Buildings, Leeds, in the County of
York, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of September, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Henry Percy Holt, Her special licence
that I, the said Henry Percy Holt, my executors, administrators,
and assigns, or such others as I, the said Henry Percy Holt, my
executors, administrators, 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 SINGLE EXPANSIVE CONDENSING STEAM ENGINES, PARTS OF
WHICH ARE ALSO APPLICABLE TO OTHER ENGINES," upon the condition (amongst
others) that I, the said Henry Percy Holt, my executors or admini-
strators, by an instrument in writing under my, or their, or one of
their hands and scals, should particularly describe and ascertain the

page_text: nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said Henry Percy Holt, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement:-
This Invention has reference to an improved steam engine, and consists
in the use of,-
Firstly. Short multiple ports in both the cut-off plate and back of
main valve faces, in number from two to ten, at an incline of about two
to one with the longitudinal centre line of steam chest, which ports in the
main valve run in its thickness into ports (on the cylinder face of value)
of the usual form. Both these main and cut-off valves are worked each
by a separate eccentric as usual. To vary the expansion, transverse
motion is imparted to the cut-off plate (which increases or diminishes
the lap) in some cases direct from the governor through the medium of
a lever, which at one end is forked so as to slide freely in the sliding
chase on the governor spindle, and at the other is attached to the cut-off
spindle, so as to allow the necessary reciprocating motion of its travel,
but at the same time to communicate the rise or fall of the governor
balls to twist or swivel on its axis the cut-off spindle, which by means
of a rack and segment or otherwise transmits a transverse motion to the
cut-off plate. In order to avoid undue friction a swivel with central
adjustable points is introduced between the cut-off spindle and eccentric
rod, and also on the governor lever. The governor has a displacement
cataract, usually containing oil, but any suitable liquid may be used.
This cataract consists of a piston working freely (but fitting) in a vertical
cylinder. In this piston is one or more adjustable openings; the top
requires no cover, but is made open to the atmosphere. The governor
balls play or roll in parabolic slots, and their motion is communicated to
the sliding chase by means of a double cross head, at the ends of which
are straight slots in which the pins passing through the centres of balls
or flat weights engage. Their exact vertical motion is thus communicated
to the lever before named. In other cases the governor is replaced by a
combined steam or hydraulic apparatus to traverse the cut-off plate.
•

page_text: The governor may be entirely omitted, and the boiler feed pump which
must be double-acting, and have an air vessel. This pump is driven by
the engine, and arranged to pump through a cylinder provided with a
piston or plunger (which is connected to the cut-off plate in the same
manner as the governor, or otherwise) and stuffing box, which piston or
plunger is loaded by means of a steam or water piston or plunger
(connected with the boiler or feed pipe) of larger area than the one
before named, the area of exit from which to the boiler is regulated by
a valve to obtain the required speed of engine. To prevent the valve
or cut-off plates wearing unevenly on the overlapping edges, sometimes
the plate is provided with slips of metal toothed either rectangularly or
diagonally into each side of it, and tongued longitudinally into back of
valve in such a manner as to be carried longitudinally by the motion of
the plate, sufficient clearance at the ends of teeth being allowed for the
transverse motion of plate without affecting the longitudinal motion of
the side slips. At other times the cut-off plate is made of hard metal
and wider than the valve, and the valve of softer metal.
Secondly. The exhaust valves are actuated by steam pistons and con-
trolled by dash pots, check straps, or chains in the chest. These valves
are double-ported, one port being in communication as usual with the
condenser, and the other with an exhaust steam feed water heater blast
pipe to increase boiler draught, or a low-pressure boiler or regenerator,
from which the steam may be used for manufacturing purposes. The
ports are so arranged that at the proper time for exhausting, momentary
communication is made, first, with the heater until the end of the
stroke; secondly, for a period nearly to the end of return stroke with the
condenser solcly; thirdly, momentarily (after opening to condenser is
closed) with the exhaust to heater. By this means the vacuum is
destroyed (by return steam from heater), and a partial cushion obtained
by compression of this steam before admission of boiler steam. In high-
pressure non-condensing engines, in lieu of the regenerating boiler
named above, I prefer to work the engine at about 120 lbs. pressure,
expand from four to six times in the cylinder, and exhaust into a boiler
working at from 20 to 30 lbs. pressure.
This boiler has a furnace, the
combustion in which is regulated by the pressure in the boiler from a
which the steam is used for manufacturing purposes. This piston
arrangement is also applicable for working the admission and expansion
valves.

page_text: Thirdly. The cylinder lining is of steel, and in order to reduce the
thickness as low as possible the side to the jacket space is stiffened by
longitudinal and transverse webs which form cells. In some cases in
place of this the web is formed spirally round the lining, but in cither
case the lining has a much larger surface for absorbing heat from the
steam or hot-water jacket than the bore of the cylinder. The spiral
form is specially applicable for hot-water jackets, the water circulating
from end to end. These forms of construction may also be used in other

page_text: ports in main valve, single on cylinder or front face and multiple at an
angle of about 2 to 1, with line of motion of main valve on back face;
d, d, ports in cut-off valve, corresponding with ports in back of slide

page_text: longitudinal centre line of valve spindle, which can be applied in any
steam chest of ordinary dimensions, and the improved arrangements for
connecting the governor and eccentric rod to lessen friction and uneven
wear of cut-off plate.
Secondly. The separate or combined arrangement of vertical cataract
and double cross head, by which the exact vertical motion of the balls is
communicated to the connecting parts of expansion gear; also when
hydraulic power is required, the use of a cylinder, piston, and adjusting
valve (which take the place of the governor), through which the water
from the engine feed pump is passed on its way to the boiler. (The
quantity passing through this cylinder regulates the time of cut-off in
the same manner as an ordinary governor.
Thirdly. The arrangement for working exhaust valves so as to utilise
part of the exhaust steam for heating or manufacturing purposes in
condensing engines without interfering with the vacuum, and some of
this exhaust steam to cushion the reciprocating parts in lieu of steam
from boiler, and in non-condensing engines the use of a secondary boiler
at a lower pressure to exhaust into (in place of a heater), from which
steam is used for manufacturing purposes as before.
Fourthly. The use of a thin cylinder lining having on its outer
surface cellular or spiral webs or ribs. through which the steam or hot
water circulates, exposing more surface to absorb than to give off heat.
Fifthly. The arrangement of waste water and relief valves, which
open
automatically at any given proportion of plus or minus pressure in the
cylinder to that in the steam chest, according to requirements of the
engine, and which in all cases open automatically when the engine stands
without working cocks.
Sixthly. The combined or single arrangement of automatic injection
valves regulated by the vacuum (which also controls the speed of air
pump when a separate engine is used to work it), and the surface con-
denser worked by the hot well water under atmospheric pressure, by
which means much less water is required for condensation.
Seventhly. The arrangement of connecting rod ends, which can be let
together without taking down or removing the bolts, and prevents small
ends from wearing the pin oval.

page_text: Eighthly. The arrangement for driving several shafts in contrary
directions off the fly wheel by means of belts, and preventing accidents
n case of a belt breaking.
All these arrangements I claim essentially, as or after the manner of
the foregoing descriptions and Drawings, Figured 1 to 23.
In witness whereof, I, the said Henry Percy Holt, have here-
unto set my hand and seal, this Nineteenth day of March, in
the year of our Lord One thousand eight hundred and seventy-
five.
Witness,
GEO. DOWNING.
HENRY PERCY HOLT. (L.S.).