IMPROVEMENTS IN EXPANSION GEAR FOR STEAM ENGINES AND OTHER MOTORS
Year: 1877

page_text: LETTERS PATENT to Aimé Robert, of Gilly, in Belgium, Engineer, for the
Invention of "IMPROVEMENTS IN EXPANSION GEAR FOR STEAM ENGINES
AND OTHER MOTORS."
Sealed the 25th June 1878, and dated the 27th December 1877.
PROVISIONAL SPECIFICATION left by the said Aimé Robert at the Office of
the Commissioners of Patents on the 27th December 1877.
"
AIMÉ ROBERT, of Gilly, in Belgium, Engineer. IMPROVEMENTS IN EXPANSION
GEAR FOR STEAM ENGINES AND OTHER MOTORS."
The object of my Invention is to simplify the construction of variable expansion
gear of steam engines and other motors.
The Invention consists in the employment of a wedge appliance or frame in
connection with a hydraulic or other governor or cataract for automatically
regulating the expansion or cut-off. The steam cylinder is formed with the
ordinary admission ports and exhaust port; on the cylinder slide face works an
ordinary hollow main slide valve with through port at each end, and on the back
of this main slide works an expansion slide consisting of two parts, which by a
wedge appliance or frame fitting and working thereon can be made to move nearer
to one another or further apart, thus altering the degree of cut-off or expansion.
Each part or half of the expansion slide may for this purpose be fitted with a
Blanting lug which works in a corresponding slanting slot in the wedge frame.
A rod driven by an eccentric actuates a frame fitting on the aforesaid wedge
frame; the same eccentric may by a rod on the opposite side of the frame serve to
work two single-acting press pumps which draw water from a small cistern, and
force it into a hydraulic cylinder, the piston rod of which is connected to the wedge
frame. There is an overflow pipe from the hydraulic cylinder to the cistern; the
opposite side of the wedge frame is connected to the piston of a small cylinder
supplied with steam by a tap or valve and pipe from the slide jacket; steam being
admitted, the wedge frame is lowered or moved against the action of the hydraulic
cylinder, and thus separates the two parts of the cut-off slide, the expansive action

page_text: is thus done away with and full steam admitted. The hydraulic cylinder piston
rod has a counterweight which is not used when the aforesaid small steam piston is
used, but is in use in the other case, that is, when the engine works without
expansion.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Aimé Robert in the Great Seal Patent Office on the 27th June
1878.
AIME ROBERT, of Gilly, in Belgium, Engineer.
GEAR FOR STEAM ENGINES AND OTHER MOTORS."
"IMPROVEMENTS IN EXPANSION
The object of my Invention is to simplify the construction of variable expansion
gear of steam engines and other motors.
The Invention consists in the employment of a wedge appliance or frame in
connection with a hydraulic or other governor or cataract for automatically
regulating the expansion or cut-off. The steam or other cylinder of the engine is
formed with the ordinary admission ports and exhaust port; on the cylinder slide
face works an ordinary or other hollow main slide valve with through port at each
end, and on the back of this main slide works an expansion slide consisting of two
parts, which by a wedge appliance or frame fitting and working thereon can be
made to move nearer to one another or further apart, thus altering the degree of
cut-off or expansion. Each part or half of the expansion slide may for this purpose
be fitted with a slanting lug which works in a corresponding slanting alot in the
wedge frame.
A rod driven by an eccentric actuates a frame fitting on the aforesaid wedge
frame; the same eccentric may by a rod on the opposite side of the frame serve to
work two single-acting press pumps which draw water from a small cistern and
force it into a hydraulic cylinder, the piston rod of which is connected to the wedge
frame. There is an overflow pipe from the hydraulic cylinder to the cistern; the
opposite side of the wedge frame is connected to the piston of a small cylinder
supplied with steam by a tap or valve and pipe from the slide jacket; steam being
admitted, the wedge frame is lowered or moved against the action of the hydraulic
cylinder, and thus separates the two parts of the cut-off slide, the expansive action
is thus done away with and full steam admitted. The hydraulic cylinder piston
rod may have a counterweight which is not used when the aforesaid small steam
piston is used, but is in use in the other case, that is, when the engine works
without expansion.
And in order that this my Invention may be fully understood, I will now proceed
to describe the same with reference to the accompanying Drawings, of which
Figure 1 is a vertical section through the slide box of a vertical engine fitted with
this expansion gear; Figure 2, a vertical section at right angles to that of Figure 1;
and Figure 3, a plan.
The cataract by preference consists of two single-acting pumps J, J, which are
actuated by an arm P from the expansion slide rod G, which receives its recipro-

