IMPROVEMENTS IN THE VALVE GEAR OF MOTIVE POWER ENGINES
Year: 1885

page_text: I, HENRY JACK, of the Canal Basın Foundry, Glasgow, in the County of
Lanark, North Britain, Engineer do hereby declare the nature of the said inven-
tion for IMPROVEMENTS IN THE VALVE GEAR OF MOTIVE POWER ENGINES to be
as follows
This Invention, which relates to Improvements in the valve gear of Motive
Power Engines, has for its object in the first place to enable an ordinary D-slide
vilve, piston valve, or other equivalent valve or valves, to be moved with a
practically equable motion during each half of the stroke at all ranges of that
motion according to the adjustment thereof, as the said adjustment is varied from
time to time correspondingly to the amount of fluid to be admitted to any engine,
or, in other words relatively with the extent and duration of opening of the ports
by the slide or equivalent valve or valves The Improvements have also for their
object to enable the aforesaid effects to be obtained both in reversing and non-
reversing engines
The improvements consist in attaching to the rod of the eccentric or its
equivalent a link or links of a parallel motion which parallel motion, with or
without accessories, oscillates on a fixed point or centre, which centre coincides
with the axis or centre of attachment of the said link or links to the rod of the
eccentric or its equivalent when the piston of the engine is at either end of the
stroke
JH JOHNSON, DAY & JOHNSON,
Petitioner's Agents

page_text: Improvements in the Valve Gear of Motive Power Engines
I, HENRY JACK, of the Canal Basın Foundry, Glasgow, in the County of
Lanark, North Britain, Engineer do hereby declare the nature of my said invention
for IMPROVEMENTS IN THE VALVE GEAR OF MOTIVE POWER ENGINES and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement
My Invention, which relates to improvements in the valve gear of motive power
engines, has for its object in the first place to enable an ordinary D slide valve,
piston valve, or other equivalent valve or valves, to be moved with a practically
equable motion during each half of the stroke at alt ranges of that motion
according to the adjustment thereof, as the said adjustment 18 varied from time to
time correspondingly to the amount of fluid to be admitted to any engine, or in
other words, relatively with the extent and duration of opening of the ports by the
slide or equivalent valve or valves-The improvements have also for their object
to enable the aforesaid effects to be obtained both in reversing and non-reversing
engines
The improvements consist in attaching to the rod of the eccentric or its
equivalent, a link or links of a parallel motion, which parallel motion, with or
without accessories, oscillates on a fixed point or centre, which centre coincides
with the axis or centre of attachment of the said link or links to the rod of the
eccentric or its equivalent when the piston of the engine 18 at either end of the
stroke
In order that my said Invention may be properly understood and readily carried
into effect, I will now proceed to describe the drawings hereunto annexed
Figure 1 (sheet 1) is a vertical section of the cylinder and D slide valve of an
inverted cylinder engine the gear for operating which slide valve is represented in
side elevation in its propei relative position at Figure 2
Figure 3, is a diagram representing the paths traversed by the several parts of
the valve gear represented at Figure 2
Figure 4, is a view similar to Figure 2, but drawn to an enlarged scale
Figure 5, 18 a side elevation (also on an enlarged scale) of a modified form of
valve operating gear as constructed in accordance with my present Invention
Figure 6, 18 a diagram indicating the paths traversed by the several parts of the
valve gear represented at Figure 5
Figure 7 is a view partly in side elevation and partly in longitudinal section of
a horizontal engine such as is suitable for driving rolling mills and provided with
valve operating app iratus constructed according to my present Invention
Figure 8 is a diagram indicating the paths traversed by the several parts of the
Baid valve operating app iratus
Figure 9 is a side elevation (drawn to an enlarged scale) of the valve operating
apparatus represented at Figure 7
Figure 10 18 an enlarged diagram indicating the paths traversed by the several
