IMPROVEMENTS IN EXPANSION GEAR FOR STEAM AND OTHER Engines
Year: 1873

page_text: LETTERS PATENT to Thomas Fardon, of the Linslade Works, Linslade,
in the County of Bucks, for the Invention of "IMPROVEMENTS IN
EXPANSION GEAR FOR STEAM AND OTHER Engines”
'
PROVISIONAL SPECIFICATION left by the said Thomas Fardon at the
Office of the Commissioners of Patents, with his 'Petition, on the
5th September 1878.
I, THOMAS FARDON, of the Linslade Works, Linslade, in the County
of Bucks, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN EXPANSION GEAR FOR STEAM AND OTHER ENGINES," to be as
follows:-
This Invention has for its object improvements in expansion gear for
steam and other engines.
In applying my improvements I use the ordinary three ports in the
cylinder valve face, and also the main slide valve as used in an ordinary
expansion gear, with two valves, one on the back of the other, except that

page_text: the ports through tho valve are expanded to a grid at the back to enable
the expansion valve to close the ports with a short travel. Tho back
valve I make of such a length as to open the ports at one end of the
valve and close the others at the same time.
The main valve is wrought by an eccentric in the usual way, and 5
attached to the bridle (or other connection with the main slido rod) is a
tube working through a stuffing box in the steam chest. Through this
tube which is fitted with a suitablo stuffing box I pass the spindlo for
working the expansion valve.
Attached to the tube is a light iron frame which carries a short lever 1
working on a pin at one end, and to which is pivotted the expansion
slide rod in such a manner as that the lever shall be at right angles to
the rod when the valve is at the half stroke. Also attached to the frame
is a pawl or detent which engages with the other end of the lever and
holds it fast when the expansion valvo is at cither end of its stroke, 1
so that the valvo moves back and forth with the travel of the main
slide.
To a bracket, or on any convenient portion of the engine or framing
that is stationary, I fix two springs, either spiral or straight, in such
a manner as when the main slide is on .one or the other side of its 2
central position the respective springs bear on the expansion slide
rod, tending to force it one way or the other, whichever spring is in
contact.
The ports in the valve are so arranged that the springs always tend to
close the passage to the port which is opened by the main slide, and 2
open the one closed by the main slido. The cut off takes place when
the pawl or detent is lifted, and the spring closes the valve.
I prefer to lift the detent by a sliding slievo cam actuated by the
governor and driven by the engine shaft, and having projections on it of
such a form as to vary the time of lifting the pawl according to the 3
position of the sliding sliove.
In cases where it is very difficult to connect with the governors or
shaft an electro-magnet may bo employed.
In the case of a vertical engine the springs should be so arranged as
to compensate the weight of the expansion slide and spindle.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Fardon in the Great Seal Patent Office
on the 5th March 1874.
filed by the said Thomas Fardon in the Great Seal Patent Office
on the 5th March 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
FARDON, of the Linslade Works, Linslade, in the County of Bucks, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of September, in the year
of our Lord One thousand eight hundred and seventy-three, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Thomas Fardon, Her special
license that I, the said Thomas Fardon, my executors, administrators,
and assigns, or such others as I, the said Thomas Fardon, 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
EXPANSION GEAR FOR STEAM AND OTHER ENGINES," upon the condition (amongst
others) that I, the said Thomas Fardon, my executors or administrators,
by an instrument in writing, under my, or their, or one of their hands
and seals, should particularly describe and ascertain the 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 Thomas Fardon, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :—
This Invention has for its object improvements in expansion gear for
steam and other engines.
I connect by a catch the rod of the main valve exterior of the steam
chest with the rod of the expansion valve. When the catch is in gear
it causes the two valves to travel together. The cut-off takes place

page_text: when the catch is disengaged, the expansion valve then moving on tho
back of the main valve and closing the ports in it. This motion is
produced by springs. The valves in the latter half of their stroke either
way compress one of the springs, and when the catch is roleased at the
moment the cut off is desired, and during the carly part of the return i
motion of the main valve, or before the return motion commences, it
shifts the expansion valve and closes the steam port in the valve by
which steam is entering the cylinder.
In applying my improvements I use the ordinary three ports in the
cylinder valve face, and also the main slide valvo as used in an ordinary 1
expansion gear with two valves one on the back of the other, except
that I prefer the ports through the valve to be expanded to a grid at the
back to enable the expansion valve to close the ports with a short travel.
The back valve I make of such a length as to open the ports at one end
of the valve and close the others at the same time.
The main valve is wrought by an eccentric in the usual way, and
attached to the bridlo (or other connection with the main slide rod) is a
tube working through a stuffing box in the steam chest. Through this
tubo which is fitted with a suitable stuffing box I pass the spindle for
working the expansion valve.
The catch arrangement is as follows:-Attached to the tube is a light
iron frame which carries a short lever working on a pin at one end and
which also engages with the expansion slide rod. There is a pawl or
detent which engages with the other end of the lever and holds it fast.
when the expansion valve is at eithor end of its stroke, so that the valve a
moves back and forth with the travel of the main slido.
To a bracket, or on any convenient portion of the engine or framing
that is stationary, I fix two springs, either spiral or straight, in such a
manner as when the main slide is on one or the other side of its central
position the respective springs bear on the expansion slide rod, tending
to force it one way or the other, whichever spring is in contact.
The ports in the valve are so arranged that the springs always tend to
close the passage to the port which is opened by the main slide, and
open the one closed by the main slide.
I prefer to lift the detent to cause the cut off to take place by a :
sliding sleeve cam actuated by the governor and driven by the engine
]

