Improvements in Steam Engines and the like.
Year: 1895

page_text: Date of Application, 28th June, 1895
Complete Specification. Left, 16th Mar., 1896-Accepted, 2nd May, 1896
Improvements in Steam Engines and the like.
We, THOMAS SMITH, WILLIAM HILL SMITH, and WILLIAM EASTWOOD,
trading as Smith Bros. & Eastwood, of Soho Works, Thornton Road, Bradford, in
the County of York, Engineers and Millwrights, do hereby declare the nature of
this invention to be as follows:-
Our invention has reference to the method of working the admission valves alone,
or the admission valves in combination with the distribution valves, of the cylinders
of steam engines, steam hammers, pumps, and the like.
The object of our invention is to obtain a quick cut-off of steam without excessive
total movement of valve, and to do this without the use of detent or trip gear and
the springs dash-pots or other accessories belonging to same generally employed
for this purpose; and we obtain our object in such a way as to make the action of
the valves compulsory throughout their whole motion, instead of releasing them at
a certain point of the stroke and using springs or other means to effect the return
stroke suddenly.
In order to effect this we employ a combination of levers, shafts, slides, and links
'or cams, of such a form and actuated in such a manner as to give a very quick
motion to the valves at the moments of closing and opening, and comparatively
slight or no motion at other times. We prefer to have the valves coupled direct
to a governor of the type known as a crank-shaft governor; but the gear may also
be used with the various forms of governor driven from the main shaft of the
engine by belts, ropes, chains, gear wheels, or other means; or it may have a
positive and constant motion, and the governing be effected in combination with a
throttle valve.
As applied to an engine having "Corliss" valves, or other valves that are semi-
rotary in their movement, motion is given to a rocking shaft or a sliding bar from
an eccentric or other means on the main shaft of the engine in the usual manner,
or, as we prefer, from an eccentric with variable stroke controlled by a crank shaft
governor. A lever on this rocking shaft, or as a substitute for this a sliding
bar whose motion has the same effect, engages with another lever on a second
shaft in such a manner as to make the second lever of constantly varying length;
so that assuming a uniform angular motion of the first lever, or uniform sliding
motion of the bar, the angular motion of the second lever at one position is at a
maximum and much greater than that of the driving lever or bar, after which the
angular motion of the second lever gradually decreases to a minimum which is much
less than that of the driving lever or bar. A third lever on the second shaft is
coupled to the cut-off valve in such a way that the maximum movement is made
use of to give the desired quick motion to the valve at the instant of its closing,
and when that point is passed the motion is reduced to a minimum both in
extent and velocity, and then increases again in the same ratio to the point at which
the valve re-opens.
After the re-opening, the angular motion is quickly
diminished to nothing, and on the return stroke it reaches its maximum again at
the instant of closing the valve.
If a pair of cams is used in conjunction with the first rocking shaft or on the
sliding bar, the second rocking shaft may be dispensed with, and the movement
derived from the cams conveyed by connecting rods direct to the valve spindles.
The shape of the cams will be such as to cause the valve to open suddenly, and

page_text: then allow it to remain open stationary whilst the rocking shaft or sliding bar
continues its movement, until the point at which it is necessary to close the valve
again, when it is closed with similar suddenness and again maintains a state of
rest.
THOS. SMITH.
W. HILL SMITH.
W. EASTWOOD.
t
improvements in Steam Engines and the like.
We, THOMAS SMITH, WILLIAM HILL SMITH, and WILLIAM EASTWOOD,
trading as Smith Bros. & Eastwood, of Soho Works, Thornton Road, Bradford,
in the County of York, Engineers and Millwrights, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
Our invention has reference to the method of working the valves of the cylinders
of steam engines, steam hammers, pumps, and the like.
The object of our invention is to obtain a quick cut-off of steam without excessive
total movement of valve, and to do this without the use of detent or trip gear and
the springs dashpots or other accessories belonging to same generally employed
for this purpose; and we obtain our object in such a way as to make the action of
the valves compulsory throughout their whole motion, instead of releasing them
at a certain point of the stroke and using springs or other means to effect the
return stroke suddenly. In order to effect this we employ a combination of levers,
shafts, slides and links or cams, of such a form and actuated in such a manner as to
give a very quick motion to the valves at the moments of closing and opening, and
comparatively slight or no motion at other times. We prefer to have the valves
coupled direct to a governor of the type known as a crank shaft governor; but the
gear may also be used with the various forms of governor driven from the main
shaft of the engine by belts, ropes, chains, gear wheels, or other means; or it may
have a positive and constant motion, and the governing be effected in combination
with a throttle valve.
