IMPROVE- MENTS IN STEAM ENGINES
Year: 1874

page_text: LETTERS PATENT to Peter William Willans, of 32, Granville Park,
Blackheath, in the County of Kent, for the Invention of " IMPROVE-
MENTS IN STEAM ENGINES."
Scaled the 29th May 1874, and dated the 19th March 1874.
PROVISIONAL SPECIFICATION left by the said Peter William Willans
at the Office of the Commissioners of Patents, with his Petition,
on the 19th March 1874.
I, PETER WILLIAM WILLANS, of 32, Granville Park, Blackheath, in
the County of Kent, do hereby declare the nature of the said Invention
" for IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
This Invention has for its object improvements in steam engines.
I employ three cylinders placed side by side; their pistons work on to
three cranks on the main shaft at angular distances of 120°, the one
from the other; or all the pistons may work on to one crank, the
cylinders then being ranged around the crank equidistant the one from
the other.

page_text: Each cylinder is single acting its piston receiving steam only on its
outer side or that further from the crank. To the other side of the
piston the connecting rod is jointed and it passes direct from the piston
to the crank. Each piston serves as a steam valve and controls the
supply of steam to act upon one or other of the other pistons.
There
is a steam chamber in the piston and a port in its side. Steam
is supplied to the piston from the boiler, and for this purpose the piston
may be provided with a hollow piston rod working through a gland at
the outer end of the cylinder and passing into a steam chest. When
the piston is at about 3/4ths of its stroke towards the inner end of the
cylinder the steam port in the piston overlaps a port formed in the sido
of its cylinder, the ports are then full open and steam passes through
these ports to another of the cylinders. The ports are so formed that
the steam passage remains open during rather more than one-third of
the rotation of the crank, and the steam enters the cylinder supplied
just before the commencement of the effective stroke, and is cut off
sometime before the end of the stroke. When a piston is at about of
its outward stroke the port in the side of the cylinder is uncovered and
this allows the steam to pass back out of the cylinder which the port
supplies, and I arrange that the exhaust shall remain open during
nearly one-half of the rotation of the crank.
The steam may escape direct into the air or into a casing through
which the crank shaft passes. This casing can if desired be connected
with a condenser.
An important feature in the engine not yet mentioned is that the
engine can be reversed simply by means of a cock or valve on the
passages leading from cylinder to cylinder. By means of this cock or
valve the steam after it has passed through the port of the piston of onc
cylinder can be directed at pleasure to cither of the two other cylinders,
and the direction of rotation of the engine will be forward or backward
according to the direction given to the steam by this cock or valve.
In place of employing the main pistons as valves, as above described,
these pistons may be connected by rods with smaller pistons working in
corresponding cylinders and serving only as valves.
The method above described of reversing three-cylinder engines is
applicable advantageously to three-cylinder engines where the cylinders
are placed side by side, and the valves of the outer cylinders are, worked.

page_text: by eccentrics. In such engines to work the valve of the middle cylinder
by means of eccentrics usually involves a loss of space between tho
cylinders or else.a complicated valve gear. Now I avoid this by taking
the motion of the valve of the centre cylinder not from the crank shaft
by means of eccentrics according to the usual practice, but from the
piston rod of one or other of the outside cylinders, and I change this
connection from one cylinder to the other in reversing the engines:
'
SPECIFICATION in pursuance of the conditions of the Letters Patent,.
filed by the said Peter William Willans in the Great Seal Patent
Office on the 15th September 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PETER
WILLIAM WILLANS, of 32, Granville Park, Blackheath, in the County.
of Kent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of March, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Peter William Willans, Her special
license, that I, the said Peter William Willans, my exccutors,
administrators, and assigns, or such others as I, the said Peter
William Willans, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all timės
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 In-
vention for "IMPROVEMENTS IN STEAM ENGINES," upon the condition
(amongst others) that I, the said Peter William Willans, 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 Peter William Willans, do
hereby declare the nature of the said Invention, and in what manner

