## Machine Design Miscellaneous

#### Machine Design

1. A band brake having bandwidth of 80 mm, drum diameter of 250 mm, coefficient of friction of 0.25 and angle of wrap of 270 degrees is required to exert a friction torque of 1000 N m. The maximum tension (in kN) developed in the band is

1. Given: b = 80 mm = 0.08 m D = 250 mm = 0.25

 R = D = 0.25 2

μ = 0.25
 θ = 270° = 270 × π = 4.712 radians 180

Ft = 100 N-m
 As p1 = eμθ p2

⇒  p1 = eμθ ⋅ p2 = e0.25 × 4.712 ⋅ p2 = 3.25p2
Now, Ft = (p1 − p2)R
 ∴  1000 = p1 − p1 0.125 3.25

Solving, we get maximum tension in the belt,
p1 = 11.56 kN

##### Correct Option: D

Given: b = 80 mm = 0.08 m D = 250 mm = 0.25

 R = D = 0.25 2

μ = 0.25
 θ = 270° = 270 × π = 4.712 radians 180

Ft = 100 N-m
 As p1 = eμθ p2

⇒  p1 = eμθ ⋅ p2 = e0.25 × 4.712 ⋅ p2 = 3.25p2
Now, Ft = (p1 − p2)R
 ∴  1000 = p1 − p1 0.125 3.25

Solving, we get maximum tension in the belt,
p1 = 11.56 kN

1. For full depth of involute spur gears, minimum number of teeth of pinion to avoid interference depends upon

1. NA

##### Correct Option: A

NA

1. For full depth of involute spur gears, minimum number of teeth of pinion to avoid interference depends upon

1. NA

##### Correct Option: A

NA

1. Modern gear tooth profile is given involute shape because

1. NA

##### Correct Option: D

NA

1. The basic load rating of a ball bearing is

1. NA

NA