Rotation of shaft 14 about fixed axis A is transmitted through meshing gears 1 and 2, and disk 3 to pawl 4 which carries a pin with roller a. Pawl 4 engages the teeth of ratchet wheel 5, and rotates it with shaft 15 about fixed axis B until roller a begins to ride the lobes of cams 6 and 7 which can be turned about fixed axis E. The feeding motion is transmitted from shaft 15 through worm 8 and worm wheel 9 to feed screw 10 which rotates about fixed axis F. The rate of feed depends upon the setting of cams 6 and 7. When angle α of pawl engagement with wheel 5 is increased, the rate of feed per revolution of disk 3 is correspondingly increased and vice versa. The feed is varied by means of dial 11 which turns cam 6 with respect to cam 7. Keyed to the shaft of dial 11 is gear 13 which is locked in the required position by a spring-loaded plunger. The number of divisions on dial 11 corresponds to the number of teeth on gear 13 and on ratchet wheel 5. The instant that the feed motion begins can be varied by turning cam 7 which is then locked in the required position by ring nut 12.
$2777$RG,SF$