HEO Tower Crane NC III cheat sheet

Daily pre-use inspection covers wire rope (broken wires, kinks, bird-caging, corrosion), hook latch function, hook throat opening, sheave wear, brake function, limit switches, and the load moment/indicator system before any lift.

Wire rope discard rule (ISO 4309 / ASME B30.5 practice): replace when broken wires in a running rope exceed 10 in any 6d length or 5 in any 30d length for a single lay; 6×19 class ropes are more sensitive than 6×37 class.

Hook inspection limits: discard a hook with throat opening increased more than 15 percent, wear exceeding 10 percent of the original dimension, or any bend/twist exceeding 10 degrees from the plane of the unbent hook.

Rigging sling angle rule: tension = load / (number of legs × sin of angle from horizontal). Two-leg sling at 30 degrees carries 1.0 × load per leg; at 60 degrees it carries 0.58 × load per leg - never rig below 30 degrees from horizontal without engineered approval.

Working load limit (WLL) of a wire rope sling decreases with D/d ratio (sheave or pin diameter ÷ rope diameter); a choked hitch derates capacity by roughly 20 percent versus a vertical hitch.

Ground bearing check: outrigger/crane pad pressure = total load ÷ pad area. A crane with 60 t total ground load on four 1.5 m × 1.5 m mats gives about 6.7 t/m²; verify against the geotechnical allowable bearing pressure.

Site preparation items: level and compacted crane base, exclusion zone barricades, overhead power line clearance (minimum 3 m for lines up to 50 kV, increasing with voltage), drainage, and a documented lift plan for critical lifts.

Tag lines are used to control load rotation; personnel must never stand under a suspended load or between the load and a fixed structure.

Foundation options: reinforced concrete pad, ballast block base, or anchor frame; the base must meet the manufacturer's specified concrete strength, level tolerance (typically 1/500 to 1/1000), and anchor bolt torque before erection.

Erection sequence: base/foundation check → mast section installation with pins and bolts torqued → slewing unit → cab → jib and counter-jib → counterweights and ballast → wiring and limit switch commissioning → load test and certification.

Mast verticality must be checked with a theodolite or plumb line; typical tolerance is 1/1000 of the height, and the maximum allowable deviation is specified in the manufacturer's manual (commonly 200–300 mm at the top).

Free-standing height is limited by the manufacturer; beyond that, the crane must be tied to the building with wall ties at specified intervals and heights, with tie forces calculated from the manual.

Climbing (jacking) operations require a climbing frame, a certified climbing crew, wind speed below the manufacturer's limit (commonly 10–13 m/s), and no personnel on the jib during the climb.

Counterweight and ballast must match the load chart configuration exactly; adding or removing ballast changes the load moment and invalidates the chart used for lifting.

Dismantling is the reverse of erection and is statistically more dangerous; it requires a dismantling plan, a mobile crane with a verified capacity chart, and a controlled exclusion zone.

After erection or climbing, the crane must be load-tested and inspected by a competent person, and the load moment limiter and all limit switches must be calibrated and function-tested before handover.

The load moment limiter (LML) compares actual load moment to the rated moment for the jib radius and stops hoisting/boom-out when the limit is reached; it must never be bypassed or defeated.

Slewing with a suspended load produces centrifugal and side-load forces; keep slewing speed low, keep the load below the jib, and avoid simultaneous travel, hoist, and slew unless the manufacturer permits it.

Wind limits: stop lifting when wind speed exceeds the manufacturer's figure (commonly 20 m/s for general lifts, lower for large sail-area loads); the allowable load chart must be reduced for wind area of the load.

Shock loading (sudden pick-up or snatching) can multiply the static load several times; always take up slack slowly and use a soft-start on the hoist.

Never lift people unless the crane is fitted with a certified personnel platform and the lift is authorized by a written risk assessment and permit.

Load control rules: keep the load within the rated radius, do not drag or side-pull, do not use the crane to pull stuck loads, and do not leave a suspended load unattended.

Two-blocking protection prevents the hook block from contacting the jib tip; the anti-two-block device must be tested before every shift and the hoist limit switch must stop the hoist before contact.

Tag line operators stay outside the fall zone and guide the load without touching it; the signaler and operator maintain line of sight or radio contact throughout the lift.

Standard hand signals (ISO 16715 / ASME B30.5) must be used when radio fails: hoist (arm up, forefinger circling), lower (arm down), stop (arm extended, palm down), emergency stop (both arms raised), slew left/right (arm extended pointing).

