71. The velocity ratio of two pulleys connected by an open belt or crossed belt is

• directly proportional to their diameters
• inversely proportional to their diameters
• directly proportional to the square of their diameters
• inversely proportional to the square of their diameters

Solution

• Sannith
• Mining Machinery

72. In roller chain, the rolling friction reduces ____

• Wear
• Frictional power loss
• Improves the efficiency of the chain drive
• All of these.

Solution

• Sannith
• Mining Machinery

73. Which bearing is Antifriction bearing

• Thick lubrication bearing
• Thin lubrication bearing
• Rolling or ball bearing
• None of the above

Solution

• Sannith
• Mining Machinery

74. A Shaft used in most of the Machinery is made of

• Iron
• Steel
• Copper
• Lead

Solution

• Sannith
• Mining Machinery

75. The machine elements that connects two shafts for power transmission is/are

• Bearing
• Clutch
• Coupling
• All of these

Solution

• Sannith
• Mining Machinery

76. Which of the following is added to steel to increase resistance to corrosion?

• Carbon
• Manganese
• Sulphur
• Copper

Solution

• Sannith
• Mining Machinery

77. What happens when Manganese is added to steel?

• Decreases strength and hardness of steel
• improves corrosion resistance
• decreases ductility
• improves strength and hardness of steel

Solution

• Sannith
• Mining Machinery

78. An induction motor with 1000 r.p.m. speed will have

• 2 poles
• 6 poles
• 4 poles
• 8 poles

Solution

• Sannith
• Mining Machinery

79. The starting torque of a squirrel-cage induction motor is

• full-load torque
• slightly more than full-load torque
• low
• negligible

Solution

• Sannith
• Mining Machinery

80. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor current will be

• 200 Hz
• 50 Hz
• 2 Hz
• 0.2 Hz

Solution

• Sannith
• Mining Machinery