NCCCO Service Truck Crane flashcards

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

Rated capacity

The maximum load a crane may lift in a specific configuration, as stated in the manufacturer's load chart for that radius, boom length, and setup.

Working radius

The horizontal distance from the crane's center of rotation to the center of the hook or load, measured with the boom under load, not the unloaded geometric radius.

Net capacity calculation

Chart capacity for the actual configuration minus deductions for attachments not already included, such as jib, auxiliary head, hook block, and rigging, before comparing to load weight.

Load moment indicator

An instrument that senses boom length, angle, and load, computes the load moment, and warns or stops operation before the rated capacity for the programmed chart is exceeded.

Anti-two-block device

A limit device that prevents the hook block from contacting the boom tip by stopping the hoist or boom-lowering function before contact occurs; it must never be bypassed.

Outrigger float pressure

The force on each outrigger float divided by the pad area; larger pads reduce ground bearing pressure, and pad area required equals float load divided by allowable soil pressure.

Crane level tolerance

Manufacturer's allowable out-of-level condition, commonly about 1 percent, required for load chart validity; beyond it, capacity and stability are not assured.

45-degree load spread

The assumption that load under a pad spreads outward at about 1:1 through fill, so at depth d the loaded width is roughly pad width plus twice d.

Boom angle to radius

For a straight boom, radius approximately equals boom length times the cosine of the boom angle, plus any offset from the rotation center.

Boom deflection effect

Under load the boom bends and the machine flexes, increasing the actual radius beyond the geometric value, which can reduce capacity from the chart entry assumed.

On-tire capacity chart

A separate, lower-capacity chart for lifting without fully set outriggers, usually with limits on tire pressure, travel speed, and boom position.

Area of operation

The quadrant of the crane (over front, side, or rear) to which a chart row applies; ratings can differ by quadrant because structural strength differs.

Chart interpolation rule

Between charted radii, use interpolation only if the manufacturer allows it; otherwise use the next longer radius, which gives the lower, safer capacity.

Configuration-specific chart

The correct chart depends on boom length, counterweight, outrigger spread, jib status, and boom mode; changing any of these selects a different chart.

Stability versus strength limit

At long radius, tipping (stability) usually governs capacity; at short radius, structural strength governs. The chart does not identify which limit applies.

Tandem lift load share

In a two-crane lift, each crane's share depends on hook height and geometry; the crane with the more vertical line carries the larger share.

Shock loading

Dynamic force from rapid hoist starts, sudden stops, or a swinging load that can exceed the static load and the rated capacity even when the weight is within the chart.

Side loading prohibition

Pulling, dragging, or swinging a hung-up load applies force sideways to the boom, a direction it was not designed for; it requires manufacturer approval.

Standard hand signals

Agreed signals for raise/lower boom, raise/lower load, swing, stop, emergency stop, extend/retract boom, and dog everything, given by one designated signalperson.

Signal loss rule

If the operator loses sight of the load or loses radio contact with the signalperson, the operation stops until communication is restored.

Unknown load weight

A stop-work condition; the load must be verified from shipping papers, markings, or a scale before any lift is planned against the chart.

Daily pre-shift inspection

Documented check of wire rope, hooks and latches, outriggers, levels, LMI, anti-two-block, alarms, and leaks; deficiencies are corrected before the crane is used.

Wire rope removal criteria

Conditions such as broken wires, kinks, bird-caging, corrosion, or diameter reduction that require removal from service, per manufacturer and applicable standards.

Hook latch requirement

The hook must have a functional latch; hooks with missing or sprung latches, cracks, or excessive throat opening are removed from service.

Counterweight function

Counterweight and carbody provide the resisting moment that balances the load moment; capacity is tied to the specific counterweight installed.

Periodic inspection

A more thorough inspection than the daily check, performed at manufacturer- and standards-set intervals, with records kept and traveling with the machine.

Swing radius barricade

The barricaded zone covering tail swing and counterweight travel, which extends beyond the boom side and is a struck-by hazard for ground personnel.

Underground hazard check

Verification for utilities, vaults, tanks, and backfilled trenches before setting stabilizers, since a void under one float causes tipping rather than slow settling.

Power line clearance

The manufacturer's minimum distance from energized lines to the highest point of boom, load line, and load; if unachievable, a spotter and documented plan are required.

Wind and sail area

Wind acting on the load's exposed area and the boom adds side load; chart capacity assumes a freely suspended load, so tag lines and wind reduce usable capacity.

Counterweight swing path

The fixed arc swept by the counterweight, set by machine geometry rather than boom length, which must be barricaded near walls, excavations, and traffic.

Chart band conservatism

When a chart lists one capacity across a range of boom angles, plan with the lowest capacity in that band rather than assuming the most favorable angle.