IMPROVE- MENTS IN SELF ACTING LET OFF MOTIONS FOR STEAM POWER LOOMS
Year: 1885

page_text: THOMAS HARGREAVES BRIGG Machine Maker & Ironfounder Thornton Rd. Bradford
in the County of York, do hereby declare the nature of my invention for IMPROVE-
MENTS IN SELF ACTING LET OFF MOTIONS FOR STEAM POWER LOOMS to be as follows :-
The great necessity for a good let-off motion has been the cause of so many attempts
to obtain one, but hitherto practically failed.
I propose to resist the pull of warp by means of an old arrangement, such as is
extensively used on woollen looms viz. the worm & worm-wheel, the latter upon the
beam end. But, instead of governing the number of picks & tension by a swing-
back-rest, which is the cause of so many complaints & totally impracticable to faster
running looms. I attach a small balance lever supported by stud or fulcrum & held
in position by the tension of all, or only a few threads of warp, or by a feeler against
the woven fabric.
On this lever is a small sliding weight or spring to be adjusted to any required
tension. The feeler is connected near to fulcrum, so that the extremity of the lever
being 10 or 12 inches long, or more, the slightest increase of tension will move it
considerably more than at point near the fulcrum. When this is done, to any degree,
some going-part of the loom such as the "sword" or cam will thrust or pull back, the
extremity of lever & by doing so it will move the worm & let off warp to suit the
demand.
This balance lever will work with most accuracy, if only allowed to register when
the healds are open & not when the weft is being beaten to its place, on account of the
warp or fabric being at that time steady & free from jerks.
I provide, when necessary, a regulator to compensate for decreasing diameter of warp,
but this will rarely, if ever be required even if the warp beam be round, square or
oval.
It will be seen that this appliance will give the exact tension required, however
untrue the beam may be. It cannot possibly get too tight, for the instant it would
begin to increase it must register, and in doing so, the extremity of lever being
connected with catch wheel of any description (plain surfaced one being preferred) on
worm shaft, (or geared with it) will let off sufficient warp to restore balance, but
cannot give more, for at that instant the contact with the going-part & the let off
motion is broken.
TH BRIGG

page_text: Improved Self-acting "Let-off" Motion for Steam Power Looms.
THOMAS HARGREAVES BRIGG Machine Maker & Ironfounder Thornton Road Bradford
in the County of York do hereby declare the nature of my invention for IMPROVED
SELF ACTING "LET-OFF" MOTION FOR STEAM POWER LOOMS and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
The necessity of a good "let off" motion, has been, and still is, a matter of such
great importance as will at once account for so many attempts to procure one.
With my invention, for the above object, I propose to resist the pull of the warp by
nicans of an old arrangement, which is extensively used particularly on woollen looms;
viz the worm & worm-wheel, the latter fixed on the beam end, & the former geared
into the worm-wheel. But instead of regulating the number of picks, and tension
of warp, by means of the ordinary powerfully constructed "back-swing-rest" which
has to resist the whole of the tension of all the warp, & the blow of the slay; which
on account of its necessary heavy construction, is not so accurate in its balance and in
its letting off as it ought to be. Again, besides being inaccurate it is an expensive
arrangement, it offers practically no support to that part of the loom where it is applied,
and where it requires to be firm in order to secure the easy running of the main shafts
in the loom, thus, by this imperfect arrangement much unnecessary wear & tear
takes place.
This and other disadvantages are experienced by the above swing-rest,
besides being totally impracticable on fast running looms, and in slow ones it is a
means of wasting considerable power, by yielding as it does " as the pick is being put
in," and thus breaking the concussion of the slay too soon.
To simplify, and improve the construction and stability of the loom, and yet retain
the use of the worm and worm-wheel, I propose to fix the back-rest quite firm, at
each end & thus stiffen the loom. (In making looms, a fixed rest will be much cheaper
and infinitely better for the machine, than a loose rest.) (In some looms a vibrating-
rest is necessary, but of a different construction,) and instead of governing the catch
or catches on ratchet wheel (the latter fixed on worm shaft) by the position of the
above swing rest, which is actuated by the increased tension of the warp, the catches
thus regulated, together with the ratchet wheel, & worm, are forced forward by any
rectilinear, or cam motion of the loom, so adjusted as to move the ratchet wheel when
the catches are brought in contact with the rectilinear motion, by the increased tension
of the warp.
I, after fixing the back-rest, apply a light feeler of wood or other suitable material,
upon, or under all, or a part of the warp, or woven fabric. This feeler is connected
with a small balance lever near to a fixed fulcrum, the other end of the lever (of
the 1st 2nd or 3rd kind) is extended to any suitable part of the loom & to such a
length, that a slight depression, or rise of the feeler, by the increased tension of the
warp, will give the extended end, a fairly good traverse, so that the catches which
are connected directly or indirectly to the extended end of lever, are allowed to
freely pass over a more or less number of teeth, in the ratchet wheel (on worm shaft)
in proportion to the tension, or pressure upon the feeler; and then when this is done,

