IMPROVEMENTS IN COMPOUND STEAM ENGINES
Year: 1879

page_text: LETTERS PATENT to George Kelson Stothert, of the Steam Ship Works, Bristol,
in the City and County of Bristol, for the Invention of "IMPROVEMENTS IN
COMPOUND STEAM ENGINES."
Sealed the 12th March 1880, and dated the 25th September 1879.
PROVISIONAL SPECIFICATION left by the said George Kelson Stothert at
the Office of the Commissioners of Patents on the 25th September 1879.
GEORGE KELSON STOTHERT, of the Steam Ship Works, Bristol, in the City and
County of Bristol. IMPROVEMENTS IN COMPOUND STEAM ENGINES."
"5
My Invention relates to the construction and arrangement of compound steam
engines and their slide valves and gear in a compact and simple form. The improved
engine is of the horizontal kind, having its two cylinders arranged in line, the high
pressure cylinder being placed in front of the low pressure cylinder with sufficient
space between them to give access to the packings of the one piston rod on which
both pistons are fixed. A continuation of the piston rod through the back cover of
the low pressure cylinder is linked to the vertical arm of a three armed lever fixed
on a rocking shaft. The two horizontal arms of this lever work alternately two
vertical air pumps arranged side by side, and a third arm on the rocking shaft works
the feed pump. The front part of the piston rod extends through the front cover
of the high pressure cylinder to a crosshead which works in guides and which is
linked by the connecting rod to the crank on the main shaft. From the crank shaft
is driven by mitre gear a longitudinal counter shaft which extends backwards some
distance along the framing of the engine, and which by mitre gear drives a short
transverse shaft carrying eccentrics which work the slides of the two cylinders, each
eccentric being linked directly to one of the slide rods. On the same transverse
shaft there is a third eccentric which works an expansion slide on the back of the
high pressure slide, the said expansion slide consisting of two metal plates sliding
over ports on the main slide, and capable of being adjusted by means of screw threads
on their rod, which for that purpose is extended through the back end of the slide
jacket, and can be turned in either direction by an external hand wheel. When a
governor is employed it is worked by bevil gear from the longitudinal countershaft
Din G31

