Maintenance and Troubleshooting 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 Maintenance and Troubleshooting flashcards as text
When inspecting wire rope on a lattice boom crane, what condition requires immediate removal from service per ASME B30.5?
Answer: Six randomly distributed broken wires in one rope lay, or three broken wires in one strand in one lay
ASME B30.5-5.4.3 specifies that wire rope must be replaced if it has six or more randomly distributed broken wires in one rope lay, or three or more broken wires in one strand in one lay.
A hydraulic mobile crane's boom drifts down slowly when holding a suspended load with no commands given. What is the most likely cause?
Answer: Internal leakage in the boom cylinder or holding valve
Slow boom drift under load with no operator input indicates hydraulic fluid bypassing internally through a worn cylinder seal or a holding valve (load-holding valve/counterbalance valve) that is not seating properly.
Which lubrication point on a mobile crane requires consistent attention during maintenance?
Answer: Wire rope and sheaves, which require lubrication per manufacturer intervals or at minimum monthly under ASME B30.5
Wire rope and sheave lubrication is critical to prevent internal corrosion and wear. ASME B30.5 and manufacturer requirements specify regular re-lubrication of running ropes and sheave bearings.
During troubleshooting, an operator notices the crane's load moment indicator (LMI) is reading significantly less than the actual calculated load. What hazard does this create?
Answer: The operator may believe there is more remaining capacity than actually exists, leading to overloading
If the LMI under-reads actual load, the system will not alarm at the true capacity limit. The operator may continue to add load beyond safe limits without warning, creating an overload and tip-over risk.
A crane's swing brake is not holding the load from rotating when power is removed. According to ASME B30.5, what is the correct action?
Answer: Remove the crane from service immediately — a failed swing brake requires repair before further use
A swing brake that fails to hold is a deficiency under ASME B30.5 frequent inspection criteria. The crane must be removed from service until the brake is repaired and properly tested.
What is the purpose of a periodic inspection on a mobile crane, and how often must it occur per ASME B30.5?
Answer: A thorough examination of structural and mechanical components performed at 1-to-12 month intervals based on usage severity
ASME B30.5-5.2.3 defines periodic inspections as covering structural members, fasteners, sheaves, drums, bearings, hooks, and all safety devices at intervals of 1 to 12 months, or as recommended by a qualified person based on usage.