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

page_text: PROVISIONAL SPECIFICATION.
Improvements in Let-off Mechanism for Weaving Looms.
I, JOHN POYSER, of Peck's Hill, Sherwood Road, Mansfield, in the County of
Nottingham, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to let off motions for looms and has for its object to provide
a let off which is positively operated to unwind the required length of warp, at
the same time maintaining a constantly even tension notwithstanding that, owing to
the interweaving of the weft threads with the warp, a slightly greater length of warp
is required than fabric produced.
According to my invention I provide for operating the let off from a positive
take up and make the point of connection between the lever of the let off and
the operating rod variable so as to slightly vary the length of the said lever.
A suitable arrangement for carrying my invention into practice.is as follows:-
I provide a frame with suitable bearings carrying two rollers one of which may be
covered with emery or other hard material, whilst the other roller may be of
rubber cr other soft material. Attached to the end of the shaft upon which the
emery roller is fitted is a disc actuated by means of a lever, upon the emery roller
shaft through the medium of a friction pawl. The end of this lever is slotted for
the reception of a friction roller or a vertical sliding block into the centre of which
a pin fixed to the end of the horizontal connecting rod between the take up lever
and the slotted let off lever projects.
The said pin also projects into another friction roller working in a quadrant
fixed upon the side of an oscillating compensator over which the warp passes
aud which takes up the slack which would be caused by the crossing of the
warps.
This arrangement is specially adapted for those looms for which Letters Patent
have already been granted to me, viz.,-No. 15431 of 1893 and No. 144 of 1895,
but may, however, be applied to any other looms. The letting off and taking up:
rollers being of the same diameter and their actuating mechanism of precisely the
same character it will be seen that the amount of warp let off should be at the
least equal to the amount taken up. In practice, however, such is not the case
the amount of warp taken up being slightly in excess of the amount theoretically
let off owing to the bending of the warp round the weft. To compensate for this,
I arrange for the slotted quadrant on the compensator under the action of the
tension and on either the forward or backward movement of the latter (whichever
may be the most convenient) to depress through the medium of the pin the end of the
connecting rod attached to the sliding block in the vertical lever of the letting off
roller thus causing it to move a slightly greater distance than the take up lever and
so give out the extra amount of warp required.
Deted the 15th dor of Tanner 1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.

page_text: Improvements in Let-oд меchanism Ior weaving Looms.
I, JOHN POYSER, formerly of Peck's Hill, Sherwood Road, Mansfield, in the
County of Nottingham, now of Bolehill, Wirksworth, near Derby, in the County
of Derby, 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 looms and has for its object to
provide a let-off which shall be positively operated to unwind or feed forward on
each take-up movement a length of warp equal to that taken up on each take-up
movement (notwithstanding that owing to the bending of the warp threads round
the weft laid in the shed in weaving, a slightly greater amount of woven warp is
taken up on each take-up movement than would be taken up if the weft thread
were not so laid and woven up and that owing to the irregularly varying thickness
in each warp and weft thread this slightly greater amount of woven warp taken up
is very frequently varied) and so obviate the variations in the tension of the warp
threads which would otherwise arise.
.
According to my invention the let-off is operated coincidently with a positive
take-up either by a direct connection with the take-up lever or with some other
going part of the loom the point at which movement is imparted to the let-off
lever by the connecting device being made variable to admit of the effective length
of the let-off lever being varied.
The point at which movement is so imparted is determined by an oscillating frame
which moves under the opening and closing of the shed by the heddles and the slight
variations in the position of the arc of oscillation of which are utilized to vary the
said point.
To enable my invention to be fully understood I will describe the same by
reference to the accompanying drawings.
Figure 1 is a side view illustrating one form of my improvements:
Figures 2 and 3 are views of a detail at right angles to each other:
Figures 4 and 5 are similar views of another detail; and,
Figures 6 and 7 are a side view and a sectional plan view illustrating another
detail:
Figure 8 is a modification of the detail shewn in Figures 4 and 5:
Figures 9, 10, 11, 12 and 13 are side views illustrating five modifications of my
invention.
