A crane with a 150-foot boom is lifting a 5,000-pound load at a 75-foot radius. If the load chart shows a capacity of 8,000 pounds at this configuration, what is the safety factor being maintained?
Correct Answer
C) 1.6
Safety factor = Rated capacity ÷ Actual load = 8,000 lbs ÷ 5,000 lbs = 1.6. This provides a 60% safety margin above the actual load being lifted.
Why This Is the Correct Answer
The safety factor is calculated by dividing the crane's rated capacity by the actual load being lifted. In this case, the load chart shows the crane can handle 8,000 pounds at the 75-foot radius configuration, but only 5,000 pounds is being lifted. The calculation is 8,000 ÷ 5,000 = 1.6, meaning the crane is operating at 1.6 times the safety margin.
Why the Other Options Are Wrong
Option B: 1.2
This would result from incorrectly calculating 10,000 ÷ 5,000 = 2.0, possibly misreading the rated capacity as 10,000 pounds instead of 8,000 pounds.
Option D: 2.0
This would result from incorrectly calculating 6,000 ÷ 5,000 = 1.2, possibly confusing the rated capacity or using wrong numbers from the problem.
Memory Technique
Remember 'CAN over ARE' - what the crane CAN lift over what you ARE lifting gives you the safety factor.
Reference Hint
OSHA 1926 Subpart CC - Cranes and Derricks in Construction, specifically load chart requirements and capacity calculations
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