NECTED WITH COVERS FOR STEAM-ENGINE PISTON RODS
Year: 1879

page_text: LETTERS PATENT to Archibald Thomson, of Southampton, in the County of
"IMPROVEMENTS IN AND CON-
Southampton, Engineer, for the Invention of
NECTED WITH COVERS FOR STEAM-ENGINE PISTON RODS."
Sealed the 11th July 1879, and dated the 17th January 1879.
PROVISIONAL SPECIFICATION left by the said Archibald Thomson at the
Office of the Commissioners of Patents on the 17th January 1879.
_ARCHIBALD THOMSON, of Southampton; in the County of Southampton, Engineer.
"IMPROVEMENTS IN AND CONNECTED WITH COVERS FOR STEAM-ENGINE PISTON
RODS."
This Invention has for its object the application of improved covers to such steam-
engine piston rods as, serving simply as guides, project through the top or back
ends of the cylinders, which covers, whilst dispensing with stuffing boxes and saving
the packing and lubricant that would be required for them, also avoid the loss of
heat ordinarily due to radiation from the bare rods, and admit of the steam acting
on the area of the rods, and thus adding to the power to an extent which is
not inconsiderable in the case of large engines such as are used for marine
purposes.
In carrying out the Invention a flanged nozzle or box is formed on the cylinder
cover or end, and inside this box there are fitted two half guide bushes to bear on
and guide the piston rod, and which bushes can be adjusted for wear by screws
entered from the outside. Two covers are by preference provided, an external one
of cast iron or other suitable metal, and a thinner internal one of iron, or copper, or
brass, these covers being in the form of tubes with their outer ends closed and with
their other ends flanged for attachment to the flanges of the box on the cylinder
The guide
cover or end. If preferred the inner cover may be dispensed with.
bushes are grooved to allow the steam from the cylinder to have access to and act
On the outer end of the piston rod, the grooves being by preference made helical;
or the communication for the steam may be by a separate pipe connecting the
interior of the cylinder with the outer end or other convenient part of the
Cover.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Archibald Thomson in the Great Seal Patent Office on the 16th July
1879.
ARCHIBALD THOMSON, of Southampton, in the County of Southampton, Engineer.
IMPROVEMENTS IN AND CONNECTED WITH COVERS FOR STEAM-ENGINE PISTON
RODS."
My said Invention has for its object the application of improved covers to such
steam-engine piston rods as, serving simply as guides, project through the top or
back ends of the cylinders, which covers, whilst dispensing with stuffing boxes and
saving the packing and lubricant that would be required for them, also avoid the
loss of heat ordinarily due to radiation from the bare rods, and admit of the steam
acting on the area of the rods, and thus adding to the power to an extent which is
not inconsiderable in the case of large engines such as are used for marine
purposes.
In carrying out my Invention I prefer to provide two covers for each piston rod,
an external one of cast iron or other suitable metal, and a thinner internal one of
iron, or copper, or brass, these covers being in the form of tubes having their outor
ends closed. Adjustable bushes are provided for guiding the piston rod, and these
bushes are grooved to allow the steam from the cylinder to have access to and
act on the outer end of the piston rod, these grooves being by preference made
helical; or the communication for the steam may be by a separate pipe connecting
the interior of the cylinder with the outer end or other convenient part of tho
cover.
And in order that my said Invention and the manner of performing the same
may be properly understood, I hereunto append a Sheet of explanatory Drawings
to be hereinafter referred to and representing my improved arrangement. In these
Drawings the same reference numerals are used to mark the same or like parts
wherever they are repeated.
Figure 1 on the accompanying Sheet of Drawings is a vertical section showing
the upper end of a cylinder forming part of an inverted-cylinder steam engine of a
kind commonly used for driving the screw propeller; and Figure 2 is a cross
section. A flangod nozzlo or box 3 is formed on the cylinder cover or end 4, and
inside this box 3 there are fitted two half guide bushes 5 to bear on and guide the
piston rod 6, and which bushes 5 can be adjusted for wear by screws entered from
the outside. To the flange of the nozzle or box 3 there are bolted by flanges formed
on them two tubes 7, 8, having their outer ends closed and acting as steam-tight
covers for the piston rod 6. The inner cover 7 is of thin metal and may be
dispensed with if preferred. The outer cover 8 is of cast iron. The covering of the
space in which the guide piston rod 6 works in this way, with a steam-tight
casing, prevents loss of heat by radiation from the rod, and also admits of the area
of the piston rod being utilised for the action on it of the steam pressure.
steam acting on the top or outer side of the piston has access to the space enclosed
by the cover or covers 7, 8, either by grooves in the guide bushes 5, or, as I prefer,
by a pipe 9 connected to the top or outer end of the cover or covers, or the pipe 9
might be connected to the side of the cover or covers.
The
Having thus particularly described my said Invention and the manner of per-
forming the same, 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 and in terms of the hereinbefore in part
recited Letters Patent is,-
The fitting of improved steam-tight covers to steam-ongine cylinders to enclose

page_text: the spaces in which guide piston rods work, and the connecting of such spaces with
the cylinder ends, substantially in the manner and for the purposes hereinbefore
described.
In witness whereof, I, the said Archibald Thomson, have hereunto set my
hand and seal, this Fifteenth day of July, in the year of our Lord One
thousand eight hundred and seventy-nine.
ARCHIBALD THOMSON. (LS.)