NCCCO Digger Derrick cheat sheet

Soil bearing capacity governs outrigger pad size: pad area (ft²) = outrigger force (lb) ÷ allowable soil pressure (lb/ft²); typical undisturbed soil 2,000–4,000 lb/ft², soft fill as low as 500 lb/ft².

Locate all underground utilities before setup; the standard tolerance zone is 18–24 in on either side of a marked utility, and hand-dig or vacuum-expose within it.

Minimum clearance from excavations: keep outrigger pads back at least a distance equal to the excavation depth (or the engineered shoring design) to avoid surcharge loading the slope.

Slope limit: most manufacturers permit setup only on grades of 1% or less unless the unit is leveled with cribbing; verify the specific load chart note.

Ground pressure under a floating pad spreads at roughly 45° through compacted granular fill; never bridge a soft spot with a single layer of timber without a load-rated mat.

Overhead obstructions set the maximum boom height at setup: measure utility line heights and maintain the employer's minimum approach distance before raising the boom.

Barricade the full swing radius plus a margin; the counterweight tail swing can extend several feet beyond the carrier and is a crush hazard.

Document the site survey: soil type, slope, utility locates, overhead lines, access route, and pad locations, and re-check after rain or freeze-thaw.

Principal components: carrier, turntable/pedestal, boom, boom extension, auger/derrick stow bracket, digger motor, pole claw or grabber, winch line, capstan (if fitted), outriggers, and controls.

Rated capacity is the smallest of boom capacity, winch line pull, auger torque limit, and stability limit at the given radius; the load chart already reflects the governing value.

Radius is measured horizontally from the center of rotation to the center of the load, not along the boom; boom angle and extension both change radius.

Deduct the weight of all rigging, the pole grabber, and the auger from the gross capacity to get the allowable load.

Boom deflection and carrier oscillation increase actual radius under load; the chart's structural rating assumes a level, properly set carrier.

Winch line pull rating applies at the bare drum; line pull decreases as layers build up on the drum - use the rated line pull for the layer in use.

Anti-two-block, load moment indicator, and boom angle/radius indicators are rated-capacity devices; a fault disables the lift until corrected.

Structural ratings apply to the boom and turntable; stability ratings apply to the whole machine and are affected by outrigger spread and ground conditions.

Inspect before each shift and after any incident: wire rope (broken wires, kinks, bird-caging, crush, corrosion), sheaves, hooks (throat opening, latch, wear), and shackles.

Wire rope removal criteria commonly include 6 or more randomly distributed broken wires in one lay, 3 or more in one strand in one lay, or 10% diameter reduction.

Check hydraulic hoses and cylinders for leaks, chafing, and cracked fittings; a pressurized pinhole leak can inject fluid and is a serious injury hazard.

Verify function of the anti-two-block device, load moment indicator, boom angle indicator, horn, and outrigger interlocks before every lift.

Check auger teeth, pilot bit, and auger flighting for wear; worn teeth reduce penetration and increase torque loading on the boom.

Inspect outrigger pads, floats, and pins for cracks and deformation; a cracked pad can fail suddenly under load.

Confirm the load chart in the cab matches the machine configuration (boom length, outrigger spread, counterweight) and is legible.

Record deficiencies and tag the machine out of service until repaired; do not operate with a bypassed or inoperative safety device.

Fully extend all outriggers and set pads on stable ground unless the load chart explicitly permits a reduced spread; partial spread uses a derated chart.

Level the carrier with outriggers before lifting; the bubble level must read level, and all tires should be clear of the ground or per manufacturer instruction.

Stability is lost when the load moment exceeds the resisting moment of the carrier plus counterweight; the load moment increases with both load weight and radius.

Increase capacity by reducing radius first: retract the boom or raise the boom angle before adding counterweight or spread.

Never use the boom, auger, or pole grabber to pull, drag, or side-load; side loads are outside the load chart and can buckle the boom.

Swing slowly and smoothly; sudden stops create dynamic load that can exceed the static rating by a significant margin.

Keep personnel out of the swing radius and never allow anyone under a suspended load or the boom.

Recheck the load moment indicator and radius after every boom movement; capacity changes continuously with radius.

Set the auger plumb over the hole location before starting; the boom must be positioned so the auger hangs vertically, not side-loaded.

Engage the digger with the auger just above grade, then lower gradually while turning; do not force the auger into the ground with boom down-pressure beyond manufacturer limits.

Expect auger torque reaction: the boom and turntable will try to rotate opposite the auger; keep the auger clear of the boom and carrier and use the digger's torque limiter.

Lift the auger slowly to clear spoil; a loaded auger is heavy and its weight counts against the load chart.

