IMPROVEMENTS IN SEWING MACHINES
Year: 1878

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for the
Invention of "IMPROVEMENTS IN SEWING MACHINES." A communication from
abroad by Lebbens Baldwin Miller and Philip Diehl, both of Elizabeth, in the
State of New Jersey, United States of America.
COMPLETE SPECIFICATION filed by the said Sydney Pitt at the Office of
the Commissioners of Patents on the 13th July 1878.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN SEWING
MACHINES." A communication from abroad by Lebbens Baldwin Miller and
Philip Diehl, both of Elizabeth, in the State of New Jersey, United States of
America.
The Invention has reference to the shuttle mechanism of sewing machines, the
feed mechanism, and the presser foot mechanism thereof, and consists of certain
constructions and combinations of mechanical devices, which are set forth in detail
in the claims at the close of this Specification.
All of the said features of Invention need not necessarily be embodied in the
same machine, but in order that the Invention may be fully understood a repre-
sentation is given in the accompanying Drawings of the principal parts of a sewing
machine embodying all of the said features in the best form in which they have
been embodied by the inventors at the present date.
In the said Drawings Figure 1 represents a top view of the said sewing machine;
Figure 2 represents a side view of the same with the side plate of the needle arın
removed; Figure 3 represents an end view of the same; Figures 4 to 15 inclusive
represent views of parts of the machine detached from the residue.
The general form of the sewing machine represented in the said Drawings does
not differ materially from that of many shuttle machines in common use, there
being a bed plate A with which the other parts are connected, a strong arm B to
support the needle bar above the cloth plate C of the bed A, and a driving shaft D
extending through the needle arm' B to drive the needle bar. The needle bar E is

page_text: arranged to slide up and down in the head F of the needle arm B, and motion is
transmitted to the needle bar E from the driving shaft D through the intervention
of a crank pin a and a connecting rod b. The under thread, which is interlooped
with the needle thread to form the stitch, is, according to this Invention, carried
by an oscillating shuttle G, which is caused to oscillate in a circular shuttle race H
by means of an oscillating shuttle driver I carried by the shuttle rock shaft J,
which is arranged below the table plate C of the machine.
The shuttle is represented more particularly at Figures 7, 8, 9, 10, 11. It con-
sists mainly of three principal parts firmly combined or connected together, these
three parts being the bobbin case d, the beak proper d', and the beak shank d²,
Figures 9 and 10. The bobbin c is made in the form of a flatted spool, whose
thickness is less than its diameter, and the cavity of the shuttle .in which the
bobbin is held is of the same form, and is fitted with a central pivot e, upon which
the spool bobbin revolves. This pivot is arranged parallel with the axis of the
shuttle driver shaft J, so that the spool bobbin sets edgewise in the shuttle, and it
is held in place by means of a spring latch e¹. The thread from the bobbin is con-
ducted to the delivery eye e2 of the shuttle, but in its passage to that eye is
operated upon by a thread tension, by means of which the tension upon the shuttle
thread can be varied. The shuttle thread tension consists in this instance of a
spring pressure plater (Figure 11), which is sunk. in a recess in the periphery of
the shuttle, and presses the thread between its inner surface and that of the bottom
of the recess.
The pressure plate is connected at its shank with a regulating
screw 8, which can be turned to adjust the amount of pressure upon the thread,
and consequently its tension or resistance to being pulled from the shuttle: The
shuttle thread is guided to the thread tension by an internal eye e³, through which
the thread passes from the spool bobbin.
The external profile of the bobbin case portion of the shuttle is a pointed oval,
whose exterior curve corresponds with the circle of the shuttle race. This bobbin
case is preceded by the beak proper d' (whose office is to enter the loop of the
needle thread presented by the needle), and by the beak shank d², which intervenes
between the beak proper (d') and the bobbin case d, and whose office is to hold
the said loop while the needle is rising until the needle eye is clear of the work
being sewed, but without material elongation of the loop, so as to obviate the
pulling of the thread downward through the needle eye while it is in the work, and
the great friction upon the thread incident to that mode of operation.
