IMPROVEMENTS IN HYDRAULIC · ENGINES
Year: 1875

page_text: LETTERS PATENT to Thomas Casson, of Portmadoc, in the County of
Carnarvon, Banker, for the Invention of "IMPROVEMENTS IN HYDRAULIC
· ENGINES."
Sealed the 9th July 1875, and dated the 13th January 1875.
PROVISIONAL SPECIFICATION left by the said Thomas Casson at the
Office of the Commissioners of Patents, with his Petition, on the
18th January 1875.
I, THOMAS CASSON, of Portmadoc, in the County of Carnarvon, Banker,
5 do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
HYDRAULIC ENGINES," to be as follows:-
My Invention relates to hydraulio engines in which water under
pressure from an elevated reservoir or an accumulator is made to work
a piston in a cylinder, the movement of the piston being com-
O municated to a crank shaft, so as to turn the same for the purpose of
hauling or raising loads.

page_text: The chief object of my Invention is to provide means of varying the
power of the engine so that the expenditure of working fluid can bo
readily adjusted to the work performed, and that when the engine is
worked backwards for the purpose of lowering a load the descent of
the load can be utilised for pumping water back to the reservoir or 5
accumulator. For this purpose I joint the piston rod to one end of a
beam, the other end of which is connected by a rod to the crank. The
fulcrum or trunnion of the beam is fitted to move in guides, so that it
can slide along the beam in a longitudinal slot therein or in guides
formed thereon, and thus the relative lengths of the two arms of the ]
beam can be varied. When the engine is employed to raise a heavy load
the fulcrum is shifted away from the cylinder end of the beam towards
the crank end thereof, and the piston has then to perform a longer
stroke, acting with greater leverage to turn the crank. When, on the
other hand, the load is light the fulcrum of the beam is shifted in the 1
opposite direction, so as to diminish the leverage and length of stroke of
the piston. As the expenditure of working fluid is proportional to the
length of stroke of the piston the expenditure can thus be adjusted to
the power required. When the engine has to lower a load I shut off
the supply of fluid under pressure from the cylinder and I admit water :
thereto, providing a set of valves like those of a force pump. The
fulcrum of the beam being then suitably adjusted the descent of the load
moving the piston causes water to be pumped through the valves to the
reservoir or accumulator, the force required for this purpose acting also
as a brake for the descending load. This operation may also be effected
without separate pump valves by suitable adjustment of the slide or
valves usually employed when the engine is performing work. The end
of the beam to which the piston rod is jointed is guided in guides or by
a parallel motion to move in a straight line, and the fulcrum of the
beam is also guided to move in a line at right angles thereto. Screws
or racks worked by hand can be employed to shift the fulcrum, or it
may be arranged to be shifted automatically by means of a governor.
Although I have abovo described the beam as a lever of the first order
with the fulcrum between the cylinder and the crank, it is obvious that
it may have the fulcrum beyond either, forming a lover of the second
order.

page_text: revolutions of crank shaft the end of the beam instead of being con-
nected to a crank may have the hauling rope or chain attached directly
to it, the one stroke of the piston effecting the required lift, and this
stroke being proportioned by adjusting the position of the fulcrum so as
5 to suit the load.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Casson in the Great Seal Patent Office
on the 12th July 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
CASSON, of Portmadoc, in the County of Carnarvon, Banker, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of January, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Thomas Casson, Her special license
that I, the said Thomas Casson, my executors, administrators, and assigns,
or such others as I, the said Thomas Thomas Casson, 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 “IMPROVEMENTS IN
HYDRAULIC ENGINES," upon the condition (amongst others) that I, the said
Thomas Casson, 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 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 Thomas Casson, 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, referenco being had to tho accompanying

