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
What is the primary purpose of outrigger pads (cribbing) when setting up a concrete pump truck?
Answer: To distribute the load over a larger ground area and prevent outrigger sinkage
Outrigger pads spread the concentrated point load of each outrigger float over a larger surface area, reducing ground pressure and preventing sinkage into soft or unstable ground.
Which soil type presents the GREATEST risk of outrigger sinkage and requires the largest cribbing area?
Answer: Soft or saturated clay
Soft or saturated clay has very low bearing capacity and is prone to plastic deformation under load, making it the most hazardous soil type for outrigger stability.
What is the minimum safe distance a concrete pump operator should maintain between outriggers and the edge of an open excavation or trench?
Answer: A distance equal to the depth of the excavation, measured horizontally from the trench edge
The horizontal setback from an excavation should equal at least the depth of the excavation to account for the soil's angle of repose and prevent wall collapse under outrigger loads.
Before extending outriggers on unfamiliar ground, what is the FIRST action a CPO operator should take?
Answer: Inspect the ground for underground utilities, voids, drainage pipes, and soil type
Before any outrigger deployment, the operator must assess the ground for underground hazards (utilities, voids, culverts) and evaluate soil conditions to determine appropriate cribbing requirements.
When setting up a concrete pump on asphalt pavement during hot weather, what additional precaution should be taken?
Answer: Use larger cribbing or steel plates because hot asphalt softens and loses bearing strength
Hot asphalt softens significantly and can creep or deform under concentrated loads, so larger cribbing or heavy steel plates are needed to distribute the outrigger load safely.
What maximum tilt angle is generally permitted for a concrete pump truck during boom operation to maintain stability?
Answer: No more than 1 degree from level
Most concrete pump manufacturers specify a maximum machine inclination of 1 degree from level during operation, as greater tilts significantly shift the center of gravity and can cause tipping.
If an outrigger begins to sink or settle during concrete pumping operations, what is the correct immediate response?
Answer: Stop pumping immediately, retract the boom to its travel position, and re-evaluate ground conditions
Any outrigger sinkage is an immediate safety emergency; the operator must stop all pumping and boom movement, return the boom to rest position, and assess and correct the ground support before resuming.