OSHA Pre-Lift Planning & Load Chart Interpretation 2

Question 1

What does 'derating' a crane mean in pre-lift planning?

Accepted Answer

Reducing the rated capacity due to site conditions such as ground stability or wind

Answer

Derating means applying a reduction factor to the crane's chart capacity to account for adverse conditions like soft ground, wind, or blocked outriggers.

Question 2

Which ground condition requires additional engineering evaluation before positioning outriggers?

Accepted Answer

Soil over underground utilities or voids

Answer

Soil over underground utilities, tunnels, or voids may collapse under outrigger loads and requires engineering evaluation of bearing capacity.

Question 3

A lift plan calls for a 40-ton load at a 30-foot radius. The load chart shows a 45-ton capacity at that radius. What is the load line percentage?

Accepted Answer

89%

Answer

40 tons ÷ 45 tons × 100 = 88.9%, approximately 89% of rated capacity, which qualifies as a critical lift.

Question 4

When must a crane operator refuse to make a lift?

Accepted Answer

When the load weight is unknown or exceeds rated capacity

Answer

OSHA requires operators to refuse any lift where the load weight is unknown or where the load would exceed the crane's rated capacity.

Question 5

What is the purpose of outrigger pads (cribbing) during a crane setup?

Accepted Answer

To distribute the outrigger point load over a larger soil area and prevent punch-through

Answer

Outrigger pads spread the concentrated load from the outrigger float across a larger surface area, reducing ground pressure and preventing sinkage.

OSHA - OSHA Certified Crane Operator Practice Test

OSHA - OSHA Certified Crane Operator Practice Test

OSHA Pre-Lift Planning & Load Chart Interpretation 2