One designated signaler per crane; only that person gives signals, except that anyone may give an emergency stop signal at any time.

Radio communication protocol: identify crane and station, use clear short phrases, acknowledge each command, and confirm the load is clear before slewing or travelling.

Blind lifts require a signaler at the load position and a second signaler or relay when the operator cannot see the load; the plan must state who signals and on which channel.

Before the lift, the team briefs the lift plan: load weight, radius, rigging, path, destination, exclusion zone, and emergency stop procedure.

Standard colors and markings: red = danger/stop, yellow = caution, green = safe; crane and rigging inspection tags (green = passed, red = out of service) must be visible.

Loss of communication means stop: the operator holds the load, does not move until contact is re-established or the load is safely landed under a pre-agreed procedure.

Signaler and rigger must be trained and competent; the operator must be able to see the signaler or maintain radio contact at all times.

Rated capacity = the lesser of the load chart value for the working radius and the structural/rigging limit; the chart value already includes the hook block, slings, and any lifting beam weight unless stated otherwise.

Working radius is measured horizontally from the slewing center to the centerline of the hook; increasing radius reduces capacity approximately with the inverse of the moment arm.

Load moment (t·m) = load (t) × radius (m). The crane's rated moment is fixed for a given configuration; the LML uses this to prevent overload.

Example: a crane rated at 100 t·m with a 20 m radius can lift 5 t gross; deduct the hook block and rigging (say 0.6 t) to get about 4.4 t net payload.

Duty/configuration factors: load charts are specific to jib length, counterweight, ballast, outrigger spread, and free-standing or tied condition - never interpolate between charts.

Lifting plan contents: load weight and center of gravity, rigging and sling angles, crane position and radius, ground bearing, path and destination, wind limit, personnel roles, and emergency procedures.

Critical lifts (over 75 percent of chart capacity, tandem lifts, loads over occupied areas, or unusual rigging) require an engineered lift plan and a competent-person review.

Percent capacity = (gross load ÷ rated capacity at radius) × 100; keep normal lifts at or below 75 percent, and never exceed 100 percent.

Hierarchy of controls: elimination, substitution, engineering controls, administrative controls, and PPE - PPE is the last line of defense.

Employer duties typically include a written risk assessment, safe system of work, competent persons, training records, and maintenance of lifting equipment with periodic thorough examination (commonly every 6 or 12 months depending on the equipment and jurisdiction).

Crane operator certification and medical fitness are required; operators must not work under the influence of alcohol, drugs, or fatigue.

PPE for tower crane work: hard hat with chin strap, safety harness with lanyard for climbing and working at height, safety boots, gloves, high-visibility clothing, and eye protection.

Environmental controls: prevent hydraulic oil and fuel spills with drip trays and bunding, manage noise and dust, and dispose of waste oil and contaminated rags through licensed contractors.

Emergency procedures: rescue plan for a person stranded at height, fire extinguisher on the crane cab, first-aid arrangements, and a means of communication with the ground.

Incident reporting: report near misses, dropped loads, and equipment damage; preserve the scene and do not return the crane to service until inspected by a competent person.

Permit-to-work and lockout/tagout (LOTO) apply to maintenance and repair; energy sources (electric, hydraulic, gravitational) must be isolated and verified before work.

Daily checks: wire rope, hook, brakes, limit switches, LML, anti-two-block, lights, horn, and fluid levels; record results in the inspection log.

Lubrication schedule follows the manufacturer's manual: wire rope, slewing ring, mast bolts, and sheave bearings at specified intervals; over-lubrication of brakes is a common cause of failure.

Torque checks on mast bolts and slew ring bolts are critical; loose bolts can lead to mast collapse - re-torque to the specified value and record it.

Brake adjustment: the hoist brake must hold the rated load without slip; test the brake by lifting a test load slightly and holding it, checking for drift.

Troubleshooting guide: no hoist response → check power supply, emergency stop, limit switch, and contactor; slow hoist → check hydraulic pressure or motor overload; LML alarm → reduce radius or load, never bypass.

Shutdown procedure: land and secure the load, park the jib in the manufacturer's specified free-slew or park position, apply slewing brake, switch off power, lock the cab, and record the shutdown in the log.

Out-of-service conditions: any safety device failure, structural crack, wire rope beyond discard criteria, or brake failure requires the crane to be tagged out and reported.

Maintenance records must be retained and made available for inspection; periodic thorough examination is separate from daily pre-use checks.