Stop digging if the auger strikes an obstruction, and reverse or withdraw rather than forcing; sudden stoppage can damage the digger motor or boom.

Keep hands, feet, and clothing clear of the auger and flighting; the auger rotates with high torque and no guard protects the digging point.

Backfill and compact per specification; loose backfill around a pole reduces uplift resistance and lateral support.

Use a spotter when digging near utilities, and stop immediately if soil color, odor, or debris suggests a buried line.

Rig poles with a pole grabber or sling at the balance point; butt-heavy poles need the pick point adjusted so the pole hangs near level.

Calculate the pole weight and add rigging weight before checking the load chart at the planned radius; a typical 40-ft Class 3 pole weighs roughly 1,000–1,500 lb.

Control the pole with a tag line whenever the load can rotate or swing; never let a tag line pass through the swing path or near energized lines.

Set the pole plumb and brace or guy it before releasing the grabber; an unbraced pole can fall or rotate unexpectedly.

Keep the pole clear of the boom and outriggers during the set; the pole grabber must not be used to push or pry the pole into the hole.

Lower and raise loads slowly; sudden load release when the pole seats in the hole can shock-load the boom and winch.

Personnel must not guide a pole by hand at the butt or near the hole while it is suspended; use a tag line and keep hands clear.

Verify hole depth, pole setting depth, and alignment before backfill; setting depth is typically 10% of pole length plus 2 ft.

Maintain the employer's minimum approach distance (MAD) from energized lines; typical distribution MAD is 10 ft for voltages up to 50 kV, increasing with voltage.

Treat all lines as energized until the utility confirms de-energization and visible grounding; a visual check is not proof of de-energization.

The digger derrick is not an insulated aerial device; the boom does not provide electrical protection, and contact can energize the entire machine.

Establish an equipotential zone and ground the machine per the utility's work plan when working near energized lines.

If the machine contacts an energized line, the operator should stay in the cab and warn others away until the utility de-energizes the line.

Maintain MAD for all parts of the machine, load, and rigging, not just the operator; account for boom deflection, wind sway, and load swing.

Use non-conductive tag lines and prohibit personnel from contacting the machine or load during energized work.

Identify the voltage class of every line before setup; if voltage is unknown, use the highest MAD for the lines present.

Use a single designated signal person; only that person gives signals, and the operator stops on any stop signal from anyone.

Standard hand signals: raise/lower boom, extend/retract, swing, hoist/lower load, stop, and emergency stop must be known by the operator and signal person.

Radio communication requires a clear channel, agreed call signs, and a check before the lift; loss of communication means stop the operation.

The signal person must be in clear view of the operator or in continuous radio contact; if neither, stop the lift.

Pre-lift meeting covers the lift plan, load weight, radius, signals, tag line assignments, exclusion zones, and emergency stop procedure.

Tag line handlers and ground crew stay outside the swing radius and never under the load; the operator confirms all personnel are clear before swinging.

The operator has final authority to stop a lift if conditions are unsafe, regardless of signals from others.

Agree on a dedicated emergency stop signal and test it before starting work.

Worked example: 1,200 lb pole plus 100 lb rigging at 15 ft radius requires 1,300 lb capacity at that radius; verify the chart entry for the actual boom length and outrigger spread.

Capacity decreases as radius increases; double the radius roughly halves the allowable load on a stability-limited chart.

Always use the chart for the actual boom extension and the actual outrigger configuration; interpolate between charted radii conservatively.

Deduct the weight of the pole grabber, auger, and any stowed attachment from the rated capacity.

When the chart lists both structural and stability ratings, use the lower value for the configuration in use.

Never exceed the chart's maximum radius or boom angle limit; the load moment indicator alarms before the limit but is not a substitute for the chart.

Recompute capacity whenever the boom is moved, the load changes, or the outrigger spread changes.

Keep a copy of the applicable load chart with the machine and confirm it matches the machine's serial-numbered configuration.

If the load moment indicator alarms, stop the movement and reduce radius or load before continuing.

If a hydraulic hose bursts, stop the operation, lower the load if possible, and shut down; do not attempt to stop a pinhole leak with your hand.

If the machine becomes unstable, lower the boom and load slowly and set the load down; do not swing or extend further.

After any contact with an energized line, keep everyone clear and call the utility; do not touch the machine until de-energized.

Report all incidents, near misses, and equipment damage to the supervisor and complete the required documentation.

Inspect the machine after any shock load, tip-over, or electrical contact before returning it to service.

Know the location of the fire extinguisher and first-aid kit, and the site emergency contact number.

Conduct a post-incident review to identify root cause and correct procedures before resuming work.