NCCCO Load Charts & Capacity Calculations 2

Question 1

What information is needed to use a crane's load chart correctly?

Accepted Answer

Boom length, operating radius, crane configuration, and ground conditions

Answer

To find rated capacity on a load chart, you need: boom length/configuration, operating radius (distance from center of rotation to load), quadrant of operation, and whether outriggers are deployed.

Question 2

What is 'operating radius' and how is it measured?

Accepted Answer

The horizontal distance from the center of rotation to the center of the load

Answer

Operating radius is measured horizontally from the crane's center of rotation (center pin) to the center of the hook/load. As radius increases, lifting capacity decreases.

Question 3

As the operating radius increases, what happens to the crane's rated capacity?

Accepted Answer

It decreases — the farther the load is from the crane, the less it can lift

Answer

Capacity decreases as radius increases because the tipping moment (load weight × radius) increases. The crane can lift the most weight closest to its center of rotation.

Question 4

What must be subtracted from the load chart capacity to determine the actual weight you can lift?

Accepted Answer

The weight of the hook block, rigging (slings, shackles), and any headache ball

Answer

Load chart capacity includes everything hanging from the boom tip. You must subtract the weight of hook block, headache ball, wire rope, and all rigging to find the available capacity for the actual load.

Question 5

A crane has a rated capacity of 50 tons at 30 feet radius. The rigging weighs 2 tons. What is the maximum load that can be lifted?

Accepted Answer

48 tons

Answer

Maximum net load = rated capacity minus rigging weight = 50 - 2 = 48 tons. The rigging is part of the total weight the crane must support.

NCCCO (National Commission for the Certification of Crane Operators) Practice Test

NCCCO (National Commission for the Certification of Crane Operators) Practice Test

NCCCO Load Charts & Capacity Calculations 2