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
What is the purpose of a crane's hydraulic oil cooler, and what symptoms indicate it may not be functioning properly?
Answer: The oil cooler removes heat from hydraulic fluid; symptoms of failure include overheating, reduced system pressure, and sluggish operation
The hydraulic oil cooler removes heat from the hydraulic system to prevent overheating. Failure symptoms include high temperature warnings, reduced crane performance, and fluid discoloration.
During crane operation, the operator notices that one hydraulic function (such as boom extension) is significantly slower than normal but other functions appear normal. What is the most likely cause?
Answer: A flow control valve, cylinder internal leakage, or restriction specific to that circuit may be the cause
When only one hydraulic function is slow while others are normal, the problem is most likely isolated to that specific hydraulic circuit — a flow control valve, worn cylinder seals, or a restriction in that circuit's plumbing.
What is the correct procedure when a new crane enters service, according to ASME B30.5 initial inspection requirements?
Answer: The crane must undergo a thorough inspection and functional test by a qualified person before being placed in service
ASME B30.5 requires that new cranes undergo a thorough inspection and functional test by a qualified person before being placed in service, regardless of factory testing.
What does it mean when a crane's hydraulic system generates a 'whining' or 'cavitation' noise from the pump area?
Answer: The hydraulic pump is experiencing cavitation — it is starved for fluid, typically due to a clogged suction filter or low fluid level
Cavitation noise (whining, chattering, or rattling) from the hydraulic pump indicates the pump is not receiving adequate fluid flow — commonly caused by a clogged suction filter, low fluid level, or a kinked suction hose.
What is the function of a crane's 'boom angle indicator limiter' (boom stop), and how does it protect the crane?
Answer: It prevents the boom from being raised beyond the manufacturer's specified maximum angle, preventing backward tip-over or structural damage
The boom stop (or maximum angle limiter) physically or electronically prevents the boom from being raised above the manufacturer's specified maximum angle, preventing structural damage from boom-to-mast contact or backward instability.
What type of hydraulic fluid contamination causes 'aeration' in a hydraulic system, and what are its effects?
Answer: Air contamination (entrained air bubbles) causes aeration, leading to spongy controls and noise
Aeration is the entrainment of air bubbles in hydraulic fluid, causing spongy, inconsistent control response, increased noise, and accelerated fluid degradation due to oxidation from the entrained air.