Improvements in Let-off Motions for Weaving Looms.
Year: 1896

page_text: Date of Application, 8th May, 1890
Complete Specification Left, 8th Feb., 1897-Accepted, 13th Mar., 1897
Date of Application, Oth May, 1990
Complete Specification Left, 8th Feb., 1897-Accepted, 13th Mar., 1897
PROVISIONAL SPECIFICATION.
Improvements in Let-off Motions for Weaving Looms.
We, JOHN POYSER, of Bolehill, Wirksworth, near Derby, in the County of Derby,
Engineer, and FRANCIS LIVINGSTONE BALL, of 16 Charlotte Street, Edgbaston,
Birmingham, in the County of Warwick, Engineer, do hereby declare the nature of
this invention to be as follows:-
This invention relates to let-off motions for weaving looms and the object of the
invention is to provide a let-off mechanism, actuated by the heddles through the
medium of the warp threads and an oscillating vibrator, whereby (automatically,
without the attention of the operative or suspense of weaving being necessary) the
length of warp let-off is equalised with the length of warp taken up notwithstanding,
or coincidently with, variations (whenever occurring and whether regular or irregular)
of the length of warp between the fell of the woven fabric and the delivering point
of the let-off rollers or warp beam (as the case may be) due to the weaving up of the
weft thread or (in looms in which a warp beam is used) to the diameter of the
roll of warp upon the warp beam decreasing as the warp is unwound or to any other
cause.
A suitable arrangement for carrying our invention into practice is as follows:-
We employ an oscillating frame or vibrator (hereinafter called the vibrator) over
which the warps pass and which keeps the warps extended between the take-up
rollers and the let-off rollers or warp beam (as the case may be) by means of springs
acting thereon. Upon one side of the vibrator at any convenient distance from the
point at which it is pivoted, we provide a pin or projection fixed to the vibrator and
oscillating with it.
The let-off roller or warp beam is carried by suitable bearings in the frame of the
machine, and the relative positions of the roller or beam and the vibrator is such that
when the position of the vibrator is varied by shortenings or lengthenings of the
extended warps, the pin or projection on the vibrator is moved respectively nearer to
or further from the centre of the roller or beam.
The let-off roller or warp beam is actuated by means of a lever (hereinafter called
the let-off lever) through the medium of a gripping pawl or clutch and we provide a
slot in the said lever for the reception of the pin or projection on the vibrator or of a
sliding block into which the said pin projects. We may instead of using a slotted
let-off lever make it of any convenient section and use a sliding block of corresponding
section adapted to slide upon the said lever into the centre of which sliding block the
pin on the vibrator projects.
In applying this invention to looms in which the let-off roller or warp beam is
revolved by means of a worm we may instead of using the arrangement hereinbefore
described connect the let-off lever with the worm shaft instead of directly to the
roller or beam in any convenient manner, for instance, as follows:-
We provide a fixed spindle or pivot attached to the frame of the loom and placed
in the same position relative to the vibrator as that which the centre of the roller or
beam would occupy. The said fixed spindle or pivot carries the let-off lever which is
connected with the vibrator and is free to oscillate about the centre of the said pivot.
Attached to the let-off lever and radiating from the same centre we provide an arm
so placed that when the let-off lever is in its mean position the arm is approximately

page_text: parallel with the worm shaft and we connect the end of the arm by means of a link to
the actuating lever of a friction pawl or clutch on the worm shaft.
It will be understood that by the reference to the let-off roller the operating or
driven let-off roller is intended.
The pin or projection oscillating to and fro in the let-off lever slot the let-off lever
is also caused to oscillate and in oscillating feeds warp forward.
The angle through which the let-off lever is caused to oscillate is greater or less
as the are of oscillation of the pin is nearer to or further away from the centre about
which the let off lever oscillates and consequently the amount of warp fed forward is
coincidently greater or less.
The vibrator is moved to and fro by the stroke of the heddles on each opening
and closing of the shed and is drawn forward a further varying distance by the
shortening of the line of the warp threads resulting from the weaving of the warps
round the weft.
Thus as the line of warp thread shortens the arc of oscillation of the pin is brought
nearer to the centre of the warp beam and the requisite amount of warp is fed
forward.
Instead of passing all the warps over one vibrator several independent let-off
apparatus such as bereinbefore described may be conveniently and inexpensively
employed each complete apparatus carrying part of the total warps employed or
an independent let-off apparatus may be conveniently employed for each independent
warp thread.
This invention is with greatest advantage employed in loons in which the warp
is wound upon a warp beam inasmuch as by its use the angle through which the
warp beam is caused to turn at every pick is varied so that the length of warp
required is let-off notwithstanding variations in the diameter of the roll of warp
upon the warp beam and the necessity for any of the various mechanisms at
present in use for the purpose of increasing the rate of revolution of the warp beam
as its effective diameter decreases owing to the unwinding of the warp is altogether
obviated. This invention is however equally applicable to looms in which the letting
off is effected by means of let-off rollers such for instance as those described in the
Specification of former Letters Patent, viz., No. 144 of 1895.
Dated the 6th day of May 1896
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Let-off Motions for Weaving Looms.
We, JOHN POYSER, of Bolehill, Wirksworth, near Derby in the County of Derby,
Engineer, and FRANCIS LIVINGSTONE BALL, of 16, Charlotte Street, Edgbaston,
Birmingham, in the County of Warwick, Engineer, 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 following statement :-
This invention relates to let-off motions for weaving looms.
In the Specification of former Letters Patent granted to one of us No. 1061 of 1896
there is described a let off mechanisu providing means for varying through the
medium of an oscillating vibrator therein described the point of connection between
a let-off lever and a rod through which motion is communicated from the loom to the
said lever, in order to vary the amount of let-off.
As the result of exhaustive experiments we have found that the let-off may be
operated directly from such a vibrator as aforesaid whereby mechanism of simpler
construction than that described in the said former specification is provided.

