Improvements in Multiple Expansion Steam Engines.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Multiple Expansion Steam Engines.
We, PETER FERGUSON and WILLIAM YOUNG FLEMING both of Phoenix
Engine Works, Paisley, Renfrewshire, Engineers and Shipbuilders, 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:—
This invention relates to multiple expansion engines having their cylinders
connected to two or more cranks on the crank shaft and it has for its cbject to
effect better distribution of the turning effort on the shaft in transmitting the
power of the engines through the cranks.
In steam engines having the cylinders connected to the cranks in the ordinary
way there are in the case of two cylinders connected to cranks placed at
90 degrees one to the other, four points at which the maximum effort of the
engines is exerted on the crank shaft i.e. one thrust and one pull on each crank
during a single revolution of the crank shaft; in engines having three cranks
disposed at regular intervals around the shaft there are six points of maximum
turning effort; and in four crank engines whose cranks are at right angles four
points of maximum turning effort; whilst under our invention by suitably
disposing the cranks around the shaft or by suitably inclining towards each other
the cylinders connected to each crank in conjunction with the improved mode of
disposing the cranks we double or further increase the points of maximum turning
effort and distribute them equally around the axis of rotation the need for balance
weights upon the cranks being obviated on their amount being reduced.
In the accompanying drawings
Figures 1 and 2 Sheet 1 represent in plan and end elevation a four crank
quadruple expansion engine with one cylinder connected to each crank in
accordance with our invention. The high pressure cylinder 1 acts on the crank a,
the first intermediate pressure cylinder 2 on the crank b the second intermediate
pressure cylinder 3 on the crank c and the low pressure cylinder 4 on the crank d.
The cranks a and b are placed at an angle of 135 degrees to each other and thus
when the crank a is on its top centre the crank bis 45 degrees from reaching its
bottom centre, and when the crank a is on its bottom centre the crank b wants
45 degrees of reaching its top centre. The crank a thus arrives on its centres
45 degrees in advance of crank b. Similarly the cranks b and c are placed at an
Therefore
angle of 135 degrees with each other as are also the cranks c and d.
the dead centres of the cranks a b c and d follow each other at regular intervals
of 45 degrees the angle between cranks a and d being 45 degrees. This
arrangement of the cranks gives a much more uniform turning effort around the
crank path. The pistons follow each other at intervals of 45 degrees thus giving
8 points of maximum and 8 points of minimum turning effort in a revolution as
against 6 similar points in a three crank engine 4 in a two crank engine or a
4 crank engine with cranks at 90 degrees. ·
Figures 1 and 2 Sheet 2 represent a quadruple expansion engine with two
cranks placed at 90 degrees to each other and two set of diagonal cylinders
inclined at 45 degrees to each other. The high pressure cylinder and first
intermediate pressure cylinder 2 act on the crank a. The action of the one
following that of the other at 45 degrees the second intermediate pressure cylinder 3
and low pressure cylinder 4 act on crank bin like manner thus giving a regular
sequence of action of the cylinder on the cranks of 45 degrees around the axis of
rotation of the shaft.
Figures 1 and 2 Sheet 3 represent a four crank quadruple expansion engine

page_text: with cranks set at 90 degrees and coupled together in pairs by hunting links and
having two sets of diagonal cylinders inclined at 45 degrees to each other. The
high pressure cylinder 1 acts on the crank a and the first intermediate pressure
cylinder 2 on the crank b which are coupled together by the hunting link e.
The
second intermediate pressure cylinder 3 acts on the crank c and the low pressure
cylinder 4 on the crank d which are coupled together by the hunting link f.
The cranks being set at 90 degrees and the cylinders at 45 degrees to each other
a turning effort is exerted on the shaft equivalent to distributing the power
through eight cranks set at 45 degrees the one to the other around the axis of
rotation.
Figures 1 and 2 Sheet 4 represent a four crank quadruple expansion engine with
cranks coupled together in pairs and two sets of diagonal cylinders inclined at
22 degrees with each other. The high pressure cylinder 1 acts on crank. a and
second intermediate pressure cylinder 3 on crank 6 which are coupled together by
the hunting link e. The first intermediate pressure cylinder 2.acts on crank. c and
the low pressure cylinder on crank d which are coupled. together by the hunting
link. The distribution of the turning effort is the same in this, example as in
that represented in Sheet 3.
Figures 1 and 2 Sheet 5 represent a quadruple expansion engine with. 6 cylinders
acting in pairs on three cranks set at 120 degrees Each pair of cylinders are
diagonal and inclined to each other at an angle of 30 degrees... There are one
high pressure, one. first intermediate pressure two second intermediate pressure
and two low pressure cylinders. The high pressure cylinder. 1 and first
intermediate pressure. cylinder 2 act on crank a. One second intermediate
pressure cylinder 3 and low pressure cylinder 4 act on crank b and the other
second intermediate pressure cylinder 3 and. low pressure. cylinder 4 on crank c.
The sequence of action in the cylinders is at regular intervals of 30. degrees
giving 12 points of maximum and 12.of minimum crank. turning, moment..
Figures and 2 Sheet 6 represent a quadruple. expansion engine with.4 cranks
and 8 cylinders two high pressure two first. intermediate pressure two second
intermediate pressure and two low pressure. The cylinders. are in, pairs and, are
inclined at an angle of 22 degrees with each other. The two high pressure
cylinders 1, 1 act on the crank a the two first intermediate pressure cylinders 2, 2
on the crank the two second intermediate pressure cylinders 3,.3 on the crank.c
and the two low pressure cylinders 4, 4 on, the crank.d... The action of each set of
four cylinders is the same as described with reference to Sheet. 1 and as.. the.
cylinders of each pair are at 22 degrees inclination the sequence of action..of
the cylinders is at regular intervals of 22 degrees. i.e. there are 16 points of
maximum and 16 of minimum crank turning effort.
Figures 1 and 2 Sheet 7 represent in plan and elevation a quadruple expansion
paddle engine with four cranks coupled together in. pairs by hunting, links. The
high pressure cylinder 1 which is horizontal acts on the crank. .a ..the second
intermediate pressure cylinder 3 which is inclined at 22 degrees to the horizontal
plane acts on the crank the cranks a and b being coupled by a hunting link.e.
The first intermediate pressure cylinder 2 acts on the crank.c and. the low pressure
cylinder 4 on the, crank d the cranks c and d being coupled by.a. hunting, link.f.
The sequence of action in the cylinder is at regular intervals of .45,.degrees all
round..
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
olaim is :-
1. In multiple expansion, and multiple crank steam engines the arrangement.of
the cranks.in such angular relation to each; other around the axis of rotation as to
ensure uniform distribution and the practical duplication of the points, of maximum
and minimum. turning effort substantially. as described...with reference...to the
drawings annexed.

page_text: 2. In multiple expansion and multiple crank steam engines the arrangement of
the cylinders in pairs one of each pair at an inclination to the other in conjunction
with arrangement of the cranks in such angular relation to each other around the
axis of rotation as to ensure uniform distribution and practical duplication of the
points of maximum and minimum turning effort substantially as described with
reference to the drawings annexed.
3. The several arrangements of multiple expansion steam engines herein
described with reference to the drawings annexed.
Dated this 30th day of December 1892.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.