GATE 2020: Machine Design Quiz 7

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Question 1

A wire rope for a vertical mine hoist to lift a load of 50 kN from a depth of 150 meters. Wire rope attain the speed of 10 m/s in 10 seconds. Additional load due to upward acceleration of rope is ___________ N.

• A5000
• B5090
• C5097
• D6000

Question 2

The horse power transmitted by a belt is dependent upon

• Atension on tight (T_t) and slack side of the belt (Ts)
• Bradius of the pulley (R)
• Cspeed of the pulley (N)
• Dall of these

Question 3

A belt drive shown in Figure A. has an angle of wrap of 160 ° on the smaller pulley. Adding an idler as shown in Figure (b), increases the wrap angle to 200 °. The slack side tension is the same in both cases and the centrifugal force is negligible. By what percentage is the torque capacity of the belt drive increased by adding the idler? (use coefficient of friction μ = 0.3.)

• A41.25%
• B39 %
• C40%
• D43%

Question 4

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

• A 0.20
• B 0.25
• C 0.30
• D 0.35

Question 5

The efficiency of a power screw is maximum, when the lead (helix) angle is

• A
• B
• C
• D

Question 6

A pulley of radius 500 mm is keyed to 25 mm radius of shaft by a 14 mm square key of length 150 mm. The tension in the tight side of the belt is 5000 N and tension ratio is 2 : 1. If ultimate shear strength is 250 MPa, then what will be the factor of safety in shear for key ?

• A8.5
• B21
• C10.5
• D5.25

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