Similar letters of reference indicate corresponding parts in the several
figures.
a, a are the take-up rollers of a loom of which the roller a¹ is positively
operated from a suitable cam on the driving shaft of the loom through the medium
of a rod b jointed to a lever c at the point the said lever carrying a gripping
pawl engaging with a flange on a wheel d fixed to the shaft of the roller a¹ as
described in the Specification of former Patent No. 15431 of 1893.
e, e are the heddles of the loom, and f is the oscillating frame hereinafter called
the vibrator. This vibrator is pivoted in a suitable bracket f fixed to or formed
in one piece with the loom framing, the pivot being in the form of a bar for carrying
a roller f¹.
At the upper end of the vibrator is a bar or roller ground which and the
roller 'the warp threads pass from the let-off rollers, and connected to its lower
end is or are a spring or springs h tending constantly to move the vibrator in the
direction indicated by the arrow f Figure 1, the movement of the vibrator in
the reverse direction being due to the opening of the shed and shortenings in the

page_text: length of the warps between the fell of the fabric and the delivering point of the
let-off rollers.
i, i are the let-off rollers of which the operating roller is of the same diameter
as the operating roller of the take-up rollers and positively driven by feed
mechanism of similar construction to that employed for operating the take-up
rollers, and the pawl of which is carried by the let-off lever j. This lever is
connected by the rod k with the take-up lever c
The operating let-off and take-up rollers being of the same diameter if their
actuating levers and c are of the same length and definitely connected together,
then owing to the bending of the warps round the weft, and the take-up roller
operating on the woven fabric, the amount of warp taken up on each movement of
the take-up roller is slightly greater (in varying amounts for reasons before stated)
than the amount let off, and the length of warp between the fell of the woven
fabric and the delivering point of the let-off rollers is shorter after the take-up has
operated than before. In consequence of this, the vibrator, when the shed is
closed, can not move quite so far away from the heddles under the action of its
spring or springs h as would be the case if the same amount of warp had been
let-off as taken up, and the vibrator is therefore deflected from the position it occupied
on the immediately preceding closing of the shed.
I avail myself of this liability to deflection for accomplishing the object of my
invention, and one mode of carrying out my invention is as follows, that is to say,
on the side of the vibrator/ I fix the plate or disc I having formed in it the slot l'
(shewn drawn to an enlarged scale in Figures 2 and 3) and I provide the let-off
lever with the slot m, as shewn in Figures 4 and 5 which illustrate the end of the
let-off lever j drawn to an enlarged scale.
On the end of the connecting rod k most remote from the take-up lever I fix
two rollers n, n as shewn in Figures 6 and 7 (which represent the parts referred to
drawn to an enlarged scale) the roller n entering the slot and the roller n' the
slot m.
The slots m are conveniently so placed or arranged that when the let-off
lever and the vibrator are respectively in their mean positions the rollers n
and n will be at about the centre of the length of the slots and m as shewn in
Figure 1, the distance of the centre of slot m from the axis of lever j being the
same as that of axis c¹ from the axis of lever c.
The effect of this disposition of parts is as follows:-
As the vibrator is drawn towards the heddles by the opening of the shed the
roller n' (having the position of its axis determined by the influence of slot on
roller n) will be lowered in the slot m and as the vibrator is drawn from the
heddles by its spring à on the closing of the shed the said roller will be raised in
the said slot.
The position which the said roller will occupy in the said slot during the period
when thrust is exerted upon the lever by the connecting rod will thus be
determined by the position of the arc of oscillation of the vibrator during each
successive stroke of the heddles. When the position of that arc is nearer to the
heddles the thrust through the said roller upou lever i will be exerted at a point
nearer the axis of the said lever which will thus have its oscillatory movement
increased and when the position of that are is further away from the heddles the
thrust through the said roller upon lever i will be exerted at a point further from
the axis of the said lever which will thus have its oscillatory movement diminished.
When the oscillatory movement of lever j is increased more warp is let-off, when
that movement is diminished less warp is let-off.
It thus follows that as the position of the are of oscillation of the vibrator is
nearer to the heddles more warp is let-off and as the position of that arc is further
from the heddles less warp is let-off.
