Improvements in Slide Valves.
Year: 1888

page_text: Date of Application, 20th Jan., 1888
Complete Specification Left, 17th Sept., 1883
Complete Specification Accepted, 19th Oct., 1883
Improvements in Slide Valves.
I THOMAS LOCKERBIE of 27 Martins Lane, Cannon Street, E.C. in the county
of Middlesex Engineer do hereby declare the nature of this invention to be as
follows:
The object of this invention is to obtain the maximum of port area, with the
minimum travel of valve, also to relieve the pressure which is usually brought to
bear on the back of an ordinary flat faced slide valve. To effect this I use three,
or four flat faces, for the improved valve, in each of which, the usual top and bottoni
steam ports, and the exhaust port are formed. In cross section the valve chamber is
triangular, or when I use four faces may be square or diamond shaped. When four
faces are used the inner faces are rigid and in the case of a square cross section the
faces are prolonged beyond the ports so as to admit of two additional sets of ports
being formed, these additional ports being intended to communicate with the back
faces of the valve chamber.
The back faces of the valve chamber are not rigid and are placed in such a
position as to enable the pressure of steam to keep all the faces tight.
On one side of the moveable back faces are sets of ports corresponding to those on
the inner or rigid faces, and at right angles to these are ports corresponding to those
on the prolongation of the inner or rigid faces.
When the cross section of the valve chamber is triangular or diamond shaped, it
is obvious that the prolongation will not be in a straight line but will be as near as
possible at right angles to the moveable back faces.
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Attached to each of the moveable back faces will be one or more bolts which
will pass through the outer shell of the valve chamber through suitable stuffing
boxes.
When steam is on these bolts will be so regulated from the outside as to take the
bulk of the pressure off the valve, only leaving sufficient pressure to keep all
the faces tight.

page_text: The valve, or moving part will consist of a top and bottom face and two side
faces exactly similar to an ordinary slide valve, but having three or four faces
according to the shape of the chamber.
The faces upon which the chambers containing the back or moveable parts slide
can be made tight by grinding or may have suitable packing to prevent leakage on
each of the two sets of ports that serve as a communication between the back ports
and the main steam and exhaust passages.
Dated this the 18th day of January 1888.
COMPLETE SPECIFICATION.
Improvements in Slide Valves.
I THOMAS LOCKERBIE of 27 Martins Lane Cannon Street, E.C. in the County of
Middlesex, 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 :-
The object of this invention is to obtain the maximum of port area with the
minimum travel of valve, and to reduce or relieve the pressure of steam which is
usually brought to bear on the back of ordinary slide valves.
In order that my invention may be better understood I will describe the same
more in detail by making reference to the accompanying sheet of drawings, in which
Fig. 1 represents a cross section of a triangular slide valve and chamber. A is the
sliding portion, and the section is taken through the usual cavity for the exhaust to
escape. B is one of the set of ports in the rigid face, and B₁ B' represent the
corresponding sets of ports in the two adjustable side pieces C. C. in which are
formed sets of passages communicating with the main steam and exhaust passages D.
through the ports E. E. F. F. represent two sets of pins or bolts, which pass
through the sides of the valve chamber in stuffing boxes or other convenient manner,
to prevent the escape of steam.
These pins or bolts are regulated from the outside, and are used for taking the
pressure of steam off the back of the adjustable side pieces C. C., and as the faces
wear the bolts are slacked, so as to enable the faces to come together in such a
manner as to ensure them being steam tight only, but not with sufficient pressure to
cause considerable strain on the valve spindle, and friction on the valve faces.
G. G are two sets of adjusting pins acting on guides forming part of the two
adjustable side pieces, C. C, and are used to keep the faces of the ports E. E in
proper position, and steam tight.

page_text: Fig. 2 is also a triangular valve section, and is the same in every respect as Fig. 1,
except that the ports E. E. are at right angles to the rigid valve face B, instead of
in line, and the regulating pins go through the cover of the valve chamber instead
of the sides.
Fig. 3 represents a section of a diamond shaped valve, and is also the same in
every respect as Fig. 1 except having four sets of ports instead of three, and having
the two rigid faces at the necessary angle. Similar letters on all the Figs., indicate
parts corresponding to each other.
Instead of the pins F. F. being applied, slightly tapered cottars working in suitable
thrust bearings vertically, and adjustable outside, top or bottom, may be used.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be carried out, I declare that what
I claim is :-
The construction of slide valves having three or more sets of ports one or two
being rigid, and the others fitted with adjustable faces and ports, from which are
formed passages which lead to the main steam and exhaust connections on the
cylinder.