Machine Design Miscellaneous
Direction: A band brake consists of a lever attached to one end of the band. The other end of the band is fixed to the ground. The wheel has a radius of 200 mm and the wrap angle of the band is 270°. The braking force applied to the lever is limited to 100 N, and the coefficient of friction between the band and the wheel is 0.5. No other information is given.
- The maximum wheel torque that can be completely braked is
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Braking torque = (T1 – T2) × r
= (2101 – 200) × 2 = 382 N–mCorrect Option: B
Braking torque = (T1 – T2) × r
= (2101 – 200) × 2 = 382 N–m
- The maximum tension that can be generated in the band during braking is
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θ = 270°
μ = 0.5
Taking moment about 0,
∑ M0 = 0
⇒ T2 × 1 - 100 × 2 = 0
T2 = 200 NT1 = eμ θ T2 T1 = e0.5 × (3π / 2) T2
T1 = 2110 N
Correct Option: B
θ = 270°
μ = 0.5
Taking moment about 0,
∑ M0 = 0
⇒ T2 × 1 - 100 × 2 = 0
T2 = 200 NT1 = eμ θ T2 T1 = e0.5 × (3π / 2) T2
T1 = 2110 N
- In a band brake the ratio of tight side band tension to the tension on the slack side is 3. If the angle of overlap of band on the drum is 180°, the coefficient of friction required between drum and the band is
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Given , Tension in tight side = T1 = 3 Tension is slack side T2 T1 = eμ θ T2
where, θ = angle of overlap = 180 = π radians
∴ 3 = eμ θ
ln(3) = μ θ∴ μ = 1 ln(3) = 0.35 π Correct Option: D
Given , Tension in tight side = T1 = 3 Tension is slack side T2 T1 = eμ θ T2
where, θ = angle of overlap = 180 = π radians
∴ 3 = eμ θ
ln(3) = μ θ∴ μ = 1 ln(3) = 0.35 π
- Which one of the following is used to convert a rotational motion into a translational motion?
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NA
Correct Option: D
NA
- For the given statements :
I. Mating spur gear teeth is an example of higher pair
II. A revolute Joint is an example of lower pair Indicate the correct answer.
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Since higher pair has a line or point contact and lower pair has a surface of Area contact. Hence both are true. i.e., spur gear has line contact (Higher pair) and Revolute joint has surface contact (lower pair).
Correct Option: D
Since higher pair has a line or point contact and lower pair has a surface of Area contact. Hence both are true. i.e., spur gear has line contact (Higher pair) and Revolute joint has surface contact (lower pair).