narts of the said valve operating gear

page_text: Figure 11 (sheet 2) is a view partly in elevation and partly in vertical section
of the cylinder of an inverted cylinder marine engine wherein a D shaped slide
valve is employed, the gear for operating which said valve is represented in side
elevation at Figure 12 in its proper position relatively with that of the said valve
Figure 13 is a plan of the valve gear represented at Figure 12
Figure 14 is a diagram indicating the paths traversed by the several parts of the
valve operating apparatus represented at Figure 12
Figure 15, is a side elevation of portion of a marine engine, steam to which is
admitted by piston valves operated by gear constructed according to my present
Invention
Figure 16 is a horizontal section through a portion of the valve gear of the
same
With reference more particularly to the apparatus represented at Figures 1, 2
and 4, the slide valve a, there shewn (at Figure 1) is of the ordinary D shape
This valve a, 1s operated through the rod b, which is jointed at c, to the connecting
rod d, only a portion of which is represented upon the annexed drawings The
lower end of the connecting rod d, is jointed to the outer end of the eccentric
rod e, the eccentric &, of which is mounted with its full part upon a radial line the
same as that of the crank pin f, which crank pin is represented in dotted lines at
Figures 2 and 4 At from one third to one fourth of the distance between the
centre of the pin h, and the eccentric d³, measuring from h, I pivot one end of the
link 2, the other end of which is connected at 3, to the rod k At a point 7, midway
between the two points g, and 2, the link 2, is pivoted to the throw crink³, the
length of which between the centres l, and m, is half the length between the
centres g, and, The throw-rank L, is supported in the fixed bearings n, which
are secured at any convenient part to the engine frame or bed plate
The afore-
mentioned rod k, is that by which the operation of the engine is manipulated, that
is to say by moving the said rod in the direction of its length, the engine is started,
reversed or brought to rest, and I desne it to be understood that the said 1od k,
may be connected to a lever or the equivalent thereof situated at an adjacent or
remote part for enabling the engine to be controlled either near or from a distance
The bearings n, in which the throw-crank ³, 1s pivoted, are arranged in such
position that when the engine piston o, is at either end of its stroke, the axis m, of
these bearings is coincident with the axis of the pin g, that is to say the pin which
connects the eccentric rod e, with the link When the parts are in this position,
that is to say when the piston is at either end of its stroke, the link 1, may be
canted over into any of its positions without affecting the position of the eccentric
rod e, or the slide valve a Since the throw-crank ³, 1 just half the length of the
link 2, and is attached to the middle point of the said link, they together form &
parallel notion and consequently the point g, at which the link 2, 18 connected to
the eccentric rod e, always travels in a straight line when the eccentric d³, 18
rotated The direction of the straight path 18 dependent upon the position of the
link, relatively with that of the eccentric rod e, for, let it be supposed that
the link, is in a position perpendicular to the mean position or direction of the
eccentric rod e, that is to say in the position indicated at A, Figure 3, and that the
eccentric d³, is being rotated, then the path of the point g, would be in the same
straight line as the mean direction of the eccentric rode By these means, the
point h, at which the connecting rod d, is jointed to the eccentric rod 6, 18 caused
to pursue a path describing an oval or ellipse such as is indicated at p, Figure 3
If the link , be canted over from the last described perpendicular position, in
either direction, the point g, when the eccentric d³, 18 rotated, is caused to travel
obliquely and consequently the major axis of the oval or ellipse described by
the point h, is parallel with the path of the point g The minor axis of the oval or
ellipse p, is only equal to the lap and lead of the valve a, so that it is obvious
when the link 2, is brought into a position such as cau-es the said ellipse to be
brought to rost When the link . is deflected from its
1.
