NCCCO Overhead Crane flashcards

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

Power line approach distance

Under OSHA crane rules, the minimum distance is 10 feet for lines rated 50 kV or less and increases 0.4 inch per kV above 50 kV; treat all lines as energized.

Wind shutdown rule

Stop outdoor lifting when wind exceeds the crane manufacturer's limit or when the load cannot be controlled with tag lines; load charts assume still air unless stated otherwise.

Lightning safety action

Land the load, lower the hook, and secure or move the crane according to the site plan; do not resume operation until the lightning threat has passed.

Floor bearing check

Before setup, confirm the slab, runway, or ground can support the crane plus its load; look for trenches, voids, soft fill, and uncompacted areas.

Illumination stop rule

If the operator cannot clearly see the load, hook, rigging, and signal person because of darkness, glare, or obstruction, the lift must not proceed.

Daily crane inspection

Before first use each shift, inspect hook, wire rope, chains, brakes, limit switches, controls, warning devices, rails, bumpers, and record any defects found.

Hook removal criteria

Remove a hook from service if its throat opening increased more than 15 percent, it is twisted more than 10 degrees, it is cracked, or its latch is missing or inoperative.

Hoist brake test

Lift a load slightly, stop the hoist, and verify the brake holds the load without drift; a brake that slips requires the crane to be taken out of service.

Limit switch test

Without a load and at safe speed, test upper and lower hoist limits and bridge and trolley travel limits to confirm they stop motion in the intended direction.

Wire rope rejection

Remove wire rope showing broken wires, kinks, birdcaging, corrosion, crushed areas, or diameter loss beyond ASME B30.2 criteria; damaged rope must not be returned to service.

Gross load calculation

Gross load equals the weight of the load plus the weight of all rigging, slings, shackles, spreader beams, and attachments; capacity ratings apply to this total.

Load weight sources

Determine weight from shipping papers, drawings, manufacturer markings, or a scale; do not rely only on appearance or volume when the actual weight is available.

Center of gravity rule

The hook must be positioned over the load's center of gravity; off-center lifts require multiple pick points or a plan to prevent tilt and load shift.

Sling tension formula

For a symmetric two-leg lift, tension per leg equals load divided by two times the sine of the angle each leg makes with horizontal: T = W/(2 sin theta).

Sling angle effect

As a sling leg moves closer to horizontal, tension increases; at 30 degrees from horizontal each leg carries the load divided by two times 0.5.

No side pulling

Hoist vertically over the load's center of gravity; side pulls, dragging, and swinging loads create forces the crane and rigging were not designed to resist.

Test lift procedure

Raise the load a few inches, stop, and check load stability, rigging security, brake holding, and crane response before continuing the lift.

Suspended load rule

Never leave a suspended load unattended and never allow personnel under or on a load; if the operator must leave the controls, land the load first.

Power loss response

If power fails, keep the area clear, set brakes, and lower the load using the crane's controlled lowering or emergency lowering procedure; do not allow free fall.

Rated capacity meaning

Rated capacity is the maximum gross load allowed for a specific crane configuration; it includes the load, rigging, and attachments and must never be exceeded.

Load chart identification

Before lifting, match the load chart to the crane model, serial number, reeving, trolley position, hook height, and any site-specific restrictions listed by the manufacturer.

Variable capacity factors

On cranes with variable ratings, capacity can change with trolley position, hoist reeving, hook height, and bridge or runway configuration; use the chart for the exact setup.

Two-blocking prevention

Two-blocking occurs when the hook block contacts the hoist drum or upper block; the upper limit switch and proper operator control prevent rope damage and load loss.

Overload decision rule

If the load weight is unknown, the chart is missing or illegible, or the calculated gross load exceeds rated capacity, do not lift until the weight and capacity are verified.

Designated signal person

The operator follows signals from one designated signal person; however, anyone may give an emergency stop signal, and the operator must obey it immediately.

Hoist hand signal

Arm extended horizontally, forearm vertical, forefinger pointing up, and hand moved in a small horizontal circle tells the operator to hoist the load.

Stop hand signal

Arm extended with palm down, moved back and forth horizontally, signals stop; emergency stop uses both arms extended, palms down, moved back and forth.

Dog everything signal

Clasp the hands in front of the body to signal the operator to dog everything, meaning secure or lock the crane motions in place.

Normal shutdown sequence

Land the load, raise the hook to a safe height, set brakes, neutralize controls, turn off power, and lock out the disconnect when required by site procedure.

Outdoor crane securing

Park at the designated location, set rail clamps or brakes, install storm anchors or tie-downs, and follow the manufacturer's wind-securing procedure when leaving the crane.

Out-of-service tag

Attach a lock and tag at the disconnect, remove the key, and record the defect; the crane remains out of service until a qualified person repairs it and returns it to service.

Rigging storage

After shutdown, inspect slings and rigging, remove them from the crane, and store them in a clean, dry area away from heat, chemicals, and sharp edges.