IMPROVEMENTS IN THE MODE OF WORKING CUT-OFF SLIDE VALVES
Year: 1876

page_text: LETTERS PATENT to Robert Hempsted and William Watkinson, both of
Grantham, in the County of Lincoln, for the Invention of "IMPROVEMENTS
IN THE MODE OF WORKING CUT-OFF SLIDE VALVES."
Sealed the 12th January 1877, and dated the 26th July 1876.
PROVISIONAL SPECIFICATION left by the said Robert Hempsted and William
Watkinson at the Office of the Commissioners of Patents on the 26th July
1876.
ROBERT HEMPSTED and WILLIAM WATKINSON, both of Grantham, in the
County of Lincoln. "IMPROVEMENTS IN THE MODE OF WORKING CUT-OFF SLIDE
VALVES."
The Invention relates to that class of combination steam engine valves in which
cut-off valves or plates are mounted on the back of the ordinary slide valve, the
action of such cut-off valves or plates being placed under the control of the
governor so as to produce a self-acting variable cut-off.
The description of slide valve herein referred to is of that variety through which
the steam passes by ports passing through the valve from back to face.
On the back of the ordinary slide valve are mounted in suitable guides a pair of
cut-off slide valves or plates, as is well understood. These cut-off slide valves or
plates are, according to our Invention, capable of being simultaneously moved
towards or from each other by the following means:-On the back of each cut-off
slide valve or plate is an inclined rib or projection. These ribs or projections are
placed in opposite directions to each other, so that at one end they approach
towards each other, and at the other end they diverge the one from the other. On
the back of these cut-off slide valves or plates is fitted a governing or operating
plate having grooves or recesses which fit the before-mentioned ribs or projections.
The governing or operating plate has also a groove or recess in the lower face
thereof, in which a projection from the main slide valve fits, and by which such
governing or operating plate is caused to travel to and fro with such main slide
valve, whilst at the same time the governing or operating plate is capable of being
moved to and fro in a direction across or at right angles with the slide valves. In
the upper face of the governing or operating plate is formed a slot, groove, or recess
in a line parallel to the motion of the slide valves. In this slot, groove, or recess is

page_text: fitted a block or slide, with capability of travelling to and fro therein so as to
permit of the required motion of the slide valves, and at the same time communi-
cate the required cross motion to the governing or operating plate. This slide or
block is operated by a crank fixed to a shaft or axis which passes out through a
stuffing box fixed to the steam chest, and is worked by means of suitable connections
from the governor. Instead, however, of employing a crank and block or slide to
operate the governing or operating plate a roller may be substituted for the slide or
block, and a cam or eccentric may be used in lieu of the crank.
If desired, both the main slide valve and the cut-off slide valves or plates may
be worked by rods operated by eccentrics, or only the main slide valve may be so
operated. Thus when the governor communicates a cross motion to the governing
or operating plate the latter, by its grooves or recesses acting in combination with
the ribs or projections on the backs of the cut-off slide valves or plates, causes the
latter to approach towards or diverge from each other, any thereby proportionately
covers or uncovers the ports through the main slide valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Hempsted and Willian Watkinson in the Great Seal Patent
Office on the 25th January 1877.
ROBERT HEMPSTED and WILLIAM WATKINSON, both of Grantham, in the
County of Lincoln.
VALVES."
"IMPROVEMENTS IN THE MODE OF WORKING CUT-OFF SLIDE
The Invention relates to that class of combination steam engine valves in which
cut-off valves or plates are mounted on the back of the ordinary slide valve, the
action of such cut-off valves or plates being placed under the control of the
governor so as to produce a self-acting variable cut-off.
The description of slide valve herein roferred to is of that variety through which
the steam passes by ports passing through the valve from back to face.
On the back of the ordinary slide valve are mounted in suitable guides a pair of
cut-off slide valves or plates, as is well understood. These cut-off slide valves or
plates are, according to our Invention, capable of being simultaneously moved
towards or from each other by the following means:-On the back of each cut-off
slide valve or plate is an inclined rib or projection. These ribs or projections are
placed in opposite directions to each other, so that at one end they approach
Lowards each other, and at the other end they diverge the one from the other. On
the back of these cut-off slide valves or plates is fitted a governing or operating
plate having grooves or recesses which fit the before-mentioned ribs or projections.
The governing or operating plate has also a groove or recess in the lower face
thereof, in which a projection from the main slide valve fits, and by which such
governing or operating plate is caused to travel to and fro with such main slide valve,
whilst at the same time the governing or operating plate is capable of being moved to
and fro in a direction across or at right angles with the slide valves. In the upper face
of the governing or operating plate is formed a slot, groove, or recess in a line
parallel to the motion of the slide valves. In this slot, groove, or recess is fitted a
block or slide, with capability of travelling to and fro therein so as to permit of the
required motion of the slide valves, and at the same time communicate the required
cross motion to the governing or operating plate. This slide or block is operated
by a crank fixed to a shaft or axis which passes out through a stuffing box fixed to
the steam chest, and is worked by means of suitable connections from the governor.
Instead, however, of employing a crank and block or slide to operate the governing
or operating plate a roller may be substituted for the slide or block, and a cum or
eccentric may be used in lieu of the crank.
If desired, both the main slide valve and the cut-off slide valves or plates may

