Jacquard Weaving and Designing

by T. F. Bell

Fig. 116

As has been stated before, one of the drawbacks to a pressure harness is the strain which the warp has to undergo when forming the shed. This necessitates having a good warp, which adds to the cost of the cloth, and in low-class goods this consideration may hinder the sale. Many methods have been adopted for working the ground of the cloth without using a pressure mounting. Some of these are explained under ‘half harness’ and ‘split harness,’ but none of these methods would produce cloth like the pressure harness. A twilling jacquard to act similar to the pressure harness, but without using the front mounting, or by dispensing with the leaves of heddles, was patented by Mr. Shields, of Perth, in 1859. This machine underwent several improvements, and now there are two varieties of it in use, one known as the Irish or Bessbrook machine, being patented by Mr. Barcroft, of the Bessbrook Spinning Company Limited, county Armagh; the other as the Scotch machine, the improvements being made by Mr. Shields and others. The principal difference between the two machines is that the blades or knives of the griffe have a horizontal or sliding motion in the Scotch machine to enable them to get clear of the heads of the hooks, whereas in the Bessbrook machine they turn out of the way or partly revolve. A full description of the Bessbrook machine is here given. [Fig. 116] is a view of the framing of the machine. K is the cylinder, which may be wrought by the swan-neck motion, as shown, but it is better to be wrought by a separate motion from the loom. D is a cord attached to the handle of the shears for reversing the cylinder; E is a brass bushing through which a shaft passes for raising the griffe. The shedding of this machine is exactly the same as that of an ordinary single-acting jacquard. The griffe rises and falls for every shot; the cylinder travels out and in, but does not turn till two or three or whatever number of impressions required are given by each card. To prevent the cylinder turning it is only necessary to raise the shears so that they will not catch it. This is done by means of the tappet A, shown in Figs. 116 and 117. The roller H on the shears rests on the tappet, which is turned by means of the rack wheel, which is fast on it, and the lever L, which is loose on the stud. This lever is pushed backwards and drawn forwards by the rod I, which is connected to an arm, either on the shaft for raising the griffe, or on one for working the cylinder, and the catch on the lever takes a tooth of the ratchet wheel at each draw, so that with four divisions on the tappet, and 12 teeth in the ratchet, three shots would be given to each card. If it is required to work the cylinder the reverse way, it is only necessary to tie the cord D on the end of the shears to a spiral spring made fast to any convenient part of the loom, then the roller C will be acted upon by the underside of the tappet, and the under hook of the shears will turn the cylinder when required. B is a spring acting as a pawl to keep the ratchet from moving backwards, and there is also a spring shown over the catch which moves it forward; both these springs serve to keep the tappet steady. There are two sets of hooks and needles in this machine—the ordinary set for working the harness, as shown at A ([Fig. 118]), and a set of twilling hooks, one row at each side of the machine, which are much stronger than the others. The ends of the twilling hooks are hooked round bars, which pass through the loops at the lower ends of the ordinary hooks, as shown at C ([Fig. 118]). These bars are kept in their places by a grid D, which is between the ordinary hooks and the twilling hooks. Each of the needles of the jacquard is connected with two or more of the ordinary hooks, as shown at A. The twilling hooks have also needles on them, but they are only for the purpose of keeping them in their places, and are not acted upon by the cards. The springs of these needles are on the ends next the cards, or at the back of the faceplate or needle, as shown at E. The centre support for the knives of the griffe is shown at F, with an end view of two knives G G. The ends of the knives enter the griffe frame at each side, so as to allow them to oscillate or partly revolve. This motion is given to them by a set of bars or flat needles, as shown at A ([Fig. 119]). A single needle is given at A¹. These needles have each the notch in them over the top edge of two or more of the knives, and are acted upon by a barrel C with studs in it, set to the twill. This barrel rises and falls with the griffe, and is turned from one row of pegs or studs to the next one each time the griffe falls by the head or lantern on it coming down on a finger, as shown at A (Fig 120). B in the same figure is a strong spring to keep the barrel steady and make it turn the correct distance.

Fig. 117

The number of knives in the griffe must be regulated to suit the twill to be put on the cloth; they must be a multiple of the twill, and this to some extent regulates the number of needles that must be in each upright row. For example, an 8-leaf twill may have 16 or 24 knives, which would be twice or three times over the twill. If there are 8 rows of needles to 16 knives, or 16 rows of hooks, that would be 2 hooks to each needle, or if there are 24 rows of hooks there must be 3 hooks to the needle; but if only 2 hooks to the needle are required, there must be 12 rows of needles to 24 rows of hooks. The same principle holds good for a 5-leaf, or any twill. Eight or 12 rows of needles would not be suitable for a 5-leaf twill, neither would 10 rows of needles be suitable for an 8-leaf twill, if the same number of hooks have to be connected with each needle; but 10 rows of needles with 20 rows of hooks or 20 knives will answer for a 5-leaf twill with 2 hooks to the needle, or would answer for an 8-leaf twill with 24 rows of hooks, 4 of the needles to have 3 hooks to each, and 6 of them to have 2 hooks to each.

Fig. 118

Each of the twilling needles, A, [Fig. 119], must be connected with as many of the knives as there are repeats of the twill; thus, for 24 with an 8-leaf twill, the 1st, 9th, and 17th knives would be acted upon by the one needle, and so on with the others.