A tower crane with a 150-foot boom is being used on a project. The load chart indicates a maximum capacity of 4,000 pounds at 120 feet radius. What is the maximum load that can be lifted at this radius including rigging equipment weighing 200 pounds?
Correct Answer
C) 3,600 pounds
The rigging equipment weight must be subtracted from the crane's rated capacity. Additionally, a safety factor should be applied, making 3,600 pounds the safe maximum (4,000 - 200 - 200 safety margin).
Why This Is the Correct Answer
Option C is correct because crane capacity calculations must account for all weights being lifted, including rigging equipment. The rated capacity of 4,000 pounds must be reduced by the 200-pound rigging weight, leaving 3,800 pounds. However, safe crane operations require applying a safety margin, which is typically 200 pounds or 5% of capacity, whichever is greater, resulting in a maximum safe load of 3,600 pounds.
Why the Other Options Are Wrong
Option A: 4,000 pounds
Option A ignores both the rigging equipment weight and safety margin requirements. Using the full rated capacity without deductions would create an unsafe overload condition.
Option B: 3,800 pounds
Option B only accounts for the rigging equipment weight (4,000 - 200 = 3,800) but fails to include the required safety margin for safe crane operations.
Option D: 3,200 pounds
Option D applies too large of a deduction (800 pounds total), which exceeds the required rigging weight and safety margin calculations.
Memory Technique
Remember 'CRS': Capacity minus Rigging minus Safety = safe lifting weight
Reference Hint
Florida Building Code Chapter 33 - Safeguards During Construction, or OSHA 1926 Subpart CC - Cranes and Derricks in Construction
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