IMPROVEMENTS IN AND RELATING TO VALVE GEAR FOR STEAM & OTHER FLUID PRESSURE ENGINES
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I THOMAS CLAXTON FIDLER of Great George Street in the City of Westminster
Engineer do hereby declare the nature of said Invention for "IMPROVEMENTS IN
AND RELATING TO VALVE GEAR FOR STEAM & OTHER FLUID PRESSURE ENGINES'
to be as follows:-
"
My Invention has for its principal object to provide an engine especially suited
for the purposes of Tramway locomotion wherein complete protection of the
mechanisin from dust and dirt is secured together with easy access to the parts,
compactness of form steadiness of running and other advantages.
•
In constructing the valve gear I employ a rocking link, formed like the open or
the box link of the ordinary link motion but vibrating at the centre upon fixed
bearings and having attached to it an arm at right angles to the link by which the
link is caused to vibrate about the fixed centre, the arm being actuated by the
driving axle of the engine by means of a small overhung crank pin or excentric
and a connecting rod, the crank pin or excentric being fixed at an angle of about
180° with the engine crank or otherwise, depending upon the inclination of the
cylinder and valve-rod. The valve rod works in guides and is actuated by the
combined motions of two connecting rods which are attached to the two ends of a
short lever whose centre is attached to the valve-rod-The position of the centre
of the lever, and therefore the position of the valve in the direction of its stroke is
always the mean between the positions of the two ends of the lever-Thus the lever
performs the function of combining the motions of the two connecting rods and for
the sake of distinction I call it the "combination " lever.
Of the two connecting rods attached to the two ends of the "combination" lever,
one which I call the "link" rod is actuated by a sliding block contained in the
rocking link above mentioned-The rocking link is curved to the radius of the
"link rod and the sliding block may be arbitrarily adjusted at any point in
the link by means of the reversing gear-When the block is adjusted at one
extremity of the link, the link rod has the motion which would ordinarily be
imparted by a forward excentric without any angular advance and when the block
is adjusted at the other extremity the rod has the.motion which would be given by
a backward excentric without angular advance-The stroke of the link rod is

page_text: increased or diminished at pleasure by moving the block away from or nearer to
the fixed centre of motion of the rocking link.
The other connecting rod attached to the other end of the "combination" lever,
which rod I call the "lead" rod is actuated not by the direct stroke but by the
pendulum motion of the connecting rod first referred to as actuating the arm of the
rocking link, and is attached to that rod at a point between the crank pin and
the arm of the rocking link and imparts to the "combination" lever the motion
which would ordinarily be produced by an excentric fixed at 180° from the engine
crank or nearly so.
By means of the combination of these two motions the valve is worked so as to
produce an efficient and equable distribution of steam to the engine whether in
forward or backward gear with a lead which is at all times constant and a cut off
variable at pleasure. I may employ outside cylinders and gearing and place the
valve chest upon the top of the cylinder and the rocking-link over the driving
axle The whole of the gear is thus contained within a very moderate width and I
enclose the whole in a casing or box which is carried outside the wheels of the
engine and forms a dust tight enclosure on every side - This is especially suitable
for Tramway Engines-In narrow guage Tramway Engines I employ outside
bearings and outside frames and I form the axle boxes with deep flanges or slides
at the back to cover the openings between the horn plates above and below the
axle box for the better protection of the gear from dust, and I fix the driving
cranks as ‘overhung” cranks on the ends of the axles outside the frame and
within the casing or dust box-In broad guage Tramway Engines I employ inside
bearings and inside frames but I carry the dust box outside the wheels enclosing
the whole of the gear as before and I form the axles with a neck between the
wheel and the crank, the neck passing through an opening in the back of the dust
box, and I fit sliding collars upon the neck of the axles to prevent the admission of
dust In the outer side of the casing I fix moveable doors or shutters for better
access to the gear. I frame the footplate of the engine to form the top of the
casing and provide openings by means of which the driver standing upon the foot-
plate can easily examine and oil all parts of the working gear while running and
without exposing the gear to view from the outside-The hereinbefore described
valve-gear is not limited in its application to Tramway Locomotives as it may be
applied to other kinds of motive power Engines.
1001

page_text: I THOMAS CLAXTON FIDLER of Great George Street in the City of Westminster
Engineer do hereby declare the nature of said invention for IMPROVEMENTS IN
AND RELATING TO VALVE GEAR FOR STEAM AND OTHER FLUID PRESSURE 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 has for its principal object to provide an engine especially suited
for the purposes of Tramway locomotion by which I obtain a compact and efficient
arrangement of the motive gear and valve gear well protected from dust and dirt
and which will allow easy access to the parts and of the employment of a low
centre of gravity.
