List of formulae (spur gear)

List of formulas used in spur gear for calculations, as per VTU CBCS syllabus

1. List of Formulae (Spur gear)
1. Angular velocity = ??????=
2????????????
60
rad/s
2. Speed Ratio / RPM ratio =
??????
1
??????
2
=
??????
1
??????
2
=
??????1
??????2
=
??????2
??????1
=
??????2
??????1
=
??????2
??????1

1 always corresponds to pinion
2 always corresponds to gear
3. Circular pitch = ??????=
????????????
??????
mm
4. Module m =
??????
??????
Also, p=?????? ?????? mm
5. Pitch circle radius = r =
????????????
2
mm
Pitch circle radius of pinion = r1 =
????????????1
2
mm
Pitch circle radius of gear = r2 =
mz2
2
mm
6. Addendum = a = mm
7. Dedendum = b = mm

8. Path of Contact = mm

If the diameter of pinion and gear are same/equal mm

9. Path of approach =


10. Path of recess =

11. Maximum Path of approach ≤
12. Maximum Path of recess ≤
13. Velocity of sliding during approach = (??????1+??????2) x Path of approach
14. Velocity of sliding during recess = (??????1+??????2) x Path of recess

mm

2. Minimum No. of teeth to avoid interference
Maximum addendum circle radius of gear to avoid interference =
mm

Minimum number of teeth to avoid interference =


If number of teeth on pinion and gear are equal =

Addendum of gear = mm