IMPROVEMENTS IN VALVE GEAR FOR STEAM ENGINES
Year: 1880

page_text: LETTERS PATENT to George Low, of Bishop's Hill, Ipswich, in the County of
Suffolk, and Edmund Joseph Davies, of Orwell Works, Ipswich aforesaid, for
an Invention of "IMPROVEMENTS IN VALVE GEAR FOR STEAM ENGINES."
PROVISIONAL SPECIFICATION left by the said George Low and Edmund
Joseph Davies at the Offico of the Commissioners of Patents on the 6th July
1880.
GEORGE LOW, of Bishop's Hill, Ipswich, in the County of Suffolk, and EDMUND
JOSEPH DAVIES, of the Orwell Works, Ipswich aforesaid. "IMPROVEMENTS IN
VALVE GEAR FOR STEAM ENGINES."
This Invention has for its object improvements in the valve gear of steam
engines, and relates more particularly to a novel construction of a single rotating
valve, by means of which the admission of the steam and the exhaust are controlled,
and the degree of expansion may be adjusted at pleasure while the engine is
running; also to the combination of a rotating valve for the admission only of
the steam, with separate rotating or other valves for the exhaust; and, lastly, to
the combination of the single valve, or the three valves above mentioned, with
the governor of the engine, so as to form as a whole an automatic expansion
gear.
In our improvements we form the port face on the cylinder concave to receive a
cylindrical tube, which tube is the valve. The steam ports are two right angled
triangles, with the bases at right angles with the axis of the valve, and the perpen-
diculars parallel therewith, the apexes of the triangles both pointing in the same
direction. Openings or ports are cut through the thickness of the tube of similar
figure (that is, in the form of similar right angled triangles) but not necessarily of
equal dimensions with those in the port face, and with the apexes of the triangles
pointing in the opposite direction. The openings in the tube are diametrically
opposite to each other, and are so disposed in the length of the tube that when the
latter is rotated each opening in the tube will pass over a port on the cylinder.
The valve is rotated in such a direction, and the triangular openings in the tube
and port face are relatively so disposed, that the opening of the ports takes place
along that side of the triangle which is parallel with the axis of the valve, the
closing of the ports being effected along the slanting side.

page_text: Now, by shifting the valve longitudinally along the port face so that the points
of the triangular openings approach each other the ports may be made to close
earlier, and if the longitudinal movement be continued far enough the ports would
not open at all. Whatever amount of longitudinal movement be given to the valve
the opening of the ports will always commence at the same part of the revolution
of the valve, because the edges of the ports and the openings in the valve which
rule the opening of the port are parallel with the axis of rotation, in other words,
the "lead" will be constant for all degrees of expansion.
For the exhaust we form the usual rectangular exhaust port midway between
the above described triangular steam ports on the port face of the cylinder, and on
the exterior of the valve recesses are formed-(in-the-thickness of the tube) for the
purpose of connecting the port at the exhaust end of the cylinder with the central
exhaust port from the time (or it may be a little before) the opposite steam port
begins to admit steam up to the end of the stroke, or thereabout.
The valve is driven direct from the crank shaft of the engine by mitre wheels,
and consequently makes the same number of revolutions as the crank. The shaft
which conveys the motion is made in two parts, with one part to slide upon the
other, so as to admit of the valve being moved longitudinally while in rotation.
A hand lever with suitable locking arrangement may be applied to the moveable
part of the driving shaft, and the valve, as above described, may be used as the
starting valve of the engine.
-Upon-the stationary part of the driving shaft a centrifugal governor may be
formed, and the longitudinal movement of the sliding part-placed under its control
(or any of the known forms of governors may be otherwise applied), whereby thic
regulation of the admission of steam to the cylinder in proportion to the power
required then becomes automatic.