•
こ
In the accompanying drawings, Figs. 1 and 2 shew plan and elevation of arrange-
ment of links, levers and rocking shafts forming our improved valve gear as applied
to admission valves of semi-rotary or
"Corliss" type.
In Fig. 1 A, A, are the spindles of the admission valves, B is a lever whose
motion is derived from an eccentric, or its equivalent, and preferably from one
of variable stroke and constant "lead" controlled by a crank-shaft governor though
this is not an essential feature of our arrangement. Lever B is keyed, forged, or
cast to shaft C working in bearings D, D. On this shaft C is also fixed the double
lever E, E, of any convenient shape, (shewn in Fig. 2 crescent shape). To
pins F, F, in this lever are attached one end of links G, G, the other end being
connected to levers H, H, by pins. or bolts K, K. Levers H, H, are keyed to, or
forged, or cast with shafts L, L, working in bearings M, M.
At the other end of these shafts are keyed to, forged, or cast with them the
levers N, N, having at their ends pins O, O, which are coupled by means of links
or connecting rods Q, Q, to pins in the levers P, P, on the valve spindles A, A.
In Fig.
on left hand side is shewn by dotted lines the direction and extent of
the movement, which is given to each lever and pin when in action and making
'full stroke; the pin R on lever B moves through arc of circle S, S, F moves
through T, T, K moves through U, U. The pin O moves through arc V, V,
causing lever P to move through arc W, W, the levers N, N, with pins, 0, 0,
J.

page_text: being so placed that at the extreme point of travel in the outward direction they
may cross or approach the centre lines of the links Q, Q, at right angles, and so
produce at that time no motion in the levers P, P, on valve spindles A, A.
The lever B gives motion to the rocking shaft C. The double lever E on this
shaft engages by means of the link G with the lever H on the second shaft L, and
the lever N on the same shaft conveys the motion through connecting rod Q to the
lever P on valve spindle.
But whereas the original movement of lever B is a simple oscillation, the effect
of the intermediate mechanism is to give a much altered character to the
movement in the last lever P; and in this way, namely, that the period of rest
at the ends of the stroke in lever P is greater than in lever B, that the
maximum movement is attained more quickly, and that the total period of motion
is also much less than in lever B.
In Fig. 2 on the right hand of figure is shewn the variable degree of motion.
given to lever P whilst lever B, or what is the same thing lever E, moves
through the same constant space. With a movement of pin F, the lever H,
at. position marked k, has practically no movement, the link Ġ only swinging on
centre, and consequently the pins K and whose movements are identical
with lever H have also during that period no appreciable motion. With the same.
extent of motion of pin F when at position a', ', the pin K (and with it the pin O)
has a proportionately much greater movement k2 k2 and, by the shaft L, lever N
and link Q, this motion is conveyed to lever P, causing in that period a move-
ment p', pl. With a similar extent of motion 2, 2, of the pin F at the extreme
limit of its travel the motion given to pin K is k 3 k 3.
At this position the pin O crosses at right angles the centre line of link Q
connecting pin O to lever P in position p 3 so that no motion whatever is given to
lever P in this position. From this it will be seen that assuming the pin R to
move at a uniform rate of speed from one extreme of its path to the other, the
oscillating movement given to lever P varies both in degree and rapidity in this
manner, namely, that from a condition of rest at point p the movement accelerates
to a maximum at point p', and afterwards retards until the lever P again comes to
rest at point p 3. It follows from this that the valve which is actuated by lever P
on spindle A will have a circumferential motion corresponding to that of lever P,
and that during the time the lever E moves from x, x, to ¹¹ the valve will move
with increasing rapidity from position p to p', p' whilst when the lever E is moving
from x', ', to a³, 23, the valve will move with decreasing rapidity from pl, p', to p 3.
During the former period the valve is shut and during the latter period it is open.
and the instant of opening or closing corresponds with the point at which the valve
attains its maximum rapidity. The distance is shewn in Fig. 2 to be one
fourth the distance.'; and with this proportion if the valve opens at dead centre
of the engine when F is going downwards from ', and shuts when F returns
upwards to ', x2, x¹, being one fourth of arc the admission of steam will be
continued to and cut-off at about of the stroke of the engine. If the movement
of F be decreased so as to oscillate through half the area, the extreme downward
direction being point the valve will only just open and immediately close again
on the return stroke commencing, and any movement of F in an arc greater than
half, x, and less than the whole x, x, will cause the valve to shut off steam at
a different relative position or fraction of the stroke of the engine.
