IMPROVED APPARATUS FOR EQUALIZING TENSION, SPECIALLY APPLICABLE AS A LETTING-OFF MOTION IN LOOMS
Year: 1878

page_text: LETTERS PATENT to Thomas George Fonnereau Dolby, of Dulwich, in the
County of Surrey, Manufacturer, for the Invention of "IMPROVED APPARATUS
FOR EQUALIZING TENSION, SPECIALLY APPLICABLE AS A LETTING-OFF MOTION
IN LOOMS."
Sealed the 31st January 1879, and dated the 30th September 1878.
PROVISIONAL SPECIFICATION left by the said Thomas George Fonnereau
Dolby at the Office of the Commissioners of Patents on the 30th September:
1878.
THOMAS GEORGE FONNEREAU DOLBY, of Dulwich, in the County of Surrey,
Manufacturer. "IMPROVED APPARATUS FOR EQUALIZING TENSION, SPECIALLY
APPLICABLE AS A LETTING-OFF MOTION IN LOOMS."
My Invention consists of improved apparatus for equalizing tension, and has
been specially designed as a letting-off motion in looms, so as to ensure that the
warp may be let off regularly from the beam. I will proceed to describe it as
applied to that purpose.
The improved apparatus mainly consists of a worm wheel, a screw or worm, and
a weight (or weights), combined or arranged in such manner that the weight shall
practically hang on one side of the warp beam, and thus hold the warp at one
uniform or equable tension, the variable grip and consequent variable letting off
produced by most existing letting-off motions being thus overcome.
In carrying out my Invention I prefer to fix the worm wheel on the end of the
warp beam, and I place the screw in gear with the wheel, the screw spindle
working freely in guides or brackets fixed to the loom frame.
To the lower end of the screw spindle I hang the weight (or if preferred the
weight may be applied so as to press upon the spindle), and this weight, which is
a known and invariable quantity, acts through the screw upon the worm wheel on
the beam, the screw working from tooth to tooth of the wheel; the warp is thus
always kept at uniform tension, notwithstanding atmospheric changes, and it is
let off in a regular and even manner.

page_text: I prefer to hang or attach the weight to a lever connected to the screw spindle,
which is better than suspending the weight directly from the spindle. The lever
of the ordinary letting-off motion, but with a much less weight than usual, can be
utilized for the purpose.
The screw spindle is loose, and is free to rise and descend to a limited extent, so
that the weight can pull freely upon the worm wheel by the screw; but as the
effect of the rotation of the warp beam would be to lift the screw without rotating
it, and the screw would therefore cease to gear with the worm wheel, I adopt
means to cause the screw to rotate sufficiently to correspond with the rise which
would be produced, so that it remains in gear with the wheel. This may be
effected in various ways; for example, a mitre wheel may be fixed to the side of
the worm wheel, and be geared to a small mitre wheel on a spindle which carries a
cog wheel, this cog wheel in its turn gears with a small cog wheel on the screw
spindle. The number of teeth of these wheels should be such that one revolution
of the screw (when it has one thread) is equal to travelling down one tooth of the
worm wheel. If the screw receives its rotating motion otherwise than from the
worm wheel it should be a faster motion, unless exactly equal, and its effect should
cease when the rise produced by the worm wheel is insufficient.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Thomas George Fonnereau Dolby in the Great Seal Patent Office on the
the 29th March 1879.
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THOMAS GEORGE FONNEREAU DOLBY, of Dulwich, in the County of Surrey,
Manufacturer. 'IMPROVED APPARATUS FOR EQUALIZING TENSION, SPECIALLY
APPLICABLE AS A LETTING-OFF MOTION IN LOOMS."
My Invention consists of improved apparatus for equalizing tension, and has
been specially designed as a letting-off motion in looms, so as to ensure that the
warp may be let off regularly from the beam. I will proceed to describe it as
applied to that purpose.
The improved apparatus mainly consists of a worm wheel, a screw or worm and
a weight (or weights) combined or arranged in such manner that the weight shall
practically hang on one side of the warp beam, and thus hold the warp at one
uniform or equable tension; the variable grip and consequent variable letting off
produced by most existing letting-off motions being thus overcome.
In carrying out my Invention I prefer to fix the worm wheel on the end of the
warp beam, and I place the screw in gear with the wheel, the screw spindle
working freely in guides or brackets fixed to the loom frame.
To the lower end of the screw spindle I hang the weight (or if preferred the
weight may be applied so as to press upon the spindle), and this weight, which is
a known and invariable quantity, acts through the screw upon the worm wheel on
the beam, the screw working from tooth to tooth of the wheel; the warp is thus

