IM- PROVEMENTS IN MOTIVE-POWER ENGINES
Year: 1876

page_text: LETTERS PATENT to Robert Douglas and Lewis Grant, both of Kirkcaldy,
in the County of Fife, North Britain, Engineers, for the Invention of "IM-
PROVEMENTS IN MOTIVE-POWER ENGINES."
ed the 17th November 1876, and dated the 13th July 187
PROVISIONAL SPECIFICATION left by the said Robert Douglas and Lewis
Grant at the Office of the Commissioners of Patents on the 13th July 1876.
ROBERT DOUGLAS and LEWIS GRANT, both of Kirkcaldy, in the County of Fife,
North Britain, Engineers. "IMPROVEMENTS IN MOTIVE-POWER ENGINES."
This Invention which relates to improvements in motive-power engines consists
in certain special arrangements and constructions of apparatus for actuating and
regulating the action of the valves of steam engines by which steam is admitted to
and cut off and exhausted from the cylinders.
These improvements consist in the application of a shaft driven from the crank.
shaft or some other moving part of the engine by toothed wheels or otherwise and
making the same number of revolutions as the crank shaft of the engines does. The
said shaft is placed parallel with the axis of the cylinder carried in suitable bearings
and has upon it a self-acting clutch or coupling permitting the part which actuates
the valve gear to be revolved by hand for starting or otherwise moving the engine.
Upon the said shaft, and opposite each pair of steam and exhaust valves an
eccentric sheave or pulley is fixed in a position suitable for communicating motion
to the valves, so as to effect the admission and cut off the steam. The eccentric
strap which passes round this sheave or pulley has an arm upon one side of it,
which is attached to a radius rod. To another part of the said strap a steel nib is
fitted, which at a certain point in the revolution of the shaft engages with another
steel nib attached to one end of a vibrating lever. The other end of this lever is
connected by suitable means to the steam valve, spindle, or rod. This lever vibrates
on a pin carried on one end of another short lever which is fixed on a weigh shaft
actuated by the governor. There are two of these weigh shafts, each connecting
the governor with one set of steam valve gear arranged so that, they may be
adjusted independently of each other, means for such adjustment being provided by
bosses with right and left-hand screws, or the equivalent thereof.
By the combined movement of the above-described nibs, after they come in con-
tact they are gradually disengaged from each other, and when the release takes place
the steam valves are closed by the means hereafter described.

page_text: When the governor is low the nibs engage more deeply and are engaged during
a longer portion of the stroke of the piston than when the governor is higher. In
this way the points are cut off by the steam valves, and the ratios of expansion of
the steam in the cylinder are variable, and are automatically regulated.
On one end of each steam valve spindle a small piston may be formed or fitted
working in a cylinder bored out in the valve chest door or attached thereto. The
one side of this piston being open to the steam pressure it receives impetus and
motion, which closes the valve whenever the nibs disengage. The air confined
between the other side of this small piston and the valve chest door forms a cushion
to soften the closing action, the amount of cushioning being regulated by suitable
means.
In connexion with, or instead of, the arrangement above described, a spring may
be used for closing the valve, or levers may be interposed between the valve spindle
and the spring. On another part of the herein-before mentioned eccentric strap a
snug or other projection is formed, to which is attached a short link connected to
one end of another vibrating lever which radiates on a fixed pin or bar. The outer
end of this lever being connected by suitable means to the exhaust valve spindle or
rod gives a reciprocating motion thereto.
Various modifications of this apparatus may be employed; for example, separate
eccentrics may be used for actuating the steam and the exhaust valves.
The arrangement is primarily applicable to gridiron valves with flat working
or other forms of valve, and may
surfaces, but it may be adopted to the "Corliss
be applied to actuate and regulate cut-off valves working in connection with slide
or other valves for admitting steam to the cylinders of steam engines.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Douglas and Lewis Grant in the Great Seal Patent Office
on the 12th January 1877.
ROBERT DOUGLAS and LEWIS GRANT, both of Kirkcaldy, in the County of Fife,
North Britain, Engineers. IMPROVEMENTS IN MOTIVE-POWER ENGINES."
«
Our said Invention which relates to improvements in motive-power engines
consists in certain special arrangements of apparatus for actuating and regulating
the action of the valves by which steam is admitted to and cut off, and exhausted
from the steam cylinders.
These improvements consist in the application of a shaft driven by toothed
wheels or otherwise from the crank shaft or some other moving part of the engine,
and making the same number of revolutions as the crank does.
The said shaft,
which is carried in suitable bearings, is placed parallel with the longitudinal axis
of the cylinder, and has upon it a self-acting clutch or coupling permitting the
part which actuates the valve gear to be revolved by hand in starting the engine.
Opposite each pair of steam and exhaust valves a sheave or pulley is fixed eccen-
trically on the said shaft so as to communicate motion to the valves and effect the
admission and cut-off of steam. A strap passing round this sheave or pulley
has an arm upon one side of it attached to a radius rod and to another part of the
said strap a steel nib is fitted, which at a certain point in the revolution of the
shaft engages with another steel nib attached to one end of a vibrating lever con-
nected by suitable means to the steam valve, spindle, or rod. This lever vibrates
on a pin carried on one end of another short lever which is fixed on a weigh shaft
actuated by the governor.
There are two of these weigh shafts, each connecting
the governor with one set of steam valve gear, and arranged so that they may be
adjusted independently of each other.
The nibs herein-before referred to after coming in contact are gradually dis-
engaged from each other, and when the release takes place the steam valves are
closed by the means herein-after described.

