Improvements in and relating to Steam Engines of the Compound.
Year: 1892

page_text: Date of Application, 3rd May, 1892
Complete Specification Left, 3rd Feb., 1893-Accepted, 29th Apr., 1893
PROVISIONAL SPECIFICATION.
Improvements in and relating to Steam Engines of the Compound
Туре.
I, JOHN THOM, Central Chambers, Hope Street, Glasgow, in the County of
Lanark, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to improvements in that class of compound engine (having
four cranks) in which the steam is expanded in three or four stages.
According to my invention when the steam is to be used four times I arrange
the cranks so that two adjacent cranks are directly opposite (or nearly so) one
another, that is, one piston will be at bottom of stroke when the other is at top of
the stroke in a vertical engine. This arrangement reduces the pressure on the main
bearings, and the momentum strains are in equilibrium, which reduces vibration.
By this arrangement two valves can be worked with one set of valve gear, as the
motion can be taken from the one slide valve to work the other if desired.
It is preferred to exhaust from a cylinder the crank in connection with which is
at right angles to the cylinder receiving the steam so as to obtain all the
advantages of a compound receiver engine.
When the steam is only to be expanded through three stages, one of the stages
will be done simultaneously through two smaller cylinders, so as to get the full
advantage of this arrangement of four cranks; and less valve gear.
Dated this Second day of May 1892.
COMPLETE SPECIFICATION.
Improvements in and relating to Steam Engines of the Compound
Туре.
I, JOHN THOM, of Central Chambers, Hope Street, Glasgow, Consulting
Engineer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
My invention relates to improvements in that class of compound engines having
four cranks, in which the steam is expanded in three or four stages.
According to my invention, when the steam is to be used four times, I arrange
the cranks so that two adjacent cranks are directly or nearly opposite one another,
that is one piston will be at the bottom of the stroke, when the other is at the top
of the stroke, in a vertical engine; and two slide or other steam distribution valves
are worked with one set of valve gear, the motion being taken from the one valve or
valve rod to work the other. By this arrangement the pressure on the main bearings
is reduced, and the momentum strains are equilibrated, and thereby the vibration of
the engine is reduced.
It is preferred to exhaust from a cylinder, the crank in connection with which is
at right angles to the cylinder receiving the steam, that is to say, the cylinders and
cranks of the engines are by preference so arranged, that the exhaust from one
cylinder using a higher grade of steam, will be taken to the cylinder using the
next lower grade, the crank in connection with which is at right angles to the
other, so that all the advantages of a compound receiver engine are obtained.
When the steam is only to be expanded through three stages, one of the stages

