Improved Means for Equalizing the Driving Force in Crank Mechanisms and the like..
Year: 1898

page_text: Improved Means for Equalizing the Driving Force in Crank
Mechanisms and the like..
We, JOSEPH LIGGINS, of 16, St. John's Terrace, Queen Victoria Road, Coventry,
Warwickshire, Carpenter, and JOHN GARDNER, of 2, St. John's Terrace, Queen
Victoria Road, Coventry, aforesaid, Builder, do hereby declare the nature of this
invention to be as follows:-
Our invention relates to the rotation of shafts and the like and it consists in
means for rotating or assisting in rotating the shaft or the like through certain
angles by the employment of a spring or springs or the like, the principal object
dead centres" in crank gearing.
being to overcome or assist in overcoming the
According to one method of carrying out our invention as applied to crank-
gearing, we provide two fixed points in or about a plane passing diametrically
through the crank shaft and at a suitable distance behind the dead centres.
each of these fixed points we attach one end of a suitable spring, such as a spiral
tension spring. The other end of each spring is attached to a loose collar or the
like on the crank pin or equivalent part.
То
After the crank pin has left one (first) dead point a suitable distance and pro-
ceeds to rotate towards the other, one of the springs will begin to become stretched.
The stretching of the spring will continue until the crank pin lies in the plane
passing through the point to which the spring is fixed and through the axis of
the crank shaft. As soon as the crank pin has passed on through this plane, the
spring will begin to contract and so will rotate or assist in the rotation of the shaft
through the segment in which lies the second dead point. The action of the spring
will cease on the crank pin approaching within a distance of the said fixed point
equal to the normal length of the spring and its connections. Meanwhile the
other spring has lain dormant, but on the crank pin reaching and passing a point
which is the same distance from the fixed point of the said other spring as such
spring is long, then the said spring will begin to be stretched and the same action
gone through with relation to the first dead point as previously described with
relation to the second dead point.
According to another method we provide the axle with a fixed double cam-like
collar and provide a pair of blade springs, spring plungers or the like which bear
on the periphery of the said collar and promote the rotation of the same and the
axle to which it is fitted, past the dead points. In some cases we may arrange
the storage of power in the spring or springs and the return of such power with a
special view to the equalising of the rotary force applied to the shaft or the like
throughout its revolution.
It will be obvious that weights, with or without suitable connections such as
levers, cords or the like may be substituted for the springs in certain cases and

page_text: that other applications of our invention may be made without exceeding the limits
thereof.
Dated this 29th day of January 1898.
G. DOUGLAS LEECHMAN,
18, Hertford Street, Coventry,
75, Chancery Lane, London, W.C., and
, Exchange Chambers, New Street, Birmingham,
Patent Agent for the Applicants.
G. DOUGLAS LEECHMAN,
18, Hertford Street, Coventry,
75, Chancery Lane, London, W.C., and
, Exchange Chambers, New Street, Birmingham,
Patent Agent for the Applicants.
Improved Means for Equalizing the Driving Force in Crank
Mechanisms and the like.
JOSEPH LIGGINS, Carpenter, 16, St. John's Terrace, Queen Victoria Road, Coven-
try, JOHN GARDNER, Builder, 2, St. John's Terrace, Queen Victoria Road, Coventry,
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 follow-
ing statement:-
Our invention consists of means for rotating or assisting in rotating shafts and
the like by the employment of a spring or springs or the like to alternately collect
and return a portion of the power applied to the rotation of a shaft or the like
the spring or springs being applied in such a manner as to take up part of the
force applied to the crank pin or the like during its passage through the portion
of its path within which is the greatest application of the driving power and to
return it during its passage through the portion of its path within which is the
least application of the driving power including the dead point. This operation
is performed twice during each rotation of the shaft or the like so as to include
both the dead points and both the points of greatest application of force the objects
being to overcome the dead points in crank motions and the like, to set the crank
pin or its equivalent in a suitable position for restarting after stoppage, and to
distribute or equalize the force applied by the pitman, driving rod, or its equiva-
lent through the whole rotation of the shaft.
To accomplish this the spring or springs or the like are arranged to assume their
normal state coincidently with the crank pin or its equivalent being midway
or thereabouts betwixt the dead point behind it and the "greatest power" point
before it so as to begin to be acted on by the force applied to the rotation of the
shaft during the passage of the crank pin through the first quadrant after passing
the dead point and so as to begin to react on and assist the shaft during its pro-
gress through the next quadrant following and is repeated so on continually.
According to one method (see Figure 1) of carrying out our invention as applied
to crank gearing so as to be applicable to a sewing machine or to any machine
of the like kind worked by a pedal bar pivoted on an axis and joined by a pitman
or the like to a crank pin, we provide two fixed points A and B in or about a plane
passing diametrically through the crank shaft Ĉ and at a suitable distance behind
the dead points D and E. To each of these fixed points we attach one end of a
suitable spring such as a spiral tension spring the other end of each spring being
attached by a suitable collar or the like on the crank pin K or its equivalent part.
Its action is as follows after the crank pin K has left one dead point D and has
proceeded to F the spring H will begin to be stretched and the stretching of this
spring will continue until the crank pin arrives at the point farthest removed from
the fixed end A of the said spring. As soon as it passes this point the spring will

page_text: begin to contract and so will rotate or assist in rotating the crank pin and shaft
attached through the segment within which lies the dead point E and continues
thus until it reaches the point G when the other spring J will begin to be stretched
and will go through the same action with relation to the dead point D as was
performed by the other spring with relation to the dead point E.
In another instance as shewn in Figure 2, the principle is applied by means of
a wheel L whose periphery is connected by teeth or a belt or the like M, with that
of another wheel N twice its size this larger wheel being fixed to the shaft C to be
rotated. A suitable spring H is applied as shewn to a crank pin P on the smaller
wheel, which spring is at its normal position of least stress when the crank pin K
or its equivalent of the shaft C to be rotated and to which the larger wheel is
affixed is at the point F as shewn or thereabouts. Its alternate stretching and
contraction during the rotation will perform the operations which constitute the
principle of this our invention.
By another example as shewn in Figure 3, by means of a spring H attached
thereto, a lever bar Q is pressed on two other opposite crank pins fitted with loose
pullies R and S each of which alternately pushes out the bar and then allows its
return the force being taken up by the stress on the spring H and returned by its
release during the course of the crank pin K or its equivalent through those por-
tions of its revolution in which are the points of greatest and least effective power,
the crank piu K being placed as shewn one eighth of the rotation or thereabouts
before the dead point when the spring H and lever bar Q are normal.
It is obvious that numerous methods of applying our invention may be made
without exceeding its scope and also that other means of storing force besides
springs may likewise be utilized.
To indicate the directions of motions in each figure, arrows are used.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:-
-
To rotate or assist in rotating shafts and the like by the employment of a spring
or springs or the like to alternately collect and return a portion of the power
applied to the rotation of a shaft or the like by the placing of the crank pin rela-
tively to the stress of a spring, springs, or the like so that the crank pin will cross
each dead point in turn with the return of fofce stored by the action of the spring
or springs or the like.
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