In some cases we prefer to combine a rotating valve, similar to that above
described, with separate valves for regulating the exhaust. In such cases the
rotating valve has merely the two triangular steam passages through it and no
recesses on its exterior surface, and the port face on the cylinder has only the two
triangular steam ports. Each of the steam passages leading to the ends of the
cylinder is connected by a branch passage with a central or common exhaust
passage. A valve is placed in each passage to close the exhaust passage while
steam is entering the cylinder. We prefer to give these valves a reciprocating
motion (although they may have rotary motion), as both valves may be actuated
by the same rocking shaft, and the movement is very conveniently derived from an
excentric on the driving shaft of the rotating valve; the setting of the excentric
and a suitable proportioning of the length of the lever upon the rocking shaft afford
facility for accurately timing the opening and closing of the exhaust passages and
giving any desired amount of compression.
Our improvements further afford great facility for providing means for reversing
the motion of the engine when required. For this purpose we mount two mitre
wheels loosely upon the crank shaft of the engine, both these wheels being
permanently held in gear with the mitre wheel fixed upon the driving shaft of the
rotating valve. Between the two wheels upon the crank shaft is a clutch sliding upon
a feather so as to engage either wheel at pleasure. Now if the clutch be thrown
from one wheel to the other and the motion of the crank be reversed at the same
time, it will be seen that the driving shaft of the rotating valve will revolve in the
same direction as before. The surfaces of contact upon the clutch and upon each of
the wheels which it engages are so adjusted that whichever wheel is driving the
"lead" will be the same, so that the engine will have the same distribution of
steam whichever way the crank is running.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Low & Edmund Joseph Davies in the Great Seal Patent
Office on the 6th January 1881.
GEORGE Low, of Bishop's Hill, Ipswich, in the County of Suffolk, and EDMUND
JOSEPH DAVIES, of the Orwell Works, Ipswich aforesaid.
VALVE GEAR FOR STEAM ENGINES."
"IMPROVEMENTS IN
This Invention has for its object improvements in the valve gear of steam
engines, and relates more particularly to a novel construction of a single rotating
valve by means of which the admission of the steam and the exhaust are controlled
and the degree of expansion may be adjusted at pleasure while the engine is
running; also to the combination of a rotating valve for the admission only of the
steam, with separate rotating or other valves for the exhaust; and lastly, to tho
combination of tho single valve or the three valves above mentioned with the
governor of the engine so as to form as a whole an automatic expansion gear.
In our improvements we form the port face on the cylinder concave to receive a
cylindrical tube, which tube is the valve. The steam ports are two right angled
triangles, with the bases at right angles with the axis of the valve and the
perpendiculars parallel therewith, the apexes of the triangles both pointing in the
same direction. Openings or ports are cut through the thickness of the tube of
similar figure (that is, in the form of similar right angled triangles), but not
necessarily of equal dimensions with those in the port face, and with the apexes of
the triangles pointing in the opposite direction. The openings in the tube aro
diametrically opposite to each other, and are so disposed in the length of the tube
that when the latter is rotated each opening in the tube will pass over a port on
the cylinder. The valve is rotated in such a direction, and the triangular openings
in the tube and port face are relatively so disposed, that the opening of the ports
takes place along that side of the triangle which is parallel with the axis of the
valve, the closing of the ports being effected along the slanting side.
Now, by shifting the valve longitudinally along the port face so that the points
of the triangular openings approach each other the ports may be made to close
earlier, and if the longitudinal movement be continued far enough the ports would
not open at all. Whatever amount of longitudinal movement be given to the
valve the opening of the ports will always commence at the same part of the
revolution of the valve, because the edges of the ports and the openings in the valve
which rule the opening of the port are parallel with the axis of rotation; in
other words, the "lead" will be constant for all degrees of expansion.
For the exhaust wo form the usual rectangular exhaust port midway between the
above described triangular steam ports on the port face of the cylinder, and on the
exterior of the valve recesses are formed (in the thickness of the tube) for the
purpose of connecting the port at the exhaust end of the cylinder with the central
exhaust port from the time (or it may be a little before) the opposite steam port
begins to admit steam up to the end of the stroke or thereabout.
