Direction: The overall gear ratio in a 2 stage speed reduction gear box (with all spur gears) is 12. The input and output shafts of the gear box are collinear. The countershaft which is parallel to the input and output shafts has a gear (Z2 teeth) and pinion (Z3 = 15 teeth) to mesh with pinion (Z1 = 16 teeth) on the input shaft and gear (Z4 teeth) on the output shaft respectively. It was decided to use a gear ratio of 4 with 3 module in the first stage and 4 module in the second stage.
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Z2 and Z4 are
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- 64 and 45
- 45 and 64
- 48 and 60
- 60 and 48
Correct Option: A
| Given, | = 12, | = 4 = | |||
| N4 | N2 | D1 |
| Now, | = | ||
| Z1 | Z2 |
| ⇒ | = | = | = | ||||
| Z2 | D2 | N1 | 4 |
Z2 = Z1 × 4 = 64
| and | = | ||
| N4 | D1 × D3 |
| ⇒ 12 = | |
| D3 |
| ⇒ | = 3 | |
| D3 |
| Also, | = | ||
| Z4 | Z4 |
| ⇒ Z4 = Z3. | = Z3 × 3 = 15 × 3 = 45 | |
| Z3 |