For the purpose of holding the loop of needle thread without elongation the
beak shank d may be of uniform cross section throughout its length, but in order
that the friction upon the needle thread may be reduced to the lowest limit during
the rise of the needle eye through the work the thread is permitted to rise with
the needle until the needle eye clear of the work, and this rise is permitted by
the peculiar form of the beak shank d², which, commencing (as seen in Figures 9
and 10) at the butt of the beak proper d', diminishes in cross section as it
approaches the bobbin case d:
The butt of the beak proper (indicated by the dotted cross lines in Figures 9
and 10) corresponds in position with the position of the needle when its eye during
rising is just below the work or thereabouts; hence when the needle eye rises
through the work the reduced beak shank of the shuttle moving through the loop
of needle thread permits it to contract, and consequently permits the needle thread
to move upward through the work with the needle in its ascent. By the continued
forward oscillation of the shuttle in its race the bobbin case of the shuttle follows
the beak proper d', and by its oval form spreads or extends the loop sufficiently to
permit the bobbin to pass through it, but as this spreading is done after the needle
has risen through the work, the whole area of the needle hole is free for the move-
ment of the needle thread, which in consequence is then readily drawn down
through the needle hole to form the extended loop.
The advantages incident to the construction of the shuttle with a beak shank d²
intervening between the beak proper d' and the bobbin case, although attained most

page_text: readily with an oscillating shuttle, are not restricted to the latter, because a shuttle
fitted to move in a straight shuttle race may be constructed with a beak shank
succeeding the beak proper and preceding the bobbin case, provided the extent of
movement of the shuttle be sufficient to permit this construction.
The circular shuttle race H is constructed with an internal peripheral groove g to
receive and guide the rim of the shuttle, and a segment ƒ of the front side of this
groove is constructed to turn edgewise upon a pivot f¹ so as to form a gate, which
can be turned out of the way to open the groove for the insertion and removal of
the shuttle from the shuttle race. This gate is secured by a spring pin f*, which
is passed through a slot made in the gate for that purpose.
The shuttle driver 1 has two horns h, h', which operate upon the shuttle to drive
it. One of these horns (h) bears against the butt of the shuttle when driving it
forward; the other horn (1) bears against the forward end of the bobbin case of
the shuttle near the butt of the shuttle beak. There is sufficient play between the
horns and the shuttle for the passage of the loop of thread between them. The
shuttle rock shaft J is driven from the driving shaft D above by means of a crank j,
connecting rod j', and arms j², j, j, two of which (j) project from the inter-
mediate rock shaft (J¹), and the other from the shuttle rock shaft J. The adjacent
arms (j,j) of the two rock shafts J, J, are connected by means of a pivot and
friction wheel or truck secured to one arm j, and working in a slot of the other
arm j³..
The object of the intermediate rock shaft (J¹) is to enable the shuttle rock
shaft (J) to be rocked through an arc of greater extent than would be convenient if
the connecting rod (1) from the crank should be connected directly with the arın
of the shuttle rock shaft. This object is attained by the arrangement of the axis
of the two rock shafts in a plane passing through the middle of the vibrations of
the arms, or thereabouts, and by constructing the arm (3³) of one rock shaft (J) to
lap by the axis of the other rock shaft (J), so that the curves described by the arms
of the two rock shafts intersect each other. Hence although the straight line
extending between the two extreme positions of the centres of the pivot connecting
the arms (as represented by the dotted line x, x³, Figure 12) is the same for both
arms, yet the arc described by the shorter arm (*) appertaining to the shuttle rock
shaft (as represented by the dotted line x, x, x³, Figure 12) is of much greater
angular extent than the arc described by the arm j³ of the intermediate rock shaft,
as represented by the line x, x2, x³, Figure 12.
The delivery eye e2 of the shuttle is at its inner edge near the centre of the
circular shuttle race, so that the distance from the delivery eye to the sewing point
remains approximately the same, notwithstanding the change in the position of the
shuttle in its race. The delivery eye however is not at the said centre or axis of
oscillation of the shuttle, but is purposely arranged at a short distance from that
axis, and at the side thereof which is nearer the outer rim of the shuttle. Hence
when the shuttle is retrograded (by the return movement of the oscillating shuttle
driver I), the descent of the delivery eye or its movement from the work exerts a
pull upon the shuttle thread, and draws it home to finish the stitch.
The work is fed past the line of movement of the needle by means of a feed
dog K, which is secured to a feed bar K¹. This feed bar is caused to rise and fall
crosswise of its length, so as to take hold of the work and to release it, and is also
caused to move to and fro longitudinally, so as to move the work or feed it and to
retrograde preparatory to making each fresh feeding movement.
The rising and descending movements of the feed bar K₁ are effected by con-
necting one end (m) of it with the driving shaft through the intervention of a
cam m¹, connecting rod m², and rock shaft m³, fitted with two arms m, ms, one
which (m) is connected by a pivot with the connecting rod (m²), while the other
(m³) is fitted with a pivot which is received in a slot formed in the end m of the
feed bar K. The forward end of the rock shaft m³ is arranged opposite one end
of the feed bar, and the arm (m³) of the rock shaft is so arranged as to extend
lengthwise of the feed bar, and parallel, or thereabouts, therewith when the arm is

page_text: at the middle of its vibrating movement; its vibration effects the rise and descent
of the feed bar.
