Updated: Sep 25, 2021
The feed may be controlled by hand or by automatic means. The spindle gets power from the top shaft through two bevel gears.
The vertical shaft is splined or feather keyed so that spindle can rotate as well as can vertically move up and down for feeding through the bevel gear which remains to rotate in a particular position.
The spindle rotates within a non-rotating hollow shaft placed two balls bearing between hollow shaft and vertical solid shaft. The hollow shaft remains in a position along the solid shaft length with the help of washers at the lower end and a nut at the top end of the hollow shaft. The hollow shaft can move up and down through a pinion meshed with the rack. The pinion gets power from the top shaft through two spur gears, a worm shaft, and a worm.
Gear A rotates with the spindle as the spindle passes through it. Gear B is connected with gear A and gear B also rotates the shaft S. At a suitable point under the shaft, there is a worm that drives a pinion. The pinion is connected with the rack on the hollow shaft fitted over the spindle. The hollow shaft does axially move with the help of the collar.
The different ranges of feed can be obtained by means of a feed gearbox. In a feed gearbox, the different sizes of gears are mounted in two shafts. They constantly mesh with each other.