NCCCO Crane Type Identification and Applications 4 — Questions and Answers
Question 1: A stiff-leg derrick differs from a guy derrick primarily because it:
- Has a telescoping boom
- Uses rigid inclined legs instead of guy wires for mast support (Correct answer)
- Travels on crawler tracks
- Requires no boom
Correct answer: Uses rigid inclined legs instead of guy wires for mast support
A stiff-leg derrick uses two rigid inclined legs (stiff legs) to support the mast rather than flexible guy wires, providing a stable, fixed-position lifting platform.
Question 2: Which crane type is most appropriate for indoor use in a facility where overhead clearance is severely limited?
- Hammerhead tower crane
- Telescopic boom truck crane
- Low-headroom hoist with underhung trolley (Correct answer)
- Luffing jib crane
Correct answer: Low-headroom hoist with underhung trolley
Low-headroom hoists with underhung trolleys are specifically engineered to minimize the vertical space required between the hook and the overhead beam.
Question 3: A climbing tower crane is designed to:
- Move horizontally on a rail system
- Raise itself as a building's floors are constructed (Correct answer)
- Travel vertically along a monorail
- Operate independently without a foundation
Correct answer: Raise itself as a building's floors are constructed
Climbing tower cranes use a hydraulic climbing frame to jump upward as new building floors are completed, keeping the crane at an optimal working height.
Question 4: Which crane type would be LEAST suitable for operation in a petrochemical plant with explosion hazard zones?
- Air-powered overhead hoist
- Explosion-proof electric hoist
- Diesel-engine truck crane positioned outside the zone
- Standard AC electric overhead crane without explosion-proof classification (Correct answer)
Correct answer: Standard AC electric overhead crane without explosion-proof classification
Standard electric cranes without explosion-proof ratings can produce sparks that ignite flammable atmospheres; only ATEX/explosion-proof rated equipment is permitted in hazardous zones.
Question 5: What operational characteristic defines a 'hammerhead' tower crane?
- A luffing boom that pivots up and down
- A horizontal jib fixed at a constant angle with a trolley that travels along it (Correct answer)
- A boom that telescopes outward
- A mast that rotates 360° with a fixed jib
Correct answer: A horizontal jib fixed at a constant angle with a trolley that travels along it
A hammerhead (flat-top or horizontal jib) tower crane has a fixed horizontal jib with a load trolley that travels in and out along its length to position the load.
Question 6: A portal crane is distinguished from a gantry crane primarily by:
- Having no hook block
- Operating outdoors only on rails with an open portal frame allowing vehicle passage underneath (Correct answer)
- Using wire rope drums instead of chain hoists
- Being permanently attached to a building wall
Correct answer: Operating outdoors only on rails with an open portal frame allowing vehicle passage underneath
Portal cranes have an arch or portal frame that allows vehicles or rail cars to pass underneath, commonly used in shipyards and rail freight yards.
Question 7: Which crane type uses a turntable mounted on a truck chassis combined with a lattice boom for heavy lifts at road-accessible sites?
- Rough-terrain crane
- Lattice boom truck crane (Correct answer)
- All-terrain crane
- Pick-and-carry crane
Correct answer: Lattice boom truck crane
A lattice boom truck crane mounts a rotating superstructure with a lattice boom on a standard truck carrier, providing high capacity at sites reachable by road.
NCCCO Crane Type Identification and Applications 4
A stiff-leg derrick differs from a guy derrick primarily because it: