_DROP-BOX LOOMS_
Where more than one kind or colour of weft is used in a fabric, it is,
of course, necessary to change the shuttles automatically. Sometimes
two or more different counts of weft of the same colour are used, and
sometimes different colours of weft. Checks of all kinds, extra weft
spots, and others are the chief classes of fabrics which require change
boxes.
[Illustration: FIG. 76.]
The oldest and commonest form is the Diggle’s chain motion illustrated
at Fig. 76. The number of boxes used in this motion is either 2, 3,
or 4. It would be possible to use more, but it is not usually done
with this arrangement for operating them. A lever, AC, is centred at C
(Fig. 76), and the friction bowl B on this lever is moved upwards by a
chain, composed of links fastened together on pins, which work round a
barrel, D. These links are of different sizes, according to the number
of boxes used. The smallest link leaves the top box in a line with the
shuttle-race, and the other links are of such a size as to raise either
the second, third, or fourth boxes (assuming that there are four) into
this position. The general method is to raise the boxes one at a time,
and drop them all together, but this is not compulsory. It will be
seen that the motion of the boxes is not positive downwards--that is,
the boxes drop by their own weight, and are not mechanically forced
down, as in Wright Shaw’s or Whitesmith’s motions--and it will be well
understood that there will thus be a limit to the speed at which the
loom can be run. The method of turning the barrel D which carries the
chain is as follows. A wheel, E, on the crank-shaft drives a larger
wheel, F, above it. On the face of this wheel, F, is a rim and two
projections, PP, or, it may be, only one projection. These projections
or pins gear into the star wheel G, which is fastened to the barrel
carrying the chain, and therefore when the star wheel is turned one
tooth, or one-eighth of a revolution, it will move the chain a space
of one link. The wheel E on the crank-shaft often has one-fourth the
number of teeth contained in the wheel F; therefore, if there are two
pins or projections, PP, in the circumference, the star wheel will be
moved one tooth every two picks, and the boxes may be changed so often
by making the chain accordingly. The lever M, which is centred at R,
has the boxes attached to one end, and the other end may be pressed
down by the foot when it is required to lift the boxes for any purpose
when the loom is stopped. Supposing the wheel E to have 15 teeth and
F 60 teeth, if there are two projections, PP, on the face of F, the
shuttle may be changed every two picks, but if there is only one
projection or pin, there may be a change every four, or a multiple of
four picks.
The chief disadvantage of this motion in the form given at Fig. 76 is
that the chain becomes very cumbersome if a long pattern is required.
To obviate this, the projections PP are, in an improved motion, made
so that they can be withdrawn from gear with the star wheel. This
is effected by a clutch motion which is subsequently described in
connection with the “pick-and-pick loom.” With this improvement, each
link in the chain may be made to represent any number of picks, the
number being regulated by a small chain of metal cards, and thus larger
patterns may be made without the long heavy chains which are required
in the ordinary “Diggle.”
The Diggle’s chain principle, although suitable for some types of
looms, is not an ideal motion, as the downward movement of the boxes
is negative. The boxes have nothing to force them down but their own
weight and the weight of the levers connected with them, and this
necessitates the loom being run at a slower speed than is the case
with some of the positive drop-box motions. Of this latter kind Wright
Shaw’s motion is one of a great variety of different types, and has
been in use for a long time.
WRIGHT SHAW’S DROP-BOX.
The principle of this motion will be understood from the diagram,
Fig. 77. The essential feature of this invention is a forked rack, G,
suspended from the free end of a treadle lever, E, fulcrumed at F,
and carrying a bowl or runner, D, near the centre. At one end of the
second motion or picking shaft, A, of the loom, are two cams, B and C,
either of which may be brought underneath the treadle bowl at will, so
as to raise the treadle and forked rack once during each revolution of
the picking shaft, corresponding to two picks. Passing midway between
the two prongs, H, H′, of the fork is a short shaft, upon which are
secured two toothed wheels, I and J. Wheel I is so placed that the
teeth on either side of the rack may be put into engagement with its
teeth just before the fork rises, so as to turn the wheel in either
direction; or the rack may occupy a neutral position when rising,
in which event the wheel remains stationary. In any case, the racks
are always clear of the wheel when descending. Immediately in front
of wheel I is another similar wheel J, whose teeth are in permanent
engagement with those of a rack, K (an extension, L, of which supports
the shuttle-boxes, M). Thus, if rack H′ is put into gear with wheel I,
boxes will be depressed as the rack rises; but if rack H operates, the
boxes will be raised. One box, or two boxes, only, may be either raised
or dropped at one change, according to which rack and which cam is put
into operation. The smaller cam moves one box, and the larger cam two
boxes, either up or down.