the
An

page_text: perpendicular or normal position, the oval or ellipse described by the point h
covers a vertical distance greater than that described by the oval or ellipse p, and
consequently the valve a, is caused to uncover the ports q, and r, to an extent
corresponding to such excess It will therefore be seen that the nearer the link 2,
1s to its perpendicular or normal position, the smaller is the volume of steam or
other motive agent admitted to the engine The oval or ellipse 8, Figure 3, is that
indicating the path traversed by the point h, when the engine is going full-steam
in one direction, and the oval or ellipse t, is that indicating the path when the
engine is going full steam in the opposite duection
In the arrangement represented it Figure 5 of the annexed drawings, the plate u,
is pivoted at its middle point v, in a fixed bearing which is not represented upon
the annexed drawings At the points w, and x, at equal distances from the point v,
the links y, and z, respectively, are pivoted The opposite ends of the links y,
and z, are pivoted to the two ends of the short link a', which is pivoted at its
middle point b¹, to the eccentric rod e, this point 62, corresponding to the point g,
Figures 2 and 3 Instead of causing the eccentric rod e, to be overhung as it is by
the employment of only one plate u, two such plates, one at each side of the said
eccentric rod e, may be employed, as in the manner hereinafter described with
reference to Figures 12 and 13, of the annexed drawings The operation of this
last described mechanism is similar to that hereinbefore described with reference to
Figures 2 and 3, the plate u, however being canted over by means of gearing
secuied upon its central shaft v, such gearing for example as that hereinafter
descubed and shewn at Figures 12 and 13 of the annexed drawings In the
diagram shewn at Figure 6, I have indicated at B the position of the points w,
and x, when the engine is brought to rest, and the circles c¹, and d¹, indicate the
extent of travel given to the point h, which is equal to the lip and lead at both
ends of the valve When the points w, and x, ale canted over into the position
indicated at C, Figure 6 the point b', travels in a direction indicated by the line e¹,
(Figures 5 and 6) and the engine is operated in the manner herein before explained
giving full steam in one direction When the points w, and x, are cinted over into
the position indicated at D, the point b', travels in the direction indicated by the
dotted line f¹, (Figure 6) and the engine is thereby caused to operate full steam in
the opposite direction
The engine to which I have, at Figure 7 of the annexed drawings, shewn my
improved vilve gear applied, is one suitable for rolling mills The steam or other
motive agent employed is admitted to the engine through the inlet g¹, and enters
the space formed between the two valves h¹, and ¹ From this space the motive
agent is admitted through the ports j¹, and k¹, and this being from the inside, the
eccentric d³, is mounted with its full part upon a radial line diametrically opposite
to that of the crank pin f, this being in direct contradistinction to the arrangement
shewn at Figures 1 and 2 wherein the motive agent being admitted from the
outside of the valve a, the full part of the eccentric is set upon a radial line the
same as that of the crank pin In the arrangement of mechanism represented
more particularly at Figures 7 and 9, the points h, and l, are disposed or situated
in a manner similar to that herein before described, the former of these points, that
18 to say the point h, being connected directly by a rod represented at Figures 7
and 9 by the dotted line d, with the valve rod b, and the latter point 7, being that
at which the eccentric rod e, is connected to the link t Under this construction
the plate, is supported at the point m¹, in a fixed bearing not represented upon
the annexed drawings This point m¹, as in the foregoing examples 18 coincident
with the point l, when the engine piston o, is at either end of its stroke At the
point n', in the plate 1, the link o¹, is pivoted, and the opposite end of this link o¹,
1s pivoted to the point p¹, of the link 2 The lower end of the link 2, that is to
say the part marked 2, is supported and free to slide in a slot formed in the
plate, and the adjustments of the valve gear thus constituted may be made from
time to time by means of a rod secured at r¹, to the plate P, or by means of the
equivalents thereof

page_text: On referring to the diagram shewn at Figure 8, it is seen that when the point q¹,
is in the position represented at E, the point h, 13 caused to travel through a
distance indicated by the two circles a³, and 63, which distance is equal to the
amount of lap and lead of both the valves h¹, and 2¹ So soon as the point q¹, 18
deflected from its E, position the steam or other motive agent is admitted to one or
other side of the piston according to the direction in which the said point q', is 80
deflected, and consequently the engine is caused to operate in one or other direction
