Ground Stability & Outrigger Setup Flashcards
7 cards from real CPO 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 Stability & Outrigger Setup flashcards as text
How should an outrigger pad (crib mat) be sized relative to the outrigger float?
Answer: The pad should be significantly larger than the float to spread the load over more ground area
The outrigger pad must be substantially larger than the float itself so that the point load is distributed over a much greater ground contact area, reducing unit pressure below the soil's bearing capacity.
When setting up on a sloped surface, in what sequence should outriggers generally be deployed?
Answer: Downhill outriggers first, then uphill outriggers
On a slope, the downhill outriggers are extended first because they bear the greater portion of the machine's weight due to gravity, and establishing them first provides the initial stable base.
Which outrigger configuration provides the MAXIMUM stability footprint for a concrete pump truck?
Answer: All four outriggers fully extended to their maximum spread
Full extension of all four outriggers creates the widest possible support polygon, maximizing the machine's resistance to tipping moments generated by boom and concrete load.
What is a key advantage of timber crib mats over steel plates for outrigger support on soft ground?
Answer: Timber mats can flex and conform to uneven ground, distributing load more evenly
Timber mats have some flexibility and can conform to slightly irregular ground surfaces, providing more uniform bearing contact than rigid steel plates which can tip or concentrate load on high spots.
What does the term 'ground bearing capacity' mean in the context of concrete pump setup?
Answer: The maximum load per unit area that the soil can support without shearing or excessive settlement
Ground bearing capacity (expressed in psi or kPa) is the maximum pressure the soil can withstand before it shears or deforms excessively, and outrigger loads must remain below this value.
When setting up a concrete pump over a basement or underground parking structure, what critical information must be obtained first?
Answer: The structural load rating of the deck or slab to confirm it can support outrigger loads
Structural slabs and decks have engineered load limits; the combined outrigger loads can easily exceed the design capacity of parking decks or basement ceilings, causing catastrophic structural failure.
How often should the operator visually inspect outrigger pads and ground conditions during an active concrete pump operation?
Answer: Continuously and at regular intervals throughout the entire pour operation
Ground conditions can change during a pour due to moisture, vibration, or load cycling; continuous monitoring throughout the operation is required to catch any early signs of settlement or instability.