Stopping a Lift and What Happens Next

Purpose

Calling a stop on a lift is the cheap half. The expensive half is the next ten minutes, because a stopped lift leaves a load in a state nobody has yet described: still suspended, still on rigging that may be carrying more than the plan said, with a crew that has stopped moving and started walking toward it. This procedure exists so that the words "stop" and "hold" produce a defined condition rather than a pause, and so the decision to resume is a re-derivation by the person who owns the plan, not a nod from whoever is closest to the controls.

The two rules the rest of this document serves: anyone on site may call a stop and no one may overrule it, and only the person who can state what is currently holding the load may release the hold.

Scope

Applies to any lift in which a load is supported by rigging, a hoist, a crane, a boom, a jack or a powered industrial truck, from the moment the rigging takes tension until the load is landed and the rigging is slack. It covers the stop itself, the state the load is brought to, the re-derivation, and the release.

Which rules govern depends on the setting, and the numbers genuinely differ. On a construction site, crane operation and signalling sit under 29 CFR 1926 Subpart CC (signals at 1926.1419, operation at 1926.1417) and slings under 1926.251. In general industry, overhead and gantry cranes sit under 29 CFR 1910.179 and slings under 1910.184. Name your Part in the lift plan; do not carry one Part's requirement into the other.

This procedure does not replace the lift plan, and it does not authorise anyone to work under a suspended load for any reason.

Roles and responsibilities

Procedure

1. Call it by word and by signal. Say "stop" loudly and give the stop signal. Do not soften it into a question. Under 1926.1419 for construction crane work, a stop signal is obeyed whoever gives it, and that is the whole design: the person with the least standing is the one most likely to be the only one who can see the problem.

2. The operator arrests motion and holds. Stop is not "set it down." Landing a load blind, on ground nobody has looked at, on a surface that may not carry the bearing pressure, is a second decision made under the pressure of the first. The operator brings motion to zero, keeps hands on the controls, and waits.

3. Establish what is holding the load, in words, out loud. Three questions, answered by the people who can see the answer: what is supporting it right now (which slings, which hitch, which hardware, which brake), is anything in contact with it besides the rigging (a parapet, a curb, a tag line under tension, a corner it is bearing on), and is it stable or is it still moving. Until those three are answered, no one approaches and no one changes anything. A tag line is a control line, not a restraint; do not hold a swinging load by hand, and do not wrap a tag line around a hand, wrist or belt.

4. Clear and re-establish the zone. People walk toward a stopped lift because a stopped lift looks safe. It is not. The exclusion zone during a hold is the same zone as during motion, and it is not the load's shadow. Set it out and hold it before anyone discusses anything. Nobody stands under the load, nobody stands in the arc the load would sweep if the machine rotates, and nobody stands in the tail-swing circle of a rotating superstructure.

5. Choose one of three end states, out loud, and name who is doing it. There are only three. Land it in a place that has been looked at and will carry it. Ground it in a controlled place that was not the target, accepting the re-rig. Or hold it suspended, with the operator at the controls, the zone maintained and an attendant, for as long as it takes to answer the question that caused the stop. There is no fourth state, and in particular a load is never left suspended unattended on a brake, whatever the brake is.

6. Name the reason in one sentence, before anyone starts solving it. "The bridle legs came in shallower than the plan." "The load came up out of level." "There is a person inside the zone." A stop that is never given a sentence gets released on mood.

7. Re-derive every figure the changed condition touches, and print the corrections. This is the step people skip, because the load is still hanging there and it plainly has not fallen. See the re-derivation section below.

8. Release, or re-plan. The hold is released by the person who owns the plan, by name, after the re-derivation clears. If it does not clear, the load goes to an end state from step 5 and the lift is re-planned before anything moves again.

Re-deriving the numbers before release

A stop means a condition changed. Every quantity downstream of that condition is now unverified, and "it has not fallen yet" is not a verification, because a rigging component that is over its rating usually does not announce it in the first minute.

Work in this order and write each line down: the share of the total load on the component in question, then the angle correction per leg, then the hitch, then any dynamic factor. Divide, do not add. Sling leg tension is the vertical share carried by that leg divided by the sine of the leg's angle measured from horizontal, so at 60 degrees a leg carries 1.155 times its vertical share, at 45 degrees 1.414 times, and at 30 degrees exactly twice. Half the trade quotes that angle from the vertical instead, and the two conventions give reciprocal answers, so state which one you are using every time you say a number out loud.

