NCCER Tower Crane cheat sheet

Minimum clearance between the crane's rotating parts and any obstruction is 2 ft (0.6 m) per ASME B30.3; many operators require 10 ft (3 m) where personnel can be present.

Slewing radius plus load radius defines the swing hazard zone; barricade the full slewing arc, not just the pick path.

Wind: stop hoisting when wind exceeds the manufacturer's limit; typical maximum in-service wind is 20 mph (9 m/s) at the jib, and out-of-service design wind is much higher (often 100+ mph depending on region).

Rail-mounted cranes need rail stops, buffers, and anti-rail-climbing devices at both ends of the runway; runway rails must be level within manufacturer tolerance and anchored to resist uplift.

Ground bearing pressure = (crane weight + load + counterweight + dynamic factor) / effective bearing area; verify against the geotechnical report for the crane's loaded and unloaded conditions.

Never operate near energized power lines without de-energizing or maintaining OSHA Table T clearance; for lines up to 50 kV, minimum 10 ft, increasing 0.4 in per kV above 50 kV.

Anti-collision systems and zoning limits are required where multiple cranes overlap; define priority, height separation, and slew limits in writing before operation.

Inspect before each shift: wire rope (broken wires, kinks, corrosion), hooks (throat opening, latches), brakes, limit switches, and anemometer function.

Foundation options: fixed concrete pad, ballasted cruciform base, or rail-mounted; each has manufacturer-specified anchor bolt patterns, embedment, and concrete strength at erection.

Concrete must reach the manufacturer's minimum compressive strength (often 75–100% of design) before erection loads are applied; verify with cylinder breaks.

Erection sequence: base/foundation, mast sections, slew ring and cab, counter-jib with counterweights, jib, then hoist rope reeving and tie bars.

Climbing: the climbing frame carries the crane while a mast section is inserted; never allow personnel under the climbing frame, and verify hydraulic pressure and mechanical locks before transferring load.

After each climb, recheck verticality (typically within 1/500 to 1/1000 of height per manufacturer), tie-in connections, and limit switches.

Free-standing height and tie-in spacing are manufacturer-specific; never exceed the free-standing height without installing wall ties or guy wires as designed.

Dismantling reverses erection; the counter-jib counterweights are removed in the reverse order of installation, and the jib is lowered before the mast is reduced.

Wind speed limits apply during erection and dismantling (often 12–20 mph); stop when gusts exceed the manufacturer's erection limit.

A qualified erection director and a written erection/dismantling plan signed by a qualified engineer are required; the plan must address stability at every stage.

Load moment = load weight × radius; the load moment limiter (LML) prevents exceeding the rated load moment for the jib configuration.

Rated capacity decreases as radius increases; always read the load chart for the exact jib length, counterweight, and reeving in use.

Hoist reeving changes capacity: 2-part vs 4-part line affects both capacity and hoist speed; never exceed the rope's safe working load.

Slewing with a suspended load induces swing; avoid rapid slewing and use tag lines to control rotation, especially in wind.

Shock loading (sudden starts/stops, snatching a load) can exceed rated capacity by 2× or more; use smooth control inputs.

Never drag or side-pull loads; the jib and mast are designed for vertical loads, and side loading can buckle the mast.

Multi-crane lifts require a written plan, a single signal person, and load sharing that never exceeds either crane's capacity at its radius.

Park the crane per manufacturer: jib free to weathervane, trolley at the specified position, hooks raised, and brakes set.

Sling angle: tension = load / (number of legs × sin of angle from horizontal); at 30° each leg carries 1.0× the load share, at 60° about 0.577×.

Never exceed a 60° horizontal sling angle from vertical without engineering approval; shallower angles multiply leg tension rapidly.

Hitch types: vertical, choker, basket, and bridle each have different capacity factors (choker typically 0.75–0.8 of vertical, basket up to 2× for two legs).

Rigging hardware working load limit (WLL) must equal or exceed the load; shackles, hooks, and master links are marked with WLL.

Standard hand signals per ASME B30.3/OSHA 1926 Subpart CC: hoist, lower, stop, emergency stop, boom/jib up/down, trolley in/out, and dog everything.

Only one designated signal person directs the operator; anyone may give an emergency stop signal.

Radio communication must use a dedicated channel, be tested before the lift, and have a backup hand-signal method.

Inspect slings before each use: remove from service for broken wires, cuts, burns, or missing tags; synthetic slings have specific wear criteria.