In constructing the valve gear according to my Invention I employ a vibrating
link which may conveniently be formed like the open or the box link of the
ordinary link motion, but capable of a vibratory motion about a fixed axis, being
hung at the centre upon fixed bearings carried by any suitable stationary part of
the engine or its framing, the said link having attached to it an arm preferably at
or about right angles to the link by which arm the link is caused to vibrate about
the fixed centre, the arm being actuated from the driving axle of the engine by
means of a small overhung crank pin and connecting rod, or by an excentric and
excentric rod, the crank pin or excentric being in a position depending upon the
inclination of the cylinder and valve rod, and as may be best adapted for con-
venience of construction and arrangement of the several parts of the class of
engine to which my Invention is applied. In general the position of the said
crank pin or excentric will be at or about 180° to the engine crank. The valve rod
works in guides and is actuated by the combined motions of two connecting rods
which are attached respectively to a lever centred to and capable of vibrating upon
the valve rod. The longitudinal motion of the centre of the lever thus attached
to the valve rod, and therefore the motion of the valve, is composed of the motions
of the two portions of the said lever operated upon by the said two connecting
rods. The said lever thus performs the function of combining the motion of the
two connecting rods (which are derived from one moving part) and for the sake of
distiuction I call it the "combination lever" and by adopting suitable proportions
of the lengths of leverage for the motions of the two connecting rods the said
motions may be combined either in equal proportions or in any desired ratio to suit
the requirements of construction and arrangement of the parts of the engine to
which my Invention is applied Of the two connecting rods attached as aforesaid
to the "combination lever," one which I call the "link rod" is actuated by a sliding
block contained in the herein before mentioned vibrating link, which link is curved
to the radius of the “link rod” and the sliding block may be arbitrarily adjusted
to any position in the link by means of the reversing gear. When the block is
adjusted at one extremity of the link the "link rod" has the motion which would
ordinarily be imparted by a forward eccentric without any angular advance and
when the block is adjusted at the other extremity of the link the rod has the
motion which would be ordinarily given by a backward eccentric without angular
advance The stroke of the "link rod" is increased or diminished at pleasure by
moving the block away from or nearer to the fixed centre of motion of the
vibrating link.
The other connecting rod attached to the "combination lever" (which rod I call
the "lead rod") is actuated not by the direct stroke, but by the pendulum motion
of the connecting rod or the eccentric rod first referred to as actuating the arm of
the vibrating link, and the said "lead rod" is attached to the connecting or
eccentric rod, which attachment may conveniently be made at a point between the

page_text: crank pin (or eccentric) and the arm of the vibrating link, and imparts to the
"combination lever" the motion which would ordinarily be produced by an
eccentric fixed at 180° from the engine crank or nearly so. By means of the
combination of these two motions derived from the one moving part, the valve
is worked so as to produce an efficient and equable distribution of motive fluid to
the engine whether in forward or backward gear, with a lead which is at all times
⚫ constant and a cut-off variable at pleasure. This valve gear is applicable to tram-
way or railway locomotives and to other engines, such for example as marine
engines and in applying it so as to suit the varying requirements of construction
and arrangement of parts, the proportions of the several levers and rods and their
points of attachment and the angular position of the crank pin or excentric may
be varied so as to suit the above named requirements, while preserving the same
combination of the two motions. I may employ outside cylinders and gear and
place the valve chest upon the top of the cylinder, and the vibrating link over the
driving axle; The whole of the gear is thus contained within a very moderate
width. I prefer to enclose the whole in a casing or box which is carried outside
the wheels of the engine and forms a dust and dirt proof enclosure on every side.
This arrangement is specially suited for tramway engines In narrow gauge
locomotive engines I prefer to employ outside frames and outside bearings for the
crank axles, and to form the axle box with deep flanges or sides at the back to
cover the openings between the hornplates above and below the axle box for the
better protection of the gear from dust and dirt, and to fix the driving cranks as
overhung cranks on the ends of the axles outside the frame and within the casing
or dust box.
In broad gauge locomotive engines I prefer to employ inside frames and bearings,
but to carry the dust box outside the wheels, enclosing the whole of the gear as
hereinbefore described and to form the axles with a neck between the wheel and
the crank, the neck passing through an opening in the back of the dust-box, and
I fit collars upon the neck of the axles sliding in a trough or groove in the dust
box to prevent the admission of dust and dirt between the axle and the hole in the
dust box through which the axle passes. In the outer side of the dust box I by
preference provide openings with movable doors or shutters for giving ready access
to the gear. I prefer to frame the foot-plate of the engine to form the top of the
dust box, and to provide openings therein, so that the driver can easily examine
and oil all parts of the working gear while the engine is running, and this
without exposing the gear to view from the outside. The hereinbefore described
valve gear may be applied to motive power engines generally which are operated
by fluid pressure controlled by means of valves.
