IMPROVEMENTS IN SLIDE-VALVE, EXPANSION AND REVERSING MECHANISM FOR LOCOMOTIVE AND OTHER ENGINES
Year: 1882

page_text: LETTERS PATENT to William Robert Lake, of the firm of Haseltine Lake
& Co., Patent Agents, Southampton Buildings, London for an Invention of
"IMPROVEMENTS IN SLIDE-VALVE, EXPANSION AND REVERSING MECHANISM FOR
LOCOMOTIVE AND OTHER ENGINES" Communicated to him from abroad by
Nicolas Alexis Bonnefond of Paris, France
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 28th September 1882.
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, London, IMPROVEMENTS IN SLIDE-VALVE, EXPANSION
AND REVERSING MECHANISM FOR LOCOMOTIVE AND OTHER ENGINES [A communi-
cation to him from abroad by Nicolas Alexis Bonnefond of Paris, France]
"
"
This invention relates to slide-valve expansion and reversing mechanism for
locomotive and other engines.
The methods of distribution of the steam, now in use upon locomotives, present
numerous inconveniences which prevent the power of the steam from being properly
utilized. The ordinary three-port slide-valves, as they are now actuated, render the
ports too narrow and produce a lamination of the steam. This is always produced
in cylinders in which the steam is compressed and diminishes the useful effect in
the cylinder. These inconveniences, and others which exist in the methods now
employed, are obviated by this invention which provides means for producing a
rapid and abrupt opening and closing of the admission-ports; the ports remaining
full open during the whole of the admission, without any lamination of the
steam.
The slide-valves are arranged in the form of pistons to diminish the resistance
caused by friction. The rod of the admission slide-valves is operated by releasing
mechanism which produces a rapid movement of these slide-valves for the admission.
This releasing mechanism is combined with an ordinary slide-link permitting of
changing the direction of working and not varying the expansion, as in the
mechanism now in use.
In carrying the said invention into practice, the movement of the distributing
valves is controlled by a cam keyed upon the axle or crank shaft, at a suitable
angle, in place of the ordinary excentrics; this cam actuates a collar provided with

page_text: friction rollers and fixed to a rod which operates upon one or the other extremity
of a slide-link, and causes the same to oscillate upon its pivot; the stud in the said
rod can only be arrested at one end or the other of the said link. The said rod is
raised or lowered by means of a bent lever actuated by mechanism for reversing
the motion by a screw or a lever. The slide-link, which serves to determine the
direction of motion, is provided with a frame or bearing at its upper end by means
of which it actuates the stud of a rod firmly connected to a parallel rod, which
actuates a couple of piston slide-valves; these valves receive an intermittent
movement so as to be alternately disengaged from the exhaust ports, leaving them
open during ninety five per cent of the stroke of the piston of the engine, or
thereabouts, thus avoiding back pressure. The rod which controls the admission
slide-valves is also actuated by the first named rod, but by means of two clicks or
pawls, which act alternately upon notches formed in the upper face of the aforesaid
parallel rod. The rod controlling the admission slide-valves is connected to the
said slide-valves and is fixed at this part to two springs of opposite curvature
which bring the said rod to its central position when one of the said clicks or
pawls, after having caused the said rod to move, is released therefrom and ceases
to hold the said rod in one of its extreme positions.
The admission of the steam to one end of the cylinder takes place while the
corresponding click or pawl is engaged with the said rod and ceases immediately
the release is effected; the duration of the admission, and consequently the
expansion, varies, therefore, with the duration of the engagement of the corre-
sponding pawl or click, because, when the release thereof is effected the slide-valves
return to their central position and close the two ports.
The mechanism for varying the expansion has, therefore, for its object to modify,
as desired, the duration of engagement of the clicks or pawls. But the release of
these clicks or pawls is effected by a device mounted upon a shaft and operated by
means of the piston rod cross-head through a connecting rod and a rod or arm
passing through the axis of the said device. When this device oscillates, its two
arms, at their extremities, come successively into contact with the said clicks or
pawls to release them. If the height of the said device is varied, it will come into
contact with the said clicks or pawls sooner or later, as the case may be, and will
operate the same more or less promptly. In order to be able to vary, at will, the
height of the said device, and thus modify the expansion, the shaft of the said device
is fixed to a lever pivotted upon a pin or stud which can be raised or lowered by
means of suitable mechanism operated by hand. The expansion in the engine
can thus be varied within wide limits, while the engine is in operation; by
lowering the said device as far as possible there is no engagement of the clicks
or pawls and the admission no longer takes place; by raising it very high there is
no longer any release of the said clicks or pawls.
The aforesaid cam is keyed on the shaft so as to correspond with the lead which
is deemed suitable, this lead remains the same for the admission and exhaust
whatever the direction of movement, and the degree of expansion may be.
