XII Tying-up of Jacquard Looms With Compound Harness Attached
Tying-up of Jacquard looms with extra compound harness, consists in applying two separate systems of harness in the loom. The warp-threads, after having passed through the Jacquard harness, are passed through harness in front. Each system of harness performs special duty, although they are both working the same warp. The Jacquard harness is used for forming the general design on a large scale; the second harness divides this pattern into detail, (twills, satins, or any other desired weave). The above tie-up is necessary in the manufacture of rich damasks and similar fabrics, where a large number of warp-ends is required, with a correspondingly small number of picks per inch. Suppose a damask fabric to contain 300 ends warp per inch, with only 75 picks per inch; or in the proportion of 4 to 1. Now, to employ this principle of making four ends warp equal to one filling, the size of the design would be produced in the fabric, but the richness, and also the fineness, of the face of the fabric would be entirely lost. To prevent this it should be the object of the designer to keep the fine warp-threads entirely on the surface, to interweave the proportion of ends varying between warp and filling (as in example above, four warp-threads) separately. This principle of textures requires the compound harness to be attached; or, in other words, a machine must be used which is capable of raising not only every alternate thread, but every third, fourth, or eighth thread, if required, for the formation of the body of the cloth.
Fig. LXVI. illustrates as plainly as possible the principle of tying-up to do this work, using a 100 Jacquard machine for figuring, comber-board threaded in three divisions, four heddles to each leash, eight compound harnesses.
In the tying-up of Jacquard harness four heddles to one leash are generally used, as illustrated at c, in Fig. LXVI.; each heddle containing one warp-thread. Fig. LXVII. shows the arrangement of these four warp-threads, when using only one heddle to each leash, but in which the mail contains four eyes. This method is less frequently employed. Instead of using a 100 machine, as in Fig. LXVI.,
A 200 machine (straight-through) will require 800 warp-threads for each division.
300 machine (straight-through) will require 1200 warp-threads for each division.
400 machine (straight-through) will require 1600 warp-threads for each division.
600 machine (straight-through) will require 2400 warp-threads for each division.
900 machine (straight-through) will require 3600 warp-threads for each division.
1200 machine (straight-through) will require 4800 warp-threads for each division.
To change the tie-up principle from the straight-through method to the point method, taking a 1200 machine using four heddles per harness-cord, 9600 warp-threads will be required for each division for repeat of pattern.
This little example plainly shows the great advantage of this method of tying-up looms for making the finest damasks, etc.
To explain the general method of this tie-up, commence with Fig. LXVI., which represents a 100 machine, three divisions, four heddles to one leash, eight compound harnesses.
It will not be necessary to explain the threading of the comber-board, as this is always done on the same plain principles. The four heddles of the first row deep of comber-board emerge below the board at the beginning of the first division, marked a, a´, a´´, a´´´. The first row deep in comber-board in the first division, and the last row deep in comber-board in the third division only are shown; but as these two rows also indicate the first and last rows in the Jacquard machine, and as the principle of a, a´, a´´, a´´´, and b, b´, b´´, b´´´, has to be observed in every one of these 75 rows deep in width of comber-board E´ to E´´ taken, it will explain the tie-up for the entire number. At c, in leash a, four distinct heddles are adjusted; the same thing is repeated in every one of the eight leashes extended in drawing below the comber-board, giving in return, thus: four heddles and three divisions in a 100 machine = 4 × 3 × 100, or 1200 warp-threads for the entire fabric.
Now, following the first heddle downwards on leash 1, a, c, marked on drawing, d, (indicated by dotted lines), No. 1 harness of the compound harness, H, is reached. The cross X on this harness indicates that the warp-thread drawn through mail fastened on heddle, d, must also be drawn through No. 1 harness; the next heddle from the same leash will reach No. 2 harness; and so on until No. 4 harness is taken up, which will finish No. 1 harness-cord of No. 1 leash in the first division. The second harness-cord, a´, will use harness 5, 6, 7, 8; the third harness-cord, a´´, will use harness 1, 2, 3, 4, over again, as used by a; the fourth harness-cord, a´´´, will use harness 5, 6, 7, 8, over again, as used by a´.
