11.2 Choker Hitches, Choke Angle and Bundles
Key Takeaways
Choke angle and horizontal sling angle are different quantities.
Do not transfer one sling family’s reduction table to another.
A double wrap does not double capacity or guarantee every bundle piece is retained.
Understand where the choke carries force
A choker hitch passes a sling around the load and through its eye or approved fitting so that tension tightens the loop. The choke introduces bending and contact conditions distinct from a vertical hitch. The applicable choker rating may be lower than the vertical rating and can depend on the angle at the choke.
Distinguish the choke angle from the angle of a sling leg relative to horizontal. The choke angle describes the geometry where the sling tightens through its eye or fitting. A horizontal leg-angle factor does not replace a choke-angle adjustment. Some problems require both checks, and the correct table must identify which angle it describes.
Different materials and products have different choker ratings and instructions. A table for wire-rope choke-angle reductions is not automatically a web-sling or chain table. Do not teach one series of percentages as universal across all six sling families. Use the actual manufacturer information or the data explicitly supplied in the examination problem.
Read a supplied adjustment once
Suppose a problem gives an applicable baseline choker rating of 8,000 lb and states that the actual choke condition requires a factor of 0.75 not already included. The adjusted capacity is 6,000 lb. A 6,500-lb demand exceeds it. The factor is training data for that described sling, not a general choke-angle rule.
| Supplied quantity | Use |
|---|---|
| Vertical WLL | Applies to the specified vertical condition |
| Baseline choker WLL | Already includes the product’s basic choker rating |
| Additional choke factor | Apply only when required and not already included |
| Leg angle | Evaluate separate tension or assembly capacity effects |
A frequent mistake is applying the basic choker reduction twice: once by selecting the choker column, then again by multiplying by a remembered generic factor. Another is applying no additional reduction when the manufacturer’s table requires one for an acute choke. Trace exactly what each value includes.
Seat the hitch as instructed
The sling should tighten at the intended location without placing an eye splice, sleeve or fitting into an unapproved bearing condition. The choke must not be forced to bend a fitting or trap the load-bearing splice against an edge. Check that the body can tighten without twisting, snagging or cutting.
A choke around a smooth or tapered load can move. Position it according to the approved handling method, considering the CG and the complete movement. An initially secure choke may loosen when orientation changes or when a load end contacts a support. Examine intermediate positions as well as lift-off.
Screw-pin shackles require particular caution when used in arrangements where the load can slide across the pin and rotate it. Manufacturer instructions can prohibit that application and recommend bolt-type hardware. Do not solve retention by backing a screw pin off or adding an improvised substitute pin. Choose the permitted connection for the actual sliding behavior.
Bundles need complete retention
A choker can gather a bundle, but not every piece is positively captured merely because the outside pieces are tight. Loose internal parts, short pieces, smooth surfaces and uneven lengths can create escape paths. A double-wrap choker may improve contact in an approved arrangement, but it does not guarantee retention or double the sling’s capacity.
The plan should specify how all pieces are secured and supported, whether lifting bands or restraints are approved, and how the bundle remains stable during travel and landing. Shipping bands may hold packaging together without being rated lifting attachments. Do not attach to them unless the manufacturer approves that use.
Bundle scenario
A long pipe bundle contains several short pieces hidden inside. Two outer chokers grip the long pipes but do not necessarily retain the short pieces. The rigger must identify and resolve that condition through an approved method before lifting. More crane capacity does not prevent an unrestrained piece from falling out.
Monitor tightening and release
As initial tension develops, keep hands out of the closing choke and clear of load contact. Observe from a protected position that the hitch seats and protection stays in place. If the sling migrates or the choke binds against an unintended feature, stop safely and lower for correction.
When landing, ensure the load is stable before slackening. A bundle that was held together partly by the choke may spread as tension releases. Provide the planned supports and restraints so the final resting condition remains safe. Remove the sling without dragging it beneath the load or allowing heavy fittings to fall.
The exam decision is a chain of checks: choose the correct hitch rating, interpret any stated choke-angle factor, evaluate leg geometry if relevant, verify contact and retention, then apply the approved operating sequence. A single remembered “choker is 80%” answer does not resolve all of these conditions.
Source: CCO reference materials and sling capacity information.
A supplied 8,000-lb baseline choker rating requires an additional stated factor of 0.75. Can it support a 6,500-lb demand?
Yes; baseline rating alone controls
Yes; the factor increases capacity
Yes; double wrapping gives 12,000 lb
No; adjusted capacity is 6,000 lb
Sections you finish are checked off in the contents.