HEO Crawler Crane NC III flashcards

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

Rated capacity definition

The maximum load the crane may lift at a given radius, boom length, and configuration; it is the lower of the structural limit and the stability limit.

Radius measurement point

Horizontal distance from the crane's center of rotation to the center of the hoist line, measured with the load suspended, not to the boom tip.

Net capacity calculation

Gross chart capacity minus the weight of everything below the boom tip: hook block, slings, shackles, spreader beam, and any auxiliary equipment.

Percent of capacity formula

Total load including rigging divided by net chart capacity, multiplied by 100; lift plans commonly require extra review above a defined threshold such as 75 percent.

Anti-two-block device

A switch and weight on the boom tip that stops hoisting and boom lowering before the hook block contacts the boom tip sheave, preventing rope and structural damage.

Load moment indicator

An instrument that senses boom angle, length, and load to display radius, capacity, and percent of capacity, and that stops operations when the rating is exceeded.

Wire rope removal criteria

Conditions requiring rope replacement include broken wires, diameter reduction, corrosion, kinking, crushing, bird-caging, and damaged end attachments, per the applicable standard.

Sheave groove wear

A worn sheave groove pinches and abrades the rope, accelerating fatigue; inspect groove diameter and flange condition and replace sheaves beyond manufacturer limits.

Track shoe wear limit

Shoe and grouser height are measured against the manufacturer's limit; shoes worn past limit, cracked, or with loose grousers must be replaced before operation.

Ground bearing pressure

The crane and load reaction divided by the effective mat area; it must stay below the soil's allowable bearing capacity to prevent settlement or tipping.

Sling leg tension formula

Tension per leg equals load divided by the number of legs times the sine of the angle from horizontal; flatter angles greatly increase tension in each leg.

Center of gravity rule

The hoist line must be directly above the load's center of gravity; otherwise the load tilts, swings, and may rotate uncontrollably once lifted.

Exclusion zone definition

A barricaded area covering the full swing radius including counterweight tail swing, where no personnel may stand during slewing or lifting operations.

Rigging rejection criteria

Reject slings with cuts, burns, knots, or missing tags; reject hooks with throats spread beyond 15 percent or missing latches, and shackles with worn pins.

Carbody leveling tolerance

The crane must be set level within the manufacturer's tolerance, commonly about one degree, before the boom is extended or any load is lifted.

Counterweight chart matching

The installed counterweight must match the load chart for the boom and jib configuration; any change alters capacity and must follow the chart.

Boom backstop function

A structural stop that prevents the boom from being raised past its maximum angle; the boom hoist limiter must stop raising before contact.

Trial lift purpose

After assembly, lift a known weight slightly off the ground to confirm stability, brake holding, and correct load moment indicator readings before production lifting.

Side load effect

Load charts assume vertical loading; side pull from dragging or booming reduces capacity and can buckle the boom lattice, so it must be avoided.

Tag line use

Ropes attached to the load to control rotation and swing; handlers stay outside the fall zone and clear of the swing path while keeping lines taut.

Pick-and-carry restriction

Travel with a suspended load is permitted only where the load chart allows it, with reduced capacity, low boom, load trailing, and firm level ground.

Standard stop signal

A hand signal or verbal command halting all crane motion; any person on site may give an emergency stop, not only the designated signal person.

Signal person designation

Only one designated signal person directs the operator at a time; if communication is lost, the operator stops and holds until contact is restored.

Power line clearance

The crane must maintain the required minimum distance from energized lines for the voltage class; otherwise de-energize and ground the line and use a spotter.

Wind speed limit

The manufacturer specifies maximum wind speed for each boom and load configuration; operations stop when it is exceeded or the load becomes uncontrollable.

Brake drift condition

A swing or travel brake that does not hold the load is a stop-work condition; the crane is tagged out until the brake is adjusted or repaired.

LMI recalibration trigger

Recalibrate the load moment indicator after any boom change, rope change, or sensor replacement, and record the date and technician identification.

Daily inspection record

A checklist recording date, machine serial number, hour meter, items checked, defects found, and the inspector's name and signature for each shift.

Lift plan contents

A document stating load and rigging weights, crane configuration, radius, boom length and angle, chart capacity, percent of capacity, ground condition, and approvals.

Defect escalation rule

Any defect affecting a safety device such as the LMI, anti-two-block, or brakes must be recorded, the crane tagged out, and the defect escalated to the responsible person.

Near-miss reporting

An unplanned event that did not cause injury or damage is recorded with time, location, sequence, and corrective action, with the same rigor as an incident.

Shutdown sequence steps

Land the load, lower the boom to rest, set swing and travel brakes, chock tracks on slopes, shut down, lock the cab, and record hours and faults.

Boom configuration limits

Boom and jib sections must match the permitted chart combinations; exceeding the maximum boom plus jib length invalidates the load chart for that setup.