page_text: will be carried on in two smaller cylinders simultaneously, so as to get the full
advantage of this arrangement of cranks and valve gear.
In the drawings heretó annexed, and forming part of this Specification, I shew
my invention applied to quadruple compound engines, of which there are two
modifications, and to a triple compound engine. In these drawings
:―
Figure 1 is an end elevation; Figure 2 is a front elevation; and Figure 3 is a
plan, of one modification of the quadruple compound engine.
Figure 4 is a front elevation, and Figure 5 is a plan, shewing, diagrammatically,
the other modification of the quadruple engine.
Figure 6 is a plan showing the triple compound engine.
Referring generally to the drawings, 1, 2, 3, 4, represent the four cylinders of
the engine; and 1, 2, 3, 4*, are the four cranks corresponding with and worked
from the cylinders 1, 2, 3, 4, respectively. 5 and 6, 7 and 8, 9 and 10, and 11
and 12, are respectively the valve casing and the valve rod, of the cylinders 1, 2, 3
and 4.
In the quadruple expansion engines shewn, cylinder 1 is the high pressure
cylinder, 2 is the first intermediate pressure cylinder; 3 is the second intermediate
pressure cylinder; and 4 is the low pressure cylinder; whilst in the triple expansion
engine, is the high pressure cylinder; 2 is the intermediate pressure cylinder;
and 3 and 4 are two low pressure cylinders.
It will be seen, that in all cases, the four valves are worked by two sets of valve
gear, which in the quadruple compound engine, and the triple compound engine,
shewn in Figures 1 to 3, and Figure 6, is that called "radial valve gear"; whilst
that shewn in Figures 4 and 5 is the ordinary link motion valve gear. The lever
which is directly connected with and works the valve rods in Figures 1, 2, 3, and 6,
and the link which is directly connected with said valve rods in Figures 4 and 5, is
designated 20. The other parts of these valve gears need not be further particu-
larized or described, as they are well known types.
In the quadruple compound engines, the valve casings of the cylinders 1 and 2
are connected by a pipe 21, the valve casings of the cylinders 2 and 3 are connected
by the pipe 22, (shewn in Figure 3, but not in Figure 5), and the valve casing of
the cylinders 3 and 4 are connected by a pipe 23. In the triple compound engine
the valve casings of the cylinders 1 and 2 are connected by the pipe 21, while the
valve casings of the cylinders 2 and 3 and 4, are connected by the pipes 22. Thus
by this arrangement, by the cranks of the cylinders 1 and 2, and those of 2 and 3,
and 3 and 4, being at right angles to each other, and the cylinders connected
together by the pipes 21, 22, and 23 in the quadruple compound, and in the triple
compound by the pipes 21 and 22, the exhaust from one of such cylinders working
with the higher grade steam exhausts into the next with the lower grade steam
with its crank at right angles to the other (except as regards cylinder 4 of the
triple compound, engine), by which arrangement all the advantages of a compound
receiver engine are obtained.
It will be seen by the drawings that the cranks 1× and 2× of the cylinders 1
and 2 are arranged at 90 degrees from each other; that the cranks 2x and 3x of
the cylinders 2 and 3 are at 90 degrees in relation to each other, and that the
cranks 3* and 4* of the cylinders 3 and 4 are at 90 degrees from each other; and
also that the cranks of the cylinders 1 and 3, and 2 and 4, are diametrically opposite
each other (that is 180 degrees removed), but that each cylinder using a higher
grade steam exhausts into a cylinder using a lower grade having its crank at right
angles to the former. It will also be seen that the valves directly worked by the
two valve gears are connected by levers designated 13 and 14 to the valves of the
cylinders having no valve gear, the motion of which levers gives to the valves
connected with them, a motion opposite in direction to that of the other valve rods
by which they are moved. The valves of the cylinders so connected, are those
connected with or belonging to the cylinders 1 and 3, and 2 and 4, that is, those
which have their cranks arranged dian etrically opposite each other. Thus, a four
cylinder engine is worked with two sets of valve gear, and the valves, and momentum

page_text: stresses thereof, of one cylinder, are balanced wholly (or partially) by the valve,
and its momentum stresses, of the cylinder connected with it.
In the quadruple compound examples shewn, the valves directly connected with
and worked by the valve gears are those of the two larger cylinders, namely, the
second intermediate pressure cylinder, and the low pressure cylinder; whilst in the
triple compound engine, the two larger cylinders, namely, the two low pressure
cylinders, are those which have their valves directly connected to and worked
by the valve gears. This arrangement, however, although preferable, is not
essential.
Of course, in cases where the steam is distributed to and from one cylinder by
two valves, the same means as above specified for operating two sets of valves by
one valve gear will still obtain.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a compound engine having four cylinders and four cranks and in which the
steam is expanded in three or four stages, effecting the motion of one steam distri-
bution valve or set of valves of one cylinder, from a valve or valve gear used in
connection with another cylinder and working in an opposite direction thereto,
substantially in the manner described, whereby the weight of one valve or set of
valves and the momentum stresses thereof assist to balance the weight and momentum
stresses of the other or others, and vibration is diminished.
2. The arrangement of quadruple compound and triple compound engines having
four cylinders and cranks (arranged as described) in combination with one or more
valves in connection with each cylinder and worked by two valve gears, in the
manner set forth with reference to and as shewn in the drawings hereto annexed
for the purposes specified.
Dated this 2nd day of February 1893.
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicant's Patent Agents.