Improvements relating to the Balancing of Steam and like . Engines.
Year: 1895

page_text: Date of Application, 22nd May, 1895
Complete Specification Left, 24th Feb., 1896-Accepted, 28th Mar., 1896
PROVISIONAL SPECIFICATION.
Improvements relating to the Balancing of Steam and like
.
Engines.
I, JOHN TWEEDY, of Neptune Works, Newcastle-on-Tyne, Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention relates to further improvements in the method of balancing
engines described by Mr. Otto Schlick in his Specification of Letters Patent
No. 2813 of 1894.
To facilitate the description of my invention I will suppose the engine to be
vertical or in other words that the movement of the reciprocating parts is vertical
and above the crank shaft and further that all the cylinders are in the same plane.
I do not however limit this invention to such vertical engines or to engines having
their cylinders in the same plane.
Assuming the revolving parts are balanced, I will call the forces tending to
tilt the engine "couples" and those forces which tend alternately to lift and
depress the engine "free vertical forces."
In engines constructed according to the Specification above referred to the main
free vertical forces and couples are eliminated.
In some modifications of the engines the connecting rods produce no unbalanced
disturbing effect, or effects so relatively small that they may be neglected. In
others however the disturbing effect may be considerable and the object of this
invention is to eliminate or reduce these residual forces especially in engines having
four cranks and where the weights of the moving parts acting on one pair
of cranks are of less magnitude than those acting on the other pair of cranks.
I confine myself in the following description to this type of engine.
The cranks forming the pair acted on by the greater weights are placed
at an obtuse angle to one another and those forming the lighter pair are placed at
an acute angle (or in the limiting case parallel).
The line bisecting the angle between one pair of cranks is placed at 180° to that
bisecting the other pair.
If then W be one of the pair of greater weights, wo one of the pair of smaller
weights, the obtuse angle and a the acute angle I construct the engine so
W
that cos (ta) when it is only desired to balance the free vertical forces
==
20 cos (6)
with the exception of those due to the obliquity of the connecting rods and
W
20
cos (a)
-
cos (180° – (3)
when it is desired only to balance the free vertical forces due
to the obliquity of the connecting rods. In cases where both the aforesaid forces
are to be balanced the parts are related so that both the above conditions are
fulfilled.
In constructing a four crank engine such as that described in the Specification
No. 2813, 1894 above referred to I use weights and angles determined as described
above, for the known elements of the design and from them determine the
remainder. I thus balance all the free forces and also the main couples, only
leaving unbalanced in some cases the relatively unimportant couples due to the
obliquity of the connecting rods.

page_text: W
COS a
When it is not desired to balance the revolving weights separately they are
balanced vertically and when required, horizontally also, as a system by including
the
them in the weights W and w noting that in the formula
cos (180° - 3)
reciprocating weights only are taken so that in this case when complete balance of
free vertical forces is desired it must be borne in mind that the weights in the two
formulæ are not the same.
10
The weights of the valves, gear, pumps and other moving parts are dealt with in
a similar manner.
It would be noted that in engines in which the power transmitted to the shaft
from each of one pair of cylinders is less than that from each of the other pairs of
cylinders the parts of these lower power cylinders will be made correspondingly
lighter and being placed at the end the revolving weights will be balanced as a
system either without the addition of balance weights or with reduced weights
depending upon the weights of the parts adopted in the design.
Dated this 22nd day of May 1895.
Haseltine, Lake & Co.,
JOHN TWEEDY.
45 Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements relating to the Balancing of Steam and like
Engines.
I, JOHN TWEEDY, of Neptune Works, Newcastle-on-Tyne, 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:-
This invention relates to further improvements in the method of balancing
engines described by Mr. Otto Schlick in his Specification of Letters Patent
No. 2813 of 1894.
In engines constructed according to the Specification above referred to the main
free forces and couples are eliminated.
In some modifications of the engines the connecting rods produce no unbalanced
disturbing effect, or effects so relatively small that they may be neglected.
In others however the disturbing effect may be considerable and the object of this
invention is to eliminate or reduce these residual forces.
To facilitate the description I will suppose the engine to be vertical or in other
words that the movement of the reciprocating parts is vertical and that the
cylinders are above the crank shaft, and further that all the cylinders are in one
plane, although I do not limit this invention to such vertical engines or to engines
having their cylinders in the same plane. I further assume that the revolving
parts are balanced by the method described in the aforesaid Specification No. 2813
of 1894.
The forces due to the momentum of the reciprocating parts on any one crank may
be expressed with great accuracy by the well known formula

