Improvements in Slide Valves for Steam Engines.
Year: 1890

page_text: Date of Application, 16th June, 1890
Complete Specification Left, 14th Apr., 1891-Accepted, 16th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in Slide Valves for Steam Engines.
We, JAMES MARSHALL of the Steam Plough Works Leeds in the County of
York, Engineer and REGINALD WIGRAM, also of the Steam Plough Works, Leeds
in the County of York, Engineer, do hereby declare the nature of this invention
to be as follows:-
Our invention relates to a construction and arrangement of slide valve and cylinder
ports governed by it in such a manner as to effect in a simple and compact manner
the control of the supply and discharge to and from a pair of parallel cylinders
placed side by side and working either as compound or as twin cylinders. For this
purpose, between the two parallel cylinders we provide a cylindrical slide casing
with internal grooves or recesses at different parts of its length, each such groove
or recess communicating with a port of the cylinder on the one side or on the other.
We fit to work in this cylindrical slide casing a cylindrical slide valve consisting of
a tube with a number of piston parts projecting from it at different parts of its
length, cach such piston part being in a suitable position for covering and uncovering
by its movement one of the port grooves or recesses above mentioned. We prefer
to pack each of these piston parts with spring rings. For governing and varying
the cut off, we fit within the tubular slide valve a second tubular slide valve
with projecting piston parts governing passages through the main slide valve to the
parts of the slide casing whence the cylinder ports receive supply. By moving
this internal slide valve relatively to the main slide valve the supply of steam to
the cylinders can be cut off' at various parts of the stroke.
Dated this 16th day of June 1890.
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Slide Valves for Steam Engines.
We, JAMES MARSHALL of the Steam Plough Works, Leeds in the County of
York, Engineer, and REGINALD WIGRAM also of the Steam Plough Works, Leeds
in the County of York, Engineer, 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 slide valve and
cylinder ports governed by it in such a manner as to effect in a simple and compact
manner the control of the supply and discharge to and from a pair of parallel
cylinders placed side by side and working either as compound or as twin cylinders.
For this purpose, between the two parallel cylinders we provide a cylindrical slide
casing with internal grooves or recesses at different parts of its length, each such
groove or recess communicating with a port of the cylinder on the one side or on
the other. We fit to work in this cylindrical slide casing a cylindrical slide valve
consisting of a tube with a number of piston parts projecting from it at different
parts of its length, each such piston part being in a suitable position for covering
and uncovering by its movement one of the port grooves or recesses above mentioned.
We prefer to pack each of these piston parts with spring rings. For governing and
varying the cut off, we fit within the tubular slide valve a second tubular slide valve
with projecting piston parts governing passages through the main slide valve to the
parts of the slide casing whence the cylinder ports receive supply. By moving

page_text: this internal slide valve relatively to the main slide valve, the supply of steam to
the cylinders can be cut off at various parts of the stroke.
Figure 1 of the accompanying drawings is a longitudinal section of a slide and
expansion valve and steam chest, according to my invention, for the pair of parallel
cylinders of a compound engine.
Fig. 2 is an end view of the slide valve at X.
Fig. 3 is an end view of each of the rings G.
Fig. 4 is a transverse section at Y Y and
Fig. 5 is a transverse section at Z Z.
The metal between the two cylinders is bored out to receive a liner A and has
formed in it recesses communicating with the ports leading to the ends of the two
cylinders, namely H₁ H2 the ports of the high pressure, and L1 L2 the ports of
the low pressure cylinder. There is also a large middle recess E for exhaust.
Facing each of these recesses the liner A has a number of round holes drilled
through it. Within the liner A is fitted the main slide valve B which is tubular
and is so shaped as to constitute a series of pistons each provided with spring packing i
rings, which, except those next the ends, slide over the round holes of the liner A,
thus closing and opening the passages to the several ports H H², L¹ L².
Within the main slide valve B is fitted to slide the tubular expansion valve, each
of its ends C¹ C² formed as a double piston with spring ring packings and between
them in each case a passage from the interior. These double pistons slide over a
set of round holes drilled at D through the internal body of the main slide valve B,
thus opening and closing passages to the supply ports of the main slide valve.
In constructing the main slide valve, we fit on the tubular internal body B a set of
rings, G, K, L, at each end recessed to receive the spring ring packings and all
secured in position by screwing the end rings L on to the internal body. The
expansion slide C is also made up at each end of a middle body C¹ or C² recessed
for spring rings with a pair of rings secured to the middle body by nuts and lock
nuts on the slide valve R. The main slide rod S is tubular and the rod R of the
expansion slide valve passes through it, these two rods being worked externally by
eccentrics or cams or in any other known manner. The steam pipe being connected
to either end of the steam chest so as to charge with steam the two end parts of the
chest and the middle of the slide valve, whilst the exhaust pipe is connected to any
part of the recess E, the steam passes alternately by the ports F1 F2, which are
governed respectively by the cut off slides C1 C2, to the ports H1 H2 of the high
pressure cylinder,-the exhaust steam from the high pressure cylinder passes
alternately by the ports H H and by passages M' M formed in the main slide
valve, to the ports L' L2 of the low pressure cylinder, and the exhaust from the low
pressure cylinder passes alternately by the ports L' Ĺ and passages M¹ M² to the
eduction cavity E.
Obviously when an expansion valve is not required the internal slide valve C
may be dispensed with.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we claim :-
1. In combination with the pair of parallel cylinders of a compound or twin engine
and their ports, a cylindrical tubular slide valve with packed piston parts governing
passages to these ports substantially as herein described with reference to the
accompanying drawings.
2. In combination with a slide valve such as is referred to in the preceding claim,
a cylindrical tubular expansion valve arranged within the main slide valve with
piston parts governing supply ports through the main slide valve, substantially as
herein described.
Dated 14 day of 2001
ABEL & IMRAY,
Agents for the Applicants.