IMPROVEMENTS IN ROTARY VALVES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said Percy Graham Buchanan
Westmacott at the Office of the Commissioners of Patents on the 1st October
1881.
PERCY GRAHAM BUCHANAN WESTMACOTT, of the Elswick Works, Newcastle-
upon-Tyne, Engineer. "IMPROVEMENTS IN ROTARY VALVES."
This Invention has for its object improvements in rotary valves.
My improved rotary valve is very suitable for use in three-cylinder hydraulic
engines, and when so employed the moving parts of the valve are carried upon
the end of the engine shaft.
The valve consists of a cylindrical plug rotating within a shell of corresponding
form. In the sides of the shell there are (if for a three cylinder engine) threo
ports from which passages lead to the respective cylinders. There is a passage
provided in the plug passing from its end where the pressure water is admitted to
its side, where it terminates in a mouth. As the plug revolves this mouth comes
in succession opposite to each of the ports in the shell, and the water passes from
the mouth into the cylinders. There is also a cavity in the plug, and as the
plug revolves this in succession covers each of the ports, and the water is then able
to flow back from the cylinders each in turn into the cavity, from which there is at
all times a free outlet.
But a main feature in the Invention is in the means by which a tight joint is
maintained around the mouth of the supply passage in the plug, and against the
walls of the cylindrical cavity containing the plug. At this part the plug is
recessed to receive two moveable pieces in which the mouth (consisting of two
adjacent apertures) is formed. These pieces are arranged to slide radially into
their places in the plug, which is radially grooved to receive radial projections
upon the moveable pieces. The pressure of the fluid within the plug forces these
moveable pieces radially outwards against the walls of the cylindrical cavity,
holding them in fluid tight contact therewith; and this fluid tight contact is
preserved notwithstanding wear, which may take place in the plug and in the
walls of its cavity. The movement of the sliding pieces of the plug being radial
no alteration in their angular positions upon the plug is brought about by fair
wear, or in other words, the lap and lead of the valve remain unchanged.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Percy Graham Buchanan Westmacott in the Great Seal Patent
Office on the 31st March 1882.
PERCY GRAHAM BUCHANAN WESTMACOTT, of the Elswick Works, Newcastle-
upon-Tyne, Engineer. "IMPROVEMENTS IN ROTARY VALVES."
This Invention has for its object improvements in rotary valves.
My improved rotary valve is very suitable for use in three cylinder hydraulic
engines, and when so employed the moving parts of the valve are carried upon the
end of the engine shaft.
The valve consists of a cylindrical plug rotating within a shell of corresponding
form. In the sides of the shell there are (if for a three cylinder, engine) three
ports from which passages lead to the respective cylinders. There is a passage
provided in the plug passing from its end to its side, where it terminates in a
mouth. As the plug revolves this mouth comes in succession opposite to each of
the ports in the shell. There is also a cavity in the plug, and as the plug revolves
this in succession covers each of the ports.
But a main feature in the Invention is in the means by which a tight joint is
maintained around the mouth of the passage in the plug, and against the walls
of the cylindrical cavity containing the plug. At this part the plug is recessed
to receive two moveable pieces, in which-the-mouth-(consisting-of-two-adjacent-
-apertures)-is-formed. These-pieces-are.arranged to_slide_radially into their places
in the plug. The pressure of the fluid within the plug forces there noveable
pieces radially outwards against the walls of the cylindrical cavity, holding them in
Huid tight contact therewith; and this fluid tight contact is preserved, notwith-
standing wear which may take place in the plug and in the walls of its cavity.
The movement of the sliding pieces of the plug being radial no alteration in their
angular positions upon the plug is brought about by fair wear, or in other words,
the lap and lead of the valve remain unchanged.
In order that my said Invention may be most fully understood and readily
carried into effect, I will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a vertical section of a rotary valve constructed according to my
Invention; it is suitable to form part of a three cylindered hydraulic engine.
Figure 2 is a transverse section of the plug or revolving part of the valve with
the shell surrounding it; the section is taken on the line 1-1 in Figure 1. The
line 2-2 in Figure 2 is that on which the section, Figure 1, is taken; Figure 3, a
front elevation of the moveable parts, which are fitted into the plug; Figure 4 is
a plan of the same moveable parts.
a is the inlet passage for the pressure water, the casting in which it is formed is
a part of the hydraulic engine; a¹ is a circular cavity with which the passage a
communicates.
6 is a passage in the same casting leading to one of the cylinders of the bydraulic
engine. There are three such passages symetrically arranged around the casting
at angular distances of 120 degrees.
c is the outlet passage in communication with the cavity c¹.,
d is a cylindrical shell or bush fitted into the casting, and having three ports or
apertures d', d¹, d', in its sides corresponding to the three passages b..
e is the main portion of the plug; it forms part of the shaft of the hydraulic
engine or driving spindle of the valve.

page_text: g is a cupped leather forming a water tight joint between the plug e and the
shell d.
h is a similar leather to prevent the escape of water around the shaft f.
i is a cover at the end of the cavity in the casting giving access to the valve.
jis a perforated ring on which the cover abuts; it serves to keep the leather
in place, and to prevent endwise movement of the shaft, whilst it allows the free
exit of water by the passage e' in the part e.
k is a hollow formed by cutting away the part e of the plug on one side; as
this hollow comes in succession opposite to each passage bit establishes commu-
nication between it and the cavity a', and the pressure water passes to the
cylinder.
1, 1, are radially moveable pieces which are fitted into the part e of the plug;
they have openings ",", communicating with cavities within them, and theso
openings form the mouth by which the water passes back from the cylinders of
the engine. The water flows from that one of the passages b, which for the moment
is opposite to the mouth, into the mouth, and by the throats 12, 1², into the
passage el in the plug, and so to the outlet c.
In this way as the plug revolves each cylinder of the engine is discharged in
turn.
13,, are radial ribs fixed into the part e of the plug, and entering corre-
sponding grooves in the moveable pieces l. Figure 5 is an end view of one of the
ribs
These ribs are inclined, so that as the plug revolves the surfaces at 1* aro kept
in contact.
When the shell & becomes larger by wear the moveable pieces 1, 1, of the plug
will still remain in close contact with the shell during the rotation of the plug in
consequence of the preponderating pressure of the water behind thein urging
them outwards from the centre of the plug. The change resulting from wear
consequently does not alter the relative positions of the ports d¹ and the
mouth A.
Having thus described the nature of my said Invention, and the manner of
performing the same, I would have it understood that I claim my improved rotary
valve having a mouth formed in radially moveable pieces in the plug, substantially
as described.
In witness whereof, I, the said Percy Graham Buchanan Westmacott, have
hereunto set my hand and seal, this Ninth day of March, in the year
of our Lord One thousand eight hundred and eighty two.