NCCCO Counterweight and Ballast Configuration 3 — Questions and Answers
Question 1: When a crane manufacturer specifies a maximum counterweight for a given boom configuration, what is the primary consequence of exceeding that limit?
- The crane becomes more stable due to added rear ballast
- The rear stability limit may be exceeded, risking backward tipover (Correct answer)
- Load chart capacities automatically increase
- The boom angle must be lowered to compensate
Correct answer: The rear stability limit may be exceeded, risking backward tipover
Excess counterweight shifts the tipping fulcrum rearward, potentially causing the crane to tip backward when working with light or no loads.
Question 2: Which crane component directly connects the counterweight to the rotating superstructure and must be inspected for cracks before adding maximum counterweight?
- The carbody
- The counterweight mounting brackets or tray (Correct answer)
- The front outrigger pad
- The boom foot pin
Correct answer: The counterweight mounting brackets or tray
Counterweight mounting brackets or trays bear the full weight and dynamic loads of the counterweight and must be structurally sound.
Question 3: A crawler crane's track gauge is widened before a heavy lift. How does this affect ballast requirements?
- More ballast is always required to compensate for the wider stance
- Ballast requirements do not change regardless of track gauge
- Widened tracks may allow reduced ballast by increasing the tipping-fulcrum width (Correct answer)
- Ballast must be removed to maintain the original load chart values
Correct answer: Widened tracks may allow reduced ballast by increasing the tipping-fulcrum width
A wider track gauge expands the crane's stability polygon, which can reduce the ballast needed to achieve the same rated capacity.
Question 4: During a pick-and-carry operation with a hydraulic truck crane, counterweight configuration should be selected based on which primary document?
- OSHA 1926.1416 appendix only
- The manufacturer's load chart specific to pick-and-carry mode (Correct answer)
- The rigging supervisor's field judgment
- The previous shift's lift plan
Correct answer: The manufacturer's load chart specific to pick-and-carry mode
Manufacturers publish separate or modified load charts for pick-and-carry operations that account for dynamic travel loads and may limit counterweight or boom configurations.
Question 5: What does the term 'self-ballasted' mean when applied to certain crawler crane designs?
- The crane uses water-filled outrigger pads for stability
- The carbody weight serves as the primary ballast without removable counterweight slabs (Correct answer)
- The operator can add ballast automatically from the cab
- The boom acts as a counterbalance to the load
Correct answer: The carbody weight serves as the primary ballast without removable counterweight slabs
Self-ballasted designs incorporate the required ballast mass into the permanent carbody structure, eliminating separate removable slab counterweights.
Question 6: A crane operator notices the counterweight is asymmetric — more slabs on the left side than the right. What is the safest immediate action?
- Proceed with the lift but limit swing to the heavy side
- Stop work and notify the crane supervisor to correct the configuration before any lift (Correct answer)
- Offset the asymmetry by booming down
- Add ballast to the front to compensate
Correct answer: Stop work and notify the crane supervisor to correct the configuration before any lift
Asymmetric counterweight creates unequal tipping margins in different swing directions, making the load chart unreliable; the configuration must be corrected before lifting.
Question 7: On a lattice boom crawler crane, the manufacturer's rated capacity assumes a specific counterweight value. If a lighter counterweight is installed, what must the operator do?
- Increase the boom angle to restore capacity
- Use a derating table or contact the manufacturer for a revised load chart (Correct answer)
- Proceed normally since lighter counterweight is always conservative
- Add a jib to compensate for lost lifting capacity
Correct answer: Use a derating table or contact the manufacturer for a revised load chart
Using less counterweight than specified reduces rear stability and requires derating the crane's capacities per the manufacturer's guidance.
NCCCO Counterweight and Ballast Configuration 3
When a crane manufacturer specifies a maximum counterweight for a given boom configuration, what is the primary consequence of exceeding that limit?