IMPROVEMENTS IN LOOMS FOR WEAVING
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by William Lawrence Mitchell at
the Office of the Commissioners of Patents, with his Petition, on
the 6th January 1871.
I, WILLIAM LAWRENCE MITCHELL, of Kirkcaldy, in the County of Fife,
North Britain, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN LOOMS FOR WEAVING," to be as follows, that is to say
t
This Invention, which relates to certain improvements in looms for
weaving textile fabrics, consists as follows:-
First. In obtaining or producing two beats of the lay by means of
one revolution of the driving shaft. This part of the Invention is
carried into effect by placing eccentrics on the driving shaft, and in
coupling the lay by toggle jointed rods to the gable of the loom framing.
The toggle jointed rods are again coupled to the eccentrics by means of
straps, and connecting rods, so that during a revolution of the eccentrics
the lay is drawn back to its extreme position when the major radii of
the eccentrics are uppermost, and the lay is thrown into its extreme
i

page_text: forward position for beating up the weft when the major radii of the
eccentrics are in a horizontal or nearly horizontal position, having passed
through the first quarter of a revolution; and when the major radii of
the eccentrics are passing through the second quarter of a revolution
-the toggle jointed rods are further depressed, thus again bringing back
the lay, and this is again thrown forward to beat up the weft as the
major radii pass through the third quarter of a revolution. In this
manner two shots of the weft or two runs of the shuttle are made during
one revolution of the driving shaft. In lieu of employing eccentrics,
as herein-before described, for driving the toggle jointed rods, cranks
may be used. By means of this part of the Invention the employment
of the usual spur gearing is dispensed with.
Second. Two beats of the lay to each shot of the weft, that is to say,
a beat for throwing up the weft in the ordinary manner so as to form
the cloth, and a second or closing beat after the shed has been reversed,
may be effected by driving the crank shaft of the loom at twice the
speed at present employed in any loom as hitherto constructed, and
by employing reducing gear for diminishing the speed of the picking
gear in the proportion of one shot for each double beat of the lay in
place of one shot to each single beat of the lay as in existing arrange-
ments of weaving looms.
Third. In obtaining or producing one entire beat of the lay and a
succeeding short beat of the lay for closing up the weft by a second
action, the result of the succeeding short. beat. Under this part of
the Invention the shuttle is run through the warp during the entire
or long beat of the lay which allows time for the shot to take place;
when the lay is in its extreme or nearly extreme backward position
and at the wide part of the shed, and as the lay returns from the said
backward position, it beats up the weft, but in practice it is found that
in weaving certain classes of fabrics, such for example as bed ticking,
the single beat of the lay does not sufficiently close the weft. In order
then the better to effect the closing of the weft the short beat of the lay
is used not however, to beat a second time on the weft itself, but to beat
on the portion of the warp which encloses the weft. Under this part
of the Invention the lay is also driven by toggle jointed-rods as described
under the first head, but as one throw of the shuttle only is required
to the two beats of the lay or to the whole and part of such beats

page_text: .
the eccentrics or cranks which drive the lay are actuated from the
first motion shaft of the loom by spur gearing arranged in such pro-
portion that two revolutions of the eccentrics or cranks are: made
during one revolution of the driving shaft., The variation in the
lengths of the two beats is effected by placing the toggle jointed rods
in such position that they are thrown to a greater distance on one side
of their, mean or straight position then they are on the opposite side of
that position.:
.
Fourth. This part of the Invention relates to an arrangement of
mechanism for driving the lay in broad looms, so that the lay is
stationary or nearly so during the time the shuttle is run through the
warp, this being a necessity for allowing time for the shot in very broad
looms to take place, and the same mechanism also produces a rapid
movement of the lay during the time the weft is being beaten up in.
place of the slow motion produced by the crank. This part of the.
Invention is carried into effect by driving the lay. by. elliptical or.
eccentric tooth wheels. The picking motion or motions for driving.
the shuttle consists of a cam on the driving shaft, which as it revolves
lifts a weighted lever, the lever is provided with a curved guide plate
that acts upon the tappets of the rod which carries the picking arm,
as soon as the step of the cam passes over or beyond the part of the
lever on which it acts the lever falls rapidly on account of the weights
with which it is provided and striking on the picking tappets produces.
the necessary motion for striking the shuttle. In place of using weights
In order
one or more springs may be used for actuating the said lever.
to produce variations in the length of the stroke of the lay, crank or
crank discs provided with slots in which the crank pins are adjusted are
employed.
.
Fifth. This Invention also relates to the construction and arrange-
ment of the upper shell and the lay of looms, and it consists, in reference
to the upper shell in forming it in the front side curved whilst on the
opposite side it is made flat. At or about the central part of the flat
sidė a shallow groove is cut, into which a narrow slip of timber is placed.
having a curved form, and from the extremities of this said piece of
wood inclined holes are formed in the shell to receive an iron strap or
tension rod, the ends of which pass outwards beyond the terminations
of the shell proper. The ends of the strap or tension rod have screw:

page_text: .
threads formed on them, and being provided with nuts, these when
screwed up tighten the strap or tension rod against the curved piece of
wood referred to and thereby stiffen the shell. In relation to the lay
this is stiffened under one arrangement by means of an iron. plate
formed with upturned ends which are entered into the under side
of the lay beam and bolted by a series of bolts passing through holes
formed in the iron plate and the said beam. A curved metallic
strap or tension bar is also applied below the iron plate herein-before
referred to, and it may be constructed with upturned ends similar to
those of the iron plate itself, or its ends may have screw threads formed
on them and passed through inclined holes to the extremities of the
lay beam.
Under the first arrangement, that is to say, when the tension bar is
formed with upturned ends, it is strained by means of screwed bolts
passing through it and through the, lay beam herein-before referred to,
ferrules of the requisite length being placed between the tension bar
and the flat iron plate..
When constructed under the second arrangement, that is to say, when
the tension bar is prolonged and passed through the holes in the end
of the lay beam, it is, besides being strained by through bolts in the
manner herein last described, further strained by nuts on the screwed
énds thereof, and the lay may be further stiffened by means of a tension
rod on the back thereof or in the upper shell herein-before set forth.
'
The sixth part of this Invention relates to the up-take motion of
looms, and its object is to instantly relieve the palls from the teeth of
the ratchet wheels used in the said up-take motion by means of the.
foot of the person attending the loom. It consists of a somewhat
quadrant-shaped plate carried on the stud or nave of the ratchet wheel
and connected to a lever which is again coupled to a treadle.
:
The above-mentioned plate has two wedge-formed projections on its
face which pass in over the teeth of the ratchet. When it is necessary
to relieve the palls the attendant by treading on the treadle causes the
quadrant by the intervention of the lever referred to, to move through.
an arc of a circle, so that the wedge-shaped projections are brought in
under the several palls, which are thereby lifted out from the ratchet
teeth.

page_text: Seventh. This Invention relates to the covering of the cloth retaining
beam with india-rubber in place of emery powder, glass, sand, or other
pulverised substance or perforated or punched metallic surfaces. The
outer surface of the india-rubber is, by preference, formed with small
protuberances or teeth, or it may be grooved, fluted, or corrugated.