IMPROVEMENTS IN STEAM PUMPS
Year: 1876

page_text: LETTERS PATENT to John Gillett, of Melksham Foundry, Melksham, in the
County of Wilts, Engineer, for the Invention of "IMPROVEMENTS IN STEAM
PUMPS."
Scaled the 18th July 1876, and dated the 23rd February 1876.
PROVISIONAL SPECIFICATION left by the said John Gillett at the Office
of the Commissioners of Patents on the 23rd February 1876.
JOHN GILLETT, of Melksham Foundry, Melksham, in the County of Wilts,
Engineer. "IMPROVEMENTS IN STEAM PUMPS."
This Invention has for its object improvements in steam pumps.
Single-acting steam pumps of the kind known as donkey pumps as ordinarily
constructed when used for feeding boilers working at high pressures, as, for example,
pressures from fifty pounds per square inch upwards, work very unsatisfactorily
owing to the resistance to the piston during the down stroke being so much in
excess of that during the up stroke, that if just sufficient steam be admitted to move
the pump plunger against the pressure on passing the bottom centre the steam
piston and plunger return with a rapid bound; hence the working is very uneven,
and there is undue wear and tear. It has been attempted to obviate this objection
by making the piston rod of almost equal diameter to the pump plunger, thus
reducing the area of piston on which the steam acts during the up stroke; but this
arrangement entails considerable increase of friction, and only remedies the defect
at a given pressure, depending upon the respective areas of the pump plunger and
steam piston. Now my Invention is designed to make a single-acting steam pump
capable of working evenly or nearly so at different pressures, for which purpose
with the main steam valve, whereby the admission of steam to and from the
respective ends of the piston is governed, I combine a supplementary valve and
means for adjusting from without the steam chest the position of such supplementary
valve relatively to the aperture in the main valve, through which steam is admitted
to the cylinder for effecting the up stroke of the piston. The valve rod passes
through a stuffing box or gland at each end of the valve chest, and is arranged to
admit of being rotated without affecting the position of the main valve, but so as by
means of a screw thread or worm on the rod to move the supplementary valve more
or less over the aperture in the main valve, through which steam is admitted to the
cylinder for effecting the up stroke.
The arrangement may be modified to suit circumstances.

page_text: The supplementary valve attached to the spindle in somewhat the same way as
above described instead of being made to slide on the back of the main slide may
be arranged to work with the main valve at the end of the latter over the valve
face, the aperture being in this case contracted by bringing the supplementary
valve up against the end of the main valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John. Gillett in the Great Seal Patent Office on the 22nd August
1876.
JOHN GILLETT, of Melksham Foundry, Melksham, in the County of Wilts,
Engineer. "IMPROVEMENTS IN STEAM PUMPS."
This Invention has for its object improvements in steam pumps.
Single-acting steam pumps of the kind known as donkey pumps as ordinarily
constructed when used for feeding boilers working at high pressures, as, for example,
pressures from fifty pounds per square inch upwards, work very unsatisfactorily
owing to the resistance to the piston during the down stroke being so much in
excess of that during the up stroke, that if just sufficient steam be admitted to move
the pump plunger against the pressure on passing the bottom centre the steam
piston and plunger return with a rapid bound; hence the working is very uneven,
and there is undue wear and tear. It has been attempted to obviate this objection
by making the piston rod of almost equal diameter to the pump plunger, thus
reducing the area of piston on which the steam acts during the up stroke; but this
arrangement entails considerable increase of friction, and only remedies the defect
at a given pressure, depending upon the respective areas of the pump plunger and
'steam piston. Now my Invention is designed to make a single-acting steam pump
capable of working evenly or nearly so at different pressures, for which purpose
with the main steam valve, whereby the admission of steam to and from the
respective ends of the piston is governed, I combine a supplementary valve and
means for adjusting from without the steam chest the position of such supplementary
valve relatively to the aperture in the main valve, through which steam is admitted
to the cylinder for effecting the up stroke of the piston. The valve rod passes
through a stuffing box or gland at each end of the valve chest, and is arranged to
admit of being rotated without affecting the position of the main valve, but so as
by means of a screw thread or worm on the rod to move the supplementary valve
more or less over the aperture in the main valve, through which steam is admitted
to the cylinder for effecting the up stroke.
The arrangement may be modified to suit circumstances.
Fig. 1 is a vertical section, shewing the steam cylinder and other parts of a
pump constructed according to my Invention; Fig. 2 is a plan shewing the main
and supplementary valves and means for adjusting the latter.
a is the steam
cylinder; b, the piston; c and d are the steam ports; e is the exhaust passage;
fis the main valve, through which the rod passes freely, its movement end wisc
independently of the valve being prevented by the lock nuts h; f¹ is a face formed
truly on the back of the valve f, and provided with apertures fi (see Fig. 2),
through which steam is admitted to the cylinder for effecting the up stroke; i is
which
the supplementary valve in gear with the screwed portion g¹ of the rod
rod is free to be rotated by means of the hand wheel k firmly pinned or fixed upon
it without affecting the position of the main valve, but so as by means of the screw
thread on the rod to move the supplementary valve more or less over the
apertures, so as to regulate the quantity of steam admitted by them and the
port to the under side of the piston b; lis a swivel frame or link, by which the
rod g is connected to the rod or link m; n is a thumbscrew for fixing the wheel k
so as to retain the supplementary valve in any position to which it may have been
moved.

page_text: Fig. 3 shews a modification, which will be readily understood from the Drawings,
the thumbscrew k being in this instance fixed on the tail end of the rod g, and the
form of the swivel being modified as shewn at o.
Fig. 4 shews a modification wherein the supplementary valve i, attached to the
spindle in somewhat the same way as above described, instead of being made to
slide on the back of the main slide valve f, is arranged to work with the main
valve at the end of the latter over the valve face, the aperture being in this caso
contracted by bringing the supplementary valve up against the end of the main
valve.
Having described the nature of my said Invention, and explained the manner of
carrying the same into practical effect, I hereby declare that what I consider to be
novel and original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent is, as an improvement in steam pumps
the combination with the main steam valve of a supplementary valve and means
for adjusting from without the steam chest the position of such supplementary
valve relatively to the main valve for regulating the admission of steam whereby
the up stroke of the piston is to be effected, substantially as herein described and
shewn in the accompanying Sheet of Drawings.
In witness whereof, I, the said John Gillett, have hereunto set my hand and
seal, this Seventeenth day of August, in the year of our Lord One thousand
eight hundred and seventy-six.
JOHN GILLETT. (L.S.)