page_text: catory motion from an excentric or equivalent appliance. These two pumps draw
water or other fluid from a small cistern V, and force it into the small cylinder R
which is fitted with a piston S, the rod of which is connected to the frame or
register I, enclosing a wedge appliance or frame H which I shall presently describe ;
the water forced into the cylinder R and thence passes off by a pipe T, the exit
being regulated by a tap or valve, according to the normal velocity of the engine.
When this speed increases the volume of water injected becomes larger than can
freely pass the cock on the pipe I, hence the piston S in the small cylinder R will
be moved towards its outer end, and as its piston rod is connected to the frame I
which encloses the wedge frame H, this latter will be moved simultaneously, the
wedge frame H is formed with two slanting slots, and the two half slides E have
corresponding lugs fitting in the said slots, the movement of the wedge frame H in
a horizontal direction will consequently cause the expansion slides E to be varied
in their relative position; these slides E when forced apart close the apertures B
through the main slide and cut off the steam admission to the steam cylinder.
When the engine attains its maximum speed, the piston S, which is at the end
of its stroke, opens to a second pipe U in order to prevent too great pressure
in the cylinder R; the water enters the cistern V from the pipes T and U, the
same water serves for a long time without being renewed; W is a small steam cylinder
fitted with a piston X, the rod of which is connected to the other end of the frame I
which encloses the wedge frame or plate H, the cylinder W is in communication
with the slide jacket (or with the boiler) by means of the pipe Y which is fitted
with a regulating cock or valve so set that the steam pressure repels the piston X
toward the bottom of the cylinder W, and thus suppresses the cut-off when the
speed of the engine diminishes as well as the pressure in the small cylinder R.
It will be understood that the amount of cut-off depends upon the speed of the
engine, that is, when the normal speed of the engine is exceeded, the pressure rises
in the little hydraulic cylinder R, and the piston S cause expansion to commence
by forcing apart the expansion slides E; when the speed goes below the normal
speed, and thereby the pressure falls in the hydraulic cylinder R, then the pressure
of the steam acting on the piston ✗ suppresses the cut-off by causing the expansion
slides E to be forced towards each other. As the wedge plate H is placed in the
frame of the rod G, it receives its vertical to-and-fro movement from the eccentric
which actuates the said rod G, and the wedge plate H receives its side motion for
varying the cut-off from the enclosing frame I which is operated from the pistons S
and X. The wedge plate H should work freely in the frame I to allow the to-
and-fro movement of the rod G, and should fit nicely in the frame of G so as to slide
therein.
The suction pipes of the pumps are united by a vacuum vessel for facilitating the
suction; the delivery pipes are connected by a sperical air vessel in order to
ensure a continuous stream. The two slides E enclosed in the wedge frame or
plate H are thus drawn together or apart each time there is a change in pressure
on the pistons X and S. The cylinders R and W are supported on brackets Z
fixed to the slide box. The two pumps J are fixed to a standard Q resting on the
slide box, and serving at the same time as a guide for the expansion slide rod G.
By this Invention the ordinary complicated arrangements for this purpose are
superseded which often preclude the employment of variable expansion gear.
In witness whereof, I, the said Aime Robert, have hereunto set my hand
and seal, this Twenty-second day of June, in the year of our Lord One
thousand eight hundred and seventy-eight.
AIME ROBERT,
(L.B.)