Continue in this manner until leash 100 in the first division on harness 5, 6, 7, 8, is finished. The second and third divisions strictly repeat the first.
Fig. LXIX. represents the side elevation for Fig. LXVI. In both of these drawings some of the letters and figures correspond, as follows: harness-cords a, a´, a´´, a´´´, in first row deep of comber-board, E, E´. H shows compound harness set 1, 2, 3, 4, 5, 6, 7, 8; figures 1, 2, 3, 4, on top of comber-board represent the first row deep from the front elevation in drawing.
New letters: B, the warp-beam; Z, the lease of the warp formed by rods, Z´ and Z´´; O, the distance between the Jacquard harness and compound harness set, H. D, the shed, as formed in loom when weaving. For illustration of this shed pick No. 7 in Fig. LXVIII., shows that leashes 2 and 3, or a´ and a´´, are raised at the same time. Leashes 1 and 4, or a and a´´´, are not raised.
The principle of forming the shed for picking the shuttle will be more particularly explained later on by Figs. LXX. to LXXV.
At c, in Fig. LXIX., the beginning of the shed is shown; also the last woven part of the fabric, c, c´, c´´, which is indicated as passing around the breast-beam, F. L, L´, L´´, L´´´, indicate leashes 1, 2, 3, 4, extending to the Jacquard machine towards neck-cords 1, 2, 3, 4.
Fig. LXX. represents a warp-thread forming the bottom part of a shed. Mail, L, and harness, H, occupy a position similar to that of mail and harness for warp-thread passing through No. 1 heddle of leash a, and harness 1 in Fig. LXIX.
Warp-thread No. 2, passing through leash a, and harness 2, in Fig. LXIX. is the same.
Warp-thread No. 4, passing through leash a, and harness 4, in Fig. LXIX. is the same.
Warp-thread No. 13, passing through leash a´´´, and harness 5, in Fig. LXIX. is the same.
Warp-thread No. 15, passing through leash a´´´, and harness 7, in Fig. LXIX. is the same.
Warp-thread No. 16, passing through leash a´´´, and harness 8, in Fig. LXIX. is the same.
Fig. LXXI. shows a warp-thread forming part of the top shed by raising the leash; hence mail, L, is shown raised. The compound harness is supposed to be resting, which allows the warp-thread to slide up to the height of the required size of shed. This figure illustrates plainly the following warp-threads in Fig. LXIX.
Warp-thread No. 5, passing through leash a´, and harness 5, in Fig. LXIX. is the same.
Warp-thread No. 7, passing through leash a´, and harness 7, in Fig. LXIX. is the same.
Warp-thread No. 8, passing through leash a´, and harness 8, in Fig. LXIX. is the same.
Warp-thread No. 9, passing through leash a´´, and harness 1, in Fig. LXIX. is the same.
Warp-thread No. 10, passing through leash a´´, and harness 2, in Fig. LXIX. is the same.
Warp-thread No. 12, passing through leash a´´, and harness 4, in Fig. LXIX. is the same.
Fig. LXXII. illustrates the side view of a warp-thread where the hook of the Jacquard is not raised; hence, the mail remains in its resting place. Following the warp-thread towards c, the compound harness is shown raised, thus forming part of the top of a shed. This figure is designed to show the passage of the warp-thread through mail No. 3 of leash a, and harness No. 3, in Fig. LXIX.
Fig. LXXIII. illustrates a thread forming part of a lower shed. In the drawing the mail is raised, but at the same time the heddle of harness is lowered, compelling the thread to rest on the bottom of the lay. This figure is designed to show warp-thread passing through mail No. 6, of leash a´, and harness No. 6, in Fig. LXIX.
Fig. LXXIV. is a side view of a thread forming the upper part of a shed where mail and harness have been raised the same as in Fig. LXIX., the warp-thread passing through mail No. 11 of leash, a´´, and harness No. 3.
Fig. LXXV. illustrates mail not raised and harness down. This change is not necessary in Fig. IV.; the warp-thread forming the lower part of the shed.
In Figs. LXX. to LXXV. the following letters correspond with the same letters in Fig. LXIX.: Z´´, nearest lease-rod to Jacquard harness; D, shed for picking shuttle; C, starting point of shed or last woven place of fabric.