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NCCCO Rigger Level II study materials
NCCCO Rigger Level II study resources

NCCCO Rigger Level II practice questions

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Question 1Site and Lift Planning

The rated capacity that a specific crane can lift at a given radius and boom length is found in:

  1. the rigging catalog supplied by the sling maker
  2. the crane's preventive maintenance log
  3. the manufacturer's load chart for that crane Correct answer.
  4. the site's daily lifting schedule

Explanation

Rated capacities are published by the crane manufacturer in the load chart, which reflects the structural and stability limits of that model in each configuration. Because charts are model- and setup-specific, a chart for a different crane cannot be substituted.

Question 2Site and Lift Planning

For a uniformly dense, symmetrical load, the center of gravity is located:

  1. below the lowest lifting lug
  2. at the geometric center of the load Correct answer.
  3. at the end closest to the crane's boom
  4. one third of the way from the top face

Explanation

When weight is distributed evenly in a symmetrical object, the center of gravity coincides with the geometric center in each dimension. Placing the hook directly over that point lets the load hang level with equal tension in symmetrical slings.

Question 3Site and Lift Planning

Under OSHA's crane standard, the minimum required clearance between any part of the crane or load and a power line rated up to 50 kV is:

  1. 6 ft
  2. 4 ft
  3. 10 ft Correct answer.
  4. 20 ft

Explanation

The OSHA clearance table requires 10 ft for lines rated 50 kV or less, with requirements increasing in steps as voltage rises (15 ft above 50 kV to 200 kV, 20 ft above 200 kV to 350 kV, and more above that). The clearance applies to the crane, the load, and the rigging.

Question 4Site and Lift Planning

The primary purpose of a tag line on a suspended load is to:

  1. increase the rated capacity of the crane at the working radius
  2. control the rotation and swing of the load Correct answer.
  3. allow the load to be hoisted at a steeper boom angle
  4. reduce the total weight of the load that the crane must lift

Explanation

A tag line lets a rigger steady and orient a suspended load from outside the fall zone, keeping hands away from pinch points and the load itself. Tag lines do not change the crane's capacity, the load's weight, or the boom geometry.

Question 5Site and Lift Planning

A lift is commonly classified as a critical lift when the load:

  1. is made with a boom angle below 45 degrees
  2. is loaded above 75 percent of rated capacity Correct answer.
  3. requires the use of more than one sling leg on the hook
  4. uses a hook block with more than one sheave

Explanation

Critical lifts are those where failure would have severe consequences, and a common industry criterion is a lift that uses more than 75 percent of the crane's rated capacity in the planned configuration. Lifts over or of personnel, of unusual or high-value loads, and lifts made without the crane fully set per the manufacturer also qualify.

Question 6Site and Lift Planning

A crane with hydraulic outriggers is being set for a lift. The outriggers must be:

  1. retracted while lifting to lower the center of gravity
  2. extended on one side only when working near a wall
  3. fully extended and set on pads as the manufacturer requires Correct answer.
  4. extended only until the tires just clear the ground

Explanation

Load charts assume the outrigger beams and floats are deployed exactly as the manufacturer specifies, typically fully extended with pads or mats on a firm surface. Partial extension invalidates chart values and can overload a beam or the ground beneath a float.

Question 7Site and Lift Planning

The most reliable way to establish the weight of a load to be lifted is to:

  1. ask the crane operator to estimate it from experience
  2. estimate the weight from the load's volume and a visual guess
  3. read the value from the crane's load chart
  4. use the shipper's stated weight or weigh the load Correct answer.

Explanation

Planning begins with an accurate weight taken from shipping papers, manufacturer's data, or an actual scale reading. Volume-based guesses and verbal estimates can be badly wrong and leave no margin for rigging weight and dynamic effects.