page_text: always kept at one uniform tension, notwithstanding atmospheric changes, and it is
let off in a regular and even manner.
I prefer to hang or attach the weight to a lever connected to the screw spindle,
which is better than suspending the weight directly from the spindle. The lever
of the ordinary letting-off motion, but with a much less weight than usual, can be
utilized for the purpose.
The screw spindle is loose, and is free to rise and descend to a limited extent, so
that the weight can pull freely upon the worm wheel by the screw; but as the
effect of the rotation of the warp beam would be to lift the screw without
rotating it, and the screw would therefore cease to gear with the worm wheel, I
adopt means to cause the screw to rotate sufficiently to correspond with the rise
which would be produced, so that it remains in gear with the wheel.
This may be effected in various ways; the way I prefer is that herein-after
described.
The accompanying Drawings represent my improved apparatus for equalizing
tension applied as a letting-off motion in a loom. Figure 1 is a side elevation;
Figure 2, a plan; and Figure 3, a back elevation of the apparatus. a is part of
the frame of the loom; b is the warp beam, the axes of which turn in suitable
bearings or supports; one of which is seen at c; d is the worm wheel fixed con-
centrically on the end of the beam b; e is the screw or worm in gear with the
wheel d; the pitch of the worin should not be so large as to cause it to slip, and it
has preferably a single thread; the spindle f, f, of this screw works freely in guides
or brackets g, g, bolted or fixed to the frame a. On the lower end of the spindle f
is a swivel or loop h in which the spindle is free to turn. To this loop is suspended
the lever i, as shown; the inner end of this lever has its fulcrum on the loom frame
or otherwise, while on its outer portion are hung the adjustable weights k, k. It
will be readily seen that these weights practically hang on one side of the warp
beam, and that as they act through the screw e upon the wheel & on the beam,
the screw working from tooth to tooth of the wheel as the beam rotates, the warp
is thus kept at one uniform tension so long as the beam remains at about the same
fulness; when the amount of warp on the beam becomes appreciably reduced the
weight must be removed proportionately nearer the fulcrum of the lever i. If
desired any suitable automatic arrangement for shifting the weight in proportion
to the diminution in diameter of the chain may be adopted.
The screw spindle f is loose, and, as herein-before stated, is free to rise and
descend to a limited extent, so that the weights are always suspended and can pull
freely upon the worm wheel by the screw. The effect of the rotation of the warp
beam would be to lift the screw without rotating it, and the screw would therefore
cease to gear with the worm wheel if means were not provided to cause a sufficient
rotation of the screw to correspond with the rise which would be produced. For
this purpose I prefer to adopt the arrangement I will now proceed to describe.
The
To the top of the spindle f I fix a disc l, on which are one or more inclined pro-
jections m (two are shown in the Figure). Above this disc is another disc n fixed
on a spindle o made to revolve at a speed somewhat greater or at least equal to the
maximum speed which the spindle f can attain even in weaving with the minimum
number of picks to the inch and with the warp beam nearly empty.
spindle o and the upper disc n are driven by a worm wheel p fixed to the said
spindle and receiving its motion from a screw or worm q on the end of a shaft r;
this shaft turns in bearings in a bracket r fixed to the loom frame, and is in its
turn driven by a pulleys and strap t from another pulley 8' on a shaft, which may
derive its motion froin the crank or tappet shaft or from any other convenient part
of the loom. On the upper disc n are one or more projections u similar to those on
the lower disc 1. The effect of the arrangement is that when the screw spindle fis
caused to rise by the rotation of the beam b and worm wheel d the projection or
projections on the upper disc as the latter rotates come in contact with the pro-
jection or projections m on the lower disc l, and therefore draw this disc into
their rotary motion, together with the screw spindle f; the contact of the respective

page_text: projections and the consequent rotation of the screw spindle continue until the
screw spindle has descended sufficiently for the projections to pass clear. Thus as
fast as the worm wheel raises the screw spindle the latter is screwed down again,
and is therefore kept in gear with the wheel.
-
As these two motions are quite distinct from and unconnected with each other
the warp beam readily oscillates to the healds as they open and shut, and thus the
warp is very much eased and the weaver relieved of much care. When slack has
to be taken up it is only necessary to turn the screw spindle f in the reverse
direction to that imparted to it by the projections on the upper disc, the warp is
thus brought to the proper tension without any alteration of the weights; the
turning of the spindle in the said reverse direction may be easily effected by hand
if one or more convenient projections or indentations be made on the disc l, such
for example as are shown at v in the Figure. The height of the upper disc n may
be rendered capable of adjustment in case of need by making the bracket r
adjustable in the loom frame. Any tendency of the worm to unduly slip round
may be prevented by a simple break at or near the swivel, but this would scarcely
be required where the screw is sufficiently large and the pitch is not too great.
Although I have described and shown the apparatus as connected directly with
the warp beam, as I consider this the best plan, yet if preferred or to suit special
circumstances the apparatus may be separate from the beam and the motion
between the apparatus and the beam be transmitted by band or other gearing.
Although my apparatus is, as hercin-before stated; intended chiefly as a letting
off motion in looms it can be applied, as will be readily understood, in other cases
where lengths of thread, cords, fabrics, or other material are being let off from a
beam, drum, or roller, and require a uniform or equable tension.
-
And having now described the nature of my said Invention and in what manner
the same is to be performed, I declare that I claim,―
First. The arrangement of a worm wheel, a screw or worm, and a weight or
weights in the manner substantially as and for the purpose herein-before described
and represented in the accompanying Drawings.
Secondly. In combination with the worm wheel, screw or worm, and weight or
weights arranged as aforesaid, I claim the employment of means, substantially as
herein-before described and represented in the accompanying Drawings, for causing
the screw to rotate sufficiently to correspond with the rise which would be produced
by the warp beam or other beam, drum, or roller.
In witness whereof, I, the said Thomas George Fonnereau Dolby, have
hereunto set my hand and seal, this Twenty-eighth day of March, One
thousand eight hundred and seventy-nine.
T. G. F. DOLBY. (L.S.)