Load Charts & Capacity Calculations Flashcards
7 cards from real NCCCO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Load Charts & Capacity Calculations flashcards as text
When a load chart lists capacity at '360°' rotation, what does this indicate?
Answer: Capacity is the same regardless of which direction the boom is pointed
A '360°' designation means the rated capacity is uniform in all directions around the crane's slewing circle.
A crane load chart shows a capacity of 18,000 lbs at 40 ft radius. If the actual load weighs 15,000 lbs and rigging weighs 800 lbs, what is the total load on the hook?
Answer: 15,800 lbs
The total load on the hook includes the weight of the load plus all rigging hardware, so 15,000 + 800 = 15,800 lbs.
What is the purpose of the 'structural' capacity line on a crane load chart?
Answer: It shows the maximum load the crane structure can withstand before tipping
The structural capacity line represents the maximum load the crane's structural components (boom, hook block, wire rope) can handle before failure.
On a telescoping boom crane, why do load charts typically show reduced capacities as the boom is extended?
Answer: Longer booms create greater bending moments and stress on structural components
As the boom extends, the lever arm increases, creating greater bending moments and structural stress that reduce the safe rated capacity.
A load chart footnote states 'capacities based on freely suspended loads.' What does this mean for a crane operator?
Answer: The load must hang vertically with no side pull on the hoist line
Freely suspended loads hang vertically; side pulls or dragging loads create additional forces not accounted for in the rated capacities.
When interpolating between two radius values on a load chart, what is the safest approach?
Answer: Use the lower capacity value or interpolate conservatively
When interpolating between chart values, always use the lower capacity or interpolate conservatively to maintain a safety margin.
A crane is rated at 20,000 lbs at 30 ft radius on outriggers fully extended. If the outriggers are only 50% extended, what capacity should be used?
Answer: The operator must consult the manufacturer's chart for that specific outrigger position
ASME B30.5 requires operators to use the manufacturer's load chart specific to the actual outrigger extension percentage; guessing or extrapolating is not permitted.