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some positive rectilinear motion, from "sword or cam, shall push, or pull back the
catches to their original position, at the same time the catches having caught more or
less teeth, the ratchet wheel will be moved forward also, thus giving off a portion of
warp to suit the demand.
This action, will continue so long as "picks" are being put in. Each succeeding
pick would increase the tension of warp, were it not for the action of this feeler which
conveys its pressure to the catches, with the above result. If the loom should run
without weft, then there is no increase of tension, there will consequently be no
"let off."
To regulate the number of picks & tension of the warp to what may be required,
I attach a light adjustable spring to the extended balance lever, from thence, to any
part of the loom, with regulating screw & nuts, or a weight, to tighten, or slacken the
spring & thus give more or less picks per inch or tension of the warp.
In order that the feeler when against the warp may register at the moment that the
healds are open, & not when the pick is being beaten into its place; or to the contrary
when the feeler is against the cloth. I attach the spring to the "sword" or other
suitable moving part of the loom so as to tighten the spring at any required moment,
to prevent the catches being actuated upon, when not required.
It will be seen, that if the pressure on the feeler by the tension of warp, is not in
excess of that offered by the spring, the catches will remain unmoved, allowing the
rectilinear motion to traverse its fixed & limited distance, without moving the ratchet
wheel, consequently there can be no "let off."
By this arrangement a perfect balance, will, automatically be maintained, between
the pull of the spring, and the tension of the warp, just as it may be set; and having
no heavy strains to bear, it can be constructed sufficiently light, and sensitive as to be
perfectly accurate and durable. Whereas the old arrangement, having the whole
tension of the warp to resist, together with the blow of the slay, all its parts must be
necessarily heavy and strong, and its bearings so large, that it is impossible to get that
accuracy of register, upon which depends the greatest aim & object in a "let-off"
motion viz the production of even pieces.
By reference to drawing A represents the ordinary worm, fixed on the worm-shaft B
geared into the worm-wheel C which is fixed upon the end of warp-beam axle D.
E is "back-fixed-rest" over which the warp F passes.
H represents the " breast-beam
"
over
which the woven fabric G passes.
I is the feeler" pressed against the fabric G by the levers J J K upon the
fulcrum L which is supported at each end.
Balance lever M is supported by connecting-rod N and the fixed fulcrum O, so that
when the woven fabric G should demand relief from the "let-off" motion on account
of the increased tension, the feeler I thus fixed, will be forced outwards, raising
(balance lever M (the loose end of which is connected to the swing-elbow-lever P PI
and) the catch over one or more teeth in catch-wheel I on worm-shaft B. This
action takes place when the "sword" S is going back and not when beating in the weft.
At the bottom of the sword is fixed a projecting arm (or a cam motion may be used)
to which is attached a rod T with an adjustable collar U, so that when the sword makes
its forward motion it shall draw down the rod and adjustable collar U against the
lever P P 1 to one & the same point at every beat of the sword. So that when the
slightest increase of tension takes place, over that at which it has been set by the
spring V regulated by the nut W (or a sliding weight, the P 1 end of elbow-lever P P 1
is raised throwing back the catch Q which is again brought back by collar U at the
forward stroke of the sword, bringing with it catch-wheel & worm, thus giving off the
required length of warp to suit the demand.
To procure a fewer or greater number of picks per inch in the cloth it is only
necessary to tighten or slacken the nut W (or adjust the collar U) which may be made
to lock and thus prevent it from being tampered with by the weavers.
X is porcupine, sand or fluted roller or beam, as used in the linen looms.
Y is end elevation of cloth beam upon which the woven fabric is wound.
Z is hand wheel by which the warp-beam is turned back or "pulled back."

page_text: Having thus, described the features of my improvements & one means of carrying
the same into effect, I would have it understood that, I do not confine myself to any
particular construction of the balance lever "simple or compound" as it may be varied
without departing from the nature of my invention but what I do claim is-
Applying a light balancing arrangement, independent of the back-swing-rest, actuated
by the tension of all, or a part of the threads of the warp, or by the tension of the
woven fabric regulated by a spring or weight, to govern the number of picks per inch
in the cloth, and connected with the worm and worm wheel in the manner described.