Mechanical Systems & Maintenance Practices Flashcards

During a pre-operational inspection, a crane operator notices the wire rope has a localized reduction in diameter of 4% in a section that also shows slight corrosion pitting. Per ASME B30.2 criteria, what is the correct course of action?

Answer: Remove the rope from service immediately, as either condition alone meets removal criteria

Under ASME B30.2, a localized diameter reduction of 3% or more is itself a removal-from-service criterion, independent of any other defect. Corrosion pitting that is visible also meets separate removal criteria. Either condition alone warrants immediate removal — they do not need to appear together. Continuing operation or delaying inspection is never acceptable when a removal criterion is met.

A hydraulic telescoping boom crane is operating at full extension. The operator notices a slow, continuous boom drift downward when the hydraulic controls are in neutral. Which component is the MOST likely cause of this specific symptom?

Answer: Internal leakage past the piston seals within the boom telescope cylinder

Slow, continuous boom drift downward with the controls in neutral is the classic symptom of internal leakage past the piston seals within the telescope cylinder. The hydraulic fluid bypasses the piston, allowing the cylinder to retract under load. A faulty boom hoist brake would cause hook/load drift, not boom telescope drift. A worn pump causes loss of lift power and pressure, while a clogged strainer causes cavitation noise and erratic movement — neither produces silent, steady drift.

An operator is inspecting a load block and notices that the swivel hook rotates freely but has detectable axial (up-and-down) play when manually pushed and pulled along the hook's vertical axis. What does this indicate?

Answer: Worn or damaged thrust bearing requiring the block to be removed from service for repair

Detectable axial play in a swivel hook indicates wear or damage to the thrust bearing that supports the hook's vertical load while allowing rotation. A properly maintained swivel hook should rotate freely but have no significant axial (vertical) play. The thrust bearing carries the suspended load, and excessive play means it can no longer do so reliably — the block must be removed from service. This is distinct from rotational freedom, which is by design.

A crane's load line sheave groove is measured and found to be 10% deeper than its original specification. What is the primary engineering reason this requires sheave replacement?

Answer: The rope contacts the groove walls rather than the groove bottom, causing pinching, accelerated wire fatigue, and reduced rope life

When a sheave groove wears deeper than the rope's diameter, the rope drops into the groove and contacts the sides rather than riding on the groove bottom. This side contact pinches the outer wires, generates uneven pressure, causes accelerated fatigue cracking in the wires, and dramatically reduces rope service life. Industry standards (such as ASME B30.2) specify maximum allowable groove wear, typically around 1/32 inch below nominal, and worn sheaves must be replaced to prevent rope damage.

A lattice boom crawler crane is being prepared for a pick. The operator checks the boom hoist wire rope and finds three broken wires in one lay length located within the boom butt section wrapping around the boom hoist drum. How should this finding be evaluated?

Answer: The rope must be removed from service because broken wires in the end connections or at the drum are an independent removal criterion

ASME B30.2 and most crane standards include a specific, separate removal criterion for broken wires located at end attachments or at the drum — regardless of the total broken wire count. Even a single broken wire at a termination point or drum wrapping can trigger removal. This is distinct from the six-broken-wires-in-one-lay rule, which applies to the running rope in the field. The location of the damage is critical to proper evaluation.

After completing maintenance that required removing and reinstalling a load-block assembly, the mechanic informs the operator that the hook latch spring was replaced but notes the new latch has slightly more resistance when manually depressed than the original. Before returning the crane to service, what is the operator's MOST appropriate next action?

Answer: Verify that the latch fully closes and springs back unassisted when manually released, then confirm the hook meets all other ASME B30.10 inspection criteria before service

The correct action is a thorough functional inspection per ASME B30.10: verify the latch closes fully, springs back without hesitation, and that no other hook criteria are deficient. While a stiffer spring is generally not a problem in itself, the operator's duty is to confirm proper function — not just accept a mechanic's verbal assurance. A rated load test is not required for latch replacement and would be excessive. Requiring the original spring reinstalled ignores that replacement springs are a normal, approved maintenance item as long as they meet specifications.