An Improved Pressure Reducing Valve.
Year: 1891

page_text: Date of Application, 25th Aug., 1891
Complete Specification Left, 12th May, 1892-Accepted, 18th June, 1892
PROVISIONAL SPECIFICATION.
An Improved Pressure Reducing Valve.
I, JAMES THORNTON, Mechanical Engineer, Great Western Dry Dock in the
City of Bristol, do hereby declare the nature of this invention to be as follows:-
A suitable casting having flanged or screwed ends. Near one of the flanges is
a cylinder, having a port on each side to allow the pressure to flow through. A
piston valve & rod is fitted in this cylinder, also a cover & stuffing box & gland.
Near the other flange is a larger cylinder into which is fitted a piston & rod;
a cover is also fitted on the top of this cylinder having a hole in it, so as to allow
air on top of piston. A fulcrum bracket is also on this cover, conveniently
placed.
Attached to the ends of both piston rods is a lever working on the fulcrum,
the long end of lever overhangs the large cylinder, where is placed a weight or
spring.
The pressure rising in the larger cylinder will force up the piston in that
cylinder.
The lever will then push down the small piston valve over the ports in small
cylinder, and thus stop the flow of pressure.
When the pressure in the larger
cylinder lowers, the weight or spring at end of lever will cause the piston valve in
the small cylinder to rise & open the port for a further flow of pressure.
Thus a low pressure can be maintained in the end of casting which is open to
larger cylinder, even if the pressure at the inlet end varies considerably.
The required low pressure is adjusted by adding or reducing the weight on end
of lever.
Thus the pressure flowing from inlet, through the ports of small cylinder, into
the reduced pressure side or end of casting; and at the same time against the
bottom of the piston which is in larger cylinder; it will be seen that when
any rise of the low or reduced pressure takes place, the piston will be forced
up and being connected to the lever, it will force the piston valve (at the other
end of lever) down over the ports & thus control the flow. The reverse action
takes place when the reduced pressure lowers slightly.
Amanded this 5th dex of October 1801
JAMES THORNTON.
COMPLETE SPECIFICATION.
An Improved Pressure Reducing Valve.
I JAMES THORNTON, Mechanical Engineer, of Great Western Dry Dock in
the City of Bristol 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 reduce a high fluid pressure to any required
lower pressure, and to maintain the same with certainty and regularity, regardless
of the initial pressure increasing, or varying in any way higher than the required
reduced pressure.
A is a suitable casting of brass or iron with flanged or screwed ends A', A².
Near the end A' is a suitable cylinder B. connected to casting A, through
which are ports B', B2, to allow fluid pressure to pass from A to A.
The bottom of cylinder B may be solid, or a suitable cover fixed thereon.
To the top end of cylinder B is also fixed a suitable cover, C, with a gland
and stuffing box, through which passes the valve spindle C¹.

page_text: Attached to the end of valve spindle in cylinder B, is a piston valve C³,
having a hole in it to allow equal pressure on both ends.
(A steam chest with a flat face, and ports, and a flat slide valve may be used
instead of cylinder & piston valve.)
A larger cylinder D is also suitably fixed to casting A, open at bottom into
the casting A.
Into this cylinder is fitted the piston and rod D', the piston being grooved for
packing.
A suitable cover D2 is fixed to top of cylinder D through which the piston-
rod D¹ passes. An atmospheric hole is also in the cylinder cover D².
Conveniently attached to cylinder cover D2 is a fulcrum bracket E, and a lever
guide bracket E'.
The lever E² is suitably connected to the fulcrum, also to the valve spindle C¹
by means of the connecting link F, and to the centre pivot double-eye F¹, which
rests upon the end of piston-rod D¹.
F2 is an adjustable weight to balance the upward pressure of piston.
A spring may be used on any convenient part of lever instead of the weight F2.
As will be seen, the pressure flowing from A' through the ports B₁ and B2,
into the casting A, and under the piston D', will force up the piston D³, when
the pressure rises a little above the load on lever; the lever will consequently
push the piston valve or slide valve over the ports B1 and B2, thus the flow of
pressure will be cut off.
When the pressure in A diminishes a little, the weight or spring on lever will
force the piston D' down and thus open the inlet ports for a further flow of
pressure.
Thus a regular pressure may be maintained in A even if the pressure at A'
increases.
The end A2, or outlet is made larger than the end A' or inlet.
Having thus described and ascertained the nature of my said invention, and in
what manner the same is to be performed, I declare that what I claim is.
First. The combination of a suitable casting attached to which is a suitable
cylinder with ports and a piston valve (or a steam chest with flat face and with
ports, also a flat slide valve). The said slide valve worked by means of a piston in
a cylinder. The reduced pressure acting on the bottom of piston only. The move-
ment of piston being communicated to slide valve by means of the lever working
on fulcrum. The adjustable weight or spring attached to any convenient part
of lever to balance the required low pressure, substantially as described and shewn.
Second. The end of lever connected to valve spindle by means of a link to
ensure valve spindle working freely through stuffing box & packing, the double-eye
spindle bearing centrally on end of piston rod so as to cause little friction. A
guide bracket to regulate the travel of piston.
Third. When the required amount of low pressure is in casting A, the slide
valve will be over the ports and the initial pressure being higher, it will keep the
valve tight against the face of the port. The low pressure will remain the same
even if the initial pressure increases, substantially as described and shewn.
Dated this Tenth day of May 1892.
JAMES THORNTON.