NCCCO Ground Bearing Pressure and Outrigger Setup 3

Question 1

When calculating ground bearing pressure under an outrigger float, you divide the outrigger load by which value?

Accepted Answer

The float contact area

Answer

Ground bearing pressure (GBP) equals the outrigger reaction load divided by the contact area of the outrigger float or pad.

Question 2

A crane is set up on asphalt in summer heat. What is the primary concern regarding outrigger pads?

Accepted Answer

Asphalt can soften and allow pads to sink or shift under load

Answer

Hot asphalt loses bearing capacity and can deform under concentrated outrigger loads, causing the crane to shift or tip.

Question 3

Which outrigger configuration provides the greatest crane lifting capacity?

Accepted Answer

All outriggers fully extended and set

Answer

Full outrigger extension maximizes the tipping fulcrum distance, providing the greatest load chart capacity.

Question 4

What term describes the tendency of a crane to rotate about its tipping axis when a load is lifted?

Accepted Answer

Overturning moment

Answer

The overturning moment is the rotational force created by the load and boom weight acting against the crane's stability.

Question 5

Before placing timber cribbing under outrigger pads, what must be confirmed about the cribbing material?

Accepted Answer

It must be sound, free of rot, and of adequate dimensions to distribute load

Answer

Deteriorated or undersized cribbing can fail under load; sound lumber of correct dimensions is required to safely spread the outrigger load.

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