Advanced Rigging (RA) cheat sheet

Sling tension for a two-leg bridle: T = (W/2) ÷ cos θ, where θ is the angle each leg makes with vertical; tension rises sharply as θ exceeds 60° from vertical.

Tension in a single leg of an n-leg sling with equal legs and symmetric attachment: T = W ÷ (n × cos θ).

Sling angle factor (multiplier applied to share of load) = 1 ÷ cos θ; at 30° from horizontal the factor is 1.155, at 45° it is 1.414, at 60° it is 2.000.

Center of gravity of a load lies on the vertical line through the lifting point only when the load is balanced; eccentric lifts shift load share to the legs nearer the CG.

Load share on each leg of an asymmetric two-point pick: share = total load × (distance from CG to opposite point ÷ span between points).

Combined stress on a shackle or eye under angled loading: resolve the resultant vector, then compare with the rated capacity at that angle, not the vertical rating.

Moment of a force about a point: M = F × d, where d is the perpendicular distance; tipping occurs when the overturning moment exceeds the restoring moment from weight.

Mechanical advantage of a simple movable pulley system equals the number of rope parts supporting the moving block; account for friction losses of roughly 3-10% per sheave.

Shackle working load limit applies only when the load is along the pin-to-bowl axis; side loading reduces capacity and requires the manufacturer's rating.

Screw-pin shackles must be fully seated with the pin threaded home; a pin not fully engaged or wired closed is a removal-from-service condition.

Wire rope sling efficiency drops with termination type: poured socket about 100%, swaged socket about 95%, hand-spliced loop about 90%, and standard wire rope clips about 80%.

Synthetic web sling capacity is quoted for a single-ply vertical hitch; choker hitches typically reduce capacity to about 80% and basket hitches roughly double it, per the sling tag.

Master links, swivel hoist rings, and eyebolts are rated for a specific direction of pull; plain forged eyebolts are not rated for angular lifts unless marked for that use.

Below-the-hook lifting beams convert a two-point pick into a vertical lift at the attachment points, eliminating the horizontal compression a bridle would impose on the load.

Spreader beams carry compressive load between attachment points; they must be designed for the bending and buckling loads imposed by the sling angles actually used.

Hooks with cracks, throat opening increased more than 5-10% (per manufacturer), or wear exceeding 10% of the original dimension are removed from service.

Standard hand signals are mandatory when voice or radio communication is unreliable; only one designated signalperson directs the operator at a time.

A stop signal may be given by anyone on the job site; the operator must obey a stop signal from any source.

Load moment (load × radius) must remain within the crane's rated capacity chart for the actual boom length, radius, and configuration in use.

Crane capacity decreases as radius increases; the load chart, not the boom angle alone, governs the allowable load.

Hoist limit switches, anti-two-block devices, and boom angle indicators are operational aids that must be functional before lifting; bypassing them is prohibited.

Tag lines control rotation and swing of a suspended load; they are held outside the load's fall zone and never wrapped around hands or body.

Personnel must never ride the load, the hook, or the sling; suspended loads are not to be passed over workers.

Outrigger floats must be fully extended and set on stable, competent ground with mats or cribbing sized for the imposed bearing pressure.

Wire rope lays: regular lay has strands twisted opposite to the rope direction, providing better resistance to crushing; lang lay has strands and rope twisted the same direction, offering greater abrasion resistance but less resistance to rotation.

Wire rope strength is reduced by broken wires, corrosion, and kinking; removal criteria are based on broken wires in a specified length, diameter reduction, and evidence of core damage.

Synthetic rope strength is affected by knots: a bowline can reduce strength by roughly 40-60%, while a proper splice retains most of the rope's strength.

Splice types: eye splice, back splice, and short splice; a short splice retains roughly 80-90% of rope strength, while an eye splice with a thimble protects the eye from abrasion.

Wire rope clips are installed with the U-bolt on the dead end (never on the live end) and spaced at roughly six rope diameters, with the first clip one saddle-width from the thimble.

