IMPROVEMENTS IN APPARATUS FOR WORKING PUNKAHS
Year: 1880

page_text: LETTERS PATENT to Charles Algernon Parsons, of Elswick, in the Borough
and County of Newcastle upon Tyne, Engineer, for an Invention of
"IMPROVEMENTS IN APPARATUS FOR WORKING PUNKAHS." A communication
from abroad by Richard Clero Parsons, of Calcutta, in the Indian Empire.
PROVISIONAL SPECIFICATION left by the said Charles Algernon Parsons at
the Office of the Commissioners of Patents on the 25th March 1880.
CHARLES ALGERNON PARSONS, of Elswick, in the Borough and County of.
Newcastle upon Tyne, Engineer. "IMPROVEMENTS IN APPARATUS FOR WORKING
PUNKANS." [A communication from abroad by Richard Clere Parsons, of Calcutta,
in the Indian Empire.]
In the Specifications to Letters Patent granted to John Imray on the 20th
March 1874, No. 981, and of Letters Patent granted to R. C. Parsons and E. Palliser
on the 5th April 1878, No. 1353, were described means of working punkahs by
compressed air acting in a cylinder on a piston connected to the punkahs. The
present Invention relates to improvements in apparatus for this purpose, particularly
in reference to the mode of working automatically the valves for alternating the
action of the air on the piston, and to modifications whereby the apparatus is
rendered capable of being worked by water under pressure supplied from a
reservoir or accumulator. According to the present Invention, the cylinder has
its admission and emission ports governed by a slide similar to an ordinary D slide,
but the rod which works this slide is made with a long slot or notch, so that it has
a considerably longer stroke than the slide, and that it moves the slide only during
the last part of its stroke in either direction. This rod is attached at each end to a
piston working in a cylindrical part of the slide jacket, and it is also extended
through a stuffing box in one end of the slide jacket, and connected to a piston
working in a cataract cylinder charged with oil, water, or other liquid. This
cataract cylinder is constructed as described in the Specification, No. 1353, of 1878
above referred to, that is to say, the piston fits the cylinder for some distance along
its middle, but on each side of the fitting portion the cylinder is bellied or made with
grooves or hollows, so as to give free passage for the liquid from one side of tho
piston to the other. There is also a passage from one end of the cataract cylinder
to the other, which passage can be more or less throttled by an adjustable screw

page_text: plug. The cylindrical portions of the slide jacket in which the pistons of the slide
1od work have ports for the admission and emission of the compressed air. These
ports communicate by passages with the main cylinder, so that the pressure'therein
acts alternately on the pistons of the main slide rod, or they may communicate with
ports of a subsidiary slide worked by a tappet on the main piston rod, or part
moving therewith. In obedience to the pressure thus brought to act on one of its
pistons, the slide rod makes a stroke, moving along with it the piston of the cataract
cylinder. At first, while this piston is moving from the end of the cataract
cylinder towards the middle, it moves rapidly, the liquid freely passing the piston, but
as it moves over the middle part of its stroke, it is retarded by the throttling of the
liquid in its passage from one end of the cataract cylinder to the other, and finally,
having passed the middle portion of its stroke, it again moves rapidly, completing
its stroke. By the final portion of its stroke, the slide rod moves the slide so as to
reverse the passage of air to and from the ends of the main cylinder, and thereby to
reverse the movement of the main piston. The piston is thus caused to reciprocate,
the number of its reciprocations in a given time being determined by the less or
greater retardation of the cataract piston during the middle part of its stroke,
according to the adjustment of the screw plug that throttles the passage of liquid
from end to end of the cataract cylinder. For the sake of compactness, the piston
of the main cylinder is made with a hollow trunk rod, at the inner end of which is
jointed a link connecting it to a lever which works the punkahs. This lever is
connected to the punkahs by wire cords which are kept in tension by weights or
springs at each end, or the lever and the successive punkahs may be connected by
rigid rods, in which case the weights or springs are unnecessary. Such rods may
with advantage be bamboos, which are light and strong, and are generally available
where punkahs are used. When water under pressure is employed instead of
compressed air, the supply pipe is provided near the working cylinder with an air
vessel of considerable capacity, or with a spring accumulator, so that the supply
water may continue to flow along the pipe during the periods of reversal of the
main piston, thus avoiding the effects of its inertia and momentum at each reversal.