page_text: According to the present invention it is preferable that the axis of oscillation
of the vibrator should be at a distance from the axis of rotation of the let-off
roller or of the warp beam and in such a position that a pin or projection upon
the said vibrator, and through which the movements of the vibrator are communi-
cated to the lever operating the let-off roller or warp beam, should approach and
recede from the axis of the said let-off roller or warp beam.
To enable our invention to be fully understood we will describe the same by
reference to the accompanying drawings, in which:-
Figure 1 is a side elevation of so much of a loom as is necessary to illustrate the
construction and application of our improved let-off mechanism :
Figure 2 is a rear view of the same; and,
Figure 3 is a section on the line 3-3 Figure 2:
Figures 4 and 5 are a side elevation and rear elevation respectively illustrating a
modification; and,
Figures 6 and 7 are views similar to Figures 4 and 5 respectively illustrating
another modification:
Figures 8 and 9 are a side view and rear view respectively illustrating a modification
wherein motion is imparted to the let-off roller or warp beam through the medium ot
worm gearing:
Figures 10, 11 and 12 are side views illustrating three other modifications.
Similar letters of reference indicate corresponding parts in the several figures.
a is the oscillating vibrator which is mounted in the frame b upon the axle or
shaft which frame may be independent of the other parts of the loom framing
or integral therewith. The said vibrator has at its upper end a roller c over which
the warp threads (indicated in the drawings by the letters d, d) pass to the heddles
and connected to its lower end a spring e which serves to retain the warp threads taut
by tending to move the vibrator in a direction opposite to that in which it is moved
by the pull of the warps on the opening of the shed by the heddles and by any
shortenings of the length of the warps between the fell of the fabric and the delivering
points of the let-off roller or warp beam, that is to say, in the direction of the arrow f
and also to rotate the let-off rollers or warp beam as hereinafter described.
g is the shaft of the warp beam or operating let-off roller; h is a lever carrying
a pawl i engaging with a flange i¹ on a wheel; on the end of the shaft g (as shewn
in Figure 2 which is a section on the line 2-2 Figure 2) and k is the pin upon
the vibrator which engages with the lever h.
In the arrangement of our invention shewn in Figures 1, 2 and 3 the pin k which
engages with the let-off lever his arranged below the axis of the shaft b₁ of the
vibrator the said pin k engaging with a slot in the said lever h.
The operation of this mechanism will be understood from the following description.
Assume that the take-up and let-off are so adjusted that the amount taken up
is, when no weft is laid and woven up, equal to that let-off.
Assume now that weft thread is laid and woven up, then as the bending of the
warps round the weft causes slightly more warp to be taken up than when weft is
not laid, and if the amount of warp let-off is kept constant, the length of warp
between the fell of the woven fabric and the delivering point of the let-off rollers
or warp beam will be so decreased that the position of the arc of oscillation of the
vibrator will be brought nearer by progressive steps to the heddles until tension on
the warps reaches breaking point.
Assume now that whilst no weft is laid and the take-up and let-off are equal in
amount the vibrator moves through the arc y, z in Figure 3 and the lever through
the arc ', . Upon weft being laid, as there will at once arise an excess of warp
taken up over that let-off whiist the lever oscillates only from y¹ to z' the vibrator.
will be drawn to a position corresponding say to the line and by our invention as
the vibrator is so drawn the pink will approach nearer to the axis of the let-off
roller and move the lever to a position corresponding say to the line a', the gripping.
pawl moving to a corresponding position on the flange so that on the return