Rotation-resistant and rotation-resistant-compacted wire ropes require special handling; they can develop twist and must not be used where load rotation is unacceptable.

Synthetic rope should be inspected for glazing, fuzzing, and abrasion; glazing indicates heat or friction damage and reduces strength.

Knot efficiency varies by knot type; the figure-eight loop and bowline are common, but the splice remains the highest-efficiency termination.

Hydraulic jack capacity is rated at the piston, not the toe or saddle; off-center loading reduces capacity and can bend the piston.

Jacks must be set on a firm, level base with a wood or steel pad sized to distribute load and prevent sinking; the jack must be plumb.

When lifting with multiple jacks, lift in small increments and crib or block the load as it rises; never rely on the jack alone to hold a load.

Rollers reduce friction during skidding; the required pull force is roughly the load times the coefficient of rolling friction plus any grade resistance.

Skidding on rollers requires control of the load's path and speed; a snubber or winch line controls run-away on slopes.

Jacking towers and climbing jacks require engineered foundations and bracing; the design must account for wind and dynamic loads during lifting.

Cribbing stacks should be built with the grain alternating and the stack stable; height-to-base ratio should be kept low to prevent toppling.

Load moving on rollers: keep the load's center of gravity low and centered over the roller group; unequal roller loading can cause the load to tip.

A critical lift plan typically includes load weight and CG, rigging arrangement, crane capacity at the planned radius, ground bearing, and contingency for a dropped load.

Rigging design begins with the load's weight and center of gravity; the lift points are chosen so the CG lies within the support polygon or on the vertical through the hook.

A lift plan must identify the rigging hardware, sling types and capacities, and the angle of each leg at the planned configuration.

Shock loading from sudden stops or slack removal can multiply static load several times; the plan should specify slow, controlled movement.

Wind loading increases with the square of wind speed; the plan should state a wind limit at which the lift is stopped.

Load movement paths must be surveyed for obstructions, power lines, and personnel; the swing radius and tail swing of the crane must be barricaded.

Pre-lift meetings confirm roles, signals, and the sequence of operations; the lift director has authority to stop the lift.

Trial lifts verify the CG and rigging before the full lift; the load is raised slightly and checked for level and stability.

Inspection intervals: a documented periodic inspection at least annually for rigging in normal service, with more frequent intervals for severe service or after any shock load.

Wire rope slings are removed from service for broken wires, severe corrosion, kinking, bird-caging, or reduction in diameter beyond the manufacturer's limit.

Synthetic web slings are removed for holes, cuts, snags, burns, or discoloration from heat or chemicals; the red warning thread, if present, indicates the sling has been damaged.

Chain slings are removed for cracks, stretch beyond the manufacturer's limit, or wear exceeding 10% of the link's original dimension.

Shackles, hooks, and rings are removed for cracks, deformation, or wear exceeding the manufacturer's allowable; magnetic particle or dye penetrant inspection may be required.

Hoists and cranes require documented inspections at intervals set by the manufacturer and applicable regulations, including daily pre-use checks by the operator.

Any rigging that has been overloaded, shock-loaded, or involved in an accident must be inspected before being returned to service.

Inspection records should identify the item, date, inspector, and findings; items removed from service must be tagged and segregated from usable gear.

OSHA 29 CFR 1926 Subpart CC governs cranes and derricks in construction; 1910.184 covers slings, and 1910.179 covers overhead and gantry cranes.

Rigging hardware must be marked with its rated capacity; unmarked or illegible gear is removed from service.

The rated capacity of a sling or hardware item is the maximum load for the configuration and angle specified by the manufacturer.

Employees must be trained and qualified for the rigging tasks they perform; the employer is responsible for verifying competency.

Power line safety: maintain the required minimum clearance from energized lines, and use a spotter or proximity alarm where required.

Fall protection is required when working at height, including on booms or elevated platforms; the rigger must be tied off.

Accident prevention relies on pre-job hazard analysis, exclusion zones under suspended loads, and a stop-work authority for all personnel.

Loads must not be suspended over personnel; a barricade and warning line keep workers out of the fall zone.

