IMPROVEMENTS IN MECHANICAL MOVEMENTS
Year: 1884

page_text: I ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Engineer do hereby declare the nature of this Invention for "IMPROVEMENTS IN
MECHANICAL MOVEMENTS" 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 improvements in mechanical movements and the object
thereof is to provide means by which an adjustable circular cam of a given
diameter may be rotated with greater or less eccentricity to its supporting shaft, or
in line with such shaft between and in contact with the bearings of two rigid
immovable arms of a lever, whereby by the adjustment of said cam toward or
from the centre of such shaft, the throw of the lever may be increased, diminished
or stopped, and whereby said lever is moved in both directions solely by said cam
without the aid of springs, and a more positive movement is attained at a less
expense of power than by the ordinary methods.
This movement is adapted to be used in converting rotary into reciprocating
motion whenever it is desired for any purpose to increase or diminish the length
of the movement of an arm which is actuated by an eccentric, and it is specially
adapted to be used in connection with a sewing machine for transmitting motion
to the feed mechanism, as by its application to such purpose, the feed mechanism is
readily adjusted for short or long stitches as required. One manner of applying
this Invention is therefore illustrated in connection with a sewing machine, and
the Drawing and Specification illustrate and describe the Invention thus applied.
Fig. 1 represents the arm and bed plate of a sewing machine, part in section,
showing a side view of the adjustable cam upon the band shaft in connection with
the vibrating lever.
Fig. 2 is a longitudinal section of the band shaft and cam in connection with
the cam adjusting device,
Fig. 3 is a side view of the cam upon a band shaft, showing the band wheel,
the adjusting knob, and part of the band shaft in section.
Fig. 4 is a vertical cross section of the band shaft, the adjustable cam, and the
device by which the same is adjusted. Like parts are represented by the same
reference letters throughout the several views. A represents the ordinary band
Prion 6.71
"

page_text: shaft, B the band wheel, and C the arm of a sewing machine. D is the improved
adjustable cam from and by which motion is communicated to the feed lever E,
through the cam lever F, the cam lever is centrally pivoted on the pivotal bolts G
in the ordinary manner.
Heretofore it has been common to provide the cam lever with one arm only,
when, as before mentioned, the said lever F is moved in one direction by the action
of the cam and in the opposite direction by the action of a spiral spring, which
spring is usually attached to the long arm of the feed lever E.
By this improvement the cam lever F is provided with two arms H H which
operate upon the respective sides of the cam D, whereby said lever is caused to
vibrate towards the right and left with each rotation of said cam.
Heretofore it has been common to use a conical cam adapted to be adjusted
longitudinally upon the band shaft A relatively to the cam bearing surface of the
cam lever F, whereby the length of stitch was increased or diminished as the
greater or less diameter of said conical cam was brought in contact with the
bearing surface of said cam lever. It is obvious that it would be impossible to uso
a conical cam with a fork or two armed lever as such arms would not simultaneously
bear upon both sides of such cam except at one point of adjustment only, for if
adjusted to the greater diameter they would not fit the less, or on the contrary if
adjusted to the less diameter could not be used with the greater.
This improvement dispenses with the conical shaped cam and makes use of one
having horizontal bearings as shown in Figs. 2 and 3, and the length of stitch may
be governed by adjusting said cam eccentrically to said band shaft, which end is
accomplished through the knob J, rod K eccentric L and pins M and N. Within
the hollow band shaft A is placed the rod K terminating outwardly in the rigid
hand knob J, and at its other extremity opposite the cam D terminating in the
rigid eccentric pin L, said rod K being adapted for a slight rotary motion within
said shaft,
Outside said shaft and opposite the pin L is placed the ring eccentric D provided
with the rigidly affixed inwardly extending longer pin M and shorter pin N, which
pins pass through apertures provided therefor in the shaft A and which pins on
their inner ends bear against the eccentric L.
The aperture inside of said cam ring D is somewhat extended relatively from
its centre towards the side to which the shorter pin N is affixed, making said
aperture slightly oblong of a width equal to the diameter of shaft A, whereby snid
cam ring D is adapted to be moved upon said shaft A to or from its centro
relatively as forced thereto by the action of the eccentric L against the pins M
and N.
The two arms H H of lever F bear against the opposite sides of said cam D, as
herein before described. When the cam D, rod K, eccentric L and pins M and N
are adjusted relatively to each other as shewn in Fig. 4, said parts all movo
together describing a true circle around a common centre without communicating
any motion whatever to the cam lover F, and the required vibrating motion is
attained only as said cam D is adjusted eccentrically to said band shaft toward the
left, which end is accomplished by turning the rod K when it is obvious by such
movement that the eccentric pin L will approach the vertical either above or below
the common centre of such parts, and thereby carry the cam D toward the left,
said cam D being adapted to be adjusted, and the length of the stitch increased or
diminished a distance less than or equal to the space between the periphery of
the band shaft, and the inner surface of said cam. The pins M and N are rigidly
fixed at their outer ends in the cam D, while their inner ends bear against the
surface only of the eccentric L and permit of the required movement of said
eccentric L as said cain D is adjusted. It is obvious that the periphery of the
cam D is formed in a true circle as well as that of the band shaft A, and adjusting
rod K, and that the same is adapted to serve as a cam only, as it is adjusted
eccentric to said band shaft by turning said rod K. In operation the band shaft A
rod K with eccentric L and cam D all rotate together.

page_text: When desirous to increase or diminish the length of the stitch, such end is
accomplished by holding the band wheel or shaft at rest and turning the knob T,
the knob J being rigidly affixed to the rod K carries with it the eccentric pin L,
which acting against the inner ends of the pins M and N move said cam D'in or
out of centre relatively to said band shaft, whereby the vibrating movement of
the cam lever F is increased or diminished corresponding to tho adjustment of said
cam, and the feed lever E which is actuated thereby, and which communicates
motion to the feed mechanism is thereby caused to move a greater or less distance,
and thus as stated increase or diminish the length of stitch.
It is obvious that the upper end of the cam lever being divided as it is into two
arms, the same is adapted to be moved both towards the right and left with a
positive movement, and the spring by which one of said movements has heretofore
been attained, is dispensed with.
Having now particularly described and ascertained the nature of the said
Invention, and in what manner the same is to be perforined I declare that what
I claim is
1 The mechanical movement herein described, consisting in the circular
adjustable cam D, having a uniform diameter, in combination with the shaft A,
and arms H H of lever F, said cam being adapted by its adjustable attachment
with said shaft to be adjusted more or less eccentric thereto within said arms,
whereby the vibration of said lever F is increased or diminished, substantially as
and for the purpose specified.
2nd The combination with the shaft A of the adjustable cam D, provided with
bearings M and N, rod K provided with eccentric pin L, and lever F provided with
arms HH, said cain D being adapted by turning said rod K to be adjusted to said
shaft H, substantially as and for the purpose specified.
3rd The combination of shaft A, adjustable cam D of uniform diameter, and
lever F having rigid arms H H, said cam being adapted to vibrate said lever Fin
both directions unaided by spring, and to be adjusted eccentric to said shaft
between said arms, all substantially as and for the purpose specified.
Dated this 17th day of June 1884.