The said cam effects the movements of the parts connected therewith in the one
eighth of a turn corresponding with the "dead point" of the crank, so that this
movement is fully effected before the piston has travelled a very small portion (in
some cases one centimetre) of its stroke, consequently the steam is fully admitted.
at the most favorable moment, that is to say when the speed of the piston is at
its minimum. If it is not desired to open the slide-valves so rapidly, the cams can
be replaced by excentrics.
In order to avoid an excessive back pressure in the cylinder, in some cases valves
are arranged at the two extremities, which valves open into the steam-chest so that
the back pressure cannot exceed the pressure in the steam-chest.
The different parts of the mechanism above described can be varied in form and
dimensions according to requirements.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
28th March 1883.
WILLIAM ROBERT LAKE, of the firm of Haseltine Lake & Co Patent Agents
Southampton Buildings London "IMPROVEMENTS IN SLIDE-VALVE, EXPANSION
AND REVERSING MECHANISM FOR LOCOMOTIVE AND OTHER ENGINES. A communi-
cation to me from abroad by Nicolas Alexis Bonnefond, of Paris, France
"
This invention relates to slide valve expansion and reversing mechanism for
locomotive and other engines.
The methods of distribution of the steam now in use upon locomotives present
numerous defects which prevent the power of the steain from being properly
utilized. The ordinary three port slide-valves as they are now actuated render the
ports too narrow and produce a lamination of the steam. This is always produced
in cylinders in which there is back pressure and diminishes the useful effect in the
cylinder. These inconveniences or defects and others which exist in the methods
now employed are obviated by this invention which is designed to provide means
for producing a rapid and abrupt opening and closing of the admission ports; the
ports remaining full open during the whole of the admission, without any
lamination of the steam.
The slide-valves are arranged in the form of pistons to diminish the resistance
caused by friction. The rod of the admission slide-valves is operated by releasing
mechanism which produces a rapid movement of these slide-valves for the
admission: This releasing mechanism is combined with an ordinary slide link
permitting of reversing the direction of motion and not varying the expansion, as
in the mechanism now in use.
The movement of the distributing valves is controlled by a cam keyed upon the
crank shaft, at a suitable angle, in place of the ordinary excentrics; this cam
actuates a collar provided with friction rollers and fixed to a rod which operates
upon one or the other extremity of a slide link and causes the same to oscillate
upon its pivot, the stud in the said rod can only be arrested at one end or the other
of the said link. The said rod is raised or lowered by means of a bent lever
actuated by mechanism for reversing the motion by a screw or a lever. The slide
link, which serves to determine the direction of motion, is provided with a frame or
bearing at its upper end by means of which it actuates the stud of a rod firmly
connected to a parallel rod, which actuates a couple of piston slide-valves; these
valves receive an intermittent movement so as to be alternately disengaged from
the exhaust ports leaving them open during ninety five per cent of the stroke of
the piston of the engine or thereabouts, thus avoiding back pressure.. The rod
which controls the admission slide-valves is also actuated by the first named rod,
by means of two clicks or pawls, which act alternately upon notches formed in the
upper face of the aforesaid parallel rod. The rod controlling the admission
slide-valves is connected to the said slide-valves and is fixed at this part to two
springs of opposite curvature which bring the said rod to its central position when
one of the said clicks or pawls, after having caused the said rod to move, is released
therefrom and ceases to hold the said rod in one of its extreme positions.
The admission of the steam to one end of the cylinder takes place while the
corresponding click or pawl is engaged with the said rod and ceases immediately
the release is effected; the duration of the admission and consequently the
expansion varies, therefore, with the duration of the engagement of the
corresponding pawl or click, because when the release thereof is effected the
slide-valves return to their central position and close the two ports..
The mechanism for varying the expansion has, therefore for its object to modify,

page_text: as desired the duration of engagement of the clicks or pawls. But the release of
these clicks or pawls is effected by a device mounted upon a shaft and operated by
means of the piston rod cross-head through a connecting rod and a rod passing
through the axis of the said device. When this device oscillates, its two arms at
their extremities come successively into contact with the said clicks or pawls to
release them. If the height of the said device is varied, it will come into contact
with the said clicks or pawls sooner or later, as the case may be, and will operate
the same more or less promptly. In order to be able to vary, at will, the height of
the said device and thus modify the expansion, the shaft of the said device is fixed
to a lever pivotted upon a pin or stud which can be raised or lowered by means of
suitable mechanism operated by hand. The expansion in the engine can thus be
varied within wide limits, whilst the engine is in operation; if the said device is
lowered as far as possible there is no engagement of the clicks or pawls and the
admission no longer takes place; if it is raised very high there is no longer any
release of the said clicks or pawls.