page_text: above mentioned, and it may be applied to work a throttle or other steam regulating
valve in the usual way, or it may work a link motion for an expansion valve. As
however it is of advantage to apply the governor to regulate the cut off I adopt the
following arrangement for that purpose:-I use a high speed central weight
governor, to the ball of which is attached a lever working a rod having at its lower
end a screw of suitable pitch engaging in a nut in the boss of a bevil wheel, which
gearing with another bevil wheel adjusts the rod of the expansion valve. Thus
every movement of the governor is conveyed at once to the expansion valves, which
can be adjusted so that the governor shall cut off any desired part of the stroke.
Although I have above described a pair of air pumps as being worked from a rocking
shaft, this arrangement being convenient in respect of compactness and also very
efficient, a single air pump might be worked directly from the piston rod or cross-
head, the engine being in other respects as above described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Kelson Stothert in the Great Seal Patent Office on the 24th
March 1880.
GEORGE KELSON STOTHERT, of the Steam Ship Works, Bristol, in the City and
County of Bristol. "IMPROVEMENTS IN COMPOUND STEAM ENGINES."
My Invention relates to the construction and arrangement of compound steam
engines and their slide valves and gear in a compact and simple form. The improved
engine is of the horizontal kind, having its two cylinders arranged in line, the high
pressure cylinder being placed in front of the low pressure cylinder with sufficient
space between them to give access to the packings of the one piston rod on which
both pistons are fixed. A continuation of the piston rod through the back cover of
the low pressure cylinder is linked to the vertical arm of a three armed lever fixed
on a rocking shaft. The two horizontal arms of this lever work alternately two
vertical air pumps arranged side by side, and a third arm on the rocking shaft works
the feed pump. The front part of the piston rod extends through the front cover
of the high pressure cylinder to a crosshead which works in guides, and which is
linked by the connecting rod to the crank on the main shaft. From the crank
shaft is driven by mitre gear a longitudinal counter-shaft which extends backwards
some distance along the framing of the engine, and which by mitre gear drives a
short transverse shaft carrying eccentrics which work the slides of the two cylinders,
each eccentric being linked directly to one of the slide rods. On the same trans-
verse shaft there is a third eccentric which works an expansion slide on the back of
the high pressure slide, the said expansion slide consisting of two metal plates
sliding over ports on the main slide, and capable of being adjusted by means of
screw threads on their rod, which for that purpose is extended through the back
end of the slide jacket and can be turned in either direction by an external hand
wheel. When a governor is employed it is worked by bevil gear from the longitu-
dinal countershaft above mentioned, and it may be applied to work a throttle or
other steam regulating valve in the usual way, or it may work a link motion for an
expansion valve. As however it is of advantage to apply the governor to regulate
the cut off I adopt the following arrangement for that purpose:-I use a high speed
central weight governor, to the ball of which is attached a lever working a rod
having at its lower end a nut engaging a screw on the boss of a bevil wheel which
gearing with another bevil wheel on the rod of the expansion valve turns the rod
in the one direction or the other. Thus every movement of the governor due to
change of speed is conveyed at once to the expansion valves, which can be adjusted
so that the governor shall thus cut off to suit the required speed. Although I have
above described a pair of air pumps as being worked from a rocking shaft, this
arrangement being convenient in respect of compactness and also very efficient, a
single air pump might be worked directly from the piston rod or crosshead, the
engine being in other respects as above described.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a side view, and Fig. 2 a plan partly in section of a compound engine
according to this Invention. A is the high pressure cylinder and B the low pressure
cylinder, placed in line with one another, both pistons being on one rod Č. This
rod, extended backwards through the bottom of the low pressure cylinder, is linked
to a three armed lever D which works two air pumps E, E. The rocking shaft on
which D is fixed has an arm working the feed pump F. The piston rod is extended
forwards to a cross head G which moves in guides and is connected to the crank on
the shaft H in the usual way. From this shaft by mitre gear I rotary motion is
communicated to a chaft I which he mitra Moon Tanke a chant
T

page_text: On this shaft are three eccentrics M directly linked to the slide of the low pressure
cylinder B, N, directly linked to the slide of the high pressure cylinder A, and P
directly linked to the rod of an expansion slide on the back of the high pressure
slide. This expansion slide consists of two slide blocks Q, Q, governing passages
through the main slide, and adjustable nearer to one another or farther apart,
according to the desired cut off, by screws on their rod which can be turned by a
hand wheel R. In order that the rod may be capable of being so turned it is pro-
vided at its front end with a swivel joint at S, and it is extended backwards through
a stuffing box in the slide jacket, and the hand wheel R is fixed on it in a convenient
position for adjusting the cut off.. I apply a governor to adjust the cut off in the
manner shewn in Fig. 3, which is part of a side view of the engine, and in Fig. 4,
which is a part plan, partly in section. T is the governor working a lever from
which descends a rod t carrying a nut engaging with a thread of rapid pitch on the
boss u of a bevil wheel U. This bevil wheel gears with another wheel V fixed
on the rod of the expansion valves. Thus, according as the speed of the engine and
governor varies, the bevil wheels U and V are turned in the one direction or the
other, shifting the expansion slides so as to cut off sooner or later, as the case
may be.
Having thus described the nature of my said Invention, and in what manner the
same is to be performed, I claim,―
First. The construction of compound engine herein described with reference to
Figs. 1 and 2 of the accompanying Drawings.
Second. The apparatus whereby the governor is applied to regulate the cut
off as herein described with reference to Figs. 3 and 4 of the accompanying
Drawings.
In witness whereof, I, the said George Kelson Stothert, have hereunto set my
hand and seal, this Twentieth day of March, in the year of our Lord One
thousand eight hundred and eighty.
G. K. STOTHERT. (L.S.)