The feed bar is caused to move to and fro longitudinally by connecting it with
the driving shaft D by means of a cainn, connecting rod n¹, toggle links n², n³,
and rock shaft n', fitted with arms no, no, no, to one of which one end of the toggle
links is applied, while the other two arms (no, no,) hold a pivot n which connects
them with the end of the feed bar n³. As the pair of arms (nº, nº,) are upright
or thereabouts at the middle of their vibrating movement, and they then stand
crosswise of the length of the feed bar K' their vibration causes the longitudinal
movement of that bar. The rock shaft n is arranged at the end of the feed bar
opposite that at which the rock shaft m³ is arranged, and the two rock shafts
support the feed bar between them.
In order that the extent of the longitudinal movement of the feed bar may be
varied for the purpose of varying the length of feed, the fulcrum pivot i (Figure 12)
of the toggle links n², n³, at the end thereof which is furthest from the arm n³ of
the rock shaft n is not fixed, but is secured to an adjusting arm N so that it may
be moved. The axis of the pivot (¹) of this adjusting arm is set near the axis of
the pivot which connects the connecting rod n with the elbow joint of the toggle
links; the length of the adjusting arm N between the axis of its own pivot i¹ and
the axis of the fulcrum pivot i which connects the arm with the end of the toggle
links being the same or thereabouts as the length of the adjacent toggle link n²;
hence the fulcrum pivot i of the toggle links can be raised or depressed by moving
the adjusting arm N up or down, and the effect of this movement is to make the
links form a greater or less angle with each other at the time when the feed bar is
retrograded to its most backward position. The greater the angle which the links
form with each other the more will the arm n³ of the rock shaft be vibrated, when
the elbow joint of the links is raised to straighten the two into line or thereabouts,
and the greater will be the feeding movement of the feed bar, hence the feeding
movement can be varied as required by raising or depressing the adjusting arm N
so as to raise or depress the fulcrum pivot of the toggle links n², n³.
In order that the adjusting arm may be moved conveniently its end is extended
through a slot in the casing of the machine, and is fitted with a handle N¹. This
system of operating the feed dog through the intervention of toggle links having
an adjustable fulcrum pivot possesses the advantages of making the movement of
the feed dog positive in both directions of dispensing with a spring to retrograde
the feed dog, and of making the movement practically noiseless. It is not however
essential that the connections between the toggle links and the feed bar should be
precisely such as are shewn in the Drawings, as the form and construction of these
connections may be varied as found expedient.
The work to be sewed is held to the surface of the feed dog K by means of a
presser foot L, which is pressed downward by a spring 1 working in a socket in the
upper end of the presser bar L', and a lever ¹ is provided to lift and lower the
presser foot when the work is to be entered upon or withdrawn from the
machine.
A presser foot operated by a spring exercises a constant pressure upon the work,
but it is expedient to relieve this pressure at times when the needle is in the work
so as to enable the work to be more readily turned when sewing curved seams; and
also when the seam is sewed over a lap or doubled portion of the fabric. This
relief is generally effected by hand, but in order that the pressure of the presser
foot in the machine represented in the Drawings may be relaxed automatically
when required, a special lifting mechanism is provided for the purpose. To this
end a cam P (Figure 14) is connected with the driving shaft for the purpose
lifting the presser foot slightly at each revolution of the driving shaft. This cam
operates upon an elbow lever P¹ which is pivotted to the needle arm B, and has the
end of its horizontal arm p slotted to receive one end of a cramp stud q which is
thus raised and allowed to descend by the action of the cam P. The shank of this
stud is inserted in a slot formed in the bar L'of the presser foot and projects
of

page_text: laterally from it, the sides of the stud being notched to embrace the sides of the
presser bar, so that the stud is combined directly with the presser bar without the
intervention of any intermediate device.
The fit of the notches of the stud upon the presser bar is loose, so that the presser
bar may be moved up and down in the notches as long as the stud stands at right
angles or thereabouts with the presser bar; but the upward movement of the stud
(by the movement applied to its outer end by the lever P¹) cramps the stud upon
the presser bar so that the latter is then grasped and lifted with the stud, and when
the stud is lowered the presser bar is lowered with it.