The aforesaid cam is keyed on the shaft so as to correspond with the lead which
is deemed suitable, this lead remains the same for the admission and exhaust
whatever the direction of movement and the degree of expansion may be.
The cam controls the slide link and the bar or rod which places the exhaust valve
at the end of its stroke by one rod and the admission valve at the end of its stroke
by another rod by means of a click or pawl. According to the elevation given to
the aforesaid device the said click is engaged for a longer or shorter period and
the admission port remains open for à longer or shorter time. As soon as the
click is disengaged, the spring which has been stretched reacts and rapidly moves
back the valve to its neutral point or mean position. The admission is stopped and
the expansion takes place during the remainder of the stroke of the piston. During
this time the second click has fallen ready to be acted upon by the admission rod,
in the contrary direction to the first click; as soon as the piston arrives at the end
of its stroke the cam will bring back the admission valve to the opposite position.
The said device will act in its turn upon the second click, will release it and the
admission valve being brought suddenly to its neutral position by the reaction of
the spring will cause the admission to cease for that side of the piston and the
expansion will take place. The same phases will occur for each turn of the crank
'shaft.
The said cam effects the movements of the parts connected therewith in the one
eighth of a turn corresponding with the "dead point" of the crank, so that this
movement is fully effected before the piston has travelled a very small portion (in
some cases one centimetre) of its stroke consequently the steam is fully admitted
at the most favorable moment, that is to say, when the speed of the piston is at
its minimum. If it is not desired to open the slide-valves so rapidly, the cams can
be replaced by excentrics.
In order to avoid an excessive back pressure in the cylinder, in some cases valves
are arranged at the two extremities, which valves open into the steam chest so
that the back pressure cannot exceed the pressure therein.
In addition to the advantages which the present invention offers for a more
effective utilization of the steam (by rapidly opening and closing the distribution
ports) than has heretofore been practicable, I may observe that it permits of
changing the direction of motion without considerable effort and that moreover,
the slide link mechanism can be very easily manipulated, and the expansion varied,
since it is only necessary to raise or lower the said device. And by depressing the
said device as much as possible the movement of the admission slide-valves is
suppressed while leaving the exhaust valves free to operate, so that there is never
any back pressure in the cylinders, which is often produced with the apparatus
now in use, for locomotives especially, and which causes damage and accidents.
In some cases I dispense with the springs for the admission slide valves and
substitute therefor two separate pistons acted upon by different pressures. I also
simplify the mechanism for controlling the distribution, as hereinafter set forth

page_text: The admission slide valve is formed, as shewn in Figure 1, of two pistons a
and b; the difference between their diameters may be from ten to fifteen
millimetres as deemed most expedient; a difference of twelve millimetres should be
sufficient, since, at seven atmospheres of pressure there will be a force of one hundred
and thirty kilogrammes superior by about one half to the resistance; of friction
due to the piston rings.
This mode of effecting the return movement of the valves, offers the following
advantages that is to say -The steam acts infallibly as a spring there being no
chance of derangement, loss, bending or fracture. Moreover the force increases
proportionately with the pressure and consequently with the resistance of friction
of the piston rings which it has to overcome.
The operation of the pistons is as follows, that is to say: Assuming the
admission rod to be pushed by one of the clicks or pawls so as to bring the
piston a into the position indicated in the drawing whilst the piston 6 also is in
the position shown, the port o is full open and remains so until the pawl or click
is disengaged, at which moment the piston a actuated by the extra pressure upon
its rear face is moved rapidly forward drawing with it the admission rod which
is thus brought into position to be operated by the other pawl or click which will
act upon it at the desired moment and will cause the piston b to have a movement
analogous to that of the piston a, so that the piston b is brought under the same
conditions. It will be seen therefore that the steam plays the part of the springs
hereinbefore referred to
In order to ensure the difference of pressure upon the two faces of the pistons,
which difference of pressure might be affected by the small amount of steam
allowed to pass by the piston rings, apertures c and c¹ permit communication
between the spaces comprised between the piston rings and the exhaust, these
apertures are closed by the large piston ring when the piston is at rest, when the
slide-valve is brought back rapidly by the steam, there is compression upon the
interior face, since all the annular space d d full of steam at a low pressure, tends
to be reduced to zero by this return and the aperture c is not large enough for the
escape of this steam to take place rapidly enough to avoid all compression.
Moreover, when in its return movement the piston has travelled a part of its
stroke, its large interior surface is in communication during the remainder of the
stroke with the side of the cylinder into which steam is being admitted, and conse-
quently the supplementary pressure which occasions the rapid return movement of
this piston is, if not annulled at least considerably reduced at the moment it gets
below the resistance of friction due to the piston rings. The result is that the
piston commences to lose its speed directly after having closed the admission
aperture so that the shock is prevented.
