A NEW OR IMPROVED DIFFERENTIAL PUMP FOR PUMPING AND DISCHARGING VARYING QUANTITIES OF LIQUID AND PRODUCING VARYING PRESSURE
Year: 1867

page_text: LETTERS PATENT to Edward Thomas Hughes, of the Firm of Hughes and
Son, Patent Agents, 123, Chancery Lane, London, for the Invention of
"A NEW OR IMPROVED DIFFERENTIAL PUMP FOR PUMPING AND DISCHARGING
VARYING QUANTITIES OF LIQUID AND PRODUCING VARYING PRESSURE.”—A
communication from abroad by Pierre du Rieux and Edouard Roettger,
of Lille, in the Empire of France, Civil Engineers.
Sealed the 9th July 1867, and dated the 11th January 1867.
PROVISIONAL SPECIFICATION left by the said Edward Thomas Hughes
at the Office of the Commissioners of Patents, with his Petition, on
the 11th January 1867.
I, EDWARD THOMAS HUGHES, of the Firm of Hughes and Son, Patent
Agents, 123, Chancery Lane, London, do hereby declare the nature of the
said Invention for "A NEW OR IMPROVED DIFFERENTIAL PUMP FOR PUMPING AND
DISCHARGING VARYING QUANTITIES OF LIQUID AND PRODUCING VARYING PRES-
SURE," a communication to me from abroad by Pierre du Rieux and Edouard
Roettger, of Lille, in the Empire of France, Civil Engineers, to be as
follows:-
This Invention relates to the arrangement and construction of pumps called
differential pumps capable of being made to discharge at pleasure variable
quantities of liquids, and to produce at pleasure pressure of varying intensity.
According to this Invention two pump cylinders of similar diameters and
length of stroke, provided each with suitable suction valves, are connected

page_text: together by a tube or pipe, to which tube or pipe is affixed the discharge pipe
with suitable valves connected thereto. Within the said pump cylinders work
suitable pistons so arranged that the piston of one pump is raised, whilst the
piston of the second pump is depressed. If motion be now communicated to
the pump handle to actuate the pistons above mentioned the liquid will pass
alternately from one pump barrel to another, and no liquid will be sucked
into the pump nor discharged therefrom, but if the position of the fulcrum on
which the pump handle or lever works be changed so as to be brought nearer
the line of axis of one or other of the pumps the length of stroke of one piston
will be increased, and that of the second piston will be diminished. If the
pump handle be now made to work, a quantity of liquid will be discharged at
each stroke of the pistons equal to a column of liquid of the same diameter as
the piston, and equal in height to the difference between the length of stroke
of the two pistons, and by varying the relative length of stroke of each piston
the quantity of liquid discharged may be readily adjusted at pleasure, and it
will be found that the pressure of the liquid discharged from the said diffe-
rential pump will be inversely proportionate to the quantity discharged, and it
will be readily understood that by suitably varying the position of the fulcrum
of the pump handle or lever so as to increase or diminish the relative lengths
of stroke of the two pistons a given power acting on the said handle
may be made to communicate at pleasure varying pressure to the liquid dis-
charged, or a varying power (such as manual or animal power) may be
made to produce a constant pressure of uniform intensity; when the said
differential pump is actuated by a lever or handle turning on a fulcrum or
pivot between the two pump barrels the length of stroke to each piston is
varied by varying the position of the said fulcrum, causing it to approach
nearer to the line of axis of one pump, and to be more distant from the line
of axis the second pump; the pin or pivot upon which the pump lever
works is supported on slide bars connected with the main framing or other
suitable part of the pump, and it is capable of motion therein as well as in a
suitable slot in the pump lever, along both of which it is made to move as
required by means of screws or other mechanical means; or the fulcrum pin
or pivot upon which the said lever works may be connected to a standard
jointed to a suitable part of the framing, which said standard is made to
revolve partially round its axis so as to bring the fulcrum pin of the lever
nearer to one or other of the two pumps as required, the said fulcrum pin
moving in a slot formed in the said lever; or the fulcrum pin may be fixed to
the pump lever, and may be moved along a slot in the frame, the said lever
being formed with slots or slides in connection with the ends of the piston rods
pump

