Engineering :: Materials Handling

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41.

In case of lifting magnets, for releasing the material lifted

A.	hooks are used	B.	direction of dc current is reversed
C.	ac current is passed through the coil

42.

Which hoist is often used in erection work?

A.	Magnetic lifting hoist	B.	Electric hoist
C.	Hand chain hoist	D.	all of the above

43.

Which hoist is generally preferred for repetitive or high speed lifting?

A.	Magnetic lifting hoist	B.	Electric hoist
C.	Hand chain hoist	D.	None of the above

44.

Braking system is invariably incorporated in case of

A.	Electric hoists	B.	Magnetic hoists
C.	Hand chain hoists	D.	all of the above

45.

Air hoists provide

A.	stepped movement	B.	slow speeds only
C.	fast speeds only	D.	infinitely variable speeds

46.

Jacks are portable, hand-operated devices for moving

A.	heavy	B.	light
C.	heavy	D.	light

47.

Jacks may be

A.	screw type	B.	rack-and-lever type
C.	hydraulic type	D.	Any of the above

48.

A cylinder and a piston is invariably a part of

A.	screw type jacks	B.	rack-and-lever type jacks
C.	hydraulic jacks	D.	all of the above

49.

Skip hoists used on blast furnaces are generally

A.	manually driven	B.	steam engine driven
C.	electric motor driven	D.	air motor driven

50.

Skip hoists are generally used where

A.	the lift is too high	B.	the lumps to be lifted are large
C.	the material is pulverized	D.	all of the above