IMPROVEMENTS IN PISTONS
Year: 1877

page_text: LETTERS PATENT to Thomas Adams, of West Gorton, near Manchester, in the
County of Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN
PISTONS"
Sealed the 5th February 1878, and dated the 16th August 1877.
PROVISIONAL SPECIFICATION left by the said Thomas Adams at the Office
of the Commissioners of Patents on the 16th August 1877.
THOMAS ADAMS, of West Gorton, near Manchester, in the County of Lancaster,
Engineer. "IMPROVEMENTS IN PISTONS."
This Invention has for its object the balancing of the packing rings of pistons
against the cylinder sides, and the preventing the tear and wear of the cylinder and
packing rings, and ensuring the piston being kept steam-tight.
For this purpose I form through the piston a passage or passages. Opposite both
ends of each passage is a valve, by which the end of the passage can be closed, and
the two valves at the two ends of each passage are connected together by a stem of
such a length that when the valve at one end of the passage is closed the valve at
the other end is open. From the passage are openings leading to the rear of the
grooves in which the packing rings are lodged. By this means when the piston is
propelled by steam acting on one side of it the valve or valves on this side will
close, and the valve or valves on the opposite side will open, and admit steam from
the back of the piston to the back of the piston rings; but in balance pistons a
hole may be substituted for the valve.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Adams in the Great Seal Patent Office on the 16th February
1878.
THOMAS ADAMS, of West Gorton, near Manchester, in the County of Lancaster,
Engineer. "IMPROVEMENTS IN PISTONS."
This Invention has for its object the balancing of the packing rings of pistons
against the cylinder sides, and the preventing the tear and wear of the cylinder and
packing rings, and ensuring the piston being kept steam-tight.
For this purpose I form through the piston a passage or passages. Opposite both
ends of each passage is a valve, by which the end of the passage can be closed, and
the two valves at the two ends of each passage are connected together by a stem
of such a length that when the valve at one end of the passage is closed the valve at
the other end is open. From the passage are openings leading to the rear of the
grooves in which the packing rings are lodged. By this means when the piston is
propelled by steam acting on one side of it, the valve or valves on this side will
close, and the valve or valves on the opposite side will open and admit steam from
the back of the piston to the back of the piston rings; but in balance pistons a hole
may be substituted for the valve.
In order that my said Invention may be most fully understood, and readily
carried into effect, I will proceed to describe the Drawings hereunto annexed.
Figure 1 is a half elevation, partly in section, of a piston constructed according
to my Invention; Figure 2 is a similar view, but with some modification in the
form of the parts; Figure 3 is a section on the line 1, 1, in Figure 2.
In Figures 1 and 2 the piston rod and a portion of the cylinder are shown; a
part of the cylinder also appears in Figure 3.
In Figure 1A is the flange of the piston, and B is the cover plate bolted on.
They hold between them the piston ring C, which is pressed outwards by the spring D
at the back. Behind the ring there is the cavity E, which is in communication
with the interior of the cylinder by the holes E¹, E'. F, F, are valves for closing
the hole on the side exposed to the greater pressure. These valves are both fixed
upon the same stem F', which passes through the holes E¹.
In Figures 2 and 3 the arrangement is similar, but two spring rings are
employed.
In cases where the piston receives the steam or actuating fluid on one side only
the holes E¹, E', will be required only on one side of the piston, and no valve will
'be needed.
Having thus described, the nature of my said Invention, and the manner of per-
forming the same, I would have it understood that I claim,-
First. The construction of pistons in such manner as to allow free communication
between the spaces or cavities in rear of the packing rings and the interior of the
cylinder on the side in communication with the exhaust.
Second. The construction of pistons with passages connecting the spaces or
cavities in rear of the packing rings with the interior of the cylinder, and with
valves closing on the pressure side of the piston, to exclude the steam or fluid from
such spaces or cavities.

page_text: Third. The construction of pistons, substantially as described, and shown in the
annexed Drawings.
In witness whereof, I, the said Thomas Adams, have hereunto set my hand
and seal, this Fifteenth day of February, in the year of our Lord One
thousand eight hundred and seventy-eight.
MITAN
R
THOMAS ADAMS. (L.S.)