Improvements in the Let-off Mechanism of Looms for Weaving.
Year: 1890

page_text: Date of Application, 20th Mar., 1890
Complete Specification Left, 18th Dec., 1890-Accepted, 24th Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Let-off Mechanism of Looms for Weaving.
We, JOSEPH LINDSAY, and ROBERT LINDSAY, of 4 Somerville Place, Dundeo, in
the County of Forfar, North Britain, Engineers, do hereby declare the nature of this
invention to be as follows, that is to say :-
Our said invention has for its object to improve the let-off mechanism of looms for
weaving, and to render the tension of the warps as uniform as possible notwithstanding
the varying diameter of the yarn on the warp beam.
In carrying out the invention we impart the required tension to the warps by means
of frictional appliances acting directly or indirectly on the warp beam, and actuated
by one or two weighted levers. In one modification in which a single weighted
lever, at one side of the loom, is used we transmit the strain of that lever through a
link or strut-link to a curved lever fast on a horizontal rocking shaft placed at the
lower back part of the loom; and this rocking shaft has also fast on it levers con-
nected to the brake blocks or other frictional appliances acting on the ends of the
warp beam. The link or strut-link acts on the curved link, by preference through
an antifriction roller; and it is connected by a link to a lever on a low horizontal
rocking shaft, which has on it one or two levers extending upwards and provided with
a roller or other suitable bearing piece or pieces made by the acting of a spring or
weight to bear against the outside of the yarn on the warp beam. As the yarn on the
bean diminishes, the bearing roller or piece follows it, and through the levers and
low rocking shaft causes the link or strut-link of the weighted lever to move along
the curved lever towards its fulcrum; and diminishes the leverage of the strain in the
same ratio that the diameter of the yarn on the beam diminishes, thereby keeping
the tension on the warps as uniform as possible.
Dated this Nineteenth day of March 1890.
EDMUND HUNT,
Applicants Agent.
COMPLETE SPECIFICATION.
Improvements in the Let-off Mechanism of Looms for Weaving.
We, JOSEPH LINDSAY, and ROBERT LINDSAY, of Somerville Place, Dundee, in
the County of Forfar, North Britain, Engineers, 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, that is to say :-
Our said invention has for its object to improve the let-off mechanism of looms
for weaving and to render the tension of the warps as uniform as possible notwith-
standing the varying diameter of the yarn on the warp beam.
In carrying out the invention we impart the required tension to the warps by
means of frictional appliances acting directly or indirectly on the warp beam, and
actuated by one or two weighted levers.
An example or modification of our improved mechanism is shown on an accom-
panying sheet of explanatory drawings, Figure, 1, being a plan, and Figure 2, a
corresponding elevation. In these drawings the same reference letters are used to
mark the same or like parts wherever they are repeated.
In the delineated modification a single weighted lever, A, is used, being centered on
a stud, B, at the after part of the gable or side frame, C, of the loom. The strain of
the lever, A, is transmitted through a link or strut link, D, which is jointed to it, to
a curved lever, E, fast on a horizontal rocking shaft, F, placed at the lower back part

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of the loom and this shaft, F, has also fast on its levers, G, connected to brake
blocks, H, (or other frictional appliances) acting on the ends of the warp beam, J.
The strut link, D, acts on the curved lever, E, by proference through an antifriction
roller as shown; and it is connected by a link, K, to a lever, I, on a low horizontal
rocking shaft, M, which has on it one or two levers, N, extending upwards and
provided with a roller, P, (or other suitable bearing piece or pieces) made by the action
of a weighted arm, Q, (or of a spring) to bear against the outside of the yarn on the
warp beam, J.
The rocking shaft, M, may be carried in bearings in the loom
framing, but it is represented as carried in bearings one of which is formed in an
extension of the curved lever, E, the other being in an arm, R, on the rocking shaft, F.
As the yarn on the beam, J. diminishes, the bearing roller, P, follows it, and through
the lever N, rocking shaft, M, lever, L, and link, K, causes the strut link, D, of the
weighted lever, A, to move along the curved lever, E, towards its fulcrum ; and
diminishes the leverage of the strain in the same ratio that the diameter of the yarn
on the beam diminishes in, thereby keeping the tension on the warps as uniform as
possible.
In the arrangement of frictional appliances shown in the drawing, the brake
block, H, is secured to a piece, S, fitted to slide in guides in a bracket, T. fixed to or
formed on the loom gable, C. The brake piece, S, is connected to the lever G, by a
link, U, the effective length of which is adjustable by means of a screw coupling.
The brake block, H, is pressed upwards against the under side of a drag head or
friction pulley, V, on the warp beam, J, and the upward pressure is resisted by a
friction strap, W, connected to the bracket, T; and when the brake block, H, is
lowered the friction pulley, V, with the beam, J, descends a short distance so as to
rest by end journals in the bearings on the loom gable, C, the pulley, V, becoming
thereby free from the friction of the strap, W, and the beam being thien free to
be turned easily by means of the ordinary gearing for that purpose.
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.
In let-off mechanism of looms for weaving, applying to the warp beam frictional
apparatus in which the pressure is transmitted from one or more weighted levers
through one or more strut links acting on one or more curved levers, the said strut
link or links being moved nearer the fulcrum of the curved lever or levers in pro-
portion as the diameter of the yarn on the warp beam diminishes by a lever or levers
which keeps in contact with the yarn on the beam, the parts being arranged combined
and operating substantially in the manner and for the purposes hereinbefore
described.
Dated this Seventeenth day of December 1890.
EDMUND HUNT,
Applicants' Agent.