page_text: The value Q consists therefore always of the sum of two values of which one is
proportional to cos and the other, which is due to the finite length of the
connecting rod, is proportional to cos 20. Figure 1 is a diagrammatic representation
of this.
The line X X being the developed circumference of the circle described by the
crank pin the curve a a a corresponds with the value P cos 0, and the curve a a aa
with PR
L
cos 20.
The curve A A A is the sum of the two other curves a a a and a a a a and
represents the real force produced by the moving masses under consideration
including that due to the effect of the finite length of the connecting rod.
If similar curves
are constructed for a second crank, forming an angle
of 90 degrees with the first, on which the same weights are working, the
curves bbb, ßßß and B B B will be obtained and it will be noticed that the force
due to the finite length of connecting rod is in the one case exactly equal and
opposite to that in the other. That is to say, the influence of the finite length of
one connecting rod is eliminated by that of the other.
The forces produced by the two weights moved by the two cranks are therefore
the same as would result if the connecting rods were of infinite length.
Two cranks of the same length forming an acute angle & and being acted on by
the weights w and W (Figure 2) have-as far as the influence of the finite length
of connecting rod is considered-the same effect as a single crank to which the
weight P is attached and of which the position is between the cranks of the
weights w and W, if the following conditions be fulfilled: viz.

page_text: But as it is necessary for balancing that at the same time the simple statical
moment acting on the cranks must be equal, it is another condition that

page_text: If only the forces resulting from the finite length of connecting rod are to be
balanced, the following condition is to be fulfilled according to formula (5).
If the revolving parts are not balanced for themselves (by counter weights) they may
be balanced as a system in a vertical and also if required in a horizontal direction
if their weights are included in the values g and G in the formula
G
=
COS a
9 cos (180° 8)
a
cos
G
0
COS 2
noting that in the formula
the reciprocating weights only are
included so that in this case the values of G and 9 are not the same in the
two formulæ.
The weights of the valve gear, pumps etc. can also be compensated for in
the same way.
In constructing engines having four cranks but with unequal moving weights
in which it is desired to eliminate or reduce the secondary as well as the primary
or principal free forces I make the weights and angles of the cranks such that the
foregoing conditions are fulfilled accurately or as nearly as may be desired and in
engines having more than four cranks 1 maintain the same relations between the
weights and angles of cranks.
When it is required to eliminate or reduce the magnitude of the main couples as
well as the free forces I embody these weights of parts and angles of cranks to the
desired extent in engines constructed according to the Specification No. 2813
of 1894 in which it is a condition that the heavier weights shall be placed

page_text: 1 being the distance between the two inner cranks acted upon by the heavier
weights, and L the distance between the outer cranks.
Figures 6 and 7 are diagrammatic views of a four cylinder engine embodying
these improvements. 1, 2, 3, 4 are cylinders the rods of which work on separate
cranks. The outer cylinders 1 and 4 have lighter moving parts 9, 9 than the
cylinders 2 and 3 placed between them, the weights of the moving parts of
cylinders 2 and 3 being G, G.
In this diagram the distances between the centres of the inner and outer pair of
cylinders are and L, respectively but in engines when only the free forces and not
the couples are to be eliminated the relative positions of the cylinders and the
distances between them are immaterial.
The formulæ given herein are not quite correct inasmuch as the connecting rod
is looked upon as if part were reciprocating only and part revolving only
which is not strictly true, although it is sufficiently accurate for all practical
purposes.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
A multiple cylinder engine with four or more cylinders in which the weights of
the moving parts and the angles of the cranks are arranged as, and for the purposes,
herein described.
Dated this 24th day of February 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.