Question 8Site and Lift Planning

The area swept by the crane's rotating superstructure and counterweight must be:

  1. cleared of barricades so tag line workers have access
  2. marked only when the lift is made at night
  3. barricaded to keep personnel out of the swing area Correct answer.
  4. left open so the operator can see the load

Explanation

Tail swing can crush a worker against a fixed object, so the swing radius is barricaded or blocked and entry is restricted. Access is allowed only when the crane is shut down or the area is otherwise controlled.

Question 9Site and Lift Planning

A 10,000 lb load is carried in a two-leg bridle sling with both legs at 45 degrees from horizontal. What is the approximate tension in each leg?

  1. 14,100 lb
  2. 10,000 lb
  3. 7,100 lb Correct answer.
  4. 5,000 lb

Explanation

Each leg carries half the vertical load, or 5,000 lb, and tension equals that vertical share divided by the sine of the leg angle from horizontal: 5,000 / sin 45 degrees = 5,000 / 0.707, about 7,100 lb. Tension rises sharply as sling legs approach horizontal.

Question 10Site and Lift Planning

The load radius used to enter a crane load chart is measured:

  1. from the front bumper of the carrier to the center of the load
  2. from the nearest outrigger pad to the edge of the load
  3. from the boom hinge pin to the tip of the boom
  4. from the center of rotation to the load's center of gravity Correct answer.

Explanation

Radius is the horizontal distance from the crane's center of rotation to the vertical line through the load's center of gravity, measured with the boom deflected as it will be under load. Using the hook position or an unloaded boom understates radius and overstates available capacity.

Question 11Site and Lift Planning

An outrigger float will impose 80,000 lb on soil that can safely support 4,000 psf. What minimum pad area is required?

  1. 32 sq ft
  2. 16 sq ft
  3. 20 sq ft Correct answer.
  4. 8 sq ft

Explanation

Required area equals force divided by allowable pressure: 80,000 lb divided by 4,000 lb/ft squared equals 20 sq ft. A smaller pad would exceed the soil's capacity and allow the outrigger to settle.

Question 12Site and Lift Planning

If the load radius is increased while boom length stays the same, the crane's rated capacity:

  1. increases because the boom is more heavily loaded
  2. decreases because the load moment increases Correct answer.
  3. depends only on the wind speed at the site
  4. stays the same as long as the boom length is unchanged

Explanation

Capacity is limited by overturning moment and by boom strength, and moving the load farther out lengthens the moment arm acting on the crane. That is why a load chart shows lower capacities at longer radii for the same boom length.

Question 13Site and Lift Planning

A large steel panel with high sail area is to be lifted, and site wind is above the limit given in the manufacturer's instructions. The rigger should:

  1. stop the lift and follow the manufacturer's wind limit Correct answer.
  2. continue at a slower hoist speed to reduce wind effects
  3. increase the boom angle to reduce the sail area
  4. continue the lift as long as tag lines are used

Explanation

Manufacturers set maximum wind speeds for crane operation, and limits are stricter for loads with large surface area because wind adds side load and effectively increases radius. Tag lines and slower hoisting do not cancel that force, and exceeding the limit requires engineering review, not field judgment.

Question 14Site and Lift Planning

Rated capacity for a crane that will travel with a suspended load is:

  1. the same as the static load chart for that radius
  2. set on site by the rigger using the static chart
  3. shown on a separate chart that is lower than static Correct answer.
  4. higher because the tires share the load with the outriggers

Explanation

Traveling with a load introduces dynamic and structural loads the static chart does not address, so manufacturers publish separate pick-and-carry charts with reduced capacities and limits on boom position and travel speed. Static ratings apply only when the crane is stationary and properly set.

Question 15Site and Lift Planning

Rapid hoisting and sudden stopping of a load can:

  1. have no effect as long as the load is under chart capacity
  2. affect only the crane's hydraulic oil temperature
  3. add load beyond the static weight to boom and rigging Correct answer.
  4. reduce the load on the slings by breaking static friction

Explanation

Accelerating or stopping a load creates inertia forces that add to the static weight and can be large enough to overload slings or the boom. Loads should be eased off the ground and moved smoothly so dynamic effects stay small.