To make this
valve gear applicable for our purpose of automatically regulating the point of cut-off
we prefer to employ a "crank-shaft" governor of such a type as will vary the stroke
of the valve-actuating eccentric, the minimum stroke being one half the maximum
stroke, and at the same time keep the "lead" practically constant.
will thus open quickly at the commencement of the stroke, and shut quickly at any
point of the stroke of the piston according to the position of the governor weights
at the moment.
.
.
The valve
When the valve is quite open it "äwells" open momentarily before its return,
less or more according to whether the cut-off is early or late, and when cut-off has

page_text: been effected the speed and quantity of movement of the valve is quickly reduced.
in so much that, considering the valve when cutting off at stroke, the movement
of the valve after the port has been closed is about equal to that which takes place
when open, although the crank moves through about two thirds of a revolution in
the former case and only through one third of a revolution in the latter.
Instead of a "crank-shaft"
in the "Porter-Allen" engine, which consists of an eccentric set coincidently with
governor we may use a single eccentric as employed
the crank, or opposite to it, with curved slotted lever formed in one piece with the
strap pivoted on its centre line and constrained by links allowing it to give the
necessary throw; the sliding block in the slotted lever would be coupled to lever B
on central rocking shaft C, or to sliding bar E (Figs. 5 and 6), by a connecting
rod, and would give to the mechanism practically the same motion as if the latter
were connected to a crank-shaft governor as already described.
The slot in this lever would be curved with a radius equal to the length of the
connecting rod. Or, we inay use a pair of eccentrics, or any of the well known
substitutes for same employed in actuating valves. Or, we may use an eccentric
capable of being moved across the shaft by means of an ordinary governor acting
on a collar and wedge to increase or decrease the stroke of the eccentric whilst
keeping the "lead" practically constant.
.
We may also use the arrangement to give a second stroke to the valvė, for
instance, for engines which are regulated by a throttle valve, or for the intermediate
or low pressure cylinders of compound engines where a governor may not be
required, in which cases variation in the point of cut-off will be attained by
advancing or putting back the eccentric, and adjusting the "lead" by the connecting
links to each valve, or the "lead may be adjusted by the pin O being fixed on a
separate disc on the face of the other and advanced relatively to it or put back as
may be required.
Figs. 3 to 18 on the sheets of drawings shew alternative methods of obtaining
approximately the same results as we obtain by the arrangement shewn in Figs. 1
and 2.
Figs. 3 and 4 will be understood by the description already given of Figs. 1
and 2. In this case the two levers H and N form parts of a double lever H N.
In Figs. 7 and 8 the arrangement is similar to Figs. 3 and 4 except that the
slotted lever HN is a substitute for and performs the work of the two separate
levers H and N in Figs. 1 and 2, or the double lever H N in Figs. 3 and 4, and the
sliding bar G takes the place of link G and pin K.
Figs. 9 and 10 are a modification of Figs. 7 and 8, the shaft L being supported
in one bearing, and the path of pin F being outside the bearing instead of between
two bearings.
In Figs. 5 and 6 a sliding bar E is used for the first motion instead of the rocking
shaft C and double lever E.
In other respects the mechanism is similar to that shewn in Figs. 1 and 2, and
the action corresponds with the description already given of those figures.
In Figs. 11; 12, and 13 are shewn arrangements whereby the sliding bar G takes
the place of link G and pin K, the first motion being derived from a sliding bar E
as in Figs. 5 and 6, the path of pin F being along the horizontal dotted line TT.
In Figs. 14 and 14 the levers on valve spindles are coupled by connecting
rods Q and pins O to cams N in disc E on rocking shaft C, or the connecting rods
may be discarded, and the valves actuated direct, by pins on the levers of valve
spindles working in the cams, in which case we should use a double cam as shewn,
or two separate single cams as might be most convenient. These cams are of such
a form that at the necessary point the valves are opened or closed quickly, and during
the remaining portions of the movement of the cams the valves are stationary.
shewn in Fig. 14 the cam has a full stroke of x, x¹, and its shape is such that no
motion is given to pin O until the cam has travelled one fourth of this distance,
namely, and after quickly actuating the valve the pin O again remains
stationary to the end of the stroke at a, and also for that portion of the return
As

page_text: stroke until the inclination of the cam quickly moves the valve and brings it to rest
again at x 1. The variation in the point of cut-off is obtained in the same manner as
already described in the earlier part of this Specification in reference to Figs. 1
and 2.
Figs. 15 and 15 shew the mechanism for one end of cylinder only. The
triangular connecting rod Q receives its motion from rocking shaft C, which gives
pin F a path TT. At one augle of the connecting rod Q the pin O is constrained
to move in the stationary cam N, the other end being connected to the lever on
valve spindle. In order to compensate for the rocking motion of the connecting
rod Q this lever may have a slot lengthwise as shewn in Fig, 15, or it may be
coupled by another connecting rod as shewn in Fig. 15^. The action of the valve
is the same as described in last paragraph.
by pin O.
