IMPROVEMENTS IN MOTIVE- POWER ENGINES TO BE WORKED BY WATER, STEAM, OR OTHER FLUID, AND APPLICABLE TO PUMPS
Year: 1867

page_text: LETTERS PATENT to Henry Purnell, of Glasgow, in the County of Lanark,
North Britain, Engineer, for the Invention of "IMPROVEMENTS IN MOTIVE-
POWER ENGINES TO BE WORKED BY WATER, STEAM, OR OTHER FLUID, AND
APPLICABLE TO PUMPS."
Sealed the 16th August 1867, and dated the 23rd February 1867,
PROVISIONAL SPECIFICATION left by the said Henry Purnell at the Office
of the Commissioners of Patents, with his Petition, on the 23rd February
1867.
I, HENRY PURNELL, of Glasgow, in the County of Lanark, North Britain,
Engineer, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN MOTIVE-POWER ENGINES TO BE WORKED BY WATER, STEAM, OR
OTHER FLUID, AND APPLICABLE TO PUMPS," to be as follows, that is to say :-
This Invention relates to improved and simplified motive-power engines to
be worked by water, steam, or other fluid, and comprises as its principal
feature of novelty the employment of three single-acting cylinders oscillating
or vibrating on trunnions or their equivalent with inlet and outlet ports dis-
posed at that side of the trunnions, the close or tight-fitting of which is insured
by the working strain of the cylinders. The improved apparatus is also
applicable for pumping.
In carrying out the Invention for the purpose of obtaining motive power
three oscillating or vibrating cylinders are used, their piston rods being jointed
on cranks disposed at equal angular distances on a shaft. The cylinders are
made single-acting in order that their working strain may always be in one

page_text: direction, namely, in the direction from the crank shaft, and they are formed
with trunnions which are by preference situated at the ends further from the
crank shaft. Or instead of each cylinder being formed with trunnions pro-
jecting laterally it has its end shaped like a portion of a cylinder to oscillate
in a seat of a corresponding form. Each cylinder is formed with ports in the
trunnion surface, and there are ports and passages in the bearing surface or
seat, to one or more of which last the incoming motive fluid has access, whilst
the other port or ports lead to the discharge pipe. As each cylinder performs
its stroke it is pressed by the working strain away from the crank shaft and
against its trunnion seat, and it is a distinguishing feature of the improved
arrangement that this unavoidable strain is taken advantage of in keeping
tight the port or "valve" surfaces, the ports being disposed at the part of the
trunnion which is thus pressed against its seat. The revolution of the crank
shaft and the consequent vibration of the cylinders causes the trunnion ports
to be put alternately into communication with the inlet and outlet passages
in the seats; and if the engine is required to reverse a four-way valve or
cock may be fitted in connection with the inlet and outlet passages for that
purpose.
In applying the apparatus for pumping the position of the ports will depend
on whether it is to be used as a force pump or as a lift pump. For a force
pump the position of the ports must be the same as for a motive-power engine,
but for a lift pump it must be reversed.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Purnell in the Great Seal Patent Office on the
22nd August 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
PURNELL, of Glasgow, in the County of Lanark, North Britain, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of February, 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 Henry Purnell, Her special licence that I, the said Henry Purnell,
my executors, administrators, and assigns, or such others as I, the said Henry
Purnell, 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

page_text: 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 "IMPROVEMENTS IN MOTIVE-POWER
ENGINES TO BE WORKED BY WATER, STEAM, OR OTHER FLUID, AND APPLICABLE TO
PUMPS," upon the condition (amongst others) that I, the said Henry Purnell,
my executors or administrators, by an 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. Scal Patent
Office within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said Henry Purnell, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, reference being had to the accompanying Drawings,
that is to say-
My said Invention relates to improved and simplified motive-power engines
to be worked by water, steam, or other fluid, and comprises as its principal
features of novelty the employment of three single-acting cylinders oscillating or
vibrating on trunnions or their equivalent, and the disposing of the inlet and
outlet ports at that side of the trunnions, the close or tight fitting of which is
insured by the working strain of the cylinders. My improved apparatus
is also applicable for pumping.
And in order that my said Invention and the manner of performing the
same may be properly understood I have hereunto appended a Sheet of
explanatory Drawings to be herein-after referred to, and representing a water-
pressure engine as constructed with my improvements.
Figure 1 is a side elevation, partly in section; Figure 2 is a transverse
vertical section; and Figure 3 is a fragmentary horizontal section.
In carrying out my Invention for the purpose of obtaining motive power by
water pressure I use three oscillating or vibrating cylinders A, B, C, provided
with plungers a, b, c, which work through stuffing boxes in the upper euds of
the cylinders, and which have fixed to them short rods jointed upon three
cranks D, E, F, disposed at equal angular distances apart on a horizontal
shaft G; this shaft is carried in bearings on an open frame H, fixed on
pillars I, which are themselves fixed in a base or bed frame K. I prefer to
make the crank sides with the bearing parts of cast iron or malleable cast
iron, the relative positions of the cranks being thereby rigidly fixed, whilst the
crank pins are of malleable iron or steel. I make the cylinders A, B, C,

