IMPROVEMENTS IN VALVES KNOWN AS OF THE SCREW-DOWN KIND
Year: 1880

page_text: LETTERS PATENT to Andrew Sweet, of 102, Hampstead Road, in the Parish
of St. Pancras & County of Middlesex, Ironmonger, for an Invention of
"IMPROVEMENTS IN VALVES KNOWN AS OF THE SCREW-DOWN KIND."
PROVISIONAL SPECIFICATION left by the said Andrew Sweet at the Office
of the Commissioners of Patents on the 23rd August 1880.
ANDREW SWEET, of 102, Hampstead Road,. in the Parish of St. Pancras &
County of Middlesex, Ironmonger. "IMPROVEMENTS IN VALVES KNOWN AS OF
THE SCREW-DOWN KIND."
The seating piece I make of a cylindrical form; this works up and down without
revolving in the body of valve; in this piece I make an internal or female left
hand screw or thread; on one end of the spindle I make a corresponding external
or male screw or thread, which works in the aforesaid cylinder; in the cap piece or
body of the valve I cut a right hand internal or female screw or thread.
Immediately above the left hand screw on the same spindle, I cut a right hand
external or male screw or thread, corresponding to that in the body or cap piece
and working in it.
Thus I have a right and left hand screw on one spindle, simultaneously operating
to open or close the valve, by which several important advantages are obtained.

page_text: screw referred to cut therein.
Fig. 1 shows plan of above seating piece, and the half circular groove B, the
corresponding half being in the body of the valve; a piece of round wire placed in
this groove prevents the seating piece revolving.
Fig. 2 gives a half section of the spindle, by which at E the opening or shutting
force is applied; B shows the left hand screw corresponding to the female screw,
Fig. 1 at A, and working therein; C represents a right hand screw, corresponding
to the female screw at E in the cap piece and working therein. At D is shown a
circular smooth division gap between the left and right hand screws, on to which
the canvas rubber, Fig. 4 at A, is sprung.
Fig 3 is a half section of the cap piece; this cap piece is cut at F, F, about two
thirds of the depth of the rubber, Fig. 4; H, H, show the screw holes to screw the
cap piece on to body of valve.
Fig. 4 is the rubber in half section which serves to keep the joint of body and
cap piece sound, and also forms a top seating to which the seating piece rises when
the valve is open.
The Drawings are full size for a ³½ valve.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed or put in practice,
I hereby declare that I claim the combination or mechanical arrangements con-
stituting the Invention of improved mechanical arrangements in valves of the
screw down kind, as herein before described with reference to the several Figures
of the accompanying Drawing, it being understood that the details may be varied
as found desirable, provided the arrangements used are substantially the same
in mechanical effect, and having the same intention with those herein before
described.
In witness whereof, I, the said Andrew Sweet, have hereunto set my hand
and seal, this Twenty eighth day of February, in the year of our Lord One
thousand eight hundred and eighty one.