With regard to the drawing functions of this machine, I have already given abundant explanation, so far as the properties and operation of the rollers are concerned. The frame-work of this part of the machine, called the roller-beam, is a cast iron bench, upon which nine bearers c, are mounted for carrying the rollers. The fluted rollers a a a, [fig. 334.], are constructed in four pieces for the whole length, which are parted from each other by thinner smooth cylindric portions z, called necks. Seven such partings for four rollers, and one parting for two rollers, constitute together the 30 fluted rollers of which the whole series consists. The coupling of these roller subdivisions into one cylinder, is secured by the square holes x, and square pins y, [fig. 334.], which fit into the holes of the adjoining subdivision. The top or pressure rollers b, are two-fold over the whole set; and the weighted saddle presses upon the neck w, which connects every pair, as was already explained under [fig. 329.] These weights g, g, [fig. 333.], are applied in this as in the drawing frame; d, are the bars faced with flannel for cleaning the top rollers. A similar bar is applied beneath the rollers, to keep the flutings clean.
The structure and operation of the spindles i, may be best understood by examining the section [fig. 335.] They are made of iron, are cylindrical from the top down to a2, but from this part down to the steel tipt rounded points they are conical. Upon this conical portion there is a pulley k, furnished with two grooves in its circumference, in which the cord runs that causes the spindle to revolve. The wooden bobbin h, is slid upon the cylindrical part, which must move freely upon it, as will be presently explained. To the bobbin another two-grooved pulley or whorl q is made fast by means of a pin r, which passes through it; by removing this pin, the bobbin can be instantly taken off the spindle. The upper end of the spindle bears a fork s t, which may be taken off at pleasure by means of its left-handed screw; this fork or flyer, has a funnel-formed hole at v. One arm of the fork is a tube s, u, open at top and bottom; the leg t, is added merely as a counterpoise to the other. In [fig. 333.], for the sake of clearness, the forks or flyers of the two spindles here represented are left out; and in [fig. 332.] only one is portrayed for the same reason. It is likewise manifest from a comparison of these two figures that the spindles are alternately placed in two rows, so that each spindle of the back range stands opposite the interval between two in the front range. The object of this distribution is economy of space, as the machine would need to be greatly longer if the spindles stood all in one line. If we suppose the spindles and the bobbins (both of which have independent motions) to revolve simultaneously and in the same direction, their operation will be as follows: The sliver properly drawn by the fluted rollers, enters the opening of the funnel v, proceeds thence downwards through the hole in the arm of the fork, runs along its tube u, s, and then winds round the bobbin. This path is marked in [fig. 335.] by a dotted line.
The revolution of the spindles in the above circumstances effects the twisting of the sliver into a soft cord; and the flyer s, t, or particularly its tubular arm s, lays this cord upon the bobbin. Were the speed of the bobbins equal to that of the spindles, that is, did the bobbin and spindle make the same number of turns in the same time, the process would be limited to mere twisting. But the bobbin anticipates the flyers a little, that is, it makes in a given time a somewhat greater number of revolutions than the spindle, and thereby effects the continuous winding of the cord upon itself. Suppose the bobbin to make 40 revolutions, while the spindle completes only 30; 30 of these revolutions of the bobbin will be inoperative towards the winding-on, because the flyers follow at that rate, so that the cord or twisted sliver will only be coiled 10 times round the bobbin, and the result as to the winding-on will be the same as if the spindle had stood still, and the bobbin had made 40 - 30 = 10 turns. The 30 turns of the spindles serve, therefore, merely the purpose of communicating twist.
The mounting and operation of the spindles are obviously the same as they are upon the household flax wheel. In the bobbin and fly frame there are some circumstances which render the construction and the winding-on somewhat difficult, and the mechanism not a little complicated. It may be remarked in the first place, that as the cord is wound on, the diameter of the bobbin increases very rapidly, and therefore every turn made round it causes a greater length of roving to be taken up in succession. Were the motions of the bobbins to continue unchanged in this predicament, the increased velocity of the winding-on would require an increased degree of extension, or it would occasion the rupture of the cord, because the front fluted rollers move with uniform speed, and therefore deliver always the same length of sliver in the same time. It is therefore necessary to diminish the velocity of the bobbins, or the number of their turns, in the same proportion as their diameter increases, in order that the primary velocity may remain unchanged. Moreover, it is requisite for the proper distribution of the cord upon the bobbin, and the regular increase of its diameter, that two of its successive convolutions should not be applied over each other, but that they should be laid close side by side. This object is attained by the up and down sliding motion of the bobbin upon the spindle, to the same extent as the length of the bobbin barrel. This up and down motion must become progressively slower, since it increases the diameter of the bobbin at each range, by a quantity equal to the diameter of the sliver. What has now been stated generally, will become more intelligible by an example.
Let it be assumed that the drawing rollers deliver, in 10 seconds, 45 inches of roving, and that this length receives 30 twists. The spindles must, in consequence, make 30 revolutions in 10 seconds, and the bobbins must turn with such speed, that they wind up the 45 inches in 10 seconds. The diameter of the bobbin barrels being 11⁄2 inches, their circumference of course 41⁄2 inches, they must make 10 revolutions more in the same time than the spindles. The effective speed of the bobbins will be thus 30 + 10 = 40 turns in 10 seconds. Should the bobbins increase to 3 inches diameter, by the winding-on of the sliver, they will take up 9 inches at each turn, and consequently 45 inches in 5 turns. Their speed should therefore be reduced to 30 + 5 = 35 turns in 10 seconds. In general, the excess in number of revolutions, which the bobbins must make over the spindles, is inversely as the diameter of the bobbins. The speed of the bobbins must remain uniform during the period of one ascent or descent upon the spindle, and must diminish at the instant of changing the direction of their up and down motion; because a fresh range of convolutions then begins with a greater diameter. When, for example, 30 coils of the sliver or roove are laid in one length of the bobbin barrel, the bobbin must complete its vertical movement up or down, within 30 seconds in the first case above mentioned, and within 60 seconds in the second case.
The motions of the drawing rollers, the spindles, and bobbins, are produced in the following manner:—A shaft c′, [fig. 332.] and [333.], extending the whole length of the machine, and mounted with a fly wheel d′, is set in motion by a band from the running pulley upon the shaft of the mill, which actuates the pulley a′. b′ is the loose pulley upon which the band is shifted when the machine is set at rest. Within the pulley a′, but on the outside of the frame, the shaft c′ carries a toothed wheel b2 with 50 teeth, which by means of the intermediate wheel c2 turns the wheel d2 upon the prolonged shaft of the backmost fluted roller (m2, [fig. 333.]) This wheel d2 has usually 54 teeth; but it may be changed when the roove is to receive more or less twist; for as the spindles revolve with uniform velocity, they communicate the more torsion the less length of sliver is delivered by the rollers in a given time. Upon the same shaft with d2, a pinion e2 of 32 teeth is fixed, which works in a wheel f2 of 72 teeth. Within the frame a change pinion g2 is made fast to the shaft of f2. This pinion, which has usually from 24 to 28 teeth, regulates the drawing, and thereby the fineness or number of the roving. It works in a 48-toothed wheel h2 upon the end of the backmost fluted roller a, [fig. 333.] The other extremity of the same roller, or, properly speaking, line of rollers, carries a pinion l2, furnished with 26 teeth, which, by means of the broad intermediate wheel k2, sets in motion the pinion i′2 of 22 teeth upon the middle roller. When the diameter of all the drawing rollers is the same, suppose 1 inch, their proportional velocities will be, with the above number of teeth in the wheel work, if g2 have 24 teeth, as 1 : 1·18 : 4·5; and the drawn sliver will have 41⁄2 times its original length. The front or delivery roller of the drawing frame is of late years usually made 11⁄4 or 13⁄8 inches in diameter. If 625 feet of the sliver from the drawing frame weighed one pound, 2790 feet of the roving will now go to this weight, and the number will be 1·12; that is, 1 hank and 12 hundredths to the pound. The front pair of fluted rollers makes about 90 revolutions, and delivers 282·6 inches of roving in the minute, when of one inch diameter.
The spindles i, ([fig. 332.] and [333.]), rest, with their lower ends, in steps l, which are fixed in an immoveable beam or bar m. To protect it from dust and cotton filaments, this beam is furnished with a wooden cover n, in which there are small holes for the passage of the spindles right over the steps. In [fig. 332.], two of the eight covers n, which compose the whole range m, are removed to let the steps be seen. The cylindrical part of each spindle passes through a brass ring o; and all these 30 rings, whose centres must be vertically over the steps l, are made fast to the copping beam p. This beam is so called, because it is destined not merely to keep the spindles upright by the rings attached to it, but, at the same time, to raise and lower along the spindles the bobbins which rest on these rings; for which purpose the two racks, or toothed bars m2 m2, made fast to it, are designed, as will be presently explained. To effect the revolution of the spindles, there are attached to the main shaft c′ two whorls or pulleys e′ f′, each bearing four grooves of equal diameter. Each of these pulleys puts one half of the spindles in motion, by means of a cord, which, after going round the whorls k, turns four times about the pulleys of the shaft c′. Two guide pulleys h′, each four-grooved, and two others i′, with a single groove, which turn independently of the others, upon the above shaft, serve to give the whorl cords the proper direction, as well as to keep them tight. The spindles revolve 200 times or thereby in the minute; and therefore impart two turns or twists to every three inches of the roving.
The revolution of the bobbins is independent of that of the spindles, although it likewise proceeds from the shaft c′, and differs from it in being a continually retarded motion. The simplest method of effecting this motion, is by means of the wooden or tin plate cone k′′, which revolves equally with the shaft c′, and at the same time slides along it.