NCCER Crane Crane Components, Configurations & Terminology — Questions and Answers
Question 1: What does the term 'parts of line' describe on a crane?
- The number of boom sections extended
- The number of wire rope lines supporting the load block (Correct answer)
- The number of outrigger jacks deployed
- The number of counterweight slabs installed
Correct answer: The number of wire rope lines supporting the load block
Parts of line is the number of hoist rope lines reeved between the boom tip sheaves and the load block. More parts of line raise lifting capacity but slow line speed.
Question 2: What is the main function of a crane's counterweight?
- To offset the load moment and increase stability (Correct answer)
- To reduce wire rope wear
- To power the swing mechanism
- To keep the boom from telescoping
Correct answer: To offset the load moment and increase stability
The counterweight sits at the rear of the upperworks. It balances the overturning moment the load and boom create, which increases the crane's stability-based capacity.
Question 3: What is the main structural difference between a lattice boom and a telescopic boom?
- Lattice booms are hydraulically extended, while telescopic booms are pinned sections
- Telescopic booms can only be used on crawler cranes
- Lattice booms are built from pinned truss sections, while telescopic booms extend nested sections hydraulically (Correct answer)
- There is no structural difference
Correct answer: Lattice booms are built from pinned truss sections, while telescopic booms extend nested sections hydraulically
Lattice booms are assembled from open truss sections pinned together, so changing length means adding or removing sections. Telescopic booms have nested box sections that extend and retract with hydraulics.
Question 4: What does 'luffing' mean in crane operations?
- Rotating the upperworks
- Raising or lowering the boom angle (Correct answer)
- Extending the outriggers
- Releasing the hoist brake
Correct answer: Raising or lowering the boom angle
Luffing is changing the boom or jib angle, which also changes the load radius. Swinging is rotating the upperworks.
Question 5: What is an 'overhaul ball' (headache ball) used for?
- To measure load weight
- To lock the swing brake
- To mark the boom tip for signal persons
- To provide weight so a single-part line pays out freely without a load (Correct answer)
Correct answer: To provide weight so a single-part line pays out freely without a load
An overhaul ball is a weighted hook on a single-part line. Its weight lets the line lower (overhaul) through the sheaves when there is no load on the hook.
Question 6: On a mobile crane, what are the 'upperworks'?
- The rotating superstructure, including the operator's cab, boom, hoists and counterweight (Correct answer)
- Only the boom tip and sheaves
- The carrier frame, axles and tires
- The outrigger beams and pads
Correct answer: The rotating superstructure, including the operator's cab, boom, hoists and counterweight
The upperworks (superstructure) are everything that rotates above the swing bearing: cab, boom, hoist drums, engine (on many models) and counterweight. The carrier or lower works stays fixed.
