Each sliver, and there maybe from four to eight or more in a set, is led from its sliver can at the far side of the machine to the sliver guide and between the retaining rollers. Immediately the slivers leave the retaining rollers they are penetrated by the gill pins of a faller which is rising from the lower part of its circuit to the upper and active position. Each short length of slivers is penetrated by the pins of a rising faller, these coming up successively as the preceding one moves along at approximately the same surface speed as that of the retaining rollers. The sheet of pins and their fallers are thus continuously moving towards the drawing rollers and supporting the slivers at the same time. As each faller in succession approaches close to the drawing rollers, it is made to descend so that the pins may leave the fibres, and from this point the faller moves backwards towards the retaining roller until it reaches the other end ready to rise again in contact with the fibres and to repeat the cycle as just described. It will thus be seen that the upper set of fallers occupy the full stretch between the retaining rollers and the drawing rollers, but there is always one faller leaving the upper set at the front and another joining the set at the back.

Fig. 17 PUSH-BAR DRAWING FRAME

The actual distance between the retaining rollers and the drawing rollers is determined by the length of the fibre, and must in all cases be a little greater than the longest fibre. This condition is necessary because the surface speed of the drawing roller is much greater than that of the retaining rollers; indeed, the difference between the surface speeds of the two pairs of rollers is the actual draft.

Between the retaining and drawing rollers the slivers are embedded in the gill pins of the fallers, and these move forward, as mentioned, to support the stretch of slivers and to carry the latter to the nip of the drawing rollers. Immediately the forward ends of the fibres are nipped between the quickly-moving drawing rollers, the fibres affected slide on those which have not yet reached the drawing rollers, and, incidentally, help to parallelize the fibres. It will be clear that if any fibre happened to be in the grip of the two pairs of rollers having different surface speeds, such fibre would be snapped. It is to avoid this rupture of fibres that the distance between the two sets of rollers is greater than the longest fibres under treatment. The technical word for this distance is "reach."

On emerging from the drawing rollers, the combed slivers pass between slicking rollers, and then approach the sliver plate which bridges the gap between the slicking rollers and the delivery rollers, and by means of which plate two or more individual slivers are diverted at right angles, first to join each other, and then again diverted at right angles to join another sliver which passes straight from the drawing rollers and over the sliver plate to the guide of the delivery rollers. It will thus be seen that a number of slivers, each having been drawn out according to the degree of draft, are ultimately joined to pass through a common sliver guide or conductor to the nip of the delivery rollers, and thence into a sliver can.

The push-bar drawing illustrated in Fig. 17, or some other of the same type, is often used as the first drawing frame in a set. With the exception of the driving pulleys, all the gear wheels are at the far end of the frame, and totally enclosed in dust-proof casing. The set-on handles, for moving the belt from the loose pulley to the fast pulley, or vice versa, are conveniently situated, as shown, and in a place which is calculated to offer the least obstruction to the operative. The machines are made with what are known as "two heads" or "three heads." It will be seen from the large pressing rollers that there are two pairs; hence the machine is a "two-head" drawing frame.

The slivers from the first drawing frame are now subjected to a further process of doubling and drafting in a very similar machine termed the second drawing frame. The pins in the gills for this frame are rather finer and more closely set than those in the first drawing frame, but otherwise the active parts of the machines, and the operations conducted therein, are practically identical, and therefore need no further description. It should be mentioned, however, that there are different types of drawing frames, and their designation is invariably due to the particular manner in which the fallers are operated while traversing the closed circuit. The names of other drawing frames appear below.