In order that my Invention may be clearly understood I will now describe with
reference to the accompanying drawings various ways in which the principle of my
Invention may be applied, it being understood that I do not limit myself to the pre-
cise details illustrated, as they may be varied without departing from the nature of
my Invention. Figure 1 of the Drawings represents in elevation the working parts
of a locomotive constructed according to my said Invention. Figure 2 is a cross
section shewing the arrangement of gear and dust-casing as applied to narrow
gauge engines, and Figure 3 is a cross section of the same parts shewing the
arrangement as applied to a broad gauge engine. In each of the above named
figures is the footplate of the engine and SSS are the sides of the dust box
'forming with the foot plate a dust proof casing enclosing the gear-VV are the
overhung cranks of the engine fixed or formed on the ends of the crank axles and
'situated within the dust casing, and W is the small crank-pin by which the valve
gear is actuated and which is fixed on a return crank at an angle of or about 173°
with the engine crank In narrow gauge engines as illustrated in the cross section,
Figure. 2, I prefer to fix the frames outside the wheels. In the said Figure 2 t is
the frame and a the axle box, the latter being provided with deep flanges a³ at the
'back to cover the space between the axle box and the dust. box for the better
-protection of the gear from dust,. In broad gauge engines-I-prefer to employ inside

page_text: bearings and inside frames as illustrated in the cross section Figure 3 in which t is
the frame and the axle box, but I carry the dust box outside the wheels, as in
the arrangement Figure 2-n is the neck of the axle between the wheel and the
crank, the said neck passing through an opening in the back of the dust box and
being provided with a collar n³ capable of sliding in a groove s³ in the dust box,
as shewn in the said Figure 3-Passing now to the valve gear, which forms the
chief part of my Invention and which is actuated wholly by the motion of the
small crank-pin W, I will refer again to Figure 1. A is the valve chest fixed upon
the top of the cylinder, and B the valve-rod working in a guide as shewn in the
Drawing, and attached to the centre of the "combination lever "C The lever C
is actuated by the two connecting rods D and E; one extremity of each of which
is attached, that of the one to the upper, and that of the other to the lower end,
of the lever C. The rod D, which I call the "link-rod," is attached at its other
extremity to the sliding block F contained in the vibrating link G, and is actuated
by the motion of the said link upon its centre H carried in bearings fixed to any
suitable stationary part of the engine or frame. The link G is shewn as being
formed like the open or the box link of the ordinary link motion, I is the arm
which is fixed at right angles to the link, by which the link is caused to vibrate
about the fixed centre. H, the arm I being actuated by the crank-pin W by means of
the connecting rod K. By this means the arm I, and the link-rod D and the upper
end of the lever C are driven by the direct stroke of the connecting rod K (in this
case a vertical stroke), but the lower end of the lever C is on the other hand driven
by the pendulum motion of the rod K by means of the connecting rod E which in
this arrangement is attached to the rod K at a point between the crank-pin W and
the arm L. The link G is curved to the radius of the "link rod" D, and the
sliding block F can be adjusted to any position in the link G by means of the
ordinary reversing gear indicated at M. When the block F is adjusted at the
bottom of the link, the link rod D has the motion which with the ordinary link-
motion would be imparted by a forward excentric (fixed at 90° to the crank),
without any angular advance. When the block F is adjusted at the upper end of
the link, the link rod D has the reverse motion, or the motion which would be
given by a backward excentric fixed at 90° to the crank. The other connecting
rod E, which I call the "lead-rod," gives to the valve the necessary lead, by
imparting to the lower end of the lever O a motion equivalent to that of an
excentric at 180° from the crank. The position of the centre of the lever C, and
therefore the position of the valve, in the direction of its stroke, is always the
mean between the positions of the two ends of the lever O. Thus the lever C
combines the half of the motion of the link rod with half of the motion of the
lead rod, and this is why I term it the "combination lever."
