Improvements in Let-off Motions for Looms,
Year: 1899

page_text: Date of Application, 22nd Aug., 1899-Accepted, 30th Sept., 1899
COMPLETE SPECIFICATION.
Improvements in Let-off Motions for Looms,
I, CHARLES FOSTER PERHAM, of 552, Broadway, Lowell, in the County of
Middlesex, and State of Massachusetts, United States of America, Gentleman, 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 has relation to let-off mechanisms for the warp-beams of looms.
The object of the present invention is to provide a device of the character
specified, to maintain the same degree of tension upon the warp threads irrespective
of the diameter of the layers on the beam.
It frequently happens that the tension upon the warp threads increases in
proportion as the threads unwind from the warp-beam, the brake mechanism
operating with a constant pressure to retard the movements of the said beam;
which latter rotates at a regular rate of speed, and therefore the picks vary,
and the cloth is uneven and of practically small value.
Hence the invention consists in a let-off m chanism for looms in which the
pressure of the brake mechanism varies with the thickness or diameter of the layers
of the threads upon the beam, being greatest when the layers are thickest and
least when the threads are almost expended, so that the rotation of the warp beam
is varied in accordance with the depth of the layers thereon, and the same amount
of thread is let off at all times, all as I shall now proceed to describe in detail and
then point out in the claims.
Reference is to be had to the accompanying drawings, and to the letters and
figures marked thereon, forming a part of this specification, the same letters
designating the same parts or features, as the case may be, wherever they occur.
Of the drawings:-
Figure 1 represents in side elevation a portion of a loom having its warp-beam
equipped with my improved let-off mechanism.
Fig. 2 is a rear end elevation of the same.
Fig. 3 is a section on the line 3-3 of Fig. 2.
Fig. 4 shows additional means for locking the warp-beam against rotation
when the reeds of the lay-beam are in engagement with the cloth.
My invention is applicable to looms of any class or pattern and is not limited to
the details of construction illustrated upon the drawings, and which I shall now
proceed to describe, since it is capable of being expressed or embodied in other
forms and in many different ways. I have shown it as being applied to a loom
having the frame a, the warp-beam b, with journals c, mounted in bearings d on
the frame.
The warp roll or beam has at its ends flanges e and is provided with a gear-
wheel meshing with a pinion g on a stud-shaft h journaled in the frame. The
said stud-shaft h is equipped with a friction or brake wheel with which my
improved brake mechanism is adapted to co-act in retarding the rotation of the
warp-beam as the warp-threads are being drawn therefrom, and the work upon
the loom progresses.
j is a long lever pivoted at k to the frame and having its upper end 7ª extending

page_text: above the frame-work of the machine. One end of the strap passes around the
rim of the brake-wheel i, and is secured to the lower end of the lever, slightly
below the pivot k, while its other end is secured to the extreme lower end of
the lever by a link m havng a hooked end adapted to take in any one of several
holes in the strap l.
If the upper end of the lever j is moved to the right, the strap is freed
from frictional engagement with the brake-wheel, and it moved to the left, the
friction of the strap against the wheel is increased.
Upon supports n, extending up from the frame a is mounted a shaft o, having
a depending arm p, and laterally and rearwardly projecting arms p¹ connected. by
a bar p, constituting a feeler. The lower end of the arm pis pivoted to a rod
passing loosely through an eye q' on a bracket secured to the frame, said rod
being provided with an adjustable collar q², and between it and the eye q', and
around the rod is placed a pressure spring q. The upper end of the lever j
is connected to the arm p at a distance from the shaft o of about one-third of its
length by a contractile or tension-spring r.
The warp-threads which have been previously wound upon the warp-beam
pass over the bar p² of the feeler and from thence to the hedules and other parts
of the loom. The springs are adjusted until the parts are in normal position and
the brake-strap locks the brake-wheel against movement. Then the warp-threads,
under the tension of the cloth-roll and the take-up devices, draw upon the feeler
with sufficient pressure to throw the lower end of the armi p to the right against
the pressure of the spring 3 and thereby allow the upper end of the lever j¹ to
move to the right far enough to decrease the frictional engagement of the brake
mechanism so that the warp beam can slowly rotate and the threads can be
drawn from it. When the beam is first put on the loom, the layers of thread are
so deep that the threads pass from it over the feeler at an angle greater than
a right angle to the latter where they exercise their least stress or force upon it
and their greatest stress upon the brake; and as they are gradually reeled off,
the diameter of the layers becomes less and less, and the pressure upon the feeler is
correspondingly increased as the threads approach a right angle to it. Therefore
it will be seen that the friction of the strap and brake-wheel is greatest when
the leverage of the threads upon the warp-beam is greatest, and least when the
diameter of the layers of threads upon the warp-beam is diminished, and
consequently their leverage upon the beam is decreased.
The yielding connection r between the brake-lever j and the feeler arm p, is
an important factor in maintaining an even pressure upon the warp. By employ
ing a spring to connect those parts, the frictional engagement of the strap with
the brake-wheel may be varied, as required, which would not be the case were
the lever and arm 2 connected by a rod or other unyielding connection. The
tension of the spring increases or decreases according to the position of the arm p,
without actually disengaging the strap from the brake-wheel, so that the tension
on the warp is correspondingly unvaried. In this way, a relatively long move-
ment of the arm p towards the lever j, which would, if the connection were
not a spring, totally release the brake-wheel, merely relieves the frictional engage-
ment to the required extent. The said spring is relatively light; and the brake-
lever is sufficiently long to exert a powerful leverage in drawing the strap about
the wheel. The main pressure of the warp is borne and resisted by the spring g
which is sufficient to normally counter-balance the spring r also. It is evident
from this explanation that when the tension of the warp is sufficient to compress
the spring 3, the movement of the feeler arm, changes the tension of the spring r
and causes the lever j to release the brake-wheel sufficiently to relieve the tension
on the warp.
In addition to these features, I provide means for locking the warp-beam
against rotation when the lay strikes the cloth, as shown in Fig. 4, to which
reference may now be had.
When the reeds of the lay strike the cloth, they increase the tension on the warp

