Part 14 (1/2)

This reversal only occupies two or three seconds, and as the motion imparted to the spindles is very slow at this stage, the practical effect is, that a small portion of yarn is ”_uncoiled_” from each spindle, sufficient to allow of two ”guide wires” to a.s.sume proper and necessary positions for winding the attenuated threads upon the spindles.

These two wires are termed ”faller wires,” and while one is controlled by the cop-shaping mechanism and termed the ”winding faller wire” the other simply keeps the threads in the requisite state of tension during ”winding on” and is termed the ”counter” or ”tension faller wire.” Both these wires can be seen in Fig. 28. During backing off, the ”winding faller wire” has a descending motion, while the ”counter faller” has an ascending motion, these being necessary for them to attain their proper positions for ”winding on.”

Image: FIG. 28.--Mule showing action of faller wires.

The movement of these faller wires into proper position, and the uncoiling of a small portion of yarn from each spindle, are both brought about by the ”backing off” motion, which formed an important part of Roberts' Mule. It may be remarked, however, that certain of the predecessors of Roberts had made great efforts in this direction, thus making the way much easier for his applications, which were entirely successful. When ”backing off” is completed, all the necessary parts are in position for winding the 64 inches of thread just given out upon each spindle.

This practically involves three primary and most important operations.

(1) The drawing-in of the carriage back to its original position. (2) The revolution of the spindles at a speed suitable for winding the threads upon the spindles as the carriage moves inwards. (3) The guiding of the threads upon the spindles in such a manner that a cop of yarn will eventually be formed upon each spindle, of such dimensions and shape as to be quite suitable for any subsequent processes or handling.

Taking these three important divisions in the order given, it may be said that the drawing-in of the carriage is effected through the medium of the ”scroll” bands, which are attached to the carriage at one end, and to certain spiral scrolls or fusees at the other end. The scrolls being revolved, wind the cords or bands round them, so pulling in the carriage. There are usually two back scroll bands and one front band, the latter being a sort of check band upon the action of the other two.

What is termed the ”rim band” revolves the spindles during the outward traverse of the carriage.

The drawing-in of the carriage in a sense causes the other two operations to be performed. With respect to the second of these, viz., revolving the spindles and thus winding the threads upon them, it may be said this action causes what is termed the ”Winding Chain” to pull off a small drum of six inches diameter, thus rotating the latter and thereby the spindles. Here, however, comes in now the action of the very beautiful and effective piece of mechanism, ”Roberts' quadrant” (see Fig. 26). The winding chain just mentioned is attached to one extremity to the arm of the quadrant, and the peculiar manner in which the quadrant moves in relation to the winding drum gives the variable motion to the spindles that is required.

When commencing a new set of cops it may take about eighty revolutions of the spindles to wind on the 64 inches of thread to each spindle, representing one stretch. The bare spindle may be about a quarter of an inch in diameter, but it may finally attain a diameter of an inch and a quarter (_i.e._, the cop upon the spindle). This cop will only require about twenty revolutions to wind on the 64 inches, which are only one-fourth of the revolutions necessary for the empty spindles. It is the action of the quadrant which gives this variation in speed to the spindles during winding-on.

But as has been pointed out previously, the quadrant imparts a ”differential winding” motion to the spindles in two distinct and different ways, and the second motion is even more important than the first.

It is necessary for practical purposes that the cop of yarn should be built up of a conical shape in the upper part, as shown in the ill.u.s.tration. Now it must be obvious to the least technical of the readers of this story, that to wind a given portion of yarn upon the thin apex of a cone, will require a greater number of revolutions than would be necessary to wind the same length of yarn upon the base of the same cop. All the way between the apex and the base of the cone are also other varying diameters, and during each return movement of the mule carriage the thread is wound upon all the varying diameters of the cone in succession.

This implies the necessity for the revolutions of the spindles to a varying quant.i.ty all the time of the return or inward movement of the spindle carriage.

The quadrant gives this varying speed in a manner which is all but mathematically correct, any slight deviation from any such mathematical correctness being easily compensated for in other ways.

For the specific manner in which this quadrant works, the reader is referred to any of the recent text-books on cotton spinning.

The third primary and important operation, which takes place during each return movement of the carriage, is the guiding of the thread upon the spindles in a correct manner. This operation is closely a.s.sociated, however, with the action of the quadrant.

That portion of a ”self-actor mule” which guides the faller wires is termed the ”shaper” or ”copping motion.” It consists of an inclined iron rail upon the upper smooth surface of which slides the ”copping bowl,”

this being a portion of the mechanism which connects the rail with the faller wires. The rail rests upon suitable inclines termed ”copping plates,” whose duty it is to regulate the movement of the rail so as to allow for the ever-increasing dimensions of the cop during the building process. When the carriage again reaches its initial position, suitable mechanism causes all the parts to return in the position required for spinning.

Such is the complete cycle of movements of the ”mule,” each succeeding cycle being simply a repet.i.tion of the preceding. It will probably take such a mule as the one described about six hours to make a ”set of cops,” _i.e._, one on each spindle, each cop being 1-1/4 inches in diameter and 7-1/2 inches long. Every fifteen seconds, while the mule is making a cycle of its movements, may be divided up approximately as follows: nine seconds for the drawing-out and twisting; two seconds for backing-off; four seconds for winding-on and resuming initial position.

A mult.i.tude of minor motions and details might be easily expanded into several chapters; in fact, more can be said about the mule than about any other spinning machine, but such detailed description would be out of place in this story.

All the motions just named are centred in what is termed the ”Head Stock,” this being placed midway in the length of the mule.

This head stock receives all the power to drive the various motions, from the shafting and gearing, and distributes it in a suitable manner to various parts of the machine.

It will have been observed by this time, that, as in the case of the bobbin and fly frames, the intricate and wonderful mechanism of the self-actor mule is not devoted to the formation of threads, but to the effective and economical placing of the threads of yarn, in the form of cops, after it has been spun.

Image: FIG. 29.--Mule head showing ”copping rail.”

The spinning processes take place during the outward traverse of the mule carriage, the mechanism involved in this motion being comparatively simple. The really complicated and difficult motions being ”backing-off,” revolving the spindles ”during winding-on,” and the guiding of the spun threads upon the spindles during the winding-on process. It was the addition of these three motions by the later inventors which gave the mule the t.i.tle of ”Self-Acting.”

CHAPTER X.