Sling tension for a two-leg bridle: T = (W/2) ÷ cos θ, where θ is the angle each leg makes with vertical; tension rises sharply as θ exceeds 60° from vertical.

Tension in a single leg of an n-leg sling with equal legs and symmetric attachment: T = W ÷ (n × cos θ).

Sling angle factor (multiplier applied to share of load) = 1 ÷ cos θ; at 30° from horizontal the factor is 1.155, at 45° it is 1.414, at 60° it is 2.000.

Center of gravity of a load lies on the vertical line through the lifting point only when the load is balanced; eccentric lifts shift load share to the legs nearer the CG.

Load share on each leg of an asymmetric two-point pick: share = total load × (distance from CG to opposite point ÷ span between points).

Combined stress on a shackle or eye under angled loading: resolve the resultant vector, then compare with the rated capacity at that angle, not the vertical rating.

Moment of a force about a point: M = F × d, where d is the perpendicular distance; tipping occurs when the overturning moment exceeds the restoring moment from weight.

Mechanical advantage of a simple movable pulley system equals the number of rope parts supporting the moving block; account for friction losses of roughly 3-10% per sheave.

Shackle working load limit applies only when the load is along the pin-to-bowl axis; side loading reduces capacity and requires the manufacturer's rating.

Screw-pin shackles must be fully seated with the pin threaded home; a pin not fully engaged or wired closed is a removal-from-service condition.

Wire rope sling efficiency drops with termination type: poured socket about 100%, swaged socket about 95%, hand-spliced loop about 90%, and standard wire rope clips about 80%.

Synthetic web sling capacity is quoted for a single-ply vertical hitch; choker hitches typically reduce capacity to about 80% and basket hitches roughly double it, per the sling tag.

Master links, swivel hoist rings, and eyebolts are rated for a specific direction of pull; plain forged eyebolts are not rated for angular lifts unless marked for that use.

Below-the-hook lifting beams convert a two-point pick into a vertical lift at the attachment points, eliminating the horizontal compression a bridle would impose on the load.

Spreader beams carry compressive load between attachment points; they must be designed for the bending and buckling loads imposed by the sling angles actually used.

Hooks with cracks, throat opening increased more than 5-10% (per manufacturer), or wear exceeding 10% of the original dimension are removed from service.

Standard hand signals are mandatory when voice or radio communication is unreliable; only one designated signalperson directs the operator at a time.

A stop signal may be given by anyone on the job site; the operator must obey a stop signal from any source.

Load moment (load × radius) must remain within the crane's rated capacity chart for the actual boom length, radius, and configuration in use.

Crane capacity decreases as radius increases; the load chart, not the boom angle alone, governs the allowable load.

Hoist limit switches, anti-two-block devices, and boom angle indicators are operational aids that must be functional before lifting; bypassing them is prohibited.

Tag lines control rotation and swing of a suspended load; they are held outside the load's fall zone and never wrapped around hands or body.

Personnel must never ride the load, the hook, or the sling; suspended loads are not to be passed over workers.

Outrigger floats must be fully extended and set on stable, competent ground with mats or cribbing sized for the imposed bearing pressure.

Wire rope lays: regular lay has strands twisted opposite to the rope direction, providing better resistance to crushing; lang lay has strands and rope twisted the same direction, offering greater abrasion resistance but less resistance to rotation.

Wire rope strength is reduced by broken wires, corrosion, and kinking; removal criteria are based on broken wires in a specified length, diameter reduction, and evidence of core damage.

Synthetic rope strength is affected by knots: a bowline can reduce strength by roughly 40-60%, while a proper splice retains most of the rope's strength.

Splice types: eye splice, back splice, and short splice; a short splice retains roughly 80-90% of rope strength, while an eye splice with a thimble protects the eye from abrasion.

Wire rope clips are installed with the U-bolt on the dead end (never on the live end) and spaced at roughly six rope diameters, with the first clip one saddle-width from the thimble.

