Mechanical Systems & Maintenance Practices Flashcards
7 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 7 Mechanical Systems & Maintenance Practices flashcards as text
When inspecting wire rope, what is the maximum number of randomly distributed broken wires allowed in one rope lay length before the rope must be removed from service?
Answer: 12 broken wires
ASME B30.2 specifies that 12 randomly distributed broken wires in one rope lay length is the threshold requiring wire rope removal from service.
A crane's load line sheave shows a groove that is too narrow for the wire rope. What is the primary hazard of operating in this condition?
Answer: Pinching and accelerated wire rope wear
A sheave groove too narrow for the rope causes the rope to ride on its sides, pinching it and accelerating wear and fatigue failure.
What does a crane's anti-two-block (ATB) device do when activated?
Answer: Cuts power to the hoist and boom raise functions
When the ATB device activates because the hook block approaches the boom tip, it cuts power to hoist-up and boom-raise functions to prevent two-blocking.
Which hydraulic system symptom most likely indicates internal bypass across a main control valve spool?
Answer: Slow or drifting cylinder movement under load
Internal bypass across a control valve spool allows fluid to return to tank without doing work, causing cylinders to move slowly or drift under load.
When should a crane operator lubricate the swing ring gear and pinion?
Answer: Per the manufacturer's maintenance schedule and as conditions require
Lubrication intervals must follow the manufacturer's maintenance schedule, with additional lubrication applied as environmental or operational conditions demand.
A crane's load moment indicator (LMI) displays a warning at 90% of rated capacity. What is the operator's correct response?
Answer: Stop operations and reassess the lift plan
An LMI warning at 90% of rated capacity means the operator must stop, reassess the lift plan, and ensure no rated capacity will be exceeded.
What is the purpose of a crane's load brake (holding brake) in a hoist system?
Answer: To hold a suspended load stationary when the hoist is in neutral
The load brake (holding brake) automatically engages when the hoist control is in neutral, preventing the load from descending by gravity.