IMPROVEMENTS IN LOCOMOTIVE ENGINES
Year: 1884

page_text: I, WILLIAM HOLMES NISBET, of Mavisbank, Partickhill, Glasgow, in the County
of Lanark, Engineer, do hereby declare the nature of my said Invention for
"IMPROVEMENTS IN LOCOMOTIVE ENGINES" and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:
My invention consists of improvements in compound locomotive engines, in
which the high and low pressure cylinders are disposed as " tandem
on each side of the carrying frame.
engines
In the accompanying drawings, which illustrate my Invention, Figure 1. is a
sectional elevation, and Figure 2 is a sectional plan of a locomotive engine showing
one arrangement of the cylinders with the valves operated by a modification of the
link motion or ordinary valve gear. Figures 3. and 4. are corresponding views
showing a modification in which my improved arrangement of valve gear is
employed. Figure is an elevation corresponding to Figure 3. but showing the
crank and valve gear in a different position, and Figure 6 is an end view showing
the hand levers.
Referring to Figures 1. and 2, the high and low pressure cylinders A and B, on
each side of the locomotive are arranged in line as tandem engines, connected
directly to the crank shaft, the valve casings A¹ B¹ being towards the inside of the
frame. The slide valve rods a, b are connected by links a¹ b₁ to sliding blocks cd
fitted in links or "quadrants" C, D, which are operated by eccentrics E, F, on the
crank shaft G as in the ordinary link motion. The sliding blocks c whose position
in the quadrant C serves to control the extent of motion of the valves of the high
pressure cylinder are moved to either side of the mid position in which they are
represented in the drawing, by means of a hand lever H and lever H3 connected
by a link I to a lever J on a cranked cross shaft K provided with arms L and
links attached to the links a¹ to which the blocks c are connected. The blocks d
whose position controls the valves of the low pressure cylinders B, are in like
manner shifted by the hand lever H' link 11, lever J¹, cross-shaft K¹, arms L' and
links and b¹. The dotted lines show the extent of movement of the parts.
In the arrangement illustrated in Figures 3 to 6 the valve chests A¹, B₁ are
formed on the upper sides of the cylinders A, B, the exhaust from the cylinder A
to the casing of the cylinder B being through the pipe P. The valve rods a, b are
connected to sliding blocks c, d in quadrants C, D, which instead of being operated
D

page_text: by eccentrics as in the link motion are held stationary while the sliding blocks
move in them. These quadrants C, D, are free to oscillate on a central axis, on
which they are turned to right or left to control the motion of the sliding blocks c, d,
and therefore the action of the slide valves, by means of hand levers H, H¹, con-
nected through suitable rods and levers to the quadrants. The quadrants C which
control the valves of the high pressure cylinders A are operated by the hand
lever H, acting through the link I, and lever J, on the cross shaft k the links land
arms L, connected to the supporting shaft K, carrying the quadrants, while the
quadrants D operating the valves of the low pressure cylinders, are operated by
the handle H acting through the link I, lever J¹ and cranked cross shaft K¹.
The sliding blocks c, d, are fitted near the ends of the links M, jointed to links N,
whose upper or inner ends are centred on connecting rods O, of the engines and
whose lower or outer ends are connected to radius rods R connected to fixed
brackets on the locomotive frame. The motion of the engine connecting rods O
imparts to the slide blocks c, d, through the links M, N, a reciprocating motion in
the quadrants C, D, and the forward and backward inclination from the central
position given to the quadrants by operating the hand levers H, H', causes the
slide blocks to impart the desired reciprocation to the slide valves of the respective
cylinders A, B. Figure 5 shows one of the quadrants (C) inclined forward, the
engine crank being shown in a position at right angles to that represented in
Figure 3.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
First. The arrangement in a locomotive of high and low pressure cylinders.
disposed as "tandem" engines on each side of the frame, the valves being operated
either by the link motion or by the improved valve gear described substantially
as herein set forth.