The oval or ellipse represented at 8, in the diagram at Figure 10, indicates the
path pursued by the point h, when the engine 19 operating in the direction
indicated by the arrows t', at Figures 7 and 8
To the cylinder u', which is represented at Figure 11, of the annexed drawings
the steam or other motive agent is admitted by the slide valve a, in a manner
similar to that herein before described with reference to Figure 1-This valve is
operated by the mechanism shewn at Figures 12 and 13 of the annexed drawings
which is substantially similar to the mechanism hereinbefore described with
reference to Figure 5, but in this arrangement the form of the u, is preferably
that shewn at Figure 12, and as shewn at Figure 13, the said plate is used in
duplicate. On the plate u, the journals v, are formed and these journals are
supported in fixed bearings not represented upon the annexed drawings-The
links Y, and zare pivoted at the points w, and x, and between the plates u, and
the opposite ends of the links are pivoted to the two ends of the short link a¹
which is pivoted at b', (Figure 13) in the eccentric rod e Upon the shaft in which
the journals v, are formed, I secure the worm wheel v', and I arrange the tangent
screw wl, to gear with the said wheel The Tangent screw w¹, is mounted upon
the shaft, which is provided with the hand wheel y, by turning which wheel the
plates u, may be adjusted to any desired angle
The diagram represented at Figure 14, of the annexed drawings is one indicating
the paths traversed by the various parts of the mechanism shewn at Figure 12, and
the description herein before given of the various diagrams represented at Figures 3
6 8, and 10, ale such as render unnecessary any further description of this said
Figure 14
In the marine engine represented in part at Figure 15, the piston valves a
and 6 there shewn are operated through the valve rod c³, and through the
connecting rod d³ By reason of the position of the condenser e it is impracticable
to operate the connecting rod d³, direct from the end of the eccentric rod e
Under such circumstances I prefer to connect the end of the connecting rod d³ to
one arm of the bell-crank lever f³, the other arm of which 18 pivoted to the
connecting rod 9 The Bell crank lever is supported upon the stud hand, the
opposite end of the connecting rod g', is secured by the stud h to the end of the
eccentric rod e, which rod is shewn more particularly in horizontal section at
Figure 16-It will be seen with reference to Figure 15, that the means employed
for obtaining a parallel motion are similar to those herein before described with
reference to Figure 1, and similar letters of reference upon these two Figures
indicate corresponding parts-As a means for adjusting the position of the link 2,
relatively with that of the eccentric rod e, I have, at Figure 15, shewn the rod k,
as connected to the lever 22 This lever 2, is secured upon the shaft ³, upon which
18 also secured the toothed quadrant This toothed quadrant gears with the
tangent screw, which is secured upon the vertical shaft m², the bevil gear
wheel n³, of which gears with the bevil gear wheel o* These two wheels n' and o
are secured upon their respective shafts m³, and p³, and the shaft p³, may be
rotated by means of the hand wheel q', secured at it outer end It will thus be
seen that by rotating the hand wheel q³, the position of the link 2, is adjusted as
may be desired
In the arrangement of mechanism represented at Figure 15 the eccentric d³, is
arranged with its full part upon radial line at right angles to that of the crank f,
this being rendered necessary by the eccentric rod e, operating in a direction the
same as that of the piston valves a³ and 6 Although the eccentrics d' herein before

page_text: referred to have been described as arranged with their full parts upon radial lines
corresponding to, diametrically opposite to, and at right angles to the radial lines
upon which are the engine crank pins, yet I desire it to be understood that the full
part of the eccentrics may be in any position relative to the crank pins so as to
bring the pin into the proper position for operating the valves either direct or
through the mechanism of levers and rods
18
It is to be understood that the valve gear hereinbefore described may be so used
in connection with the engine governors, for example connected there with through
the rod k, or its equivalent as to secure that the engine shall be operated at an
approximately constant speed, that is to say in a manner analogous to the governors
and throttle or equivalent valve as ordinarily employed
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim 18
In the gear for operating the valves of motive power engines the mounting of
the eccentric rod e, upon a pin it from one third to one fourth of the distance
between the centres of the pin h, and of the eccentrics d, measuring from the
centre of the said pin h, the same being combined with a parallel motion constructed
and operating substantially as and for the purposes herein before described with
1cference to the two annexed sheets of Drawings