Which of the following motions are not needed for spur gear cutting with a hob?
1. Rotary motion of hob
2. Linear axial reciprocatory motion of hob
3. Rotary motion of gear blank
4. Radial advancement of hob
Select the correct answer using the codes given below
(a) 1,2 and 3 (b) 1,3 and 4
(c) 1,2 and 4 (d) 2,3 and 4