NCCCO Boom Angle and Radius Calculations 2

Question 1

A crane's load chart shows a rated capacity of 18 tons at a 30-foot radius. If the operator extends the boom to increase the radius to 45 feet, what will happen to the rated capacity?

Accepted Answer

It will decrease because the load moment increases

Answer

It will increase because the boom is longer

Answer

It will remain the same as long as the boom angle stays the same

Answer

It will double because the radius doubled

Question 2

If a crane has a 100-foot boom at a 45-degree angle, what is the approximate working radius from the crane's center pin to the load?

Accepted Answer

70.7 feet

Answer

50 feet

Answer

86.6 feet

Answer

100 feet

Question 3

When a crane operator lowers the boom angle from 75 degrees to 55 degrees while keeping the same boom length, what happens to the working radius?

Accepted Answer

Working radius increases

Answer

Working radius decreases

Answer

Working radius stays the same

Answer

Working radius becomes zero

Question 4

What instrument on a crane helps the operator verify the current boom angle during a lift?

Accepted Answer

Boom angle indicator (inclinometer)

Answer

Anti-two-block alarm

Answer

Load moment indicator only

Answer

Hydraulic pressure gauge

Question 5

If a crane's load chart only shows capacities at 20-foot and 30-foot radii, and the operator needs to lift at a 25-foot radius, what should the operator do?

Accepted Answer

Interpolate between the two chart values and use the lower (more conservative) result

Answer

Use the 30-foot radius capacity since it is the closest

Answer

Use the 20-foot radius capacity since it gives more capacity

Answer

Average all chart values for the best estimate

Question 6

A mobile crane has a 120-foot boom. The operator needs a working radius of 60 feet. At what approximate boom angle should the operator position the boom?

Accepted Answer

60 degrees

Answer

30 degrees

Answer

45 degrees

Answer

75 degrees