NCCCO Maintenance and Troubleshooting 2

Question 1

What is the purpose of a crane's hydraulic oil cooler, and what symptoms indicate it may not be functioning properly?

Accepted Answer

The oil cooler removes heat from hydraulic fluid; symptoms of failure include overheating, reduced system pressure, and sluggish operation

Answer

The oil cooler heats hydraulic fluid in cold weather; symptoms of failure include slow boom extension

Answer

The oil cooler filters contaminants from hydraulic fluid; symptoms of failure include unusual hydraulic sounds and jerky motion

Answer

The oil cooler stores reserve hydraulic fluid; low fluid warning lights indicate cooler failure

Question 2

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?

Accepted Answer

A flow control valve, cylinder internal leakage, or restriction specific to that circuit may be the cause

Answer

The hydraulic pump is failing and requires immediate replacement

Answer

Low hydraulic fluid level is causing all functions to slow simultaneously

Answer

The crane's load moment indicator is restricting that function as a precautionary measure

Question 3

What is the correct procedure when a new crane enters service, according to ASME B30.5 initial inspection requirements?

Accepted Answer

The crane must undergo a thorough inspection and functional test by a qualified person before being placed in service

Answer

New cranes require no inspection since they were tested and certified at the factory

Answer

New cranes require only a visual exterior inspection before first use

Answer

New cranes must undergo a 30-day break-in period with limited loads before full inspection

Question 4

What does it mean when a crane's hydraulic system generates a 'whining' or 'cavitation' noise from the pump area?

Accepted Answer

The hydraulic pump is experiencing cavitation — it is starved for fluid, typically due to a clogged suction filter or low fluid level

Answer

The hydraulic pump is working correctly and has reached optimal operating speed

Answer

The noise is normal for high-viscosity hydraulic fluids in cold weather conditions

Answer

The pump motor is overloaded and requires immediate electrical inspection

Question 5

What is the function of a crane's 'boom angle indicator limiter' (boom stop), and how does it protect the crane?

Accepted Answer

It prevents the boom from being raised beyond the manufacturer's specified maximum angle, preventing backward tip-over or structural damage

Answer

It limits the maximum load weight the crane can hoist at any boom angle

Answer

It sounds an alarm when the boom angle exceeds the load chart's recommended angle for the current load

Answer

It automatically adjusts the counterweight position to compensate for changes in boom angle

Question 6

What type of hydraulic fluid contamination causes 'aeration' in a hydraulic system, and what are its effects?

Accepted Answer

Air contamination (entrained air bubbles) causes aeration, leading to spongy controls and noise

Answer

Water contamination causes aeration, leading to corrosion of metal components

Answer

Metallic particle contamination causes aeration, leading to valve scoring and pump wear

Answer

Biological contamination causes aeration through microbial gas production in the reservoir