Question

In gears, interference takes place when:

• A. Tip of a tooth of a mating gear digs into the portion between base and root circles
• B. Gears do not move smoothly in the absence of lubrication
• C. Pitch of the gear is not same
• D. Gear teeth are undercut

Hint:

Interference in gears occurs when a tooth tip enters the non-involute zone — that is, between the base and root circles of the mating gear.

Answer 1

The Correct Option is A

Interference in gears occurs when the tip of a tooth on one gear makes contact with the non-involute portion (between base and root circles) of the mating gear.
This usually happens when the gear design parameters, like the number of teeth or the pressure angle, are not properly chosen to ensure conjugate action.
Key points:
- Involute profile is valid only above the base circle.
- If the addendum of a mating gear extends below the base circle of the other gear, interference results.
- This leads to undesirable contact and possible gear damage.
Other options are incorrect:
- (2) Lubrication affects smoothness, but not interference.
- (3) Pitch mismatch leads to transmission errors, not interference.
- (4) Undercutting is a remedy for interference, not its cause.