Whether the are of oscillation for any single stroke of the heddles will be nearer
to or further from the beddles than on the immediately preceding stroke is
determined by the relation of the length of warp between the fell of the fabric

page_text: stroke.
rollers to that on the immediately preceding
When the said length is reduced the said arc will be nearer them and vice versa.
It thus follows that as the length of warp is reduced the amount of warp let-off
is increased and vice versa.
If on any stroke less warp is let-off than is taken up the said length will be
reduced and nice tierad.
It thus follows that any tendency to deficiency or excess in the amount of warp
let off will result in the letting off of more or less warp.
As the effective length of lever j and its amount of oscillation may be increased
or diminished beyond or below that of levere the amount of warp let-off will thus
tend to be constantly equalised with the amount taken up.
The position of the arc of oscillation of the vibrator and the amount of warp let-
off will thus tend to be constant about a mean and any artificially induced extreme
deficiency or excess of warp and consequent variation in the position of the said
are of oscillation will be compensated for until the said mean is again obtained.
The amount of warp let-off is thus self regulated or self determined and the
tension on the warp threads is thus automatically adjusted and kept absolutely or
approximately constant.
To obviate the movement of lever j and consequent feeding forward of warp
resulting from the movement of roller a through the arc of a circle having its
centre at the centre of pivot el (a movement additional to that imparted by the
let-off operating mechanism) the slot m may be curved to an are of a circle having
its centre at the point c as shewn in Figure 8.
The angle at which the slot is placed relatively with the slot m can be varied
according to the amount of warp desired to be let-off for any given variation in the
position of the are of oscillation of the vibrator; for instance, the more nearly the
slot approaches the horizontal the less alteration will a given variation in
the position of the are of oscillation of the vibrator cause in the operative (or
thrusting) position of roller n' in the slot m, whilst the more nearly the slot
approaches the vertical the greater will be the alteration.
To permit of varying this quantity the disc I having the slot in it may be
attached to the vibrator frame by means which permit of adjustment.
In the modification of my invention shewn in Figure 9, the arrangement of the
mechanism is substantially the same as hereinbefore described the only difference
being that the vibrator/instead of being pivoted on an independent axis, as shewn
in Figure 1, is pivoted on the axis of the let-off roller i.
In the modification of my invention shown in Figure 10, the position of the
roller n' in the slot m of the let-off lever j instead of being varied by means of a
slotted plate and roller n is varied by means of an arm q formed upon the
vibrator and connected by a link g' with the connecting rod k. In this figure
the vibrator f is represented as being pivoted on the axis of the let-off roller i as.
in Figure 9.
In the modification of my invention shewn in Figure 11 the arrangement is
substantially the same as that shewn in Figure 10 except that I dispense with the
arm g and substitute therefor a bell-cranked lever r one arm of which is slotted to
engage with the roller n on the end of the connecting rod k whilst the other arm
is connected by a link to the vibrator f, the said lever r being pivoted at its elbow
upon a fixed axis in the frame of the loom.
In the modification shewn in Figure 12 the arrangement is substantially the
same as that shewn in Figure 11 except that the vibrator and let-off roller have
independent axes and that instead of connecting the bell-crank lever with the
vibrator by means of a link I provide a slot in the vertical arm of the bell-
erank lever and a pin on the side of the vibrator which pin projects into the
slot r
In the modification shewn in Figure 13 the bell-crank lever r, instead of being
pivoted upon the frame of the loom as in Figures 11 and 12, is pivoted upon an

page_text: extension upon the vibrator f, one arm of the lever r being connected to th
rod k by a links and the other arm to the let-off lever j by means of a
link a'.
Although I have described the take-up.and let-off levers as connected by a rod
both may be operated separately from any suitable going parts of the foom, for
instance, the rod à might be arranged in connection with a cam or the like similar
to that used for operating the take-up lever c, and in this case instead of the take-
up and let-off levers being operated simultaneously, the take-up lever may ba
actuated at any selected time alternately with the let-off lever.