page_text: Sheet of Drawings, and to the figures and letters marked thereon, that
is to say:-
-
My Invention relates to hydraulic engines in which water under
pressure from an elevated reservoir or an accumulator is made to work a
piston in a cylinder, the movement of the piston being communicated to
a crank shaft, so as to turn the same for the purpose of hauling or raising.
loads or doing other work, such as driving hydraulic presses.
The chief object of my Invention is to provide means of varying the
power of the engine, so that the expenditure of working fluid can be
readily adjusted to the work performed, and that when the engine is
worked backwards for the purpose of lowering a load the descent of
the load can bo utilized for pumping water back to the reservoir or
accumulator. For this purpose I joint the piston rod to one end of a
beam, the other end of which is connected by a rod to the crank. The
fulcrum or trunnion of the beam is fitted to move in guides, so that it
can be slid along the beam in a longitudinal slot therein or in guides
formed thereon, and thus the relative lengths of the two arms of the
beam can be varied. When the engine is employed to raise a heavy load
or otherwise to exert greater power the fulcrum is shifted away from the
cylinder end of the beam towards the crank end thereof, and the piston
has then to perform a longer stoke, acting with greater leverage to turn
the crank. When, on the other hand, the load is light or less power is
otherwise required, the fulcrum of the beam is shifted in the opposito
direction, so as to diminish the leverage and length of stroke of the
piston. As the expenditure of working fluid is proportional to tho
length of stroke of the piston, the expenditure can thus be adjusted
to the power required. When the engine has to lower a load I shut off
the supply of fluid under pressure from the cylinder and I admit water
thereto, providing a set of valves like those of a force pump. The
fulcrum of the beam being then suitably adjusted the descent of the
load moving the piston causes water to be pumped through the valves to
the reservoir or accumulator, the force required for this purpose acting
also as a brake for the descending load. This operation may also be
effected without separate pump valves by suitable adjustment of the
slide or valves usually employed when the engine is performing work.
The end of the beam to which the piston rod is jointed is guided in
guides or by a parallel motion to move in a straight line, and the fulcrum

page_text: Fig. 1 represents the side view of a hydraulic engine arranged to
operate according to my Invention, shewing how the beam fulcrum is-
placed when the engine is working to raise a load; and Fig. 2 shews
diagrammatically the condition of the engine when the load is being
lowered, the descent of the load being utilized to work the engine as a
pump to force water back to the accumulator or cistern head.
A is the cylinder with a slide B, by which water is alternately
admitted to and emitted from the two ends of the cylinder. A slide of
any known form, such as is employed for a steam engine, may be used,
being worked from an eccentric or cam on the crank shaft O, and care
being taken so to arrange the lap of the slide and its stroke in reference to
the ports that the supply to and discharge from the respective ends of the
cylinder are maintained up to the end of each stroke of the piston. The
piston rod D terminates in a head which works in vertical guides E, and
by which it is jointed to one end of the beam F. This beam has a slot
in which works a block G carrying the pin or trunnion of the beam,
which trunnion is carried by another block G³ fitted to work also in
horizontal guides H, along which it can be moved by a screw J worked
by a hand wheel or rope wheel K. The other end of the beam is con-
nected by a connecting rod L to the crank on the crank shaft C.

page_text: Although a single engine is shewn in the Figures it may be readily
understood that two such engines can be placed side by side, working
cranks at right angles to one another on the same shaft. This arrange-
ment is to be preferred, as it gives greater uniformity of action and
renders a fly wheel unnecessary. In such an arrangement the screw J
is mounted, and the guides H are fixed betweon the two beams, and there
is a single sliding block, G³ carrying the trunnions of both beams, one
on each of its sides.
When the fulcrum of the beam is in the position shewn in Fig. 1 the
piston acting at the end of the beam has considerable leverage to move
the same, and thereby turn the shaft C for the purpose of raising or
hauling a load or driving machinery. When the load or work to be
performed is less the fulcrum can by turning the wheel K and screw J
be drawn towards the piston, thereby giving less leverage to it and
diminishing its stroke, and effecting a corresponding reduction in the
expenditure of the working fluid; or when a load is to be lowered the
fulcrum of the beam may be drawn still farther towards the piston, as
shewn in Fig. 2, so that the descending weight by turning the crank
shaft works the engine as a pump. In this case the supply and discharge
by the slide B are cut off, and valves like those of an ordinary force
pump, arranged at any convenient parts of the cylinder, are brought
into use.

page_text: forth in the preceding claims, with a slotted beam and sliding fulcrum
for the same, substantially as herein described.
In witness whereof, I, the said Thomas Casson, have hereunto set
my hand and seal, this Tenth day of July, in the year of our
Lord One thousand eight hundred and seventy-five.