(120) It has been the ordinary practice to place the flexible bend outside the framing, but it is becoming the practice to decrease the width of the cylinder, and consequently the length of the flat. The cylinder is now ordinarily made 37in. wide when fed from 40in. laps, the lap being narrowed as it approaches the feed roller by specially placed and designed guides. By diminishing the length of the flat, the tendency to deflection is also lessened, and, in addition to this, an improvement occurs in the selvedge of the sliver. It will be seen that in diminishing the width of the lap 3 inches, it is only possible to do so by squeezing in its edges or folding them over somewhat. Thus any thin place on the edge of the lap is thickened, and the sliver when produced has a better selvedge. This advantage is partially derived by the means mentioned, but there is a further cause of ragged selvedges, to which a good deal of attention has been given. Usually between the edge of the cylinder and the bend a space has been left, through which, when the cylinder is revolving, a current of air is induced. As the cotton is held in the wire clothing, which comes right up to the edge of the cylinder, the suction thus caused draws it out and causes ragged places. Messrs. Ashworth Brothers remedied this defect by the employment of a circular shield about the height of the cylinder wire, which is fixed to and revolves with the cylinder. This gap is now entirely closed by all makers.
Figs. 51 and 52.
(121) Messrs. John Hetherington and Sons adopt the plan shown in Figs. 51 and 52, which are cross sections of the cylinder, bends, and flats. Fig. [51] represents the old method of construction. The flat T is sustained by the flexible bend Z, which is controlled by the setting screws W, and is attached to the framing Y by the bolt shown. The cylinder V in this case is 40in. wide, and between it and the fixed bend a space is left, which is filled up by the introduction of the wood packing X. The latter is fastened to the fixed bend Y by screws as shown. The new plan is shown in Fig. [51]. In this case the flexible bend Z is fastened on the inside of the framing Y, the setting screw W being placed as shown. It will be seen that the edge of the cylinder V comes close up to the bend Z, and no induced air current is possible. The cylinder is reduced to 37in. wide as previously mentioned. The same firm adopt a very good method of dealing with the flexible bend, which is shown in Figs. [53] and [54] in transverse section and side elevation respectively. On the cylinder shaft a segmental rack V is fixed, which is driven by means of worm gearing, and the bands W U from the pulley X placed on the shaft. This also drives a spindle Z, borne in frames attached to the cylinder, on each end of which is a milling cutter. The cutters are kept in contact with the flexible bend Y, which is made a little larger than is necessary, and is bolted in its place after being accurately set. It is weighted with suspended weights R T, together equal to the weight of the flats when resting upon the bends, and attached to the bends at points midway between those at which they are set. In this way the actual conditions of working are established as nearly as possible before the mechanism is started. On commencing operations the milling cutters are at one end of the bend, and the cylinder is slowly revolved so as to traverse them over its surface. In this way it is accurately shaped to suit the conditions of the case, and is as true as a fixed bend could be made. Of course, as soon as the bend requires to be reset it is necessary to adopt the ordinary plan, but the treatment described undoubtedly facilitates subsequent setting.
Figs. 53 and 54.J.N.
(122) The plan adopted by Messrs. Platt Bros. and Co. Limited is shown in Figs. [55] and [56], the former being the new, and the latter the old, method. A perspective view of this machine fitted with the new bend is given in Fig. [57]. Dealing with Fig. [56] first, the cylinder A is separated from the framing B by the distance shown, this being filled up by the wood packing G. The flexible bend C is fastened to the framing on the outside, and is set by the screws shown. The cylinder in this case is 40 inches wide, and it will be noticed that the arms of the cylinder are level with its edge. In Fig. [55] the cylinder A is recessed so that it projects beyond the arms sufficiently to permit the bend B to come within the recess. The flexible bend C is attached in the manner shown to B, and is fulcrumed on the pin in its centre. The setting is obtained by means of the screws, as in the previous case. The clothing on the flat is secured at the ends by the clip or plate F, shown separately in side view and plan, and a thin plate E is fastened to the cylinder by which means the ingress of air is quite prevented. There is also a reduction in the widths of the cylinder and machine, in the latter case about 8 inches, so that a machine fed from a lap 45 inches wide occupies only the same space as a machine made on the old principle with a 40 inch lap.
Fig. 57.
(123) Before leaving this point there is one thing to be noticed which is important. A reference to either Fig. [52] or [56] will show that the chain is attached at the end of the flat immediately over the bend, whereas in Figs. [51] and [55] it is further from it. The former method is best, as being less likely to deflect the flat, and is being adapted to the new construction by both the firms named.