,
In order that the presser foot may be free to rise and descend at times when
the stud is not being lifted or lowered, a stop t is formed in the head F of the
needle arm B to stop the descent of the shank of the stud a little before the outer
end of the stud reaches the limit to which it is lowered by the cam P, so that the
continued downward movement of the outer end of the stud after its shank is
stopped by the stop rocks the stud upon the presser bar, causing the stud to stand
when in its lowest position at right angles with the presser bar, and frees the bar
from the grasp of the stud.
'
The rocking of the stud in the opposite (or upward) direction when the cam
raises the outer end of the stud is ensured by the action of a small spring 2¹ placed
in the head of the needle arm, which spring slightly resists the raising of the shank
of the stud when its head is raised by the cam and lever, and thus ensures the
cramping of the shank of the stud upon the presser bar.
A stop pin t is provided to determine the position of the elbow lever, and con-
sequently of the head of the stud, when the cam is not acting on the stud. In
consequence of the freeing of the grasp of the stud upon the presser bar at all times,
except when the cam P is operating upon the stud, the presser bar is free to vary
its position according to the varying thickness of the work, but as the stud works
upon the presser bar with the capacity to grasp any part of the presser bar which
may be embraced by it the stud when operating will always raise the presser bar
and presser foot a fixed distance; however, the distance between the presser foot
and the table plate may vary by reason of variations in the thickness of the work
being sewed. The lifting mechanism thus adjusts itself to the variations in the
thickness of the work without requiring any attention on the part of the operator
for such adjustment.
In order that the lifting mechanism may however be thrown out of operation.
when it is not required to work, a conical pointed stop screw R (Figure 15) is pro-
vided to screw through a hole in the needle arm head (F) in a position to pass
below the shank of the cramp stud q and raise it at least as high as the cam P can
raise it. When therefore the stop screw is turned inward the cramp stud becomes
for the time inoperative.
In order that the conical point of the stop screw may operate properly upon the
stud the under side of the shank of the stud is bevelled, so as to form an inclino
plane, upon which the conical point of the stop screw acts as a wedge. The cam
for operating the stud and the stop pin may of course be replaced by equivalent
mechanical devices or substitutes for performing their respective functions.
The loop of needle thread is taken up after the passage of the shuttle mainly by
means of a vibrating take-up lever S operated at the proper times by a cam T upon
the driving shaft. A vibrating yielding spring take-up V is employed in connection
with the positive take-up lever S to hold the needle thread with a yielding force
and adapt the size of its loop more perfectly to the irregular form of the shuttlo
than would be possible with a positive take-up without involving great care and
expense in the formation of the take-up cam.
As the parts of the machine which have not been described need not differ sub-
stantially from those of sewing machines in common use it has not been deemed
necessary to describe them.
What is claimed as the Invention is,-
First. The sewing machine shuttle contracted with a beak proper and with a

page_text: beak shank, which intervenes between the beak proper and the bobbin case, and is
of uniform cross section from the butt of the beak towards the bobbin case, sub-
stantially as before set forth.
Second. The sewing machine shuttle constructed with a beak proper, and with
its beak shank diminishing in size as it extends from the butt of the beak proper
towards the bobbin case, substantially as described and represented.
Third. The adaptation and combination of the circular shuttle race and a shuttle
constructed with a beak shank intervening between its beak proper and its bobbin
case, substantially as described and represented:
Fourth. The adaptation and combination of mechanism for driving the shuttle
through the intervention of adjacent connected vibrating arms, substantially as
described and represented.
Fifth. The construction of circular shuttle race with an internal peripheral groove
for guiding the shuttle, and with a moveable gate to permit the shuttle to be
applied to said groove, substantially as described and represented.
Sixth. The adaptation and combination of the circular shuttle race, the shuttle
driver for moving the shuttle to and fro in said race, and the shuttle having
a thread delivering eye slightly distant from the centre of said shuttle race, so that
the said thread delivering eye is caused to move from the work during the retro-
grade movement of the shuttle, and draw the shuttle thread home to finish the
stitch, substantially as described and represented.
Seventh. The adaptation and combination of the feed bar and two rock. shafts
arranged to operate upon the opposite ends of said feed, bar, substantially as
described and represented.
Eighth. The adaptation and combination of the toggle links, the moveable
fulcrum pivot thereof, and the adjusting arm for regulating the movement of the
feed bar and the length of the stitch, substantially as described and represented.
Ninth. The adaptation and combination of mechanism for relieving the pressure
of the presser foot when the needle is in the work, as described and represented.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand and
seal, this Fourth day of July, in the year of our Lord One thousand eight
hundred and seventy-eight.
SYDNEY PITT. (L.S.).