[Illustration: FIG. 77.]
The selection of racks and cams is made by pattern cards (detached)
which pass over an octagonal prism, N. The cards are presented
separately, once in two picks, to three selecting needles, 1, 2, 3.
The two outer needles, 1, 3, are attached one at each end of a double
arm secured at the top of a long vertical shaft, O, the bottom of
which communicates with the forked rack G. Thus a depression of boxes
is effected by a blank part of a card pressing against needle 1, and
an elevation of boxes by pressing back needle 3. Shaft O is loosely
contained within a long tube or sleeve, P, which carries a short arm,
R, at the top, and a forked clutch, Q, which acts upon the boss of
cams, B and C. If it is desired to move two boxes, needle 2 is pressed
back, thereby causing an inclined piece, S, secured to it, to act upon
arm R so as to slightly turn the sleeve P, and move the larger cam C
under the treadle bowl at a time when the short side of the cam is
uppermost, as indicated in the diagram, Fig. 77. At one point, the
larger and outer cam is slightly lower than the smaller one, and can be
readily moved under the bowl.
The various changes which can be made by this motion may be seen by
referring to the cards at Fig. 77. When there is a blank opposite the
first needle only, the rack H′ is pushed to the left and the boxes are
moved “down one.” When there is a blank opposite the third needle only,
rack H is moved to the right and the boxes are forced “up one.” When
there are blanks opposite the first and second needles, they are pushed
backward, thus moving rack H′ to the left, and also forcing the larger
cam under the treadle bowl, in which case the boxes will be moved “down
two.” When there are blanks opposite the second and third needles, they
are pushed backward, and the boxes are “raised two.” When there are
three holes in the card, the racks, when lifted, miss the wheel, and
there is “no change” in the boxes. It will be seen that the boxes may
be moved either up or down, a space of one or two boxes only at a time.
There may be more than three boxes, as many as five being regularly
used; but if there were five, it would not be possible to change from
the first box to the fourth or fifth. The greatest change which can be
made is from the first to the third, fourth to second, and so on.
WHITESMITH’S DROP-BOX.
[Illustration: FIG. 78.]
[Illustration: FIG. 79.]
[Illustration: FIG. 80.]
The principle of Whitesmith’s motion is probably the best for any
number of boxes. It is usually made for four, and the change may be
made with certainty from one box to any other. The arrangement for
working four boxes in a loom is illustrated at Figs. 78, 79, 80. The
principle will be best understood by referring first to Fig. 80. The
four different positions of the boxes are here shown. The boxes are
connected to the ring or strap of an eccentric at the point E, and
at A the position of the parts is shown when the boxes are at their
lowest point. The eccentric, F, on the shaft has a lift of one box,
and therefore by causing it to make half a revolution intermittently
every two picks, the boxes would be alternately lifted and dropped a
space of one box, as will be seen by referring to C (Fig. 80), where
it has made half a revolution from its position at A. It will be seen
that E is one box higher at C than at A. Starting again from the first
position, as at A, by turning the outer ring halfway round and leaving
the eccentric stationary, there will be a lift of two boxes. This is
shown at B (Fig. 80). Again starting with the first position, as at A,
if we turn the outer ring halfway round, and at the same time turn the
eccentric F half-round, we lift a space of three boxes--that is, from
the first to the fourth box. The position of E in this case is shown
at D (Fig. 80). We thus see how from the bottom box any other of the
four can be reached. By turning the eccentric halfway we lift one box,
by turning the ring halfway round we lift two boxes, and by turning
both ring and eccentric halfway round we lift three boxes. If we are at
the third box, as at B (Fig. 80), and we wish to reach the second box
or one lower, by turning the eccentric half a revolution and the ring
half a revolution we shall get the position required. It will thus be
seen that any one of the four boxes may be reached at will. At Fig. 79
another view of the eccentrics and boxes is given. The wheel H is keyed
to the shaft on which the eccentric is fixed, and riding loosely upon
this shaft is another wheel, I, of the same size, to which a fork, K,
is attached. This fork fits on to a pin at the back of the ring, and
thus by turning the wheel I the ring can be moved independently of the
eccentric. If the wheel H is moved it moves the cam, and if the wheel
I is moved it moves the ring. Referring now to Fig. 78, the wheel H is
shown. This wheel is driven by a wheel, I (Fig. 79), twice its size. On
the face of the wheel L there are four pins, and by lifting the lever
OP at O, the pulling hook M is dropped round one of the pins, and the
hook being moved forward by the crank Q will cause the wheel L to make
a quarter of a revolution and the wheel H to make half a revolution,
and therefore the eccentric is moved half a revolution. On the same
stud as the wheel L there is another wheel exactly the same size and
with four pins; this wheel (which cannot well be shown in the diagram)
gears into the wheel I shown in Fig. 79. There is also another pulling
hook which works along with M. This second pulling hook is operated by
another lever like OP. There are two levers, X, which are lifted by
the cards, and by lifting X, either, or both, of the pulling hooks may
be dropped, and either of the wheels I or H (Fig. 79) turned half a
revolution, but always in the same direction.