page_text: movement of the vibrator under the action of the spring or springs e the let-off
rollers or warp beam will be moved a distance corresponding with the are a', y',
thus letting off a greater amount of warp than would be let off by the lesser
oscillation to y'. If the relation of the parts is such that the additional amount
of warp let-off by the movement of the lever to z' does not compensate for the extra
amount of warp taken up by the laying of the weft the vibrator will not return to
its initial position at and during the next vibration will move still further to the
left towards and u and oscillate the lever further to the right towards ', u' until
positions are reached in which the oscillation of the vibrator through its are will
let off an amount of warp equal absolutely or approximately to that taken up
weft is being laid.
If a thicker weft thread be laid the same process will be carried further and if
weft thread cease to be laid or a thinner thread be laid the reverse process will
take place.
When let-off rollers are used the position of the arc of oscillation of the vibrator
will be practically invariable or constant about a mean arc of oscillation; when,
however, the warp is drawn direct from a beam the diameter of which is constantly
diminishing as the warp is being used the position of the arc of oscillation will vary
very considerably, for instance, when the benim is nearly full a very slight rotation
will give the required length of warp whilst when the diameter is small a much
larger angle of rotation is required. In this case therefore when the warp beam is
full the vibrator will be in such a position that the pin k will be carried towards
the outer end of the slot in the lever h, that is to say, the vibrator will have an are
of oscillation say from to te whilst the amount of rotation imparted to the warp
beam will correspond with the are v', we'. As the diameter of the warp beam decreases
the vibrator will gradually assume an upright position, say, corresponding with the
arc y, z and as the warp is nearly exhausted from the beam it will assume an arc of
oscillation t, u so that the beam will have an amount of rotation imparted to it
corresponding to the are t', u'.
The modification of my invention shewn in Figures 4 and 5 is substantially the
same as that shewn in Figures 1 and 2 the only difference being that the pin k
instead of being placed below the axis of the shaft & of the vibrator is placed above
the said axis.
In the arrangement shewn in Figures 6 and 7 the only difference is that instead of
directly connecting the let-off lever & with the pin k the said lever is connected with
the said pin by a link 1.
In Figures 8 and 9 we shew an arrangement wherein the motion of the vibrator is
transmitted to the feed roller or warp beam through the medium of worm gearing; in
this modification the lever & instead of directly rotating the feed roller or warp beam
is provided with an arm m connected by a link n with the lever o of a gripping pawl i
which pawl engages with a wheel p on a shaft q having fixed to it a worm r engaging
with a worm wheel on the end of the warp beam or feed roller.
The modifications of our invention shewn in Figures 10, 11 and 12 only differ from
the arrangement shewn in Figure 1 in that the pin k is not rigid relatively with the
vibrator but is carried by a rod a jointed to the vibrator at a' which necessitates
the employment of an adjusting devices. As shewn in Figure 10 this device is
in the form of a bell crank pivoted on the framing to which the vibrator also is
pivoted the said hell crank lever being slotted at one end to engage with a pin
on the rod whilst the other end is connected to the vibrator by a link . In
Figure 11 the device s is a simple pivoted arm, whilst in the arrangement shewn in
Figure 12 the adjusting device is in the form of a slotted plate. In all three cases it
will be obvious that the wore the vibrator is inclined to the left the nearer will the
pink approach the axis g to increase the let off.
We wish it understood that the above arrangements are only given as examples
there being various other mechanical arrangements whereby the motion of the
vibrator may be directly transmitted to the feed roller or warp beam, and in such

page_text: a manner that the movement of the vibrator in one direction or the other (as may
be desired) shall give to the let off roller or warp beam a progressively increasing
amount of rotation.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. In a let-off for weaving looms wherein a vibrator is employed oscillated as aforesaid
during the operation of the heddles to form the shed and capable also of slight
variations of movement due to variations in the length of warp between the fell of
the fabric and the delivering point of the let-off, the utilization of the oscillations of
the said vibrator for the purpose of positively operating the let-off roller or warp
beam, substantially as described.
2. A let-off motion for looms wherein such a vibrator as aforesaid is directly
connected with, or directly operates, step by step mechanism or the like for rotating
the let-off roller or warp beam, substantially as described.
3. A let-off motion for looms wherein such a vibrator as aforesaid is mounted upon
an axis different from the axis of the let-off roller or warp beam and wherein mechanism
for rotating the let-off roller or warp beam is directly connected with and operated by
the vibrator, substantially as described.
4. The combination with such a vibrator as aforesaid of step by step mechanism or
the like upon the feed roller or warp beam, the lever carrying the pawl of the said
mechanism being connected with the said vibrator so as to be oscillated thereby and
having its axis independent of that of the vibrator, substantially as described.
5. A let-off mechanism combined with and directly operated (through the medium
of step by step mechanisın or the like) by such a vibrator as aforesaid having its axis
so situated relatively to the axis of the let-off roller or warp beam that the movement
of the vibrator in one direction shall give to the let-off roller or warp beam a
progressively increasing amount of rotation, substantially as described.
6. The improvements in let-off mechanism for weaving looms hereinbefore described
and illustrated in the accompanying drawings.
Dated the 8th love of Fahm1807
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.