Improvements in Constructive Arrangements for Preventing or Diminishing Vibrations due to the Moving Parts of Steam Engines.
Year: 1897

page_text: Date of Application, 9th Sept., 1897-Accepted, 30th Oct., 1897
.
COMPLETE SPECIFICATION.
Improvements in Constructive Arrangements for Preventing or
Diminishing Vibrations due to the Moving Parts of Steam
Engines.
I, JOHN HENRY MACALPINE, of 3303 Sixteenth Street, Washington, D. C. United
States of America, 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, that is to say:-
:-
My said Invention relates to the same subject and objects as those referred
to in Macalpine's Patent Specification No. 9746 of 1895, and comprises modifica-
tions of or improvements on the devices, described in that Specification, for pre-
venting or diminishing vibrations due to the moving parts of steam engines. As
described in the said earlier Specification counter-acting weights suitably moved
by mechanism were to be employed for the purposes in view; and may in some
cases be partially employed in carrying out my present Invention, by my present
Invention however, I arrange so, that certain parts of an engine may move in
opposite directions to and so balance other parts, thereby, to a large extent avoiding
the use of added balancing weights. I connect the oppositely moving parts to the
opposite ends of levers on rocking shafts; and as such parts may be arranged
in various ways for the purpose in view, I have shown on three accompanying
sheets of explanatory drawings and will hereinafter describe several examples of
arrangements made according to my Invention.
In the accompanying drawings the examples of engines shown are of the
inverted-cylinder class as frequently used for driving the screw propeller, the
engines may however be arranged with the cylinders vertical horizontal or inclined,
and they may be adapted for driving electrical or other apparatus.
In one arrangement, of which Figure, 1, is an elevation and Figure, 2, a vertical
section as at right angles to Figure, 1, a high-pressure cylinder, H, is placed
below a low-pressure cylinder, L; and the piston rods, H 1, L1, extend downwards
and upwards respectively. The high-pressure piston rod, H 1, has fixed to it a
slide block and crosshead, H2, and by means of the usual connecting rod, H3,
acts on the crank shaft, C, which has on it weights, C1, to counterbalance the
crank and part of the connecting rod. The cross head, H2, is also connected by
links, H4, to a pair of levers, A, fixed on the ends of a rocking shaft, A 1, parallel
to the crank shaft, and carried in bearings between the two cylinders, H, L. The
piston rod, L1, of the upper low-pressure cylinder, L, has fixed to it a cross-
head, L2, which is connected by links, L3, to the ends of the levers, A, opposite
to those to which the lower links, H 4, are connected. With these arrangements
and connections the pistons of the cylinders, H, and L, and the parts respectively,
in connection, move oppositely. If the weights and proportions of the two sets
of parts are made such as when reciprocating to have equal momenta in opposite
directions, the parts will be balanced so as not to produce vibrations due to inertia
or to changes of motion. At the same time, even if the conditions for obtaining
a perfect balance are only approximated to, any vibrations produced will be very
small. In Figure, 1, the upper and lower parts are shown as connected to the

page_text: levers, A, at points equally distant from the axis, with which arrangement the
masses of the two sets of parts should be as nearly equal as conveniently possible.
A torsional balance may be effected in the manner explained in the earlier Specifi-
cation hereinbefore referred to.
Figures, 3, and 4, are elevations as at right angles to each other of a second
arrangement, which differs from that shown in Figures, 1, and 2, in having the
rocking shaft, A 1, at right angles to instead of being parallel with the crank
shaft, C, and in having the cylinders, H, L, with their axes, although vertical,
not quite coincident. The rocking shaft, A 1, may be in any convenient angle
intermediate to those shown in Figures, 1, and 2. In this arrangement also the
rocking-shaft levers, A, have the links, L3, and H4, connected to them at different
distances from the axis. It may in some cases be convenient with such an arrange-
ment to have a comparatively heavy low-pressure piston with a shorter stroke
balancing a comparatively light high-pressure piston with a longer stroke.
In the arrangements shown in Figures, 1, to 4, single cranks only, are
represented, but two similar sets of parts may be arranged to act on two cranks.
Figures, 5, and 6, on sheet, 2, are diagrams each showing an arrangement of
three inverted vertical cylinders placed in line on the same level, the piston-rod
crosshead of the middle cylinder being connected to a crank on the shaft, C, and
by reversing rocking levers, A, to the piston-rod crossheads of the two other
cylinders. In Figure, 5, the plane of the rocking levers, A, is parallel to that
of the shaft, and in Figure, 6, it is at right angles thereto; or it may be in any
other convenient intermediate angle.
In some cases in which, as in the examples shown in Figures, 5, and 6, a balance
is arranged between the moving parts of a central cylinder and two outer cylinders
it is essential and sufficient for the two outer cylinders to be disposed symmetrically.
They may be placed nearer to or further from the crank shaft than the central
cylinder, and they may be parallel or equally inclined in opposite directions to
that cylinder.
Figure, 7, is a plan and Figures, 8, and 9, are elevations of an arrangement,
in which high-pressure and low-pressure cylinders, H, L, placed side by side are
arranged to act on a single crank. The piston-rod crosshead, H2, of the high-
pressure cylinder, H, is connected to the cranks, and also to a pair of reversing
levers, A, on a rocking shaft, A 1, the other ends of the levers being connected
by links to the piston-rod crosshead, L2, of the low-pressure cylinder, L.
Figures, 10, and 11, sheet, 3, are elevations showing a double arrangement
for two cranks, the parts for each crank being similar to what is shown in
Figures, 7, 8, and 9.
The valves and parts attached thereto may be balanced in the same manner as
the pistons, and an example arrangement for this purpose is shown in Figure, 11,
the balancing being effected by means of a lever, A 2, which might be connected
by links to the valve rods; but as the versed sine of half the angle of vibration
of the lever is small, the connection with the valve rods is shown as being effected
by blocks on pins at the ends of the lever and sliding in short slots in small
crossheads on the valve rods. The valve gear indicated in Figure, 11, is a
reversing link, D, to be actuated by a pair of eccentrics. The eccentrics with parts
of the rods may be balanced by one or more counterweights on the shaft, the
masses of the other parts being suitably combined with that of the valve directly
acted on, in the calculations for balancing the parts by the lever, A 2.
Figures, 12, 13, and 14, are diagrams showing further arrangements of the
rocking shafts reversing levers and connecting parts. In Figure, 12, the rocking
shaft with its levers is placed above the cylinders and the connection to the piston
rods is by links. In the arrangements shown in Figures, 13, and 14, the rocking
levers, A, have pins working in blocks fitted to move in slots in crossheads fixed
to the piston rods or to rods made to move with the piston rods.
In order to further facilitate the understanding and practical application of my
Invention I proceed to compare the weights of certain moving parts and their