Rotation-resistant and rotation-resistant-compacted wire ropes require special handling; they can develop twist and must not be used where load rotation is unacceptable.

Synthetic rope should be inspected for glazing, fuzzing, and abrasion; glazing indicates heat or friction damage and reduces strength.

Knot efficiency varies by knot type; the figure-eight loop and bowline are common, but the splice remains the highest-efficiency termination.

Hydraulic jack capacity is rated at the piston, not the toe or saddle; off-center loading reduces capacity and can bend the piston.

Jacks must be set on a firm, level base with a wood or steel pad sized to distribute load and prevent sinking; the jack must be plumb.

When lifting with multiple jacks, lift in small increments and crib or block the load as it rises; never rely on the jack alone to hold a load.

Rollers reduce friction during skidding; the required pull force is roughly the load times the coefficient of rolling friction plus any grade resistance.

Skidding on rollers requires control of the load's path and speed; a snubber or winch line controls run-away on slopes.

Jacking towers and climbing jacks require engineered foundations and bracing; the design must account for wind and dynamic loads during lifting.

Cribbing stacks should be built with the grain alternating and the stack stable; height-to-base ratio should be kept low to prevent toppling.

Load moving on rollers: keep the load's center of gravity low and centered over the roller group; unequal roller loading can cause the load to tip.

A critical lift plan typically includes load weight and CG, rigging arrangement, crane capacity at the planned radius, ground bearing, and contingency for a dropped load.

Rigging design begins with the load's weight and center of gravity; the lift points are chosen so the CG lies within the support polygon or on the vertical through the hook.

A lift plan must identify the rigging hardware, sling types and capacities, and the angle of each leg at the planned configuration.

Shock loading from sudden stops or slack removal can multiply static load several times; the plan should specify slow, controlled movement.

Wind loading increases with the square of wind speed; the plan should state a wind limit at which the lift is stopped.

Load movement paths must be surveyed for obstructions, power lines, and personnel; the swing radius and tail swing of the crane must be barricaded.

Pre-lift meetings confirm roles, signals, and the sequence of operations; the lift director has authority to stop the lift.

Trial lifts verify the CG and rigging before the full lift; the load is raised slightly and checked for level and stability.

Inspection intervals: a documented periodic inspection at least annually for rigging in normal service, with more frequent intervals for severe service or after any shock load.

Wire rope slings are removed from service for broken wires, severe corrosion, kinking, bird-caging, or reduction in diameter beyond the manufacturer's limit.

Synthetic web slings are removed for holes, cuts, snags, burns, or discoloration from heat or chemicals; the red warning thread, if present, indicates the sling has been damaged.

Chain slings are removed for cracks, stretch beyond the manufacturer's limit, or wear exceeding 10% of the link's original dimension.

Shackles, hooks, and rings are removed for cracks, deformation, or wear exceeding the manufacturer's allowable; magnetic particle or dye penetrant inspection may be required.

Hoists and cranes require documented inspections at intervals set by the manufacturer and applicable regulations, including daily pre-use checks by the operator.

Any rigging that has been overloaded, shock-loaded, or involved in an accident must be inspected before being returned to service.

Inspection records should identify the item, date, inspector, and findings; items removed from service must be tagged and segregated from usable gear.

OSHA 29 CFR 1926 Subpart CC governs cranes and derricks in construction; 1910.184 covers slings, and 1910.179 covers overhead and gantry cranes.

Rigging hardware must be marked with its rated capacity; unmarked or illegible gear is removed from service.

The rated capacity of a sling or hardware item is the maximum load for the configuration and angle specified by the manufacturer.

Employees must be trained and qualified for the rigging tasks they perform; the employer is responsible for verifying competency.

Power line safety: maintain the required minimum clearance from energized lines, and use a spotter or proximity alarm where required.

Fall protection is required when working at height, including on booms or elevated platforms; the rigger must be tied off.

Accident prevention relies on pre-job hazard analysis, exclusion zones under suspended loads, and a stop-work authority for all personnel.

Loads must not be suspended over personnel; a barricade and warning line keep workers out of the fall zone.