Question 16Site and Lift Planning

Before setting outriggers or cribbing at a site, the rigger should first confirm:

  1. the direction of the prevailing wind at the site
  2. the crane's fuel and DEF tank levels
  3. the date of the crane's last oil change
  4. the location of buried utilities, vaults, and drains Correct answer.

Explanation

Outrigger reactions are concentrated loads that can collapse a vault, sewer, or utility line beneath the surface and tip the crane. Utility locates and a review of site drawings are completed before the crane is positioned.

Question 17Site and Lift Planning

Operating a crane that is out of level is dangerous mainly because:

  1. the outrigger pads wear out faster
  2. the load chart becomes more conservative and adds capacity
  3. capacity drops and the boom is side-loaded Correct answer.
  4. the crane's hour meter records time inaccurately

Explanation

Load charts are developed for a level crane; out of level, the effective radius grows on the downhill side and side loads are imposed on the boom, cutting stability and capacity. Manufacturers specify a maximum out-of-level tolerance, commonly 1 percent, that must be met at setup.

Question 18Site and Lift Planning

Before a complex lift begins, the rigger should make sure that:

  1. the plan is revised on the spot by whoever is closest to the load
  2. everyone involved has reviewed the plan and their role Correct answer.
  3. the lift plan is filed away until after the lift is complete
  4. only the crane operator has reviewed the lift plan

Explanation

A pre-lift meeting communicates sequence, rigging, signals, and assigned duties so each crew member knows what to do and when to stop the work. Changes to the plan are made by the person in charge, documented, and re-briefed rather than improvised.

Question 19Site and Lift Planning

When the soil conditions under a crane's outriggers are unknown, the rigger should:

  1. set the outriggers directly on the ground without mats
  2. rely on the crane's automatic level indicator
  3. use conservative values and get a soils evaluation when in doubt Correct answer.
  4. assume a bearing capacity of 10,000 psf for all soils

Explanation

Bearing capacity varies widely between rock, compacted fill, and soft clay, so unknown soils are treated conservatively and confirmed by a geotechnical evaluation or load test when reactions are high. Mats and cribbing spread the load but cannot compensate for an inadequate or unknown subgrade.

Question 20Site and Lift Planning

A 20,000 lb load is supported by two vertical slings 10 ft apart. The center of gravity is 4 ft from pick point A and 6 ft from pick point B. What load does sling B carry?

  1. 6,000 lb
  2. 4,000 lb
  3. 12,000 lb
  4. 8,000 lb Correct answer.

Explanation

The share taken at each pick point is inversely proportional to its distance from the center of gravity, so the point nearer the center of gravity carries more. Sling B carries 20,000 times 4 divided by 10, or 8,000 lb, and sling A carries the remaining 12,000 lb.

Question 21Site and Lift Planning

Ignoring boom deflection, what boom length places the boom tip 60 ft above the boom hinge point at a radius of 40 ft from the hinge point?

  1. About 50 ft
  2. About 80 ft
  3. About 100 ft
  4. About 72 ft Correct answer.

Explanation

Boom length is the hypotenuse of the right triangle formed by the vertical rise and the horizontal radius: the square root of 60 squared plus 40 squared equals the square root of 5,200, about 72 ft. Deflection and head sheave height would require slightly more length in practice.

Question 22Site and Lift Planning

Two cranes share a 60,000 lb load with pick points 20 ft apart. The load's center of gravity is 12 ft from crane A's pick point and 8 ft from crane B's. What load should crane A be planned for?

  1. 48,000 lb
  2. 30,000 lb
  3. 24,000 lb Correct answer.
  4. 36,000 lb

Explanation

Each crane's share is inversely proportional to the distance from the center of gravity to its pick point, so crane A carries 60,000 times 8 divided by 20, or 24,000 lb, and crane B carries 36,000 lb. The crane farther from the center of gravity takes the smaller share.

