NCCCO Articulating Crane flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ground bearing pressure

The load per unit area the crane's outriggers or tracks impose on the soil, equal to total weight divided by total support area; it determines whether mats or cribbing are needed.

Outrigger float area

The contact area of an outrigger pad, computed as pi times the radius squared for a circular pad; larger pads reduce ground bearing pressure for the same load.

Level tolerance

The maximum slope on which a crane may be set up, typically 1% or less per the manufacturer; the level indicator must be centered before any lift.

Pre-shift inspection

The walk-around check of wire rope, hooks, slings, outriggers, and the load moment indicator performed before each shift and documented per the employer's procedure.

Power line clearance

The minimum distance crane parts and load must stay from energized lines, 10 ft up to 50 kV plus 0.4 in per kV above 50 kV unless de-energized and grounded.

Cribbing

Sound, full-contact blocking placed under outrigger pads to level the crane and spread load; it must be sized to the pad and free of voids or soft spots.

Rated capacity

The maximum load a crane may lift in a specific configuration, equal to the smallest of the load chart value, the LMI limit, the rigging capacity, and the structural limit.

Radius measurement

The horizontal distance from the crane's center of rotation to the center of gravity of the load, measured at the load, not at the boom tip.

Net capacity

The load chart capacity minus the weight of the hook block, slings, spreader bars, and other below-the-hook devices attached to the boom.

Load chart selection

Choosing the chart page that matches the outrigger configuration, boom mode, counterweight, and jib or extension in use; using the wrong page invalidates the capacity.

Interpolation limits

Estimating capacity between charted radius or boom length values is permitted only within the charted range and only when the chart allows it; extrapolation beyond the chart is prohibited.

Boom deflection effect

Boom bending under load increases the actual radius beyond the geometric value, so the chart radius must reflect the loaded condition, not the unloaded boom position.

Pick-and-carry chart

A separate reduced-capacity chart used when traveling with a suspended load; it accounts for travel speed, ground conditions, and boom position and never equals the static lift chart.

Two-crane lift share

Each crane's portion of a shared load depends on the load's center of gravity; the crane nearer the center of gravity carries more and must be rated for its share.

Sling angle factor

The multiplier applied to sling capacity based on the angle from horizontal; at 30 degrees the factor is 0.5, so each leg carries twice its share of the load.

Bridle tension formula

Tension per leg in a two-leg bridle equals half the load divided by the sine of the angle from horizontal; a shallower angle dramatically increases tension.

Center of gravity pick

Rigging so the hook is directly above the load's center of gravity; an off-center pick shifts weight to one leg and can cause rotation or sling failure.

Shackle loading axis

Shackles and hooks must be loaded along the pin or bowl axis; side loading reduces capacity and can bend or open the hardware.

Shock loading

A dynamic force from sudden starts, stops, or a slack sling taking up load, which can multiply the static load several times and exceed rigging capacity.

Tag line use

A rope used to control load rotation and swing from a safe distance; it keeps hands off the suspended load and personnel out of the fall zone.

Sling removal criteria

Conditions that require removing a sling from service, including missing tags, knots, cuts, broken wires, or wear beyond the manufacturer's published limits.

Standard hand signals

The agreed set of arm and hand motions for boom, swing, hoist, and stop commands; the operator obeys a stop signal from any person on site.

Designated signalperson

The single qualified person who directs the lift; the operator takes signals only from that person except for a stop signal, which is honored from anyone.

Radio communication check

Confirming a dedicated channel and clear voice commands with the signalperson before the lift, using standard terms such as boom up and load down.

Pre-lift checks

Verifying load weight, rigging, radius, chart, LMI reading, and that all personnel are clear; then sounding the horn and lifting slowly to test stability.

Swing control

Leading the load with the swing and avoiding sudden stops so the load does not swing out of control; tag lines help steady it when practical.

Suspended load rule

Never leave the operator station with a load suspended; lower the load and shut down per the manufacturer's procedure before leaving the controls.

Travel with load

Moving the crane with a suspended load only per the manufacturer's pick-and-carry chart, with the boom in the recommended position and the load kept low.

OSHA crane standard

29 CFR 1926 Subpart CC governs cranes and derricks in construction; 29 CFR 1910.180 covers general industry cranes, and the work being performed determines which applies.

LMI and RCL

The load moment indicator or rated capacity limiter warns and stops the crane before capacity is exceeded; operating with a failed or bypassed unit is prohibited.

Annual inspection

A competent person inspects the crane at least annually and functionally tests the LMI, RCL, and limit switches; the inspection record is retained.

Personnel lifting rules

Lifting people only with an approved platform, a pre-lift meeting, and manufacturer approval; never lift personnel directly on the crane hook.

Critical lift plan

A written plan required for lifts over 75% of capacity, multiple-crane lifts, or personnel lifting, covering rigging, radius, capacity, and contingency steps.