Round in the conservative direction at every line and say which direction that is: round a tension up, round a rated capacity down, round an available clearance down. Never round a capacity up.

Two corrections that are re-basings rather than additions, and both are commonly charged twice. A sling tag's choker or basket line already contains the hitch derate, so you compare against that line, you do not multiply it again. A rated capacity already contains its design factor, so a dynamic factor does not get added to the design factor, it spends it. Compounding derates in the wrong order, or charging one of them twice, is its own subject and a sibling article carries the full case.

The stop record, filled in

A rooftop package, two-leg bridle, vertical hitch to four lifting lugs, picked to clear a parapet. The rigger called the stop about four feet up because the legs looked shallower than the drawing.

Reason, one sentence: the bridle legs came in at a visibly shallower angle than the plan, measured on a photo at the hook as roughly 35 degrees from horizontal against a planned 60.

What is holding it: two round slings, vertical hitch on the two lugs at each end, to a single hook. No contact with the parapet. Two tag lines slack. Load stationary and level.

End state chosen: hold suspended. Operator at the controls, hands on, zone maintained by the signal person, one attendant. Not landed, because the only ground inside the radius is the membrane roof and nobody had checked what it carries.

Re-derivation, printed line by line:

• Total load: 3,000 lb, from the equipment data plate, verified as an operating weight rather than a shipping weight.
• Share per leg: pick points symmetric about the centre of gravity and the load hung level, so an even split is supportable. 1,500 lb vertical share per leg.
• Angle correction, as planned: 60 degrees from horizontal. 1,500 / sin 60 = 1,500 / 0.866 = 1,733 lb, rounded up to 1,750 lb per leg.
• Angle correction, as found: 35 degrees from horizontal. 1,500 / sin 35 = 1,500 / 0.574 = 2,615 lb, rounded up to 2,650 lb per leg.
• Hitch correction: vertical hitch, so the tag's vertical line governs and the correction is 1.0. Printed anyway, because a correction that is 1.0 today is the one that gets forgotten tomorrow.
• Dynamic factor: 1.0. The load was raised smoothly and is now stationary. Had it been snatched off the curb, a dynamic factor would apply to the tension above before any comparison.
• Comparison: sling tag vertical rating 3,000 lb per leg. Planned tension used 58% of it. As-found tension uses 88% of it.

The call: the hold stands. The as-found tension is under the tag, and that is exactly why this is the dangerous case. Nothing in the re-derivation says the lift failed, and everything in it says the plan is no longer the thing being executed. The lift resumes only after the angle is restored, by a longer bridle or a spreader, not on the argument that 88% is still under 100%. The margin between 58% and 88% was the margin that was going to absorb the next surprise, and there is always a next surprise.

Released by: the lift director, by name, after the longer bridle was fitted and the angle re-measured at 58 degrees from horizontal, which recomputes to 1,500 / sin 58 = 1,500 / 0.848 = 1,769 lb, rounded up to 1,800 lb per leg, or 60% of the tag.

Verifying the procedure works

Two checks, both from the record rather than from memory. First, count the stops. A site running lifts weekly with zero stops recorded in a quarter is not a site with no surprises, it is a site where stopping costs the caller something, and that cost is worth finding before it is found for you. Second, read the reason sentences. If most of them describe something that could have been established before the load left the ground, such as an angle, a weight or a centre of gravity, the fix is in lift planning, not in stop discipline.

References

• 29 CFR 1926 Subpart CC (cranes and derricks in construction), including 1926.1417 on operation and 1926.1419 on signals
• 29 CFR 1910.179 (overhead and gantry cranes, general industry) and 29 CFR 1910.184 (slings, general industry)
• 29 CFR 1926.251 (rigging equipment for material handling, construction)
• ASME B30 series (B30.5 for mobile cranes, B30.9 for slings), in the edition your jurisdiction, contract or employer programme has adopted, which is what gives it force
• See related: Where the Zone Under a Suspended Load Actually Is; The Lift That Was Within Capacity and Still Went Wrong; Why a Hoist Brake Is Not a Parking Device