page_text: be worked by rods operated by eccentrics, or only the main slide valve may be so
operated. Thus when the governor communicates a cross motion to the governing
or operating plate the latter, by its grooves or recesses acting in combination with
the ribs or projections on the backs of the cut-off slide valves or plates, causes the
latter to approach towards or diverge from each other, and thereby proportionately
covers or uncovers the ports through the main slide valve.
And in order that our said Invention may be more clearly understood and readily
carried into effect, we will proceed, aided by the accompanying Drawings, more
fully to describe the same.
Figure 1 is a longitudinal section through a cylinder and its valve chest, showing
our improvements applied thereto. Figure 2 is a cross section thereof, and Figure
3 is a plan showing the cover of the valve chest removed therefrom.
Figures 4 and 5 are plan views of the valve and cut-off plates separately, showing
then in two different positions.
Figure 6 is a plan and Figure 7 a sectional edge view of the two cut-off plates
separately, and Figure 8 is a plan.
Figure 9 an under side view, and Figure 10 a cross section of the governor plate
separately, and Figure 11 is a longitudinal section, and Figure 12 a cross section
through part of a cylinder and its valve chest, showing a modification of our
Invention in which the cut-off plates are also operated by a rod which is connected
to the governor plate.
a is a cylinder; b, a steam chest; and a¹, a², ports of the ordinary construction;
c is the main slide valve, which is formed with ports c¹ passing through the valvo
from back to face, and is operated by a rod c worked by an eccentric in the usual
manner. On the back of the slide valve care mounted in suitable guides c³ a pair
of cut-off slide valves or plates d, as is well understood. These cut-off slide valves
or plates & are, according to our Invention, capable of being simultaneously moved
towards or from each other by the following means:-On the back of each cut-off
slide valve or plate d is an inclined rib or projection , and on the backs of these
cut-off slide valves or plates d is fitted a governing or operating plate e having
grooves or recesses e¹ which fit the before-mentioned ribs or projections d'. The
governing or operating plate e has also a groove or recess e² in the lower face
thereof, in which a projection (in the present case the nut c) from the main slide
valve c fits, and by which such governing or operating plate e is caused to travel to
and fro with such main slide valve, whilst at the same time the governing or
operating plate e is capable of being moved to and fro in a direction across or at
right angles with the slide valve c and cut-off plates or valves d. In the upper
face of the governing or operating plate e is formed a slot, groove, or recess e³ in a
line parallel to the direction of motion of the slide valve and cut-off valves or
plates. In this slot, groove, or recess e³ is fitted a block or slide f, with capability
of travelling to and fro therein so as to permit of the required motion of the slide
valve and cut-off valves or plates, and at the same time communicate the required
cross motion to the governing or operating plate e. This slide or block f is
operated by a crank y¹ fixed to a shaft or axis g, which passes out through a
stuffing box b' fixed to the steam chest b, and has fixed on the outer end thercof a
crank g², which is worked by means of suitable connections from the governor.
Instead, however, of employing a crank g¹ and a block or slide f to operate the
governing or operating plate e a roller may be substituted for the slide or block f
and a cam or eccentric may be used in lieu of the crank g'. If desired, both the
main slide valve c and the cut-off plates or valves & may be worked by rods
operated by eccentrics, as shown at Figures 11 and 12, or only the main slide valve
c may be so operated, as shown in Figures 1 to 10. In the case of the arrange-
ment shown at Figures 11 and 12 the governing or operating plate e is formed with
a slotted opening e' therethrough from end to end, through which is passed the

page_text: slide rod h, which is worked by an eccentric in the usual manner. This slotted
opening is made wide enough to permit of the governing or operating plate e
being moved the required distance to and fro in a transverse direction to the rod h,
and the latter has lock nuts h¹ fixed thercon so as easily to fit the plate e and not
bind tightly thereon. The groove or recess e² in the plate e and the projection c¹
from the slide valve c are also dispensed with in this arrangement to permit of the
required motion of the parts, and the rod passes out of the valve chest at each
end thereof through a stuffing box to give the required support thereto against the
transverse motion of the plate e thereon. By the arrangements herein shown and
described when the governor communicates a cross motion to the governing or
operating plate e, the latter by its grooves or recesses e¹³ acting in combination with
the ribs or projections on the backs of the cut-off slide valves or plates & causes
the latter to approach towards or diverge from each other and thereby proportion-
ately covers or uncovers the ports c¹ through the slide valve c, whereby a variable
cut-off is obtained, whilst by the arrangement shown at Figures 11 and 12, in
addition to such action, the cut-off plates & are also operated by the rod h, thereby
producing a regulated cut-off in addition to such variable cut-off.
Having thus described the nature of our said Invention, and the mode in which
the samo is carried into effect, we would have it understood that what we claim is
operating the cut-off slide valves or plates c by the governing or operating plate e
actuated by the governor and working in manner substantially as herein shown
and described.
In witness whereof, we, the said Robert Hempsted and William Watkinson,
have hereunto set our hands and seals, this Twenty-third day of January
in the year of our Lord One thousand eight hundred and seventy-seven.