Mobile Crane Operator 4 Flashcards

During a critical pick at 87% of rated capacity, the Load Moment Indicator (LMI) on a hydraulic mobile crane loses power and goes blank. According to ASME B30.5, what must the operator do?

Answer: Immediately lower the load to the ground and remove the crane from service until the LMI is repaired

ASME B30.5 requires that anti-two-block devices and load moment indicators be operational before use. A malfunctioning LMI is not merely a convenience item — it is a required safety device. If it fails during a lift, the operator must suspend the operation, safely lower the load, and take the crane out of service until the device is repaired and verified functional.

A mobile crane is configured on full outriggers for a tandem lift. Midway through the pick, the operator notices that one outrigger float has settled approximately ¾ inch into the ground compared to its position at setup. What is the MOST appropriate immediate action?

Answer: Suspend the lift immediately, hold the load stationary, and reassess ground conditions and bearing capacity before proceeding

Any unexpected or unanticipated movement of the crane or its supporting structure during a lift is an immediate stop-work condition. Ground bearing capacity can fail rapidly and non-linearly once settlement begins. The operator must immediately suspend all motion, hold the load, and have a competent person reassess the ground conditions, outrigger pad sizing, and rated capacity assumptions before the lift resumes.

An overhead transmission line rated at 345 kV is located 16 feet from the nearest point of a mobile crane's maximum swing arc. The operator has not established an encroachment prevention plan or obtained utility owner approval. Under OSHA 1926.1408 Table A, what is the correct conclusion?

Answer: The crane may NOT operate; the required minimum clearance for 200–350 kV lines is 20 feet

OSHA 1926.1408 Table A establishes voltage-tiered minimum clearances. For lines rated 200–350 kV, the minimum clearance is 20 feet. At 345 kV, this tier applies, so 16 feet is insufficient — the crane cannot operate without an encroachment prevention plan, a dedicated spotter, and utility owner or registered engineer authorization. The 15-foot threshold applies only to lines rated 50–200 kV.

During inspection of a 6×36 classification wire rope on a mobile crane hoist, a qualified person finds 9 broken wires distributed across multiple strands within a single rope lay length. No more than 3 broken wires exist in any single strand. What is the correct disposition?

Answer: The rope must be removed from service because 9 broken wires in one lay exceeds the limit of 8 for 6×36 class rope

For 6×36 class wire rope (which includes constructions with 27 to 36 wires per strand), ASME B30.5 sets the rejection threshold at 8 randomly distributed broken wires in one rope lay length, or 4 broken wires in a single strand. With 9 broken wires across multiple strands in one lay, the rope exceeds the per-lay threshold of 8 and must be immediately removed from service — even though no individual strand exceeds its limit.

In a two-crane tandem lift, Crane A is rated at 100 tons and Crane B is rated at 60 tons. The load weighs 130 tons. The lift plan assigns 70 tons to Crane A and 60 tons to Crane B. Midway through the lift, the load shifts unexpectedly and load cell readings indicate Crane B is now carrying 68 tons. Who bears ULTIMATE responsibility for ensuring neither crane exceeds its rated capacity at any moment during the lift?

Answer: The designated lift director, who is responsible for overall coordination and ensuring no single crane is overloaded

ASME B30.5 requires that a designated person (lift director) be assigned to direct all aspects of a multi-crane lift. This individual bears ultimate responsibility for the entire operation, including continuous monitoring of load sharing to ensure no crane is overloaded at any point. While individual operators must not exceed their crane's ratings and riggers control the rigging, the lift director has overall command authority and accountability for the coordinated lift.

A hydraulic truck crane is set up on outriggers with maximum counterweight installed for a near-capacity pick. After completing the lift, the site superintendent asks the operator to travel 40 feet with the suspended load to reposition it rather than setting it down and re-rigging. Which condition MOST critically governs whether this is permissible?

Answer: The load chart must contain explicit manufacturer-approved ratings for traveling with a suspended load at that configuration, and ground conditions must be assessed

Traveling with a suspended load on a hydraulic truck crane is only permissible when the crane manufacturer's load chart explicitly includes rated capacities for that travel configuration, and those ratings must be used — not the static on-rubber charts. Additionally, ground conditions along the travel path must be evaluated by a qualified person, the path must be firm and level, and many manufacturers impose strict boom angle and load limits. Without manufacturer-approved traveling-with-load ratings, the operation is prohibited regardless of load weight.