Improved Means for Lessening Vibration in Reciprocating Engines and Machines.
Year: 1896

page_text: Date of Application. 31st Aug., 1895
Complete Specification Left, 19th Feb., 1897-Accented, 24th Apr., 1897
PROVISIONAL SPECIFICATION.
Improved Means for Lessening Vibration in Reciprocating Engines
and Machines.
MICHAEL HOLROYD SMITH of Albany Buildings 47 Victoria Street
Westminster in the County of Middlesex Consulting Engineer do hereby declare
the nature of this invention to be as follows:-
The object of my invention is to lessen the vibration in reciprocating engines.
In order to balance the reciprocating parts of an engine, it is a common practice
to load the crank, disc or fly wheel with a balance weight placed diametrically
opposite to the crank pin, but this method though balancing the to and fro
movement of the reciprocating parts produces a vibration at right angles thereto
by reason of the weight crossing the "dead centres" in opposite directions at each
end of the stroke.
In order to overcome this I employ an auxiliary crank, disc, or fly wheel
(making two) and load each with half the weight necessary to balance the piston
and the reciprocating parts, I preferably drive each with a separate connecting
rod and so couple them by wheels, pulleys links, or other suitable device that they
revelve in opposite directions the weights crossing and counteracting each other
at the dead centres prevent vibration at right angles to the reciprocating
movement.
Dated this the Thirty-first day of August 1896.
Improved Means for Lessening Vibration in Reciprocating Engines
and Machines.
1, MIOHAEL HOLROYD SMITH of Albany Buildings, 47 Victoria Street
Westminster, in the County of Middlesex Consulting Engineer do hereby declare
the nature of this invention and in what manner tho sanie is to be performed, to be
particularly described and ascertained in and by the following statement :-
The object of my invention is to lessen the vibration in reciprocating ongines.
In order to balance the reciprocating parts of an engine, it is a customary
practice to load the crank disc or fly-wheel with a balance weight, placed
diametrically opposite to the crank pin, but this method, though balancing the
to and fro movement of the reciprocating parts, produces a vibration at right
angles thereto, by reason of the balance weight crossing the "dead centres" in
opposite directions at each end of the stroke.
In order to overcome this, I employ an auxiliary crank, disc, or fly-wheel,
(making two) and load each with half the weight necessary to balance the piston
and the reciprocating parts.

page_text: 1 preferably drive each with a separate connecting rod, and so couple them by
wheels, pulleys, links or other suitable device, that they revolve in opposite
directions, the weights crossing, and counteracting each other at the dead centre,
prevent vibration at right angles to the reciprocating movement.
In order that it may be clearly understood how this invention may be usefully
employed, reference is made to the accompanying drawings, in which like lotters
and figures represent like parts throughout.
Figs. 1 and 2 shew an application to a single-heting trunk piston engine.
Figs. 3 and 4 an application to an engine with the piston rod and crosshead.
Figs. 5, 6, 7, 8, 9 and 10 slew various devices for securing opposite rotation of
the cranks and balance weights.
Fig. 11 is a device for facilitating the opposite rotation of the cranks.
Fig. 12 is an application to a two cylinder engine for driving twin propellors or
the like.
It is obvious that if two connecting rods are pivoted on one crosshead, and the
opposite ends connected to separate cranks, and a reciprocating motion given to
the crosshead, the cranks may be set to revolve together or in opposite rotation,
simply by the direction in which they are removed from the dead centre before
starting. In the case of engines that run continuously for long periods, such as
shop engines; engines for electric installations etc.; it is not necessary to make
the opposite rotation positive, skilful adjustment of the cranks before starting
would be sufficient, but in order to facilitate this, I prefer constructing the cross-
hend substantially as shewn in Fig. 11, wherein it will be seen that when the
cranks A. A are at the dead centre, the connecting rods B. B' form an angle with
cach other, being spaced apart on the crosshead C, on the pins D. D'.
In order that the cranks shall readily assume and slightly pass this position,
I overload the balance weights on one side, which gives them a tendency to move
in the direction shewn by the small arrows e. el and when the crosehead is forced
down the cranks will turn in opposite directions.
In many cases it will be necessary for the opposite rotation to le positive,-for
example, in emall oil or gas engines, often so situated that it would be difficult to
operate two flywheels when starting the engine, and in launch engines, which have
frequently to be stopped and reversed.
A simple method of accomplishing this is shown in Fig. 10, viz. :-Instead of
cranks, loaded discs are employed, the peripheries having teeth upon them
forming bevil wheels A, A1 engaging with a pinion or carrier wheel G, turning on
a stud secured to the bed plate, side bracket, or any convenient place.
As the bevil wheels have only duty to perform when the cranks are passing the
dead centres, the wear would mostly occur in two placos; therefore, when bevil
wheels are employed for this purpose, I preferably make the tooth rims distinct
from the disc, and attach them in a suitable way, so that they can be conveniently
shifted, bringing another portion of the periphery into the working section.
A modification of this method is shewn in Figs. 8 and 9, where, instead of bevil
wheels on the crank discs, the crosshead ends of the connecting rods are provided
with toothed segments H. H' connected by a bevil pinion I; therefore, if the
connecting rod B is moved in the direction indicated by its arrow, then the
connecting rod B' will be moved in the opposite direction, na indicated by its
arrow. Forked or cam shaped levers working on balls or pins may be used in
place of the pinion or quadrant. The auxiliary crank and balance weight instead
of being in the same axial line as the main crank shaft, may be situated out of
direct line, but still kept parallel with the axis of the main shaft, and the two
balance weights kept in the same vertical plane, in which case the opposite
rotation can be secured by ordinary toothed wheels only, or in conjunction with
connecting rods.
Having described how positive opposite rotation of the balance weights may be
secured, by tooth wheels and the like, I will now proceed to describe how the
object may be obtained by means of levers.

