Question 1

How do I calculate the load on a sling and ensure it is safe for the weight being lifted?

Accepted Answer

First, determine the total weight of the load (including rigging hardware and spreader bars). Measure the angle of each sling from horizontal to the load. Use load calculation tables or software to determine the tension in each sling based on weight and angle. The rule: as the angle decreases (slings more horizontal), the tension increases (a 90-degree angle is 50% load per sling, a 45-degree angle is 71% per sling). Select rigging hardware with a safe working load (SWL) that exceeds the calculated tension by the required safety factor (usually 4:1 for synthetic, 5:1 for wire rope). Never guess; a failed sling is a catastrophic drop.

Question 2

What is the difference between a vertical hitch, choker hitch, and basket hitch?

Accepted Answer

A vertical hitch has slings running straight up from the load; low angle, low tension, safe and stable. A choker hitch wraps the sling around the load; tension increases as the sling angle increases, so the SWL is reduced. A basket hitch spreads two parts of the same sling under the load; it is strong (tension is reduced by spreading the load across two parts) but only works on stable loads that won't slip. The choice depends on the load shape and stability. Vertical hitches are preferred for most loads.

Question 3

What does a signal-person do and what are the standard hand signals?

Accepted Answer

The signal-person (or signaler) is the direct link between the crane operator and the work site. They give hand signals (visible from the cab) or radio commands to the operator. Standard ANSI signals: arm straight up (raise load), arm down with fingers curled (lower load), arm pointing left or right (move in that direction), hand across neck (emergency stop—all motion stops immediately), both arms extended and moving inward (slow down), fingers folded (higher precision/slow). The signaler must maintain constant, clear communication. If the signaler loses sight of the load or operation, they must call STOP immediately. One confused signal causes a dropped load.

Question 4

How do I rig a steel beam or structural element so it does not rotate or swing in the wind?

Accepted Answer

Use a spreader bar or lifting beam to distribute the sling load evenly and keep the load horizontal and stable. The spreader bar must be rated for the load and positioned so the center of gravity is directly under the hook (no twisting moment). Install taglines (guide ropes) to the load, held by ground personnel, to prevent swinging and rotating. In high winds, reduce load size or delay the lift. Never rig a load that will spin or swing uncontrollably; a moving load can hit equipment, workers, or structures.

Question 5

What is a below-the-hook lifting device and when is it required?

Accepted Answer

A below-the-hook device (such as a spreader bar, clamp, or custom lifting lug) attaches to the load and distributes the hook load. Custom devices must be engineered and certified per ASME B30.20 standards. The engineer specifies the load capacity, safe sling angles, and attachment points. Using an unapproved or incorrectly calculated device is a major hazard. Always verify the device's certification tag and load rating before using it.

Question 6

How do I safely lower a load if the crane loses power or the sling slips?

Accepted Answer

Emergency lowering is a trained procedure: the operator uses a manual descent valve on the crane hydraulics to lower the load slowly and controllably. Never attempt to lower the load manually unless absolutely necessary (trained riggers only, with load cells to verify control). If a sling slips partially, call STOP immediately, stabilize the load, and reassess. If the load is about to fall, ensure all personnel below are out of the fall zone. Every crane crew must practice emergency procedures quarterly.

Question 7

What is load testing and when must it be done?

Accepted Answer

Load testing is the proof that a rigging assembly (spreader bar, custom device, or sling set) can safely handle the load. A load cell measures the actual tension during the test lift, which must be within the calculated limits. Test lifts are performed with the load suspended but not swinging, at full height where the load will be used, and with the device manufacturer's engineer present. Test results are documented. For critical lifts or high-value loads, load testing is mandatory. Regular inspection of rigging hardware is also required: slings, shackles, and hooks are inspected annually or more often if in heavy use.

क्षेत्र	जूनियर	मिड	सीनियर
USA	$40k	$72k	$95k
UK	£25k	£44k	£58k
EU	€29k	€52k	€68k
CANADA	C$48k	C$86k	C$114k

क्षेत्र	जूनियर	मिड	सीनियर
USA	$40k	$72k	$95k
UK	£25k	£44k	£58k
EU	€29k	€52k	€68k
CANADA	C$48k	C$86k	C$114k

Crane Rigging and Signaling

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