In applying the valve-gear to other forms of engine, the motion of the two
rods may be combined in any other desired proportion by adopting suitable
proportions of the arms of the levers C. and I and the point of attachment of the
rod E. Figure 4 represents a vertical stationary or marine engine to which the
valve-gear is applied in accordance with this Invention. A is the valve chest
fixed on the side of the cylinder, B is the valve rod working in a guide, and
C is the combination lever having arms of unequal length. The valve gear is
driven by an excentric W and an excentric rod K which actuates the vibration
link G by means of the arm I, as hereinbefore. described, but for convenience of
construction in this class of engine the stroke of the "link rod" D is in this case
made somewhat less in proportion than that of the "lead rod" E, and the lever C
imparts to the valve rod a motion in which (in this example) two thirds of the
motion of D is combined with one third of the motion of E, or thereabouts-The
proportions may, it is evident, be otherwise varied in such manner as to produce
the desired travel and lead of the valve according to the requirements of the class
of engine to which the Invention is applied, and to suit the convenient arrange-
ment of the parts. In Figure 4 H is the centre on which the link vibrates and
M indicates the reversing gear, Figures 5, 6, and 7 represent locomotive engines

page_text: in which the valve gear is constructed according to this invention upon the principle
hereinbefore expressed. In each of these figures A is the valve-chest fixed on the
top of the cylinder and B is the valve-rod working in guides as shown in the
figures.
In figures 5 and 6 the engine is driven by. overhung cranks and the valve gear
is actuated in each case by an excentric W fixed at the back of the crank and an
excentric rod K which actuates the vibrating link G by means of the arm I fixed
at or about right angles to the link, and causing it to vibrate about the fixed
centre as before. In the arrangement shewn in Figure 5 the combination lever O
is attached to the valve rod by a centre which is nearly in the centre of its length,
and the "link rod" D and the "lead rod" E are attached respectively to the
upper and lower ends of the * combination lever" hereinbefore described In
Figure 6 the essential members of the valve gear and their action are the same as
hereinbefore described but with a modification of the points of attachment, which
will, it is obvious, produce the same motion of the valve in substantially the same 1
manner, although for constructive reasons I prefer the arrangement shewn in
figure 5. In figure 6 the "combination lever C" and the excentric rod K are
each prolonged at their upper ends and connected by the "lead rod" Ę above the
vibrating link instead of below it as in the examples hereinbefore given. In
Figure 7 the engine is driven by crank pins fixed on the outer faces of the wheels,
the valve gear is actuated by a return crank and small crank pin W, for con-
venience of construction, fixed with regard to the crank axle at 180° from the
position shewn in Figure 1, i-o at an angle about 7° from the crank. The "
bination, lever" O is attached to the valve rod at the centre of its length or
thereabouts, according to the required travel and lead of the valve; G is the link 2
vibrating upon a fixed centre and actuated as herein before described by the arm I
by means of the connecting rod K. D is the link rod attached to the lower end of
the combination lever C, while E is the "lead rod" attached to the upper end of
the combination lever and to the upper end of the connecting rod K.
com-
By the arrangement of the valve gear as hereinbefore described and illustrated 3
by the examples shown in the drawings I obtain in every case the requisite motion
of the valve, by means of the lever which I have called the "combination lever,"
which combines in the valve motion the direct stroke and the transverse pendulum
motion of the connecting rod or excentric rod K, and I thereby obtain the following
among other advantages; 1st the distribution of the steam is very nearly equal on 3
both sides of the piston, and the lead is invariable in all positions of the gear,-
which is not the case in the ordinary link motion; 2nd the motion being entirely
taken from one moving part, the valve is not thrown out of adjustment by any
wear of the engine connecting rod, which throwing out of adjustment occurs or is
liable to occur in other arrangements of gear where the motion is taken from more
than one moving part; 3rd There is no rubbing guide friction in changing the
direction of the vertical stroke.
Further by the general arrangement of motive gear and valve gear as above
described and illustrated in Figures 1, 2 and 3 I obtain a compact arrangement of
parts, perfect protection from dust, and facility of access to the mechanism, while
the arrangement allows the boiler and tanks to be placed low down between the
wheels, thus ensuring a low centre of gravity which is of great importance more
especially for Tramway engines.
I wish it to be understood that I do not claim the employment of a vibrating
link as novel in itself, nor the employment in itself alone of a " combination lever," 5
or "differential lever," nor do I claim in itself alone a dust proof casing enclosing
the gear of a tramway or other engine.
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 is

page_text: means of a lever the separate motions of two connecting rods both of which are
actuated by one excentric and rod, or crank pin and rod, one of the said two
connecting rods being actuated by the direct stroke, and the other of the said two
rods being actuated by the transverse pendulum motion of the said excentric or
crank rod, substantially as hereinbefore described and illustrated by the examples
shewn in the accompanying drawings.
Second: The general arrangements and combinations of parts constituting the
valve gear, as and for the purposes herein before described and separately illustrated
in Figures 1, 4, 5, 6 and 7 of the accompanying Drawings.
Third: The combination in a tramway or other locomotive, of my improved
valve gear with the general arrangement of motive gear and enclosure of the same
in a dust-proof casing, substantially as hereinbefore described and illustrated in
Figures 1, 2 and 3 of the accompanying Drawings.
Dated this fifth day of November One thousand eight hundred and eighty
four