Mobile Crane Operator 4 Flashcards
6 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 6 Mobile Crane Operator 4 flashcards as text
What is the primary operational difference between an all-terrain mobile crane and a rough terrain crane?
Answer: All-terrain cranes are designed for highway travel and off-road operation with multi-axle steering, while rough terrain cranes have dedicated two-axle carriers for off-road use
All-terrain cranes combine road mobility (highway speed capability, all-axle steering) with off-road performance, while rough terrain cranes use a specialized two-axle carrier optimized for job site mobility but requiring transport vehicles for highway moves.
When operating a telescoping boom mobile crane, what is the relationship between boom extension and rated capacity?
Answer: Rated capacity decreases as the boom is extended due to increased radius and reduced structural efficiency
As a telescoping boom extends, the working radius typically increases and the structural efficiency of the multi-section boom decreases, both of which reduce rated capacity compared to the retracted configuration.
What is the purpose of the load moment indicator's (LMI) audible pre-warning alert?
Answer: To alert the operator that the crane is approaching rated capacity, typically at 90%, allowing corrective action before the limit is reached
The LMI pre-warning alert (typically at 90% of rated capacity) gives the operator advance notice before reaching the limit, allowing crane repositioning, load reduction, or boom angle adjustment before the rated capacity cutout activates.
What is a 'duty cycle' lift and how does it differ from standard crane operation?
Answer: Duty cycle lifting involves repetitive pick-and-carry or clamshell operations where the crane repeatedly lifts and swings loads in a continuous cycle
Duty cycle operation involves repetitive lifting cycles (such as clamshell excavating, magnet work, or concrete bucket operations) where the dynamic fatigue loading exceeds what standard load charts address, requiring derating.
What is the minimum safe clearance required between a crane's rotating superstructure and adjacent structures during operation?
Answer: A minimum 2-foot clearance (or manufacturer's specification) must be maintained to prevent pinch point crushing hazards
OSHA and crane safety standards require a minimum clearance (typically 2 feet) between the crane's rotating structure and any fixed object to prevent workers from being crushed in the pinch point zone.
What is the purpose of the boom hoist limiting device on a mobile crane?
Answer: To prevent the boom from being raised above the maximum allowable angle or into a two-blocked position
The boom hoist limiting device (boom angle indicator and upper boom limit switch) prevents the boom from being raised beyond the maximum angle specified in the load chart, which could cause over-luffing (boom falling backward).