(135) A further consideration in connection with this question is the problem of adjustment after the cylinder bearing has worn so as to alter the position of the centre of the cylinder. In this case the cylinder can be followed by the flexible bend and concentricity re-established, whereas, in the case of other arrangements which are based upon an unyielding surface attached to the framing, no such practice is possible. In this case it is necessary to provide a means by which the cylinder centre can be restored to its original position. The methods of doing this will be touched upon at a later stage.
(136) Before leaving the question of setting, it may be stated that the distance between the licker-in and the dish feed-plate is regulated according to the quality of cotton treated. Ordinarily the thickest gauge ·013 is used by Messrs. Platt, but if the cotton is deficient in strength the distance is increased by the thickness of the medium gauge, or in all is made ·024 inch. The licker-in is set by the medium gauge ·011, which is slipped easily between the licker-in teeth and those on the cylinder. The space left between the doffer and cylinder teeth is smaller, the finest gauge ·007 being employed in this case.
(137) In paragraph 132 it was stated that setting was mainly conducted by means of a gauge and by ear. It is often desirable to ascertain during work how the flats and cylinders are set relatively, and it is highly desirable to do this without disturbing the flexible bend. Up to quite recently this could only be done by gauging at each end in the ordinary way, and in the centre by the ear. Messrs. Platt Brothers and Company have, however, devised a method by which the setting of the flats can be instantaneously ascertained, and power is thus given to a spinner or overlooker to check the setting. In the flexible bend, at four points, narrow oblong slots are formed by casting, and are made of such a width that the carder’s gauge can be easily slipped between the cylinder and flat teeth, whatever may be the condition of the wire. The slots are, during work, stopped by plugs, which can be instantaneously withdrawn. The makers state that they have made careful tests to ascertain whether the presence of the slots affects the deflection of the bend, but do not find any ill effects. This is an extremely simple but very valuable improvement, and affords an opportunity of checking the setting, which cannot but be beneficial.
(138) The third form of carding engine is that known as the “Wellman,” or “Self Stripper.” It is extensively employed on the Continent, and in the United States. It is the direct descendant of Paul’s machine, inasmuch as it is based upon the principle of the employment of fixed flats superimposed upon the cylinder. In the early days of carding machines the flats surrounded a certain portion of the cylinder, and when they became charged with fly were lifted and stripped by hand. This practice was found to be very inconvenient, and a method of raising the flats automatically was therefore welcomed. For the finer counts of yarn cards on this principle were extensively employed in England, but the improvement of the revolving flat card has displaced it, and in this country at least it may be looked upon as an extinct type. The mechanism of the Wellman is ingenious, but for the reasons stated only a brief description of it will be given. Students who are interested in the subject can study it in the works of Mr. Evan Leigh in English, Mr. Neiss in German, or in one or two French books.
(139) The self-stripping card as made by Messrs. Dobson and Barlow, is shown in side view in Fig. [68]. The flats A cover the surface of the cylinder for about the same extent as in the revolving flat card. They are, however, stationary, and rest upon brackets B, each of which is capable of separate and delicate adjustment. On the cylinder shaft C an arm or lever D is placed, which is free to oscillate as required, its position being regulated by a pinion engaging with the rack E. The motion is driven from a grooved pulley, fixed on the cylinder shaft, which gives movement to a wheel behind the catch plate or wheel F. A sliding jaw traverses in the long slot at the top of the arm D, and is raised by a cam fixed on the spindle of the wheel F. When this upward movement of the jaw takes place the flat is lifted and held tightly between it and a fixed jaw formed on the arm D. While in this position the lever G, hinged at its lower end to D, is drawn inwards, and as it carries a wire stripping brush H it causes the teeth of the latter to pass through those of the raised flat, and thus remove the dirt and short fly. Immediately one passage is made the brush returns, and the flat is at once lowered into its position above the cylinder. By an extremely ingenious arrangement of mechanism the flats are not stripped consecutively, but are arranged to be stripped oftener near the licker-in than at the doffer end. The reason of this is obvious. By virtue of their position the earlier in the series of flats retain more dirt, and therefore require stripping oftener.
Fig. 68.J.N.
(140) From the mechanical point of view, the Wellman card and its predecessors will repay careful study, but as stated in paragraph 138, it has ceased to be used in England, and does not, therefore, come under the head of “modern” machinery. Yet there are principles involved in the Wellman which are of high merit and importance, and a system of carding is possible on this machine which is not possible on any other. To begin with, the distance of the flats from the cylinder may be varied at will, and instead of each flat being concentric with the latter, the circle described by the series may have another and distinct centre. That is to say, the flat at the feed end could be 1⁄8th inch away from the cylinder, while the one at the doffer end approached within 1⁄500th inch, all the intermediate ones being set proportionately. Again, the pitch of the wire teeth upon the various flats can widely vary. Those at the feed end may be, and often are, much coarser than those at the delivery end, a proportionate gradation of pitch occurring throughout the whole series. It will be at once seen that the conditions prevailing in a revolving flat machine are entirely contrary to this practice. In that machine the setting of all the flats is devised so as to make them equidistant from the cylinder centre, and every flat must of necessity be covered with wire clothing of the same counts.
(141) The effect of the peculiar setting referred to is, that, as the cotton is carried round by the cylinder, the fibres are gradually straightened by a series of combs which are at once nearer to the cylinder surface and finer in pitch, as the doffer is approached. Supposing, for instance, the pitch of the teeth on the first flat was 1⁄8th inch and their distance from those on the cylinder also the same, it would follow that the fibres flung up by the rotation of the cylinder would be at most only lightly treated. If, however, the pitch of the teeth and their setting became gradually finer, until the latter was reduced to 1⁄500th inch, it is easy to understand that the fibres would be, by a series of grades or steps, carded or combed. This treatment, on account of its gradual nature, results in the fibres being drawn out very straight, and is, when properly conducted, the nearest approach to combing which has been attained on a continuous carding machine. For the longer stapled cottons the use of a machine by which settings of gradually increasing fineness are obtained is especially suitable, and it was for these that the machine was mostly employed. Of course, the figures given above are merely hypothetical, and are used only to illustrate the point at issue.