CPO Ground Stability & Outrigger Setup

Question 1

What is the primary purpose of outrigger pads (cribbing) when setting up a concrete pump truck?

Accepted Answer

To distribute the load over a larger ground area and prevent outrigger sinkage

Answer

To protect the asphalt from oil spills during operation

Answer

To raise the truck higher for better boom reach

Answer

To anchor the truck to prevent movement from concrete pressure

Question 2

Which soil type presents the GREATEST risk of outrigger sinkage and requires the largest cribbing area?

Accepted Answer

Soft or saturated clay

Answer

Compacted gravel

Answer

Dense sand

Answer

Bedrock with thin topsoil

Question 3

What is the minimum safe distance a concrete pump operator should maintain between outriggers and the edge of an open excavation or trench?

Accepted Answer

A distance equal to the depth of the excavation, measured horizontally from the trench edge

Answer

At least 1 foot from the trench edge

Answer

Exactly 6 inches past the shoring line

Answer

No restriction if shoring is in place

Question 4

Before extending outriggers on unfamiliar ground, what is the FIRST action a CPO operator should take?

Accepted Answer

Inspect the ground for underground utilities, voids, drainage pipes, and soil type

Answer

Extend outriggers slowly and watch for any ground movement

Answer

Park the pump truck perpendicular to the concrete pour location

Answer

Contact the ready-mix supplier to verify slump

Question 5

When setting up a concrete pump on asphalt pavement during hot weather, what additional precaution should be taken?

Accepted Answer

Use larger cribbing or steel plates because hot asphalt softens and loses bearing strength

Answer

Use smaller outrigger pads to avoid cracking the asphalt

Answer

Only extend the rear outriggers to reduce total load

Answer

Run the engine at low RPM to reduce vibration

Question 6

What maximum tilt angle is generally permitted for a concrete pump truck during boom operation to maintain stability?

Accepted Answer

No more than 1 degree from level

Answer

No more than 0.5 degrees from level

Answer

No more than 3 degrees from level

Answer

Up to 5 degrees, if the boom is not fully extended

Question 7

If an outrigger begins to sink or settle during concrete pumping operations, what is the correct immediate response?

Accepted Answer

Stop pumping immediately, retract the boom to its travel position, and re-evaluate ground conditions

Answer

Continue pumping but reduce boom reach to compensate

Answer

Add more cribbing under the sinking outrigger while maintaining pump operation

Answer

Shift the concrete load by repositioning the discharge hose