The valve is driven direct from the crank shaft of the engine by mitre
wheels, and consequently makes the same number of revolutions as the crank.
The shaft which conveys the motion is made in two parts, with one part to slide
upon the other, so as to admit of the valve being moved longitudinally while in
rotation. A hand lever, with suitable locking arrangement, may be applied, to the
moveable part of the driving shaft, and the valve, as above described, may be used
as the starting valve of the engine.
Upon the stationary part of the driving shaft a centrifugal governor may be
formed, and the longitudinal movement of the sliding part placed under its control

page_text: (or any of the known forms of governors may be otherwise applied), whereby the
regulation of the admission of steam to the cylinder in proportion to the power
required then becomes automatic.
In some cases we prefer to combine a rotating valve similar to that above
described, with separate valves for regulating the exhaust. In such cases the
rotating valve has merely the two triangular steam passages through it and no
recesses on its exterior surface; and the port face on the cylinder has only the two
triangular steam ports. Each of the steam passages learling to the ends of the
cylinder is connected by a branch passage with a central or common exhaust
passage. A valve is placed in each passage to close the exhaust passage while
steam is entering the cylinder. In the Drawings annexed these valves are shewn
as having a revolving motion given to them; they might however be so formed as to
be worked with a reciprocating motion, as both valves.may be actuated by the same
rocking shaft, and the movement is very conveniently derived from an excentric-on
the driving shaft of the rotating valve; the setting of the excentric and a
suitable proportioning of the length of the lever upon the rocking shaft afford
facility for accurately timing the opening and closing of the exhaust passages, and
giving any desired amount of compression.
Our improvements further afford great facility for providing means for reversing
the motion of the engine when required. For this purpose we mount two mitre
wheels loosely upon the crank shaft of the engine, both these wheels being per-
manently held in gear with the mitro wheel fixed upon the driving shaft of the
rotating valve. Between the two wheels upon the crank shaft is a clutch sliding
upon-a-feather so as to engage either wheel at pleasure. Now if the clutch be
thrown from one wheel to the other, and--the-motion-of the crank be reversed at
the same time, it will be seen that the driving shaft of the rotating valve will
revolve in the same direction as before. The surfaces of contact upon the clutch
and upon each of the wheels which it engages are so adjusted that whichever whicel
is driving the "lead" will be the same, so that the engine will have the same
distribution of steam whichever way the crank is running.
In order that our Invention may be fully understood and readily carried into
effect, we will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a longitudinal section of an engine with valve gear constructed as
above described; the engine is shown as fitted upon the top of an ordinary cylin-
drical boiler. Figure 2 is a transverse section of the same taken through the
cylinder and valves. Figure 3 is a plan view in section. In this engine rotating
valves are used for the exhaust separate froin the steam valve.
A is the steam cylinder enclosed, as shown at Figure 2, within a jacket, to which
steam is admitted from the steam boiler. B is the valve chest of the steam valve;
to it steam is admitted at C from the jacket surrounding the cylinder. In this
valve chest are two triangular ports, shown in plan at Figure 4, one leading to each
end of the cylinder. Upon these ports rests the tube D open at both ends. E is
the valve shaft secured at its end to one end of the tube, as shown at Figures 1
and 3, so that when the rod is moved endwise the tube moves with it. In the 4
interior of the opposite end of the tube are lugs with recesses in them, into which
projections on the valve shaft enter, as shown at Figure 3, so that when the valve
shaft is turned the tube turns with it. On opposite sides of the tube are two
triangular ports, as shown at Figure 5. The valve shaft E passes out from the end
of the valve chest through a stuffing box, and is coupled to, so as to be revolved by, 5
a continuation F of the shaft. On the shaft F is a bevil wheel gearing with two
bevil wheels G of the same size, that can turn loosely around the crank shaft of the
engine, but either one or other of which can be made fast on the crank shaft by a
sliding clutch H, which can be moved endwise to and fro along the crank shaft by

page_text: a lever arm I' on a shaft I. On this shaft I is also a weighted lever arm I³, and
by throwing this arm over to the right or left, the clutch can be caused to make
either one or other of the bevel wheels G fast on the crank shaft, and so cause
the engine to be driven either forwards or backwards, the valve shaft E boing
driven in the same direction, whichever way the engine is running.
