Personnel platforms gross loads cannot exceed what percent of a crane's capacity at the farthest necessary radius?

Personnel platforms gross loads cannot exceed what percent of a crane's capacity at the farthest necessary radius?

• A. 60%
• B. 50%
• C. 75%
• D. 90%

Answer: (B)

The key idea is that when a crane lifts with a personnel platform at the farthest necessary radius, you must limit the platform’s gross load to half of the crane’s rated capacity at that radius. The farthest radius creates the largest tipping moment, so the crane’s safe lifting capacity is reduced to leave a generous safety margin for dynamic effects, wind, and operator control. Therefore, the maximum allowable gross load on the personnel platform (including workers, platform itself, and any tools) should not exceed 50% of the crane’s rated capacity at that radius. For example, if the crane’s rated capacity at the farthest radius is 20,000 pounds, the maximum permissible gross load on the personnel platform would be 10,000 pounds. The other percentage options would not provide an adequate safety margin given the lever arm and stability considerations.

The key idea is that when a crane lifts with a personnel platform at the farthest necessary radius, you must limit the platform’s gross load to half of the crane’s rated capacity at that radius. The farthest radius creates the largest tipping moment, so the crane’s safe lifting capacity is reduced to leave a generous safety margin for dynamic effects, wind, and operator control. Therefore, the maximum allowable gross load on the personnel platform (including workers, platform itself, and any tools) should not exceed 50% of the crane’s rated capacity at that radius.

For example, if the crane’s rated capacity at the farthest radius is 20,000 pounds, the maximum permissible gross load on the personnel platform would be 10,000 pounds. The other percentage options would not provide an adequate safety margin given the lever arm and stability considerations.