Question 23Site and Lift Planning

A load chart shows 22,000 lb capacity at the planned radius. The hook block and slings weigh 1,500 lb, and a stowed jib attachment requires a 2,500 lb deduction. What is the greatest payload that may be lifted?

  1. 22,000 lb
  2. 20,500 lb
  3. 18,000 lb Correct answer.
  4. 19,500 lb

Explanation

Chart values are gross, so all lifting equipment and attachments below or on the boom are subtracted before the payload is compared: 22,000 minus 1,500 minus 2,500 leaves 18,000 lb. Forgetting either deduction overstates what can safely be lifted.

Question 24Site and Lift Planning

A load has a 10,000 lb section whose center of gravity is 4 ft from a reference end and a 6,000 lb section whose center of gravity is 12 ft from the same end. Where is the combined center of gravity?

  1. 7.0 ft from the reference end Correct answer.
  2. 8.0 ft from the reference end
  3. 6.0 ft from the reference end
  4. 4.0 ft from the reference end

Explanation

Take moments about the reference end and divide by total weight: (10,000 times 4 plus 6,000 times 12) divided by 16,000 equals 112,000 divided by 16,000, or 7.0 ft. The combined center of gravity always falls between the two section centers, nearer the heavier section.

Question 25Site and Lift Planning

A crawler crane and its load total 180,000 lb. Each of the two tracks has 60 sq ft of ground contact. What is the average ground bearing pressure?

  1. 3,000 psf
  2. 750 psf
  3. 9,000 psf
  4. 1,500 psf Correct answer.

Explanation

Total contact area is 2 times 60, or 120 sq ft, and average pressure is 180,000 divided by 120, which equals 1,500 psf. Actual pressure is not uniform and rises under the ends of the tracks and during booming, so peak values must be considered when mats or cribbing are specified.

Question 26Site and Lift Planning

When a lift plan calls for a crane to operate near energized overhead power lines, the first planning step is to:

  1. Confirm line voltage and required approach distance with the utility. Correct answer.
  2. Schedule the lift for a time when the transmission lines carry less load.
  3. Instruct the operator to keep the boom below the line level at all times.
  4. Post warning signs at the site entrance and continue with the planned lift.

Explanation

The line voltage establishes the minimum approach distance that must be maintained, and only the utility can confirm voltage or de-energize the line. Warning signs and operator technique do not establish a safe clearance. Electrical loading changes do not make the line safe to approach.

Question 27Site and Lift Planning

Before a mobile crane travels across a site to a new lift position, the planned route should be:

  1. Approved by the crane operator alone before the move begins.
  2. Marked at the entrance only so the operator can choose the path.
  3. Inspected for soft spots, voids, utilities, and excessive slope. Correct answer.
  4. Cleared of personnel but not of parked equipment or material.

Explanation

A crane travel route must be surveyed for ground stability, buried hazards, and grade because the carrier and crane can be overturning or sinking hazards while moving. The route also must be clear of obstructions and reviewed by appropriate site personnel, not the operator alone.

Question 28Site and Lift Planning

The main purpose of a pre-lift meeting for a planned critical lift is to:

  1. Decide the load weight by agreement among the crew members.
  2. Let the operator practice booming up and swinging the load.
  3. Complete insurance paperwork after the load has been landed safely.
  4. Review the plan, assign duties, and confirm communications. Correct answer.

Explanation

A pre-lift meeting ensures everyone involved understands the lift plan, their responsibilities, the signals, and contingency actions before the lift begins. It is a coordination and safety review, not a time to determine load weight by consensus or complete post-lift paperwork.