When the tube of the valve is at one end of the valve chest, in the position shown
in the Drawings, full steam is admitted to the ports of the valve face when the
valve is rotated, but if the tube is shifted end wise to the opposite end of the valve
chest no steam will be admitted to the steam ports. K is a lever by which the
tube can be so moved endwise, so that by it the engine can be stopped when
desired. L, L, are governor balls, the arms of which are pin jointed to a hollow
shaft L', through which the valve shaft E can slide to and fro, but which turns
with the valve shaft by reason of a cotter on the shaft E entering slots in arms L²
which are fast upon the hollow shaft L'; the arms L² are also connected, as shown,
to the shaft F and are driven by it. The balls are linked, as shown, to a tubular
sleeve M, which is free to slide on the shaft F. When the engine is running and
the shaft F, and consequently the shaft E, are rotating, the governor balls fly
outwards and move the sleeve towards the valve chest. The sleeve presses back
the shaft E, and moves back the revolving tube of the valve, so as to diminish the
amount of steam allowed to pass to the cylinder, as before explained.
In place of the governor being mounted upon the valve shaft, as shown in these
Figures, it may be on a shaft driven from it, as shown at Figure 6. In this case
the sliding sleeve of the governor gives an endway to and fro motion to the valve
shaft E by a crank lever N, as shown.
Other arrangements of governor than those shown might also be used for
controlling the to and fro endway movement of the rotating tube of the valve, to
control the amount of steam admitted to the cylinder. Or the tube of the valve
may be set into any desired position by means of the lever K, so as to cut off steam
after any desired portion of the stroke, and then if a governor is used, it may act
as a separate valve.
The exhaust from the two ends of the cylinder is effected as follows :--In each of
the passages leading from the two ends of the cylinder to the two steam ports of
the steam valve is a revolving cylindrical valve O; these are shown at Figure 7;
they are caused to revolve at the same speed as the shaft of the steam valve by a
shaft P, on which is a toothed wheel Q. This toothed wheel gears with a tooth
wheel R on the hollow shaft L', and is so turned with it. The cylindrical valve
covers over ports which open from the steam ports into an exhaust passage S, sco
Figure 2. When a recess in the side of the valve comes over the port, steam can
escape through it, but when the cylindrical circumference is over the port the port
is closed. As before stated, in place of employing rotating valves for the exhaust,
other forms of valve might be employed.
The steam valve also, as before stated, might be formed to control the exhaust.
In this case a rectangular exhaust port Tis formed on the port face of the cylindrical
valve chest, as shown at Figure 8, and the rotating tube which rests on this valve
face is formed with two recesses Ū on its exterior, each of sufficient length to cover
the exhaust port, and also one or other of the outer ports, as shown at Figure 9.
Having thus described the nature of our Invention, and the manner of performing
the same, we would have it understood that we claim,-
First. The rotating valve, substantially as described and illustrated at Figures 1,
2, and 3, for controlling the admission of steam to the cylinder of a steam engine.
Second. The rotating valve, substantially as described and illustrated at
Figure 8, for controlling both the admission of steam to, and also the exhaust from,
the cylinder of a steam engine.
Third. The combination of the rotating valve with a governor, by which tho
rotating tube of the valve can be moved endwise to and fro, and the admission of
steam to the cylinder so regulated, substantially as described:

page_text: Fourth. Giving motion to the valve shaft, substantially in the manner described,
so that the engine may be reversed, and the valve shaft always driven in the same
direction, whichever way the engine is running.
In witness whereof, I, the said Edmund Joseph Davies, have hereunto set my
hand and seal, this Sixth day of January, in the year of our Lord One 5
thousand eight hundred and eighty onc.