Consider the following motions and setting in a hobbing machine
1.Hob rotation
2. Job rotation
3.Axial reciprocating job rotation
4. Tilting of hob to its helix angle
Which of these motions and setting in a hobbing machine are required to machine a spur gear?
(a) 1, 2 and 3 (b) 2 , 3 and 4
(c) 1, 2 and 4 (d) 1, 3 and 4