page_text: When the governor is low the nibs engage more deeply and are engaged during
a longer portion of the stroke of the pistion than when the governor is higher. The
points of cut-off by the steam valves and the ratios of expansion of the steam in
the cylinder are in this way made variable, and are automatically regulated.
On one end of each steain valve spindle a small piston is formed or fitted so as
to work in a cylinder bored out in the valve chest door or attached thereto, and
one side of this piston being open to the steam pressure it receives impetus and
motion which closes the valve whenever the nibs disengage. Air confined between
the other side of this small piston and the valve chest door forms a cushion to soften
the closing action, the amount of cushioning being regulated by an air valve or its
equivalent.
On another part of the herein-before mentioned eccentric strap a snug or other
projection is formed to which is attached a short link connected to one end of
another vibrating lever which radiates on a fixed pin or bar. The other end of
this lever is connected to the exhaust valve spindle or rod, and gives a recipro-
cating motion thereto.
And in order that our said Invention, and the system, mode, or manner in or
under which the same is or may be used or carried out in practice may be properly
understood, we have hereunto appended an explanatory Sheet of Drawings, on
which Figure 1 is a transverse section of the cylinder of a horizontal engine
having two admission and two eduction "gridiron" valves, in connection with
which the apparatus constructed in accordance with our said Invention is shewn
applied.
Figure 2 is a partial elevation of the cylinder shewing the valve gear for one'
steam and one eduction valve and the governor connexions for both steam and
both eduction valves. The horizontal shaft herein-before referred to is on the
Drawings marked A, and it is driven from the crank shaft of the engine by mitre
wheels (not shewn). On the shaft A an eccentric sheave or pulley B for each pair
of valves is fixed in a position suitable for giving motion to the respective valves at
the proper times. The strap passing round the sheave or pulley is marked C, and
it has an arm D formed on it and jointed to a radius rod E. The steel nib attached
to the strap C is marked F, and it at certain intervals in the revolution of the
shaft A, engages with another steel nib G fixed on one end of a vibrating lever H
whose opposite extremity is connected by the links I, I, to the spindle or rod J of
the steam valve K. This lever H vibrates on a pin L fixed in the lever M which
is centred on a rocking shaft N actuated from the governor by the lever O, Figure 2.
The rocking shaft belonging to the valve gear at the other end of the cylinder is
partly seen at N¹, Figure 2. These two rocking shafts are independent of each
other, and can be adjusted separately by the right and left hand screws of the
governor side rods P, P¹
On the end of the steam valve spindle J, opposite to the connecting links I, is
fixed a small piston Q fitted to work steam tight in a bored portion of the valve
chest door. The face of this piston being exposed to the pressure of steam in the
valve casing the valve is thereby closed instantaneouly so soon as the nibs F and G
are disengaged. The shock which would otherwise be occasioned by such instan-
taneous closing of the valve is tempered or cushioned by the air contained between
the larger end R of the piston and the end of the valve chest door, the amount of
cushioning being regulated by an air valve S or by equivalent means.
Upon another part of the eccentric strap Can eye is formed to which the link T
is connected, the said link being also attached to the lever U, which gives recipro-
cating motion through the connecting rod V to the spindle W of the exhaust
valve Y. The clutch X, which is provided in conjunction with the shaft A to allow
the part of the said shaft which carries the valve gear, to be turned round by
hand in starting the engine is kept in gear by a spring or its equivalent.
Having now described and particularly ascertained the nature of our said Inven-
tion, and the system, mode, or manner in or under. which the same is or may be
used or carried out in practice, we would observe in conclusion that we do not

page_text: confine ourselves to construct and employ the apparatus precisely in the manner
herein-before set forth and delineated on the accompanying Sheet of Drawings as
the same is susceptible of being varied or modified without departing from the
essential features of the Invention. For example, separate eccentric sheaves or
pulleys may be used for actuating the steam and exhaust valves constituting one
pair, and instead of closing the admission valves or both the admission and eduction
valves by the pressure of steam on a piston, as herein-before described, a spring
may be used for closing them, or springs with levers interposed between them and
the valve spindles may be employed, or these arrangements may be used in con-
junction with the piston.
"
Further, it is to be understood that we do not confine ourselves to employ the
apparatus in conjunction with "gridiron" valves, as it may also be adapted to
Corliss" or other forms of valves, and it may be applied to actuate and regulate
cut-off valves working in connexion with slide or other valves for admitting steam
to the cylinders of steam engines. What we consider to be novel and original, and
therefore claim as the Invention secured to us by the herein-before in part recited
Letters Patent is-
First. The general arrangement and combination of the apparatus herein-before
described and shewn on the appended Sheet of Drawings, or any mere modification
thereof, wherein projecting nibs or catches of steel or equivalent material fixed or
formed on the straps of eccentric sheaves or pulleys operated from the crank shaft
or other rotating part of the engine are employed to actuate the admission and
eduction valves of steam and other engines, and to regulate the cut-off motion
according to the motion of the governor balls or weights, substantially as set forth.
Second. Closing gridiron or other steam or exhaust valves by steam pressure
acting on pistons formed or fitted upon or attached to the spindles of the said
valves, substantially as is berein-before described and shewn on the appended Sheet
of Drawings.
Third. Constructing the shaft A in two parts, these being connected by a clutch
and spring, substantially as herein-before described with reference to the Drawings
hereunto annexed.
In witness whereof, we, the said Robert Douglas and Lewis Grant, have here-
unto set our hands and seals, this Eighth day of January, One thousand
ht undued and antre coKAN