The wheel L and its companion are prevented from turning too far by a
strong friction arrangement.
This motion may be adapted to work six boxes, or even more. For six
boxes there is another eccentric inside the first eccentric, which can
be worked independently; this will, of course, require a third pulling
hook, and so on.
Many loom-makers have patented arrangements on the same principle,
which do away with the pulling hooks M, and it is probably in this
direction that the motion may be improved.
The Whitesmith principle is simple, and positive throughout, and it is
difficult to see why it is not in more general use. It is generally
admitted by those who have had practical experience of drop-box looms
on this principle that it is the best. There are other drop-box
motions, but the foregoing are the chief kinds.
CIRCULAR-BOX LOOMS.
These are not used in the cotton trade to anything like the extent
they are in the woollen and worsted trades, especially in Yorkshire.
It is remarkable that this should be the case, as it is claimed for
circular boxes that they can be run at a higher speed than any other
kind. Circular boxes are usually made for six shuttles, generally
to move only one box at a time, but they are made to skip one box,
although the arrangement is by no means so simple or satisfactory as in
a well-made loom on Whitesmith’s principle, where the changes are made
from one box to another almost noiselessly. At Fig. 81 the mechanism of
a circular-box motion is shown. There are two hooks, A and B, which act
upon pins outside the boxes. When the hook A is pulled down the boxes
will be turned one to the right, and when B is pulled down they are
turned one to the left. A lever, EF, is connected with the lower part
of each hook, and another lever, M, is lifted every two picks by means
of a cam, C. The cards lift or drop the ~L~ lever QS at S, and so
the hook H can either be lifted or left down by the lifter M, and the
boxes can be turned one in either direction. A disadvantage of circular
boxes is that they cannot be used in fast-reed looms on account of the
difficulty of operating the stop rod from the back of the boxes. They
are therefore only used for weaving the lighter classes of fabrics.
[Illustration: FIG. 81.]
PICK-AND-PICK LOOM.
The majority of box looms are made with movable boxes at one side of
the loom only, so that single picks of any colour cannot be put in the
cloth at will. As it is very desirable in many fabrics to use single
picks of a colour or count of weft, it is necessary to have movable
boxes at both sides of the loom, and where this is the case it is usual
to have picking mechanism which will allow of several picks being made
in succession from either side of the loom. If the matter be carefully
thought over, it will be easily apparent that even with drop boxes
worked quite independently of each other at both sides of the loom,
if the picking mechanism is of the ordinary kind--viz. to pick once
from each side alternately--it would be impossible to obtain that
variety of changes in the shuttles which is in many cases necessary. In
a loom with two boxes at each side worked independently, it would be
impossible to obtain single picks alternately of two colours or counts.
But by being able to pick twice in succession from each side this can
be done. By going through all the changes possible with a given number
of boxes, the advantage of this kind of picking arrangement will be
very apparent, in the command it gives over any shuttle in the series
for any pick. It is therefore necessary to have the picking mechanism
aforementioned in order to allow of all the boxes being emptied at one
side if required. A loom of this character is called a “pick-and-pick”
loom; the picking motion is sometimes called a “pick at will” motion.
The loom which we take as an example is one on the Diggle’s chain
principle. There are two chains, placed at one side of the loom for
convenience. Both chains are on one barrel, A (Fig. 82). The chain for
working the boxes at the right-hand side of the loom operates the lever
B, and the left-hand chain operates the lever C, the fulcrum of both
levers being at D. When these levers are lifted they lift the levers E
and F, and when E is lifted it lifts the boxes at the right-hand of the
loom, and when F is lifted it lifts the left-hand boxes. The connection
of the left-hand boxes with the lever F is shown at Fig. 83. The shaft
G is placed under the loom, and the left-hand boxes are connected to
the lever H, which is fast to the shaft G. The lever F is also fast
to the shaft G, but the lever E rides loosely upon this shaft, which
merely serves as a fulcrum for E. From these two figures it will be
clearly understood how the boxes may be worked independently at both
sides of the loom by two chains placed side by side upon the barrel A.
[Illustration: FIG. 82.]
[Illustration: FIG. 83.]