page_text: in order to enable the said lever sliding along the said piston rod heads to
assume its required position; or other well-known mechanical arrangements may
be used to increase and diminish the relative length of stroke of the pump
pistons; and these said differential pumps, which may be worked by any
suitable motive power, may be used either as force pumps for hydrostatic
presses, or other forcing purposes where pressure is required, or as feed pumps
for feeding varying quantities of liquid, as in the case of steam boiler, when
the said pump may be put in communication with the boiler float, which
float by rising or falling increases, or diminishes, or stops the feed as required;
or the said pumps may be used to register pressure, or as meters for measuring
liquids; the said differential pumps being generally applicable where a given
power is required to produce a variable feed or discharge, or variable pressure,
or where a power varying in intensity is required to produce a given feed or
discharge, or a given pressure.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edward Thomas Hughes in the Great Seal Patent Office on
the 11th July 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
THOMAS HUGHES, of the Firm of Hughes and Son, Patent Agents, 123,
Chancery Lane, London, send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of January, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirtieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Edward Thomas Hughes, Her special licence that I, the said Edward Thomas
Hughes, my executors, administrators, and assigns, or such others as I, the
said Edward Thomas Hughes, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "A NEW
OR IMPROVED DIFFERENTIAL PUMP FOR PUMPING AND DISCHARGING VARYING QUAN-
TITIES OF LIQUID, AND PRODUCING VARYING PRESSURE," a communication to me
from abroad by Pierre du Rieux and Edouard Roettger, of Lille, in the
Empire of France, Civil Engineers, upon the condition (amongst others) that
I, the said Edward Thomas Hughes, my executors or administrators, by an

page_text: instrument in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Edward Thomas Hughes, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement thereof (that is to say):-
This Invention relates to the arrangement and construction of pumps
called "differential pumps," capable of being made to discharge at pleasure
variable quantities of liquids, and to produce at pleasure pressure of varying
intensity.
According to this Invention two pump cylinders of similar diameters and
length of stroke, provided each with suitable suction valves, are connected
together by a tube or pipe, to which tube or pipe is affixed the discharge pipe
with suitable valves connected thereto. Within the said pump cylinders work
suitable pistons so arranged that the piston of one pump is raised whilst the
piston of the second pump is depressed. If motion be now communicated to
the pump handle to actuate the pistons, above-mentioned, the liquid will pass
alternately from one pump barrel to the other, and no liquid will be sucked
into the pump nor discharged therefrom; but if the position of the fulcrum
on which the pump handle or lever works be changed so as to be brought
nearer the line of axis of one or other of the pumps the length of stroke of
one piston will be increased and that of the other piston will be diminished.
If the pump handle be now actuated a quantity of liquid will be discharged at
each stroke of the pistons equal to a column of liquid of the same diameters
as the piston, and equal in height to the difference between the length of stroke
of the two pistons, and by varying the relative length of stroke of the two
pistons the quantity of liquid discharged may be readily adjusted at pleasure.
It will be found that the pressure of the liquid discharged from the said
differential pump will be inversely proportionate to the quantity discharged,
and it will be readily understood that by suitably varying the position of the
fulcrum of the pump handle or lever so as to increase or diminish the relative
lengths of stroke of the two pistons a given power acting on the said pump
handle may be made to communicate at pleasure varying pressure to the liquid
discharged or a varying power (such as manual or animal power) may be
made to produce a constant pressure of uniform intensity. When the said
differential pump is actuated by a lever or handle turning on a fulcrum or

