Fig. 26.J.N.
(78) The regulation of the air current is one of the most important features in the working of a scutcher. Other things being equal, it is not too much to say that success or failure largely depends upon it. On the one hand, it is necessary to provide sufficient suction to draw the cotton forward and lay it evenly on the cages; on the other, an excess of suction is very detrimental, as, if the movement of the cotton is too rapid it will be drawn over the dirt grids before instead of after the dirt and leaf has fallen. More especially for the sake of the removal of leaf does the current require to be slow. With any other procedure the lighter matter cannot fall, and is carried forward to the cages. An excess of suction further results in the cotton fibres being drawn into the interstices of the cage surface, and the fleece does not in that case leave the latter easily. This results in a rough surface of the lap, and leads when it is rolled up to “licking,” or adhesion of the different layers.
(79) It is therefore desirable to get the draught as nearly balanced as is consistent with the required onward movement of the cotton. What is wanted is rather a large volume of air moving at a slow pace than a smaller one travelling more quickly. The fan should therefore be as large as can be conveniently arranged, and should be run at a comparatively slow velocity. Its exit orifice must be of ample size, and no obstruction be presented to the current of air. The latter is delivered into a passage or conduit running below the floor and terminating either in the open air or a specially-arranged chimney. All these passages must be made of ample size, and cases are numerous in which neglect of this requirement has resulted in the inefficient working of a machine which otherwise ought to have worked well. The atmospheric changes render it necessary to watch the regulation of the current so as to suit them, within limits.
Fig. 27.J.N.
(80) The precise effect of the arrangement of the dead-plate and beater-sheet referred to in paragraph 77 is to decrease the work thrown upon the fans. The beater, by reason of its rapid rotation, creates a sufficient current to carry the cotton on to the grids or extractor, if the space between the dead-plate and sheet is narrowed as described. If that be increased the effect of the impulse thus given is diminished proportionately. When so arranged, the cotton impelled as described passes gently over the leaf extractor, being aided by the slow current created by the fans, and thus allows the leaf to fall freely and without difficulty.
(81) In Fig. [27] a diagrammatic representation of Messrs. Platt Brothers and Company’s arrangement is given. In this case, also, the dead-plate is arranged so as to narrow the exit orifice from the beater, with a similar beneficial effect to that described. The cotton then passes over the bars of a dirt box L, into which the leaf can fall, being periodically removed.
(82) The feed apparatus used is now almost universally combined with a regulator which bears the name of its inventor, the late Mr. E. Lord, of Todmorden, and is commonly known as the “piano feed.” It is one of the most effective motions in the whole range of textile mechanics, and has considerably increased the regular working of this particular machine. Referring now to Figs. [28] to [31], which are respectively side, end, and plan views, it will be seen that the cotton is fed from the lattice H over the nose of the pedal lever A and under the feed roller B. After this it is struck by the beater G in its rotation. The shape of the pedal nose varies considerably, according to the length of the cotton used, the modification in Fig. [28] being that used for short, and the one in Fig. [29] being employed for long stapled cotton. The pedal lever is hinged upon a rod, and has behind its fulcrum a long tail piece which terminates in a hook I. On to this a pendant lever C is suspended. The lower portion of each of these pendants is widened so as to form a double taper surface, as shown in the end view at D. Between each pair of pendants, at its lower end, small runners or bowls are placed, these being fixed in rods sliding in the double frame F, which at the end E is tied together. The last of the series of pendants C1 is formed with a slot, as shown, with which a lever is jointed, as will afterwards be described, and as is further shown in Fig. [23], which is an end view of the machine shown in Fig. [22]. All the pendants can swing freely upon the pedal levers. The latter are placed, as shown in the plan, in close proximity to each other, so as to cover the whole space below the feed roller, while at the same time they have freedom of movement.
(83) Referring now more particularly to Figs. [22] and [23], the last pendant lever is coupled by the connecting rod O and the levers shown to the two strap levers E, which have sectors formed at one end gearing with each other. These levers carry the guides for the strap N, which is tightly placed upon the cones D D1. These are respectively convex and concave, their outline being a parabola. The cone D1 is driven by means of the strap shown from a pulley on a counter shaft, and revolves at a velocity of 600 revolutions. The other cone D is driven from D1 by the strap N, and is fixed upon a spindle or shaft which is carried upward (Fig. [23]). On the upper end of the shaft is a worm P engaging with a worm wheel R on the feed roller, which is driven by these means, or a change wheel may be interposed if desired.