IMPROVE- MENTS IN SLIDE VALVES FOR STEAM ENGINES
Year: 1885

page_text: I, PERCY BAYLIS of Hurstleigh Fairfield Road, Croydon in the County of Surrey
Associate M. Inst C.E do hereby declare the nature of my invention for "IMPROVE-
MENTS IN SLIDE VALVES FOR STEAM ENGINES" to be as follows:-
.
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This invention has for its object improvements in slide valves for steam engines.
My improved slide valve is a piston valve working within a cylindrical casing-
the steam is admitted into the interior of the valve, which is hollow, and it passes
to the steam cylinder by ports or openings in the side of the valve.
The steam enters the cylinder when the valve is so placed that either of these
ports or openings coincides with or overlap the mouth of the corresponding passage
communicating with the steam cylinder.
The exhaust takes place when a cavity on the exterior of the valve coincides
with one or other of the cylinder ports. This valve may receive its movement
from an eccentric in the usual manner.
The novel feature however in my invention consists in providing within this
main valve a pair of sliding rings which as in the well known Meyer valve, cover
and uncover the valve ports, and so control the passage of the steam independently
of the eccentric which operates the main valve. The sliding rings are carried by a
rod having right and left hand screw threads upon it by turning the rod the rings
can be drawn nearer together or moved further apart, and by so doing a change is
made in the grade of expansion at which the engine works, the rod carrying these
interior rings may receive motion from a second eccentric.
By means of this compound piston valve I can obtain any desired degree of
expansion and at the same time the valve is not exposed to a steam pressure forcing
it into contact with the valve face.
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In the use of the Meyer valve, great friction results from this cause with a
consequent loss of power and an injurious wear of the working parts.

page_text: I PERCY BAYLIS of Hurstleigh Fairfield Road Croydon in the County of Surrey
Associate M. Inst: C.E. 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:-
This Invention has for its object improvements in slide valves for steam engines.
My improved slide valve is a piston valve working within a cylindrical casing or
valve chest. There are steam ports in the side of the valve chest and these are
connected in the usual way by passages with the working cylinder Also between
the steam ports is an exhaust port in connection with a passage leading to a
condenser or otherwise.
The valve is a compound valve and consists of parts constituting a main slide
valve and an expansion valve. The main slide valve is itself cylindrical and hollow
it fits the cylindrical valve chest within which it slides.
There are ports or apertures in the sides of the main slide valve and when these
overlap the steam ports, steam enters the cylinder from the interior of the main
slide valve which is always open to the steam.
Between the steam ports of the main slide valve there is an exhaust cavity and
when this cavity overlaps either of the steam ports leading to the working cylinder
exhaust takes place through this port and the exhaust port.
The main slide valve may receive its movement from an eccentric in the usual
manner.
The novel feature however in my invention consists in providing within this
main valve a pair of sliding rings which as in the well known Meyer valve, cover
and uncover the valve ports and so control the passage of the steam independently
of the eccentric which operates the main valve. The sliding rings are carried by
a rod having right and left hand screw threads upon it; by turning the rod the
rings can be drawn nearer together or moved further apart, and by so doing a
change is made in the grade of expansion at which the engine works. The rod
carrying these interior rings may receive motion from a second eccentric.
By means of this compound piston valve I can obtain any desired degree of
expansion and at the same time the valve is not exposed to a steam pressure forcing
it into contact with the valve face.
In the use of the Meyer valve, great friction results from this cause with a
consequent loss of power and an injurious wear of the working parts.
In order that my said invention may be more fully understood and readily
carried into effect I will proceed to describe the drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a section taken in the plane of the axis of the cylinder and of the

page_text: Figures 4 and 5 are transverse sections through the valve taken on the lines 4, 4,
3, 5, in Figures 1 and 2.
Figure 6 is a diagram showing the eccentrics and crank.
Figure 7 is a section of a valve similar to that shown by the preceding figures
but provided in every part with ring packings.
A is the steam cylinder-B and C are the steam passages leading to and from
the steam cylinder-D is the exhaust passage-E is a valve chest; The steam is
supplied to the ends of the valve chest by the passages F-G is the main cylin-
drical valve it works in a portion of the valve chest which is bored to receive it.
The valve G has ports G¹G in its sides by which steam passes to the cylinder, and
it has also a central cavity G³ around its exterior by which, when this cavity
coincides with either of the steam passages B or C, steam passes out of the cylinder
and by the exhaust passage D either to the condenser or into the air as the case
may be. His the rod of the main valve Gand I is the rod passing to the eccentric
from which this valve takes its movement. J in Figure 6 is the main eccentric.
KK are the sliding rings within the main valve G they receive motion from an
eccentric L with which they are connected by the rods M and N. O is the crank.
The eccentric rod N is so coupled with the ród M that the latter can be turned by
means of a hand wheel M upon its end. At M² the rod M has right and left hand
threads upon it and when the rod M is turned the sliding rings K K are by the
action of the screw threads drawn nearer together or separated from each other.
The detail of the connection between these valves and the eccentrics may be varied,
but the arrangement shown at Figure 6 is suitable, and taking the width of the
ports G¹ as unity the travel of the valve G may be four and the travel of the
sliding rings K K may be also four. As in the well known Meyer valve the cut
off is caused to take place sooner by increasing the distance between the sliding
rings K K and on the other hand a later cut off is obtained when the rings K K
are brought nearer together. This applies only when as is preferred the outer
edges K K¹ of the rings K K are employed to effect the cut off. The adjustment
is effected by turning the spindle M by means of the hand wheel at its end.
The same effect may be produced but less conveniently by varying the relative
positions or throw of the eccentrics J and L.
The parts KK are spoken of throughout as rings, the periphory being the
operative part, but obviously it is not essential that there should be a free aperture
through the part and in Figures 1 and 2 no such aperture is shown.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that I do not
claim any of the parts separately but what I claim is :-
1. The combination with the main piston slide valve G admitting steam to the
cylinder by ports G³ in its sides, of internal sliding rings K K controlling and
regulating the cut off substantially as described.
2.-The combination with the main piston slide valve G admitting steam to the
cylinder by ports G³ in its sides, of internal sliding rings K K controlled by a
spindle M with right and left hand screw threads substantially as described.