Question 29Site and Lift Planning

A written lift plan for a critical lift should include, at a minimum:

  1. The color of the tag lines and the crew's lunch schedule.
  2. Load weight, configuration, radius, rigging, and sequence. Correct answer.
  3. The site address, the date, and the name of the signal person.
  4. The crane's maximum rated capacity and the operator's name.

Explanation

A critical lift plan must document the load, crane configuration, planned radius, rigging arrangements, ground conditions, and the sequence of operations so the lift can be reviewed and controlled. Basic identifying information alone is not sufficient.

Question 30Site and Lift Planning

Before setting outriggers on a paved area, the rigger learns that underground utilities run beneath the spot. The best planning action is to:

  1. Assume the pavement protects the utility and proceed with the setup.
  2. Locate and mark utilities, then reposition or use an approved mat. Correct answer.
  3. Reduce the load weight by 10 percent and proceed with the lift.
  4. Set the outrigger directly over the utility to spread the load out.

Explanation

Underground utilities must be located and marked before outrigger loads are imposed over them. If the crane cannot be relocated, an approved load-spreading method designed for the utility crossing may be used. Reducing load weight slightly does not address the concentrated outrigger load.

Question 31Site and Lift Planning

An outrigger must be set on firm soil next to a freshly backfilled trench. The rigger should:

  1. Fill the trench with loose spoil and set the float on it.
  2. Place the float at the trench edge and rely on the pavement.
  3. Use engineer-approved cribbing to bridge the trench or relocate. Correct answer.
  4. Lower the outrigger slowly and watch for settlement during the lift.

Explanation

Backfilled trenches can settle or collapse under outrigger loads, so the crane must be moved to undisturbed soil or supported by cribbing designed for the load. Watching for settlement during the lift is too late to prevent an overturn.

Question 32Site and Lift Planning

A lift plan involves a load with large sail area. If the wind is at the manufacturer's limit but gusty, the rigger should:

  1. Increase hoist speed to shorten the load's exposure to the wind.
  2. Proceed because the average wind speed is within the stated limit.
  3. Add tag lines, treat as critical, and delay if gusts exceed the limit. Correct answer.
  4. Remove the tag lines to reduce wind drag on the suspended load.

Explanation

Gusts can impose loads beyond those expected from average wind speed, especially on loads with high sail area. Tag lines help control rotation, and the lift should be delayed or re-planned when gust speeds exceed the manufacturer's limit.

Question 33Site and Lift Planning

To reduce the required load radius for a lift, the most effective planning choice is to:

  1. Add counterweight beyond the manufacturer's approved configuration.
  2. Use a longer boom to reach farther over the load from the same spot.
  3. Place the crane as close to the pick point as conditions allow. Correct answer.
  4. Swing the load faster to shorten the lift cycle and reduce radius.

Explanation

Load radius is measured from the crane's rotation center to the load, so moving the crane closer to the pick point directly reduces radius and usually increases capacity. A longer boom or extra counterweight does not reduce the required radius, and unauthorized counterweight is unsafe.

Question 34Site and Lift Planning

For a two-crane lift, the lift plan must establish:

  1. Each crane's load share, the load CG, and one signal person. Correct answer.
  2. That both cranes operate independently without communication.
  3. That each crane is rated to carry the entire load by itself.
  4. That the load will be lifted by only one crane at a time.

Explanation

A multi-crane lift requires planned load sharing based on the load's center of gravity and a single person directing the operation. Each crane's actual share must be compared to its capacity at the working radius, and coordinated communication is essential.

Question 35Site and Lift Planning

When the load will be out of the operator's view during a lift, the lift plan should specify:

  1. That tag lines be removed to avoid confusion with hand signals.
  2. That the operator estimate load position from boom angle and radius.
  3. A qualified signal person with a clear view and reliable communication. Correct answer.
  4. That the load be moved only after dark when the site is quiet.

Explanation

A blind lift requires a qualified signal person who can see the load and communicate reliably with the operator, often by radio. The operator should not rely on estimated boom geometry to judge load position.