page_text: arrangement in a set of marine engines such as is at present in existence, with
the weights and arrangement of a set of engines having the same stroke and
dimensions of cylinders, but constructed so as to embody my improvements, it
being understood that the data thus referred to by way of example are approximate.
In a set of quadruple or four-stage expansion engines similar to engines at
present in use and having, for example, cylinders, respectively, 33, 49, 60,
and 98 inches in diameter acting on four cranks Nos. 1, 2, 3, and 4, of which
Nos. 1, and 2, are diametrically opposite to each other, Nos. 3, and 4, being also
diametrically opposite to each other but at right angles to Nos. 1, and 2, the
.11.
10124
10992
13316
15556
There are thus 868 pounds acting on crank, 2, more than on crank, 1, and
2240 pounds acting on crank, 4, more than on crank, 3; in other words those
weights are unbalanced. It must also be remembered that the total weights on
crank, 1, act in a different transverse vertical plane from that in which the weights
on crank, 2, act; and the case is the same with the total weights on cranks, 3,
and 4.
In constructing such engines according to my Invention and assuming in this
example that the parts are arranged as in Figures, 10, and 11, the first-stage
cylinder being placed above one crank and the third-stage cylinder above another
crank, there being only two cranks, the second-stage and fourth-stage cylinders
would be placed at the sides of the first-stage and third-stage cylinders, respectively,
their piston rods being respectively connected by levers to the piston rods of those
cylinders.
The weights would then be as follows, the crossheads slide blocks and connect-
ing rods over the cranks being supposed to be strengthened and increased in
weight. The second-stage and fourth-stage pistons have also to be increased in
weight:
Thus not only are the weights appertaining to the cylinders of each pair balanced,
but in the case of each pair the oppositely moving weights act in the same
transverse vertical plane.
In taking ths of the weight of the connecting rod, it has been assumed that
the centre of gravity of the rod is at ths of its length from the upper end. The
remaining ths of each connecting rod must be balanced along with the crank
and crank cheeks by suitable counterweights on the shaft.
In any case in which it is not wished to have steam working in a second cylinder
or pair of cylinders the moving parts of which are arranged and connected for
counterbalancing purposes as hereinbefore described, the piston or pistons of such
second cylinder or pair of cylinders may move without being acted on by steam,
or there may be substituted a weight or weights arranged to move in suitable
guides or in an equivalent manner. In some cases an approximate balance may
be obtained by suitably weighting the counterbalancing levers: thus in the
example herein before described instead of additional weights being applied to
the pistons or parts moving therewith they may be applied to prolongations of

page_text: the levers the weights being reduced in amount inversely corresponding to the
increased leverage.
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:-
1. The preventing or diminishing of vibrations due to the moving parts of
steam engines by connecting certain parts by means of rocking shafts and levers
to other parts which are arranged to move oppositely, the weights of the connected
parts and the connections being made such as to produce counterbalancing or
approximately so, substantially as hereinbefore described.
2. The arranging or combining of the parts of steam engines substantially as
and for the purposes hereinbefore described with reference to Figures, 1, and 2,
of the accompanying drawings.
3. The arranging or combining of the parts of steam engines substantially as
and for the purposes hereinbefore described with reference to Figures, 3, and 4,
of the accompanying drawings.
4. The arranging or combining of the parts of steam engines substantially as
and for the purposes herein before described with reference to Figures, 5, and 6,
of the accompanying drawings.
5. The arranging or combining of the parts of steam engines substantially as
and for the purposes hereinbefore described with reference to Figures, 7, 8, and 9,
of the accompanying drawings.
6. The arranging or combining of the parts of steam engines substantially as
and for the purposes hereinbefore described with reference to Figures, 10, and 11,
of the accompanying drawings.
7. The arranging or combining of the parts of steam engines substantially
as and for the purposes hereinbefore described with reference to Figure, 12,
of the accompanying drawings.
8. The arranging or combining of the parts of steam engines substantially as
and for the purposes hereinbefore described with reference to Figures, 13, and 14,
of the accompanying drawings.
Dated this Eighth day of September. 1897.
EDMUND HUNT,
Applicant's Agent.