The arrangement of. niechanism hereinbefore described for operating the
positively driven roller of a pair of let-off rollers may also be used in connection
with a warp beam, the gripping pawl feed mechanism simply serving for positively
-rotating the beam from which the warps are drawn.
I wish it understood that the above arrangements are only given as examples of
my invention there being various other mechanical arrangements whereby alterations
in the position of the are of oscillation of the vibrator may be made to determine
the effective.length of the.let-off lever.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. Ina loom for weaving, the combination of positive take-up mechanism, positive
let-off mechanism, a vibrator extending the warps between the fell of the fabie
and the delivering point of the let-off rollers or warp beam and allowing of
deflection on the opening or closing of the shed and on variation arising in the
length of the warps between the said points and means whereby variations in the
length of the said warps serve to vary the point at which movement is imparted to
a lever operating the let-off mechanism, substantially as described,
2. In a loom for weaving, the combination of positive take-up mechanism, positive
let-off mechanism, a vibrator the movements of which are due to the motion of the
heddles when opening and closing the shed and means whereby variations in the
length of warp between the fell and the point of let-off serve to vary the point at
which movement is imparted to a lever operating the let-off mechanism,
substantially as described.
3. In a loom for weaving, the combination of positive take-up mechanism, positive
let-off mechanism, a vibrator extending the warps between the fell of the fabric and
the delivering point of the let-off rollers or warp beam and allowing of deflection
on the opening or closing of the shed and on variation arising in the length of the
warps between the said points and a rod or the like for transmitting motion from
the loom to a lever for operating the let-off mechanism, the said rod or the like
having one end, which is in adjustable connection with the said let-off lever,
supported in or by an arm or attachment upon or in connection with the said
vibrator in such a manner that the deflection of the vibrator varies the point at
which the movement for operating the let-off is communicated to the let-off lever
and thus varies the effective leugth of the said lever so that the latter has its
effective length increased or diminished relatively with the length of the take-up
lever, substantially as described.
4. In a loom for weaving, the combination of a lever operating positive take-up
mechanism, a lever operating positive let-off mechanism, a rod connecting the said
levers so that their respective mechanisms operate simultaneously the point of
connection between the 'let-off lever and the said connecting rod being made
variable, in combination with a vibrator extending the warps between the fell of
the fabric and the delivering point of the let-off rollers or warp beam and allowing
of deflection on the opening or closing of the shed and on variations arising in the
length of the warps between the said points and an arm or device on the said
vibrator connected with the rod, substantially as, and for the purpose, described.
5. In a loom for weaving, a lever operating the let-off mechanism under the

page_text: thrust or pull of a rod or other motion transmitting piece having the end or part
engaging with the said lever adapted to be automatically controlled from an
oscillating vibrator for the purpose of varying the point at which movement is
imparted to the said lever and of thus varying the effective length of the said lever,
substantially as described.
6. In a loom for weaving, a vibrator such as described for extending the warps
between the fell of the fabric and the delivering point of the let-off rollers or warp
beam and allowing of deflection on the opening or closing of the shed and on
variation arising in the length of the warps between the said points in combination
with means whereby variations in the length of warp between the fell of the fabric
and the point of let-off serve to vary the point at which movement is imparted to a
lever operating the let-off mechanism, substantially as described.
7. In a loom for weaving, having a vibrator operating as aforesaid the employ-
ment of a rod or other motion transmitting piece for transmitting the motion from
the loom to a lever for operating the let-off mechanism the said rod or piece having
the end or part engaging with the said let-off lever in adjustable connection
therewith and supported in or by an arm or attachment upon or in connection with
or controlled by the said vibrator in such a manner that the movements of the
vibrator under the tension of the warps vary the point at which the movement for
operating the let-off is communicated to the let-off lever and thus vary the effective
length of the said lever, substantially as described.
8. In a loom for weaving, let-off mechanism consisting of the parts constructed
and combined, substantially in the manner herein before described and illustrated in
Figures 1 to 8 of the accompanying drawings, and operating as, and for the
purposes, set forth.
9. The modifications of my invention, substantially as described with reference
to Figure 9, Figure 10, Figure 11, Figure 12 and Figure 13 of the accompanying
drawings.
D
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.