page_text: Figure 1 shews a plan of the gear as applied to an horizontal engine;
Figure 2 shows an elevation of the same with the piston in its forward
stroke; Figure 3 is an elevation with the crank in the opposite position ;
Figure 4 is an end view showing the position of the governor and other
parts.
A is an ordinary steam engine cylinder with the usual steam ports and
valve face; B, the steam chest; C is the main slide of ordinary con-
struction, when intended to be fitted with an expansion valve, but with
the back of the ports expanded to a grid as shewn; D is the expansion
valvo; E is a tubular valve rod leading from the bridle which holds the
main valve through the stuffing box of the steam chest. The tubo E is
screwed into the slotted bar or frame F, the other end of which is
suited to work in a guide and terminates in a joint to receive the
eccentric rod leading off the eccentric G. At the insertion of the tube E
is formed a stuffing box fitted with a gland as shewn.
The expansion valve D is attached to a rod H passing through the
tube E and the stuffing box on the slotted bar F; it extends along the
slot as shewn. For convenience the rod H is made in two pieces coupled
by the notched block I.
Fixed to the bar F in the position shewn is a bracket J on which
pivots a catch or lever K with two members; one engages in the notch
of the block I and the other engages by its projection with the corrc-
sponding projection on the lever L; when the parts are thus locked the
rod H and bar F, and consequently the two valves are moved back and
forth as one by the eccentric G. On the bed or other fixed part of the

page_text: engine is fixed a bracket M having on it four projections through which
pass a screw, proferably square threaded. Between the two centro
projections fits the block O slipped over the thread of the screw, and
passing up into the slot of the bar F. A hole is bored through this into
the centre portion of which the enlarged end of the rod H fits. Each
end of this hole is bored larger, forming two shoulders, against which
press on one side a washer passed over the rod H and on the other side
a disc with a pin in its centre to keep the spiral spring in its place.
Against these press two spiral springs V & W, as shewn, the other
ends of the springs pressing on two butts slipped over the thread of the
screw N and set up by nuts. The distance between the shoulders in the
block O is such that when the eccentric is at half stroke the expansion
valve can be moved so as to open and close cither port without the
enlarged end of the rod H removing cither spring from the shoulders in
the block O; Q is a rock shaft on which is keyed the lever L at one end
and the quadrant P at the other, which engages into the other quadrant
also marked P; these are segments of toothed mitre wheels. This last
quadrant is keyed on to a spindle R, on which is also keyed the lever S
engaging with the sliding sleeve or cam T on the spindle of the governors
U. As the governor balls open they raise the cam T up the spindle, and
bring a different part of it to act upon the lever S, and the form of the
cam is such that the higher it is raised the earlier in the stroke it raises
the lever L and frees K; I apply a spring to return the lever L when
released by the cam.
The detail of the form of some of the smaller parts is shown by the
Figures on Sheet 2. The action is as follows:-The ports at either end
of the cylinder can only be opened when the valve is on the other side
of its mid position to that on which such port is situated, and the
enlarged end of the rod II is in contact with that spring which, if
allowed would close the ports in the back of the main valvo by which
the steam has to pass by means of the expansion valve, and at the same
time open the corresponding ports at tho other end of the valvo
ready for admitting steam to the other end of the cylinder when tho
main slide opens the cylinder port. But tho catch K will not allow tho
expansion valve to move upon the main valve until the lever L is
withdrawn from its engagement with K. After the lever L is withdrawn
the parts aro in the position shown in the Drawing, the cut off is effected,
and before the opposite port is opened the lever will have fallen back

page_text: into such a position as to lock the valve against the pressure of the
opposite spring when it comes into action, the lever L may be withdrawn
at the right moment by any means preferred, but I prefer accomplishing
this by means of the cam T with a spiral projection on it which shall
regulate the point of cut off by the position of the cam on the spindle of
the governor U. The governor represented in the Drawing is that
known as Head's.
Having thus described the nature of my said Invention and the
manner of performing the same, I would have it understood that I
claim, the means of operating an expansion valve by a catch locking
together the rods of the main valve, and of the expansion valve, such
catch being liberated automatically at the instant the cut off is desired,
and then allowing the expansion valve to be shifted substantially as
described.
.
I also claim the construction of expansion gear for steam and other
engines, substantially as described.
In witness whereof, I, the said Thomas Fardon, havo hercunto
set my hand and scal, this Twenty-eighth day of February, in
tlic year of our Lord One thousand cight hundred and seventy-
four.