page_text: A method couvenient to use in single acting engines with trunk piston, is shewa
in Figs. 1. and 2 in which the two connecting rods B and B are provided with bell
cranks K and K' carrying, by means of pins the connecting rods or links L. L'
each at the other extremity hinged to the sleeve M, which is free to slile up ani
down the guide pin N, secured by the bridge O to the end of the trunk piston.
It follows that if the connecting rod B is moved to the right, the bell crank 'K
would descend by the link L and push the sleeve M downwards, the sleeve by
means of the link L' would also pull downwards the bell crank K, which would
cause the connecting rod B' to move to the left. An arrangement similar to this
and suitable to cases where the two crank shafts are not necessarily in the gaine
axial line, is shewn in Fig. 5, by separating the ends of the two connecting rols B
and B, and turning the hell cranks inward; the one link R serves the same
purpose as the two links shewn in Figs. 1 and 2.
In Figs. 3 aul 4 is shewn an arrangement applicable to double acting engines.
The crossbend S is provided with an arin or bracket T which carries the rocking
lever or benin V, to opposite ends of which, are, by the links L, L, eupled to the
connecting rods B. B'; the arrows placed upon the links indicate the action.
The arrangement shewn in Fig. 6 shows how the bell cranks and rocking beam
can be dispensed with. In it the connecting rods B. B are respectively pivoted to
the crosshead at W. W, B having an extension X; a link R couples the two
connecting rods, the extension X being equal to the distance between Wan Y
when the connecting rods aud cranks are of equal length, but X and W-Y may
differ when it is desirable to vary the length of the connecting rods, or the throw
of the cranke.
Fig. 7 shews a method of applying an anti-vibrating balance to an existing
engine, and is similar to Fig. 6 as regards the connecting rods B, B, and the
link R, but in order that the auxiliary balancing crank may be removed further
from the main crank, I employ the "grass-hopper" beam Z, aupported at a fixed
point 1 and carrying the connecting rod B at the point 2; the grasshopper beam is
worked from the cross-head either by the link 3, or by a pin on the crosshoad
working in a slot on the end of the beam.
This arrangement is capable of inany modifications; the remarks as to tho
relative lengths of links, levers, connecting levers and cranks made in roference to
Fig. 6, apply to this figure also.
Fig. 12 shows an application suitable to a two-cylinder engine, driving twin
screw propellors (or like purpose) the screws revolving in opposite directions would
of course be made right and left hand.
The method of securing opposite rotation is similar to that shewn in Figs. 1
and 2, but with this modification:-the pin N carrying the sleeve M may be
attached to a crosshead coupling the two piston rods, or be allowed to slide on a
stationary rod, and the bell crank levers could be formed as slotted links 4. 4',
then, when the links L. L' are in the position shown, the cranks must rotate in an
opposite direction, but when they are drawn back, their respective ends being
concentric with the pins of the connecting rods B, B',-then the cranks would be
free to revolve in the same direction.
This arrangement is also capable of many variations, for example, the sleeve
might be split or two sleeves used, and a device employed for allowing them to
work together or separately.
It is obvious that the auxiliary crank or disc used for balancing the reciprocating
parts, might be advantageously employed for reversing purposes.
Having now particularly described and ascertained the nature of my said inveu-
tion, and in what manner the sume is to be performed, I declare that what I
claim is :-
(1.) In reciprocating engines, or other reciprocating machines, the method of
balancing any reciprocating part by dividing the revolving balancing weight into
two parts, and so arranging them that they balance each other, and are caused by

page_text: the reciprocating part to revolve in opposite directions, in such manner that whou
the reciprocating part comes to either end of its stroke, the revolving weights
are crossing each other at the dead centre, at the same time.
(2.) In reciprocating engines the method of balancing any reciprocating part by
dividing the balancing weight into two parts, each part being in the form of a
loaded disc, or a loaded crank, and causing auch parts to rotate in opposite
directions by means of separate connecting rods in such manner, that when the
reciprocating part comes to either end of its stroke the revolving balance weights
are crossing each other, and the dead centre, at the same time, substantially as
described and as illustrated in the accompanying drawings.
(3.) In reciprocating engines, in which the balancing of the reciprocating parts
is made by two opposite revolving weights, the application of levers, links, toothed
wheels, segments of wheels, or equivalent devices, in such manner as to secure the
positive rotation of the balancing weights in opposite directions substantially as
described, and as illustrated in the accompanying drawings.
(4.) In reciprocating engines in which the balancing of the reciprocating parts is
made by two opposite rotating weights, the employment of mechanism substantially
as described in the accompanying drawings, by means of which the balancing
weights can, if so desired, be allowed to rotate in the same direction.
Dated this Eighteenth day of February 1897.
M. HOLROYD SMITH.