Ground Bearing Pressure and Outrigger Setup Flashcards
7 cards from real NCCCO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Ground Bearing Pressure and Outrigger Setup flashcards as text
When a crane is set up on a slope, which outrigger typically carries the greatest load?
Answer: The downhill outrigger on the low side
The downhill (low-side) outrigger carries the highest reaction load because the crane's center of gravity shifts toward the lower side on a slope.
What is 'mat bearing pressure' in the context of crane setup?
Answer: The distributed ground pressure beneath a timber or steel mat used to support outriggers or crawlers
Mat bearing pressure is the load per unit area transmitted to the ground through a mat system used to spread crane outrigger or crawler loads.
A crane manufacturer requires outrigger pads to be used whenever the crane is set up on outriggers. An operator decides to skip pads on a paved parking lot. This is:
Answer: Unacceptable; manufacturer requirements must be followed regardless of surface type
Manufacturer requirements for outrigger pads are mandatory; pavement does not exempt operators from following setup specifications.
When outrigger beams are extended and the floats are down, what must be confirmed before beginning a lift?
Answer: That the crane is level within manufacturer's specified tolerance
The crane must be level within the manufacturer's tolerance (typically ±1%) before lifting, as unlevel conditions shift loads and reduce stability.
Which of the following best describes 'outrigger reaction force'?
Answer: The downward force transmitted from the crane to the ground through each outrigger
Outrigger reaction force is the vertical downward load each outrigger transmits to the supporting surface, determined by the crane's weight, boom configuration, and lifted load.
Why is it important to position outrigger pads under the outrigger float rather than offset to one side?
Answer: An offset pad creates an eccentric load that can cause the float to tip off the pad under load
The float must bear directly and evenly on the pad; an offset causes the float edge to dig into the pad or ground, potentially tipping the crane.
After a heavy rain, a previously approved crane setup area should be:
Answer: Re-evaluated for bearing capacity because saturation significantly reduces soil strength
Water saturation dramatically reduces soil bearing capacity, so any previously approved area must be re-inspected and re-evaluated after significant rainfall.