Maintenance and Troubleshooting Flashcards

What is the purpose of performing a 'load test' on a repaired or modified crane, and who must witness it?

Answer: A load test verifies that the repaired or modified crane can safely handle its rated capacity; it must be performed and witnessed by a qualified person or competent person as specified by the manufacturer

Load tests verify structural and functional integrity after repairs or modifications, and must be performed per the manufacturer's specifications, typically witnessed and documented by a qualified person.

What does a 'swing brake dragging' condition feel like in crane operation, and what can it cause?

Answer: The crane swing is slow and requires more hydraulic power than normal; if uncorrected it causes brake overheating, premature brake wear, and possible brake failure

A dragging swing brake partially engages even when not commanded, increasing resistance to swing, generating heat, wearing the brake components rapidly, and potentially causing the brake to fade and fail.

When checking crane engine oil during pre-operation inspection, what condition of the oil warrants immediate concern beyond just checking the level?

Answer: Oil that has a milky or foamy appearance, indicating possible coolant contamination

Milky or foamy engine oil indicates coolant contamination — a symptom of a blown head gasket, cracked engine block, or failed cylinder head — requiring immediate investigation before the crane is operated.

What is 'gear backlash' in crane slewing (swing) drives, and what problems can excessive backlash cause?

Answer: Gear backlash is the free play (gap) between meshing gear teeth; excessive backlash causes impact loading, noise, accelerated gear wear, and imprecise load control

Gear backlash is the clearance between meshing gear teeth. When excessive, it causes impact (shock) loads when swing direction changes, accelerating gear and bearing wear and reducing precise load positioning.

What does 'motor megger testing' mean in the context of crane electrical maintenance, and when is it performed?

Answer: Megger testing uses high-voltage DC to measure insulation resistance of electrical windings, identifying degraded insulation that could cause electrical shorts or grounds

Megger testing measures electrical insulation resistance using high DC voltage to identify degraded or failing winding insulation before it causes shorts, grounds, or motor failure.

A crane's slewing (swing) ring is found to have a 'hard spot' during operation — a point where swing motion is noticeably more difficult. What does this indicate?

Answer: A hard spot indicates localized bearing damage, spalling, or a flattened section in the slew ring raceway, requiring inspection by a qualified person

A hard spot in swing ring operation indicates localized bearing damage — typically spalling, flat spots, or debris in the bearing raceway — which requires inspection by a qualified person and may require ring replacement.