An Improvement in Cut-off Valves for Engines Worked by Steam or other Elastic Fluid.
Year: 1887

page_text: Date of Application, 20th Jan., 1887
Complete Left, 19th Oct., 1887
Complete Accepted, 22nd Nov., 1887
An Improvement in Cut-off Valves for Engines Worked by Steam
or other Elastic Fluid.
We, WILLIAM MATHER of Salford Iron Works, Manchester in the County of
Lancaster, Engineer, and JAMES HOLGATE also of Salford Iron Works, Manchester
in the county of Lancaster, Foreman, do hereby declare the nature of this invention
to be as follows:-
Our invention relates to a construction and arrangement of a cut-off valve fitted
on the back of the ordinary slide valve of a fluid pressure engine and worked in such
a manner that, while the main slide valve and the cut off slide reciprocate, the cut off
valve has its position or setting whereby it governs the ports of the main slide valve
maintained or varied independently of the reciprocating movements of the slide valve
and the cut off slide. For this purpose, instead of carrying the supply passages
through the body of the main slide valve in a straight direction, we bend them in
such a manner that they present curved apertures at the back of the slide valve, and
on a cut-off slide reciprocating parallel to the main slide valve we mount a shutter
valve upon a pivot on which it can be turned as on an axis perpendicular to the
plane of the slide, so as to overlap more or less the curved apertures presented at the
back of the slide valve. This shutter valve being connected to a lever (worked by a
governor or by hand or otherwise) by a link at right angles to the direction in which
the slide valve and the shutter slide reciprocate, has no sensible rotary movement
imparted to it by their reciprocation, and, consequently, its angular position in
relation to the apertures at the back of the slide valve, which position determines the
time of cut-off, is maintained or varied independently of the reciprocating movements
of the slides. In engines having comparatively short slide valves, the shutter valve
above described is conveniently made in one piece, with two wings, one to govern
each of the two slide passages; but, when the slide valve is of considerable length, or
when there are two separate slide valves, one for each end of the cylinder, two
separate shutter valves may be used, these or the levers which move them being
inked together.
Dated this 20th day of Janue1007
ABEL & IMRAY,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
An Improvement in Cut off Valves for Engines Worked by Steam
or other Elastic Fluid.
We, WILLIAM MATHER, of Salford Iron Works, Manchester, in the County of
Lancaster, Engineer, and JAMES HOLGATE also of Salford Iron Works, Manchester,
in the County of Lancaster, Foreman, do hereby declare the nature of this invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:—
Our invention relates to a construction and arrangement of a cut off valve fitted
on the back of the ordinary slide valve of a fluid pressure engine and worked in such
a manner that while the main slide valve and the cut off slide reciprocate the cut off
valve has its position or setting whereby it governs the ports of the main slide valve
maintained or varied independently of the reciprocating movements of the slide valve
and the cut off slide.
For this purpose, instead of carrying the supply passages through the body of the
main slide valve in a straight direction we bend them in such a manner that they
present curved apertures at the back of the slide valve and on a cut off slide
reciprocating parallel to the main slide valvo we mount a shutter valve upon a pivot
on which it can be turned as on an axis perpendicular to the plane of the slide,
so as to overlap more or less the curved apertures presented at the back of the
slide valve.
In
This shutter valve being connected to a lever (worked by a governor or by hand
or otherwise) by a link at right angles to the direction in which the slide valve and
the shutter reciprocate, has no sensible rotary movement imparted to it by their
reciprocation and consequently its angular position in relation to the apertures at
the back of the slide valve, which position determines the time of cut off, is
maintained or varied independently of the reciprocating movements of the slides.
engines having comparatively short slide valves the shutter valve above described is
conveniently made in one piece, with two wings, one to govern each of the two
slide passages, but when the slide valve is of considerable length or when there aro
two separate slide valves one for each end of the cylinder, two separate shutter
valves may be used, these or the levers which move them being linked
together.
Fig. 1 of the accompanying drawings is a plan partly in section-Fig. 2 is a
transverse section and Fig. 3 is a longitudinal section showing a cut off valve
according to our invention applied to a short slide valve.
In Figs. 4, 5, and 6 are corresponding views shewing its application in the case
where separate slide valves are used for the two ends of the cylinder.
Corresponding parts in all the figures are marked by similar letters.
a a¹
In Fig. 1 the cut off or shutter valve is in one piece having two wings a
and turning on a central axis or pivot b which is carried on a slide block c.

page_text: This block is worked by the rod d receiving reciprocating motion like an ordinary
cut off slide valve.
The wings a a¹ have curved edges corresponding with curved apertures in the
back of the ordinary slide valve e these apertures being the mouths of passages
through the body of the slide valve, terminating in rectangular mouths or ports
on the face of the valve corresponding with the cylinder ports. An arm h
projecting from the shutter valve a a¹ is connected by a link y and an arm and
rocking spindle k to a lever and rod worked by the governor or by hand or
otherwise. By moving the rod the wings a a are caused to turn on their
pivot moving their convex edges towards or away from the concave edges of the
slide apertures and thus varying the point of the stroke at which each port is
closed.
The link g being at right angles to the direction in which the slide valve and the
shutter valve reciprocate, no sensible rotatory movement is imparted by the
reciprocation to the shutter valve.
In the arrangement shewn in Figs. 4, 5 and 6 the cut off valve is made in two
parts each having a single wing a a¹, at the back of one of the two main slide
valves e el and each being pivotted at 6, 6' on the sliding blocks cc' which are worked
by the rod d.
The arms are connected by links gg to a lever on the rocking spindle k
worked by the governor or otherwise for determining the point of cut off.
The action of these separate valves is the same as that of the single valve
previously described, that is to say, as long as the spindle remains at rest, the
wings a a¹ act as an ordinary rider slide on the back of a main slide valve cutting off
at some determined part of the piston stroke; but when by the governor or otherwise
the spindle is partly turned so as to move the convex edges of the wings a a¹ nearer
to or farther from the concave edges of the slide ports the cut off is made to take
place sooner or later as the case may be.
When the flaps a a' are of considerable size or subject to considerable pressure their
friction on the slide valve may be more or less reduced by applying to them any of
the known means of relieving the pressure of slide valvos on the facings on which
they work.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed we declare that what wo
claim is :-
Forming a cut off valve on the back of a main slide valve as a partially rotating
wing or flap pivotted on a slide block which is worked as an ordinary cut off slide,
the said wing or flap being turned on its pivot by an arm acted on by a link
perpendicular to the line in which the slide valve reciprocates, substantially as and
for the purpose set forth.
Dared this 19th day of October 1887
ABEL & IMRAY,.
Agents for the Applicants.