page_text: pivot between the two pump barrels, the length of stroke to each piston is
varied by varying the position of the said fulcrum, causing it to approach
nearer to the line of axis of one pump, and to be more distant from the line of
axis of the second pump. The pin or pivot upon which the pump lever works
is supported on slide bars connected with the main framing or other suitable
part of the pump, and it is capable of motion therein as well as in a suitable
slot in the pump lever, along both of which it is made to move as required by
means of screws or other mechanical means; or the fulcrum pin or pivot
upon which the said lever works may be connected to a standard jointed to a
suitable part of the framing, which said standard is made to revolve partially
round its axis so as to bring the fulcrum pin of the lever nearer to one or other
of the two pump barrels as required, the said fulcrum pin moving in a slot
formed in the said lever; or the fulcrum pin may be fixed to the
pump lever,
and may be moved along a slot in the frame, the said lever being formed with
slots or slides in connection with the ends of the piston rods in order that the
said lever sliding along the said piston rod may head to assume its required
position; or other well-known mechanical arrangements may be used to
increase and diminish the relative length of stroke of the pump pistons; and
these said differential pumps which may be worked by any suitable motive
power may be used either as force pumps for bydraulic presses or other forcing
purposes when pressure is required, or as feed pump for feeding varying
quantities of liquid, as in the case of steam boilers, when the said pumps may
be put in communication with the boiler float, which float by raising or falling
increases or diminishes, or stops the feed as required; or the said pumps may
be used to register pressure, or as meters for measuring liquids, the said
differential pump being generally applicable where a given power is required
to produce a variable feed or discharge or variable pressure, or where a power
varying in intensity is required to produce a given feed or discharge or a given
pressure.
Having now described the nature of this Invention, as communicated to me,
I will proceed to describe means adopted in carrying the same into effect,
reference being had to the accompanying Drawings, and to the letters and
figures thereon marked, and in which Fig. 1 represents a vertical longitudinal
section of a differential pump constructed according to this Invention; Fig. 2
is an end elevation of the same, and Fig. 3 is a plan of the same.
a, a', are two pump barrels or cylinders, provided with suitable valve boxes
b,, and pistons A, A', and connected together by a tube or pipe c, to which tube
or pipe c is affixed the discharge pipe d (Fig. 3) and valve box d¹ (Fig. 1);
e, e, is a frame or standard formed at its upper end with slides e¹, e¹, curved

page_text: On the centre of
the link C, and
from the centre. B, on which centre B is jointed the link C, on the upper end
of which link C is a handle or lever D. Motion is communicated to the
pistons, A, A, by means of a beam or lever f actuated by a steam engine or
other suitable motive power by means of the rod g jointed to one end of the
said beam f. The piston heads are connected to the said beam f by pins or
bolts h traversing the piston heads and slots f¹, f', in the beam f, the said
beam being capable of a sliding motion on the said pins h.
the beam is a boss f, which said boss få passes through
a pin or bolt h¹ passing through the curved slides e¹, e¹, the links C and the
boss or centre f of the beam or lever facts as a pivot or fulerum upon which
the said beam f is made to oscillate. By moving the handle or lever D of the
link C nearer to the line of axis of one or other of the pumps the said
lever D and its link C will rotate partially on their centre B, and the pin or
bolt h will have corresponding motion in the slides e', e', drawing the beam f
along with it. Supposing the lever D were moved in the direction, of the
.arrow, and had assumed the position indicated by the blue line D', the centre
or fulcrum of the beam f would have assumed the position indicated by
the red circle ", and the length of stroke of the piston A' woull be increased
whilst that of the piston A would be diminished, and a quantity of liquid
would be discharged at each stroke of the pistons equal to a column of liquid of
the same diameter as the pistons, and equal in height to the difference between
the length of stroke of the two pistons; and it will be readily understood that
by moving the handle or lever D in one direction or the other the length of
stroke of either piston may be correspondingly increased or diminished, and
the quantity of liquid discharged may be readily adjusted according to the
extent to which the lever D is moved from its vertical position; also when
the differential pump is used for forcing liquids, the pressure of the liquid
will be inversely proportionate to the quantity discharged, and may be regu-
lated at pleasure by changing the position of the axis or fulcrum h¹ in its
slides e by moving the lever D, and if required the said lever D may be con-
nected with self-acting apparatus or other well-known mechanical contrivances
in order that the position of the said lever D, and consequently the discharge
or pressure from the pump, may be varied from time to time to suit the feed
or forcing purposes to which the said pump is applied, such as the feeding of
steam or other boilers, or the forcing of liquids.
The accompanying Drawings represent one mode of carrying this Invention
into effect, but other well-known mechanical means may be employed for
varying the relative length of stroke of each piston.
Having now described the nature of this Invention, and means for carrying

page_text: the same into effect, I wish it to be understood that I do not confine myself
to the precise details, herein-before described and illustrated in the accom-
panying Drawings, as the same may be varied without departing from the
nature of this Invention. What I claim is, -
First, the construction, adaptation, and arrangement of pumps, called
differential pumps, in which two pumps connected together are made to
discharge at pleasure varying quantities of liquids, or to produce varying
pressure, substantially as herein-before described and illustrated in the
accompanying Drawings.
And, second, the mode of varying the discharge and pressure obtained from
such differential pumps by varying the relative length of stroke of each pump
piston, substantially as berein-before set forth.
In witness whereof, I, the said Edward Thomas Hughes, bave here-
unto set my hand and seal, this Tenth day of July, A.D. 1867.
E. T. HUGHES. (L.S.)