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A short shoe external drum brake is shown in the figure. The diameter of the brake drum is 500 mm. The dimensions a = 1000 mm, b = 500 mm and c = 200 mm. The coefficient of friction between the drum and the shoe is 0.35. The force applied on the lever F = 100 N as shown i n t he figure. The drum is rotating anti - clockwise. The braking torque on the drum is ____ N-m (round off to two decimal places)
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- 20.35
- 25.35
- 20
- 22.35
Correct Option: A
Taking moment about hinge point,
F × a + μ × N × C – N × b = 0
⇒ 100 × 1000 + 0.35 × N × 200 – N × 500 = 0
⇒ N × 430 = 100 × 1000
Reaction force, N = 232.558 Newton.
Braking torque, T = μN × r
| 0.35 × 232.558 × = | 1000 |
T = 20.348 N ≈ 20.35 N - m