In this case, instead of one double acting cylinder, two single acting cylinders may
be employed, or a cylinder having a trunk piston with the water pressure always
acting on the annular area of its one side, whilst the pressure is alternated on the
full arca of its other side; and instead of a slide for alternating the admission and
emission of the water, valves may be employed, these being seated and unsented by
the movement of a rod worked in a manner similar to the slide rod above described
for the apparatus when worked by air pressure. By employing an oscillating
cylinder the connecting rod may be dispensed with.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Algernon Parsons in the Great Seal Patent Office on the
24th September 1880.
"
CHARLES ALGERNON PARSONS, of Elswick, in the Borough and County of
Newcastle upon Tyne, Engineer.
IMPROVEMENTS IN APPARATUS FOR WORKING
PUNKAHS." A communication from abroad by Richard Clere Parsons, of Calcutta,
in the Indian Empire.
In the Specifications to Letters Patent granted to John Imray, on the 20th
March 1874, No. 981, and of Letters Patent granted to R. C. Parsons and
E. Palliser, on the 5th April 1878, No. 1353, were described means of working
punkahs by compressed air acting in a cylinder on a piston connected to the
punkahs. The present Invention relates to improvements in apparatus for this
purpose, particularly in reference to the mode of working automatically the valves
for alternating the action of the air on the piston, and to modifications whereby
the apparatus is rendered capable of being worked by water under pressuro
supplied from a reservoir or accumulator. According to the present Invention the
cylinder has its admission and emission ports governed by a slide similar to an
ordinary D slide, but the rod which works this slide is made with a long slot or
notch so that it has a considerably longer stroke than the slide, and that it moves
the slide only during the last part of its stroke in either direction. This rod is
attached at each end to a piston working in a cylindrical part of the slide jacket,
and it is also extended through a stuffing box in one end of the slide jacket, and
connected to a piston working in a cataract cylinder charged with oil, water, or
other liquid. This cataract cylinder is constructed as described in the Specification
No. 1353, of 1878, above referred to, that is to say, the piston fits the cylinder for
some distance along its middle, but on each side of the fitting portion the cylinder
is bellied or made with grooves or hollows so as to give free passage for the liquid
from one side of the piston to the other. There is also a passage from one end of
the cataract cylinder to the other, which passage can be more or less throttled by
an adjustable screw plug. The cylindrical portions of the slide jacket in which
the pistons of the slide rod work have ports for the admission and emission of the
compressed air. These ports communicate by passages with the main cylinder,
so that the pressure therein acts alternately on the pistons of the main slide rod,
or they may communicate with ports of a subsidiary slide worked by a tappet on
the main piston rod or part moving therewith. In obedience to the pressure thus
brought to act on one of its pistons the slide rod makes a stroko moving along
with it the piston of the cataract cylinder. At first, while this piston is moving
from the end of the cataract cylinder towards the middle, it moves rapidly, the
liquid freely passing the piston, but as it moves over the middle part of its stroke
it is retarded by the throttling of the liquid in its passago from one end of the
cataract cylinder to the other, and finally having passed the middle portion of its
stroke it again moves rapidly, completing its stroke. By the final portion of its
stroke the slide rod moves the slide so as to reverso the passage of air to and from
the ends of the main cylinder and thereby to reverse the movement of the main
piston. The piston is thus caused to reciprocate the number of its reciprocations in a
given time, being determined by the less or greater retardation of the cataract
piston during the middle part of its stroke, according to the adjustment of the
screw plug that throttles the passage of the liquid from end to end of the cataract
cylinder. For the sake of compactuess the piston of the main cylinder is mado
with a hollow trunk rod, at the inner end of which is jointed a link connecting it
to a lover which works the punkahs. This lever is connected to the punkahs by
wire cords which are kept in tension by weights or springs at each end, or the
lever and the successive punkahs may be connected by rigid rods, in which case

page_text: Fig. is a longitudinal section of one construction according to is
the cylinder and its adjuncts in which compressed air acts on a piston for working
punkahs. A is the cylinder fitted with a trunk piston B which is linked to
a lever C connected to the punkahs. The ports of the cylinder A are governed by
the slide D. The slide rod E has a long gab or notch over the slide, and has on it
two pistons c, c, working in cylindrical ends of the slide casing; it is also connected
to the piston of a cataract cylinder F, which is charged with oil or other liquid.
