Which D.C. motor is generally preferred for cranes and hoists?

Which type of load is offered by cranes and hoists ?

A

Gradually varying load

B

Non-reversing, no-load start

C

Reversing, light start

D

Reversing, heavy start

Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of

A

D.C. series motor

B

D.C. shunt motor

C

Induction motor

D

All of above motors

Which of the following motors are preferred for overhead traveling cranes?

A

Slow speed motors

B

Continuous duty motors

C

Short time rated motors

D

None of the above

Short time rated motors are preferred for overhead traveling cranes

A

True

B

False

The rated loads of lifting cranes, as percentage of tipping load at specified radius, for crawler-mounted and pneumatic tyre-mounted machines would be respectively

A

80 and 90

B

90 and 80

C

85 and 75

D

75 and 83

Light duty cranes are used in which of the following?

A

Power houses

B

Pumping stations

C

Automobile workshops

D

All of the above

The traveling speed of cranes varies from

A

20 to 30 m/s

B

10 to 15 m/s

C

5 to 10 m/s

D

1 to 2.5 m/s

For which of the following applications a D.C. motor is preferred over an A.C. motor?

A

Low speed operation

B

High speed operation

C

Variable speed operation

D

Fixed speed operation

If a D.C. motor is to be selected for conveyors, which motor would be preferred ?

A

Series motor

B

Shunt motor

C

Differentially compound motor

D

Cumulative compound motor

Slip ring motor is preferred over squirrel cage induction motor where

A

High starting torque is required

B

Load torque is heavy

C

Heavy pull out torque is required

D

All of the above

Which D.C. motor is generally preferred for cranes and hoists?

Related Questions