In Fig. 16 a similar result is obtained by using a cam N at the end of connecting
rod Q constrained to move in a suitable path by any convenient means, such as
rocking link R.
The lever on valve spindle is coupled direct to the cam N
Fig. 17 shews another modification of the cam arrangement in which the first
motion may be given to the link R and the cam be stationary, or motion may be
given to the cam and the link R have only a rocking motion from centre S. In
either case the effect on the valve is the same as described above.
In Fig. 18 the bar E, which has a horizontal reciprocating motion on rocking links
R or in a slide takes the place of the connecting rod Q and link R in Fig. 16 and
the duplicates of same for actuating the valve at opposite end of cylinder.
The cams N are coupled direct to the levers on valve spindles, and produce the
same result as is obtained by the arrangement in Fig. 16.
Having now particularly described and, ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is
Firstly. For operating the admission valves or the admission valves in combina-
tion with the distribution valves of the cylinders of steam engines and the like, the
combination therewith of mechanism suitably arranged, constituting part of the
valve gearing of such steam engines, consisting of a central rocking shaft C with
disc or double lever E engaging by links G with two secondary levers H operating
secondary shafts L on each of which shafts is a third lever N coupled by a
connecting rod Q to a lever on the valve spindle of semi-rotary valves, all arranged
and operating substantially as herein described and illustrated in Figs. 1, 2, 3,
and 4.
Secondly. For operating the admission valves or the admission valves in combina-
tion with the distribution valves of the cylinders of steam engiues and the like, the
combination therewith of mechanism suitably arranged, constituting part of the valve
gearing of such steam engines, consisting of a central rocking shaft C with disc or
double lever E engaging by pin F and sliding bar G with two secondary levers H
working secondary shafts L on each of which is a third lever N coupled by a
connecting rod Q to a lever on the valve spindle of semi-rotary valves, all
arranged and operating substantially as herein described and illustrated in Figs. 7,
8, 9 and 10.
Thirdly. For operating the admission valves or the admission valves in combina-
tion with the distribution valves of the cylinders of steam engines and the like, the
combination therewith of mechanism suitably arranged, constituting part of the
valve gearing of such steam engines, consisting of a sliding bar E connected by
links G and levers H with two shafts L on each of which is another lever N
coupled by a connecting rod Q, to a lever on the valve spindle all arranged and
operating substantially as herein described and illustrated in Figs. 5 and 6.
Fourthly. For operating the admission valves or the admission valves in combina-
tion with the distribution valves of the cylinders of steam engines and the like, the
combination therewith of mechanism suitably arranged, constituting part of the

page_text: valve gearing of such steam engines, consisting of a sliding bar connected by means
of pins F and other sliding bars G with two shafts L on each of which is a lever N
coupled by a connecting rod Q to a lever on the valve spindle, all arranged and
operating substantially as herein described and illustrated in Figs. 11, 12, and 13.
Fifthly. For operating the admission valves or the adınission valves in combina-
tion with the distribution valves of the cylinders of steam engines and the like, the
combination therewith of mechanism suitably arranged, constituting part of the
valve gearing of such steam engines, consisting of a double rocking cam on central
-shaft, or of two separate single cams for the same purpose, each cam being
connected with a lever on the valve spindle, all arranged and operating substantially
as herein described and illustrated in Figs. 14 and 14ª.
Sixthly. For operating the admission valves or the admission valves in combina-
tion with the distribution valves of the cylinders of steam engines and the like, the
combination therewith of mechanism suitably arranged, constituting part of the
valve gearing of such steam engines, consisting of a central rocking shaft C with
double lever or disc coupled by connecting rods Qconstrained by cams N to
move suitably to give the required motion to the valves by levers on the valve
spindles, all arranged and operating subtantially as herein described and illustrated
in Figs. 15 and 15ª.
Seventhly. For operating the admission valves or the admission valves
combination with the distribution valves of the cylinders of steam engines and the
like, the combination therewith of mechanism suitably arranged, constituting part of
the valve gearing of such steam engines, consisting of a central rocking shaft C with
disc or double lever coupled by connecting rods Q, having cams N at one end of
each, to levers on the valve spindles, all arranged and operating substantially as
herein described and illustrated in Fig. 16.
Lastly. We claim the combination and general arrangement of the mechanism
substantially as herein shewn and described or any mere modification thereof for
-operating the admission valves of steam engines..
Dated this 13th day of March 1896.
TASKER & CROSSLEY,
Halifax, Patent Agents.