Grooves are formed in the interior of this cylinder near each end of it, so that in
those parts of the stroke of the cataract piston the liquid can freely pass it; but
when the piston is at or about tho middle of its stroke the only passage for liquid
being by a by-pass channel governed by an adjusting screw fi; the movement of
the cataract piston during the middle part of its stroke can be retarded as desired
by throttling more or less the by-pass channel by the screw f¹. From cach end of
the cylinder A there is a small passage a, a, to the opposite end of the slide casing,
so that the compressed air acting on the piston B, so as to move it to right or to
left, is at the same time acting on one or other of the pistons e, e, so as to imove the
slide rod E in the opposite direction. The slide rod E being thus moved, and being
controlled in its movement by the cataract cylinder as it approaches the end of its
stroke moves the slide 1), and so causes reversal of the piston B. The reciprocation
of the piston B may be effected by tappet action in the manner shewn in Fig. 2,
which is a side elevation of the air cylinder A, with a part section of a subsidiary
lateral slide and casing for effecting the movement of the main slide. According
to this arrangement a tappet b is fixed on the trunk of the piston B, and a three
arned tappet lever G is mounted on a bracket projecting from the cataract
cylinder F. The upper arm of this lover is linked to the rod of the subsidiary
slide, which governs passages h, h, leading to tho ends of the main slide casing
like the passages a, a, in Fig. 1. When the piston B makes its stroke in either
direction its tappet b acting on one or other of the arms of the lever G moves that
lever, thereby shifting the subsidiary slide d. By this means air under pressure
passes by one or other of the passages h, h, to act on one or other of the pistons e, e,
of the slide rod E, as described with reference to Fig. 1, and thus, subject to the
controlling action of the cataract piston, the main slide D is shifted and the move-
ment of the piston B is reversed. In some cases, instead of employing compressed
air to act in the cylinder A, water under pressure from an clevated cistern or
accumulator may be employed, the construction of the cylinder and its adjuncts
being substantially the same as described above, with suitable enlargement of the
ports and passages to allow for the less rapid flow of water through them. When
water is thus employed, especially in cases whero there is a considerable length of
communicating pipes, air vessels or cylinders with spring pistons are connected to

page_text: the pipes close to the working cylinder A, so as to avoid the loss of time in over-
coming the inertia and momentum of the large body of water contained in the
pipes. The piston B by its reciprocation may work a number of punkahs, arranged
in succession in an apartment or hospital ward. Fig. 3 is a part section, and
Fig. 4a part sectional plan of such an apartment, shewing the two extreino
punkahs of a set and their connections to the working piston B. The lever C
worked by the piston has its long arm connected by a wire or wire cord K to a
corresponding lever C. Both the levers C, O, have short arms c, c', from which
extend downwards vertical rods strained by weights or springs, so las to keep tho
wire or cord K always in tension. This wire or cord is connected to the successive
punkahs P. A convenient mode of forming the connection is shewn to an enlarged
scale at Fig. 5, M is a piece of leather having a hole through its, middle. It is
secured to K by thread or wire m bound round both, and by its hole it is attached
to a hook on the punkah. It is of advantage to connect the successive punkalis
by diagonal ties N to maintain their parallelism while they swing to and fro.
Having thus described the nature of this Invention, and in what manner the
same is to be performed, as communicated to me by my correspondent abroad, I
claim in respect of apparatus for working punkahs by fluid under pressure acting
on a piston in a cylinder,-
Governing the cylinder ports by a slide moved by a rod having an elongated
notch or gab, so as to act on the slide only in the last part of its stroke, the said
rod being moved by pressure of the working fluid on pistons at its ends, and having
its movement controlled by an adjustable cataract, substantially as and for the
purposes berein set forth.
In witness whereof, I, the said Charles Algernon Parsons, have hereunto set
my hand and seal, this Third day of September, in the year of our Lord
One thousand eight hundred and eighty.
CHARLES A. PARSONS. (L.s.)