page_text: the same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say :—
1
This Invention has for its object improvements in steam engines.
I employ three cylinders placed side by side, their pistons work on to
three cranks on the main shaft at angular distances of 120° the one
from the other; or all the pistons may work on to one crank the
cylinders then being ranged around the crank equidistant the one from
the other.
Each cylinder is single acting, its piston receiving steam only on its
outer side, or that further from the crank. To the other side of the
piston the connecting rod is jointed and it passes direct from the piston
to the crank. Each piston serves as a steam valve and controls the
supply of steam to act upon one or other of the other pistons.
There
is a steam chamber in the piston and a port in its side. Steam
is supplied to the piston from the boiler, and for this purpose the piston
may be provided with a hollow piston rod working through a gland at
the outer end of the cylinder and passing into a steam chest. When
the piston is at about 3/4ths of its stroke towards the inner end of cylinder
the steam port in the piston overlaps a port formed in the side of its
cylinder, the ports are then full open and steam passes through these
ports to another of the cylinders. The ports are so formed that the
steam passage remains open during rather more than one-third of the
rotation of the crank and the steam enters the cylinder supplied just
before the commencement of the effective stroke, and is cut off some-
time before the end of the stroke. When a piston is at about one-half of
its outward stroke the port in the side of the cylinder is uncovered, and
this allows the steam to pass back out of the cylinder which the port,
supplies, and I arrange that the exhaust shall remain open during nearly
one-half of the rotation of the crank.
The steam may escape direct into the air or into a casing, through
which the crank shaft passes. This casing can if desired be connected
with a condenser.
An important feature in the engine not yet mentioned is that the
engine can be reversed simply by means of a cock or valve on the
passages leading from cylinder to cylinder. By means of this cock or a
valve the steam after it has passed through the port of the piston of one
cylinder can be directed at pleasure to either of the two other cylinders,

page_text: heating the feed water may be coiled or otherwise arranged with the
casing ... The tubes which bring the steam to the interior of the pistons
are also useful in running the engine at high speeds as the pressure upon
them destroys the momentum of the pistons and connecting rods in the
upward and ineffective stroke.
If desired the exhaust steam may be confined without the employ-
ment of a casing surrounding the cranks by the introduction of trunks,
in the manner shown by Figure 5; or the pistons may give motion to
the shaft by means of ordinary piston rods and connecting rods or other-
wise.
The amount of expansion in these engines may if desired be varied in
the manner indicated by Figure 6. Here, as will be seen, the connection
between the steam chest e and hollow piston rods 6* (with the cavities
in the pistons with which they communicate) is cut off before the piston
ports ° coincide with the cylinder ports a°. Thus the steam to perform
the stroke is as it were measured out before being admitted to the
cylinder, and the degree of expansion will depend on the capacity given
to the measuring cavities in the pistons.
Figure 7 shews an arrangement in which the tubular piston rods 6*,.
which serve to convey steam to the ports 6° of the pistons are dispensed.
with, the pistons being made longer and the steam being led in through
the sides of the cylinders by passages A.
For some purposes a single throw crank may be used, the cylinders
being placed angularly at about 120 degrees apart, as is shewn by
Figure 8. Or where it would be inconvenient to place the cylinders
all around the shaft they may be placed at about 60 degrees apart and
made to actuate a two-throw crank, as is shewn at Figures 9 and 10,
Figure 9 being a longitudinal section, and Figure 10 a transverse
section.
•
Figure 11 is the section of the cylinders and other parts of an engine,
in which the main pistons do not themselves act as valves, but are
connected by rods with separate valve pistons h³, h², h³. These valves
work in cylinders i¹, 22, 23, which are always open at their upper ends to
the steam supply and at their lower ends to the exhaust, and which
have ports,,, in their sides corresponding to the ports a° in the
other Figures.

page_text: The engine may be made compound, for example in the manner
shewn at Figure 12. The piston valve 2 admits the high pressure
steam to the working cylinder a', from which cylinder the steam having
performed its work returns to the space in the cylinder beneath the
piston .. Thence the steam passes into the cylinder over the piston h³,
and when this piston passes beneath its port i° the steam is free to pass
into the working cylinder a². Having worked in the cylinder a the
steam returns to the cylinder & beneath its piston ½³, and thence passes
to the upper side of the piston h' which feeds the working cylinder a³..
The space beneath the piston valve h¹ communicates with the final
exhaust leading either into the air or to a condenser.
It is obvious that these steam engines are capable of being worked
also by compressed air or other elastic fluid.
Having thus described the nature of my said Invention and the
manner of performing the same, I would have it understood that I
claim,―
First. The construction of three-cylinder engines with the piston of
one cylinder serving as the valve of another, substantially as described.
Second. The construction of three-cylinder engines with separate
valves connected with the pistons, so that the piston of one cylinder
actuates directly the valve for another cylinder, substantially as
described.
Third. The means of reversing three-cylindered ongines by inter-
changing the passages between the cylinders and the valves, sub-
stantially as described.
Fourth. The construction of three-cylinder engines, substantially as
described and shewn in the annexed Drawings.
In witness whereof, I, the said Peter William Willans, have
hereunto set my hand and seal, this Seventh day of September,
PETER WILLIAM WILLANS. (L.S.)