page_text: single-acting in order that their working strain may always be in one direction,
namely, in the direction downwards from the crank shaft G, and they are
formed with trunnions L which are by preference situated at the bottom ends
or those further from the crank shaft. The end of each cylinder between the
trunnions is shaped like a portion of a cylinder, and is continuous or flush with
the under sides of the trunnions, and a continuous bearing is formed therefor
in a block M fixed upon the bed frame K, whilst caps are fixed over the
trunnions projecting at each side to prevent accidental displacement; ports p
are formed in what may be termed the trunnion surface, and also in the
bearing surface of the block M beneath for the entrance and exit of the
water or motive fluid.
In Figure 3 one of the bearing blocks M is shown in plan as with the
cylinder removed; each block M is hollow, and is divided into two compart-
ments by a partition disposed transversely as regards the axis of the trunnion.
Two passages P, Q, are formed in the bed frame, one along each side, and of
each pair of compartments in the three blocks M, one communicates with one
passage P and the other with the other passage Q; these passages com-
municate by branches p', 9, at the side with a four-way cock R, the two other
ways of which are an inlet S through the axis of the plug, and an outlet T at
the outer side; by means of this cock R, the water may be made to pass in
by the passage P and out by the passage Q, or vice versa, according to the
direction in which it is desired to turn the shaft G. The ports p in the
trunnion surface and in that of the block M are disposed so that when the
cylinder is inclined to one side those on one side of the division of the block
will be in communication, whilst those on the other side will be shut; but the
last will be open and the first shut when the cylinder is inclined to the other
side. When any crank is passing the top or bottom centre all the ports of its
cylinder are momentarily shut, the communications being then in the act of
being reversed, and the continuous revolution of the crank shaft G with the
consequent oscillation or vibration of the cylinders causes the ports to be put
alternately into communication with the inlet and outlet passages.. With
the cranks disposed at equal angles apart as described only one of the cylinders
is on the centre at once, and the action on the shaft is rendered very uniform
throughout the revolution. As each cylinder performs its stroke it is pressed
by the working strain away from the crank shaft and against its trunnion seat,
and it is a distinguishing feature of my improved arrangement that this
unavoidable strain is taken advantage of in keeping tight the port or "valve "
surfaces, the ports being disposed at the part of the trunnion surface which is
thus pressed against its seat.

page_text: In the example delineated each cylinder is shown with three inlet and
three outlet ports in order to give as free passage as possible to the water,
but in constructing the apparatus to be worked by steam one or two inlet
ports and one or two outlet ports will be sufficient.
When constructing the apparatus for steam I prefer to fit the cylinders with
pistons instead of plungers; it will however be obvious that these and various
other variations may be made without affecting the special features of my
Invention; thus the trunnions may be placed at any part of the cylinder, and
one or two cylinders may be employed instead of three.
In applying the apparatus for pumping the position of the ports will depend
on whether it is to be used as a force pump or as a lift pump. For a force
pump the position of the ports must be the same as for a motive-power engine,
but for a lift pump it must be reversed.
Having thus particularly described my said Invention, and the manner in
which the same is to be performed I have to state that I do not restrict myself
to the precise details herein described or delineated; but that what I believe
to be novel and original and claim as the Invention secured to me by the
herein-before in part recited Letters Patent is, the making of motive-power
engines and pumps with single-acting cylinders having inlet and outlet
ports in trunnion surfaces kept tight by the working strain of the cylinders,
substantially as herein-before described.
In witness whereof, I, the said Henry Purnell, have hereunto set my
hand and seal, this Twenty-first day of August, in the year of our Lord
One thousand eight hundred and sixty-seven.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
HENRY PURNELL. (L.B.)