NCCCO Mechanical Systems & Maintenance Practices 4

Question 1

When inspecting wire rope, what is the maximum number of randomly distributed broken wires allowed in one rope lay length before the rope must be removed from service?

Accepted Answer

12 broken wires

Answer

ASME B30.2 specifies that 12 randomly distributed broken wires in one rope lay length is the threshold requiring wire rope removal from service.

Question 2

A crane's load line sheave shows a groove that is too narrow for the wire rope. What is the primary hazard of operating in this condition?

Accepted Answer

Pinching and accelerated wire rope wear

Answer

A sheave groove too narrow for the rope causes the rope to ride on its sides, pinching it and accelerating wear and fatigue failure.

Question 3

What does a crane's anti-two-block (ATB) device do when activated?

Accepted Answer

Cuts power to the hoist and boom raise functions

Answer

When the ATB device activates because the hook block approaches the boom tip, it cuts power to hoist-up and boom-raise functions to prevent two-blocking.

Question 4

Which hydraulic system symptom most likely indicates internal bypass across a main control valve spool?

Accepted Answer

Slow or drifting cylinder movement under load

Answer

Internal bypass across a control valve spool allows fluid to return to tank without doing work, causing cylinders to move slowly or drift under load.

Question 5

When should a crane operator lubricate the swing ring gear and pinion?

Accepted Answer

Per the manufacturer's maintenance schedule and as conditions require

Answer

Lubrication intervals must follow the manufacturer's maintenance schedule, with additional lubrication applied as environmental or operational conditions demand.

NCCCO (National Commission for the Certification of Crane Operators) Practice Test

NCCCO (National Commission for the Certification of Crane Operators) Practice Test

NCCCO Mechanical Systems & Maintenance Practices 4