[Illustration: FIG. 84.]
[Illustration: FIG. 85.]
In order to make each link in these chains represent any number of
picks, and thus prevent long cumbersome chains, the mechanism shown
at Figs. 84 to 87 is employed. The barrel A in Fig. 84 is the same as
barrel A in Fig. 82, and carries the chains for lifting the levers B
and C. At the end of the barrel the star wheel I is fixed, and this
star wheel is turned by the pins J. These pins are worked by a clutch
motion shown at Fig. 86, by which they can be withdrawn from gear with
the star wheel as desired. The pins KK are fixed, and turn one tooth
of the star wheel Y every pick, the wheel M having twice the number of
teeth contained in L, which is on the crank shaft of the loom. The star
wheel Y is fast to the end of a small octagonal barrel, which carries
a pattern chain N composed of small metal cards, and we have seen how
this barrel is turned one division every pick. Above this pattern chain
N a finger, O (Fig. 86), is placed, and is lifted up against a spring
every pick by the cam P on the face of the wheel M. When the finger
is up, the pins JJ are taken inside the wheel M, as shown at Fig. 86.
The cam P only raises the finger a sufficient length of time to allow
the barrel Y to be turned round, and if there is a blank in the cards
opposite the finger O when it is let down by the cam it will still keep
the pins J inside the wheel, and will thus prevent either of them from
engaging with the star wheel I, and will leave the boxes unchanged.
This can be repeated any number of picks. If a change is required in
the boxes, a hole is placed opposite the finger O, and when it is let
down the pins J project through the wheel M (as indicated by the dotted
lines in Fig. 86), and the star wheel I will thus be turned one tooth,
and the chain can make the change required in the boxes.
[Illustration: FIG. 86.]
[Illustration: FIG. 87.]
Fig. 87 is another view of the cam-shaped projection P, which raises
the finger every pick, and Fig. 85 is another view of the chain barrel
A. The letters in the six Figs. 82 to 87 inclusive refer to the same
parts in each case.
In this way the chains on A are rarely required to be very long, as one
link may be made to represent any number of picks from one upwards. Of
course a separate card on Y is required for each pick, but these are
very small, only about 1½ inch in length, and a large pattern can be
made with very little trouble.
When a Jacquard is used on one of these looms it is sometimes necessary
to work the pattern from the Jacquard cards. This can be done in a very
simple manner by covering the hole in the barrel carrying the cards N
with a metal plate, which is held over the hole by a spring. When a
change is required in the boxes, a Jacquard hook pulls the plate from
over the hole, and allows the finger O to drop, and thus causes the
star wheel I to be engaged by the pins J.
The picking mechanism in a pick-and-pick loom may be either over or
under pick. In the former the picking tappets are sometimes moved on
the shaft by a clutch arrangement. In the latter the top of the picking
treadle is movable. As the under pick is perhaps the best adapted for
this loom, we will describe it.
[Illustration: FIG. 88.]
Fig. 88 is a side view of the loom, and the top of the picking treadles
consists of a metal plate with the “shoe” S of such a shape as to give
the required force and character to the pick. This metal plate works
round a pivot, P. The treadles at both sides of the loom are the same
in this respect. At the back of the loom a rod, R, is connected to the
extreme ends of the loose plates or the treadles, and when one plate
is _on_ the treadle, the other is fixed _off_ its treadle, as shown
in Fig. 89. The consequence is that when the picking bowls come round
(there are two bowls on the bottom shaft at each side of the loom) the
loom will pick always from that side where the loose plate is _on_ the
treadle, and at the other side, where the plate is _off_, the bowls
will pass over the treadle without touching it. By moving the rod R
sideways, the plates may be moved alternately off and on their treadles.
[Illustration: FIG. 89.]
[Illustration: FIG. 90.]
If the loom has four boxes at each side, it may be necessary to pick
four times in succession from one side of the loom, and by a simple
arrangement the picking can be regulated at will. The mechanism
for moving the rod R sideways is shown at Fig. 90. Inside the loom
framework a lever, L, is centred at C, and by a combination of levers
is connected to the rod R, which is the rod referred to in the previous
diagrams. A strong spring keeps the plates right for picking from one
side, but when it is required to pick from the other the lever L is
lifted, which moves the rod R sideways and moves the plate off one
treadle and on the other. A chain is used for lifting the lever L, and
the star wheel A is turned by two pins on the wheel B on the bottom
shaft of the loom, or by one pin if on the crank shaft, thus causing
the star wheel to be turned one division every pick. The loom may thus
be made to pick four times from the right side, three from the left,
twice from the right, and so on, of course always taking care that the
shuttles are there to be picked.