The control of the distributing mechanism represented in sectional side elevation
in Figure 1, in sectional plan in Figure 2 and in transverse section in Figure: 3, is
ensured by a cam keyed at any desired angle upon the crank shaft, in place of the
ordinary excentrics; this cam & imparts an alternative intermittent movement to a
collars which motion the extremity of the bar transmits to a slide-link u occupying
a fixed position and capable only of oscillating around an axis placed at the centre
of its length..
The extremity of the bar of the collar 8 is coupled by means of a connecting
rod to the reversing shaft and can actuate, as desired, the slide link u by either of
its two extremities according to the direction of motion it is desired to obtain
The slide link u serves only to determine the direction of motion and has no
influence upon the expansion.
This slide link u controls an intermediate rod x connected securely to a second
rode (Figure 2) upon which is mounted the exhaust slide-valve which consequently
receives an alternative intermittent motion in such a manner as to open,.at. the
desired moment, the exhaust apertures and to leave them open during ninety five
per cent, of the stroke of the piston.
The lar or rod g, upon which the two admission valves a and b are free to slide,

page_text: also receives its movement from the intermediate rod x by means of two clicks or
upper face
pawls ii acting alternately upon notches formed for this purpose on the
of this rod. Assuming that the click or pawl i has driven the rod g into the
position represented in the drawings the piston h will occupy the position indicated
and the rear admission port will be opened full. As the pressure of the steam on
the front face of the piston a is greater than that on its rear face, this piston will
rapidly reassume its first position and close the admission port as soon as the click
or pawl is released. In returning, the piston a moves back the rod g to its mean
position, the click or pawl i is engaged and when the operating cam causes this
click or pawl to move, it will cause the piston 6 to operate in the manner described
with reference to the piston a, the duration of the admission will therefore be
determined by the successive release of the two clicks or pawls i i.
The release of the two clicks is effected by means of the lever k mounted upon
the extremity of the small shaft m and receiving oscillatory motion from an
excentric n mounted upon the crank shaft and keyed at any desired angle opposite
to the crank.
The shaft m is supported upon the extremities of two levers forming part of a
transverse shaft o and can consequently be raised or lowered at will according to
whether the lever p is moved in one direction or the other by means of the rod r
which will constitute the rod for regulating the expansion, since it is evident that
the lever k will release the clicks i sooner or later according to whether it is lowered
more or less
The limits between which the duration of admission can be varied are from 0.08
to 0.85 of the stroke of the piston.
The rod is controlled by a screw and a small fly-wheel designed to be operated
by hand
The different parts of the mechanism above described can be varied in form and
dimensions according to requirements
Having thus fully described the said invention as communicated to me by my
foreign correspondent and the manner of performing the same I wish it understood
that I claim
The above described improvements in slide-valve, expansion and reversing
mechanism for locomotives and other engines, the distinctive characteristics of
which improvements are as follows, that is to say:-
First. The rapid operation of the admission slide-valves for opening and closing
the ports in such a manner that they will be full open during the whole of the
admission without producing any wire-drawing or lamination of the steam, the
slide-valves being operated for this purpose by releasing mechanism combined with
a slide-link for changing the direction of motion.
Second. The suppression of back pressure in the cylinders, the exhaust taking
place through special slide-valves which uncover the exhaust ports during the
whole of the return stroke of the piston.
Third. The control of the admission slide-valve rod by two clicks or pawls in
inverse directions which clicks or pawls are released by an oscillating lever the
height of which can be varied at will relatively to the said clicks to modify the
duration of the admission and consequently the expansion of the steam..
Fourth. The arrangement of the admission slide-valve rod with two springs
which move back the valves to their mean position when one of the clicks is
released.
Fifth. The oscillation of the releasing lever by mechanism actuated by the cross-
bead of the piston-rod.
Sixth. The control of the two rods of the admission and exhaust slide-valves by
an oscillating slide-link which can be raised or lowered at will by means of reversing
mechanism according to the direction of motion desired.
Seventh. The independence thus obtained of the reversing mechanism and the
mechanism for varying the expansion.

page_text: Eighth. The control of the slide-link by a rod connected to a collar surrounding
a cam and actuated thereby, which collar acts upon rollers held therein.
Ninth. The combination of two separate pistons of different diameters upon the
same rod, to constitute the admission slide-valves, the difference of pressure thus
obtained serving instead of the springs.
Tenth. The simplified construction and arrangement of the devices for giving
movement to the admission piston-slide-valves substantially as above described and
as shown in the drawings.
In witness whereof I the said William Robert Lake have here unto set my
hand and seal this twenty eighth day of March in the year of our Lord
one thousand eight hundred and eighty three.
WM RORT LAKE rol