page_text: threads and consequently partially rotate the warp-beam, so that at the next pick
the warp-threads are loose, and an irregular and uneven fabric is the result.
Hence I employ a locking lever s, fulcrumed at s¹ on the frame a, and having a
projection at its upper end to extend behind the arm p. The lower end of the
lever is connected by a link t with the lay-operating sword (not shown) so that
each time the lay is thrown forward, the upper end of the lever is thrust rearward,
until the projection engages the lever and prevents it from yielding under
the increased tension of the warp-threads, and hence the brake mechanism remains
locked to the brake-wheel and the warp-beam is preventd from unwinding.
When the lay is in its inoperative position, the projections is withdrawn from
the lever p and the latter is free to move as before described.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. In combination, a warp-beam, under constant tension from the warp, a
friction-brake mechanism for checking the rotation thereof, a pivoted feeler con-
nected yieldingly with the brake mechanism having a portion arranged with such
relation to the warp-beam that when the beam is full the warp is at an angle to the
feeler greater than a right angle, and the angle decreases as the warp is unwound.
2. In combination, a warp-beam under constant tension from the warp, a
friction brake mechanism for checking the rotation thereof, a spring-held feeler
pivoted above the warp-beam and connected yieldingly to the brake-mechanism,
said feeler having a portion over which the warp passes arranged with such relation
to the warp beam that when the beam is full, the warp between the feeler and the
beam is at an angle to the feeler greater than a right angle and the angle decreases
as the warp is unwound.
3. In a loom, the combination with a warp-beam and a friction-brake for the
beam, of a lever for operating the brake, a laterally extending feeler journaled
in supports, and in the path of the warp-threads, said feeler being arranged above
the warp-beam, and having a depending arm, a spring connection between the
said arm and the said lever, and a spring bearing against said arm against the
stress of the spring connection.
4. In combination with a warp-beam, and a friction-brake therefor, of a lever
for operating the brake, a feeler journaled in the path of the warp-threads, having
a depending arm, yielding connections between the arm and the said lever, and
means coacting with the lay for engaging the said depending arm and holding it
against motion.
5. In combination with a warp-beam, and a friction brake therefor, of a lever
for operating the brake, a feeler journaled in the path of the warp-threads, having
a depending arm, yielding connections between the arm and the said lever, and a
pivoted lever connected with the lay and arranged to intermittingly engage the
depending arm, for the purpose described.
6. In a loom in combination, a warp beam, a brake mechanism therefor, an
upwardly projecting lever for operating the brake strap, a feeler pivoted above
the warp-beam and arranged to move in accordance with the varying tension of
the warp, and having a rigid downwardly projecting arm, a contractile spring
connecting the end of the brake lever with the feeler arm, and a tension spring
connected to the end of said arm and arranged to act against the first said spring.
Dated the 22nd day of July A.D. 1899.
CHARLES FOSTER PERHAM.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.