An Improved Crank Mechanism.
Year: 1891

page_text: Date of Application, 17th Nov., 1891-Accepted, 19th Dec., 1891
COMPLETE SPECIFICATION.
[Communicated from abroad by THE SINGER MANUFACTURING COMPANY, of
New York, in the United States of America, Sewing Machine Manufacturers.]
An Improved Crank Mechanism.
I, ALEXANDER ANDERSON, Manager of The Singer Manufacturing Company's
Works, Kilbowie, Dumbartonshire, do hereby declare the nature of this invention
and in what manner the same is to be performed, as communicated to me, to be
particularly described and ascertained in and by the following statement :-
My invention has for its object to provide a novel mechanical movement by
which a differential vibratory motion may be imparted to a bell-crank lever, the
movement of the said lever to be utilized for any desired purpose.
To this end my improved mechanical movement comprises a link one end of
which is connected to a stationary pivot-pin, a rotating crank, and a bell-crank
lever pivoted at its central or angular portion to the free end of the said link and
having the outer end of one of its arms jointed to the said crank. When mounted
and operated in this manner the said bell-crank lever will have a movement bodily
up and down and will also be vibrated on its pivotal connection with the link so
that the operated arm of the said lever will have a comparatively slow downward
movement, requiring the time occupied by about two-thirds of the rotation of the
crank-pin, or slightly more, and will then move quickly upward during the time
required for about one-third of the rotation of the crank-pin, or slightly less. In
other words, the operated arm of the bell-crank lever will move downward com-
paratively slowly and upward comparatively quickly.
In the accompanying drawing,
Fig. 1 is an elevation to illustrate the construction of my improved mechanical
movement, and
Figs. 2 and 3 are views similar to Fig. 1 but shewing the parts in different
positions.
B is a
A denotes a link secured at one end to a stationary screw or pivot pin a.
rotating crank herein shown as consisting of an ordinary crank disk provided with
a crank-pin b. C is a bell-crank lever jointed at its middle or angular portion at c
to the free end of the link A and having its lower arm connected to the crank
pin b.
The operation of the above described construction is as follows:-
When the crank disc is rotated as denoted by the arrows the outer end of the
horizontal arm of the bell-crank lever will be in its highest position when the parts
are as represented in Fig. 1.
As the crank rotates the bell-crank lever will be caused to descend bodily
while the crank pin 6 moves from the position shewn in Fig. 1 to the position
shewn in Fig. 2, in which latter figure the said crank pin is represented as being
in its lowermost position. As the said crank pin moves upward from the position
shewn in Fig. 2 to that shewn in Fig. 3 the bell-crank lever will be vibrated en its
pivotal connection with the free end of the link A, so that its outer arm will con-
tinue to descend, Fig. 3 showing the free end of the said outer arm as being in
its lowermost position. Thus the free end of the said outer arm will have been
descending comparatively slowly during rather more than two-thirds of the revolu-
tion of the crank, and while the said crank is moved from the position shown in
Fig. 3 to that shewn in Fig. 1 the said lever will be moved upwards bodily and
will also be vibrated on its pivotal connection with the link A, thereby causing the
free end of its outer arm to move upward quickly or in about one-half of the time,
or a little less, occupied by it, in its descent.
From the foregoing it will be apparent that I am enabled to impart a differential

page_text: vibratory movement to the operated arm of the bell-crank lever from a uniformly
rotating crank-pin. This differential movement may be utilized for any purpose
for which it may be adapted in machines of any kind.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me,
I declare that what I claim is :-
1. A mechanical movement consisting of the combination with a rotating crank,
of a link, one end of which is connected to a stationary pivot, and a bell-crank lever
pivoted at its middle or angular portion to the free end of said link and having one
of its arms connected to said crank.
2. A mechanical movement consisting of the combination with a stationary pivot
pin a, and a link jointed thereto, of a rotating crank, having a crank-pin b, and a
bell-crank lever C pivoted at c to the free end of said link and having one of its
arms jointed to the said crank-pin.
Dated this Sixteenth day of November 1891
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.