(84) The action of this mechanism is as follows. As the cotton is delivered by the lattice it passes over the nose of the pedal and between it and the feed roller. If there happens to be a thick piece in the feed it depresses the nose of the pedal over which it passes. This raises the pendant rod C. Now the space between the thinnest portion of the pendant foot and the bowls is only sufficient to enable the pendant to rise a little before pressing on the bowl next it. Its motion being limited in this way, and the tendency to rise still occurring, either the pendant must become jammed or the bowl must have liberty to move to one side. This is what occurs, the lateral movement of the bowl being permissible to the extent which corresponds to the space between the remaining pedals and their adjoining bowls. After this is taken up, pressure exercised by the rising pendant upon the bowl causes the bar in which the latter is fixed to move in the box to an extent which is regulated by the depression of the pedal nose. In other words, the pendant swings on the end of the pedal lever either to the right or the left as may be required, giving a similar movement to the rest of the series. The movement thus set up is communicated to the strap levers E by means of the connecting rod O and its attachments, and the strap is accordingly raised or lowered as required by the circumstances of the case. The weight of the parts connected to the pedal levers are sufficient to press their noses against the feed roller unless prevented by means of the cotton being fed. Thus a thin place in the material at any part of the width of the feed roller is followed by the reverse action to that named, the strap being moved on the cones in a similar manner. The presence of a thick place in the feed decreases the velocity of the driven cone and feed roller, while the reverse action occurs when a thin place is presented. Thus the retardation of the cotton in the one case leads to any extra thickness being rapidly beaten out, more blows being given to the same length fed than would be under ordinary circumstances. On the other hand, a thin place results in the quickening of the feed roller and a greater quantity of cotton is beaten off in the same time. In this way an evenly-weighted delivery takes place, and this, in conjunction with the lap feed, of which more will be said hereafter, enables a lap to be finally produced, in which the variations of thickness are comparatively slight.
Figs. 28, 29, 30, and 31.J.N.
(85) At one time it was the universal custom to strike the cotton directly from the pedal nose Fig. [32], a practice which, however the latter was shaped, had many defects. A much better method is adopted by Messrs. Platt Brothers and Company, and is shown in Fig. [33], which illustrates the new practice. It will be seen that, when the beater strikes the cotton directly from the pedal nose, the fibres will be bent sharply round an angle. In the case of long-stapled cottons especially this is detrimental, as it is liable to lead to rupture or breakage of the fibre. With the shorter-stapled varieties this is not so likely to occur, and the use of a pedal and feed-roller is more permissible. The arrangement shown in Fig. [33] is a much better one, and consists in the employment of an additional pair of feed rollers placed between the pedal and the path of the beater. There are two distinct advantages from this procedure. The cotton is bent round a larger curve when it is struck by the beater, and is, therefore, less liable to rupture; and the feed-rollers exercise a certain amount of drawing action. The latter point is of some value. The cotton in passing under the feed roller and between it and the pedal nose is held by them. The correction of thick or thin places and the alteration of the speed of the feed to meet them is controlled from this point. If the second set of rollers revolves at a slightly quicker speed than the one above the pedal the cotton will be a little drawn. In any case, this action will take place to a greater or less extent, and the thick places will thus be partially thinned out before being struck by the beater. The shock of the stroke is thus considerably diminished, and the risk of damage much lessened.
Figs. 32-34.J.N.
(86) It only remains to be said with regard to the Lord pedal motion shown in Figs. [28] to [31] that it is now amended by the introduction of two bowls between each pair of pendants, which are acted upon singly by the pendant they adjoin. The latter point is illustrated in Fig. [34], which represents the old method of arranging the pendants and rollers, and an improved plan of Messrs. Howard and Bullough. In the former case each pendant engaged with one side of a bowl, with the other side of which the adjoining pendant also engaged. In the event of both of the latter rising at once, it is apparent that the bowl will tend to be rotated in opposite directions. In effect it becomes practically inoperative, and the friction set up is considerable, preventing the easy movement of either pendant. To obviate this, the three-bowl arrangement shown in Fig. [34] is adopted. The pendants are made with one flat face, and with one on which a rib is formed. On the spindle three bowls are placed, the centre one being of smaller diameter than the others. The two outer bowls engage with the flat side of one of the pendants, but are entirely out of contact with the adjoining one. On the other hand, the central bowl engages with the rib formed on one pendant, but is too small in diameter to engage with the flat face of the next of the series. Thus the whole of the pendants could rise simultaneously without setting up the friction referred to owing to the cross torsion on the rollers. The sensitiveness of the motion is thus largely increased. The adoption of two bowls, each independent of and out of contact with the other, produces a similar result.
Fig. 35.J.N.