Question 36Site and Lift Planning

A crane is to be set up on ground that slopes more than the manufacturer allows. The planning response is to:

  1. Build a level, engineered pad or select a different setup location. Correct answer.
  2. Use the crane's level indicator and proceed if it is close to level.
  3. Place the outriggers on the high side only.
  4. Operate at reduced capacity to compensate for the slope.

Explanation

Cranes must be set up within the manufacturer's leveling limits because slope affects rated capacity, swing, and stability. Reducing capacity or partially extending outriggers does not correct an out-of-level condition; the setup must be made level or relocated.

Question 37Site and Lift Planning

Before using a crane load chart, the rigger must confirm that the chart applies to:

  1. Only the weight of the load being lifted and the rigging.
  2. The actual boom length, radius, counterweight, and outrigger setup. Correct answer.
  3. The maximum capacity printed on the boom's load chart.
  4. Any configuration as long as the crane is level on its outriggers.

Explanation

Load charts are configuration-specific and depend on boom length, radius, counterweight, outrigger extension, jib status, and other factors. Using a chart for a different configuration can overstate the crane's capacity.

Question 38Site and Lift Planning

A lift plan calls for landing a load on an existing roof, but no one can confirm the roof's load capacity. The most appropriate planning action is to:

  1. Land the load slowly and watch the roof for visible deflection.
  2. Reduce the load by removing the tag lines before landing it.
  3. Assume the roof can carry the load because it is a permanent structure.
  4. Get engineering confirmation of roof capacity or pick another area. Correct answer.

Explanation

The landing area is part of the lift plan, and its capacity must be known before the load is set down. Visible deflection may not occur before failure, and permanent construction does not guarantee adequate capacity for a concentrated load.

Question 39Site and Lift Planning

A crane must be set up near the edge of a 12 ft deep excavation. The only nearby level area is within the excavation's influence zone. The best planning decision is to:

  1. Fill the excavation with spoil before setting up the crane nearby.
  2. Reduce load radius by booming out farther over the excavation.
  3. Have a qualified person evaluate and direct shoring, mats, or relocation. Correct answer.
  4. Set the outriggers at the excavation edge and monitor crack movement.

Explanation

Excavation edges can have a zone of influence where crane and outrigger loads may cause collapse or slope failure. A qualified person must evaluate the condition and specify safe support or relocation; monitoring cracks or filling with loose spoil is not an engineered solution.

Question 40Site and Lift Planning

During a pre-lift review, the rigger finds that the crane's chart capacity at the planned radius is adequate, but the outrigger load exceeds the slab's capacity. The best planning response is to:

  1. Place the outrigger floats directly on the slab without any mats.
  2. Reduce the load weight by 5 percent and continue with the setup.
  3. Use engineered mats, reposition the crane, or select a lower-load crane. Correct answer.
  4. Proceed because the crane is within its published load chart.

Explanation

Crane capacity and ground or slab bearing capacity are separate checks; both must be satisfactory. If outrigger loads exceed the slab capacity, the setup must be revised with engineered load spreading, relocation, or a different crane.

Question 41Rigging Selection and Configuration

A load is lifted with a symmetric two-leg bridle. If the legs are spread wider so that the angle each leg makes with the horizontal becomes smaller, the tension in each leg:

  1. Increases Correct answer.
  2. Remains the same
  3. Increases only if the load is perfectly rigid
  4. Decreases

Explanation

Each leg must supply the same vertical force no matter how wide the bridle is spread, and only the vertical component of leg tension holds the load. A flatter leg angle therefore requires a larger total tension, so the slings must be rated higher. Tension rises as the angle from horizontal falls.

Question 42Rigging Selection and Configuration

A hook used for overhead lifting is fitted with a safety latch. The primary function of the latch is to:

  1. Increase the hook's working load limit
  2. Center the load in the bowl during the lift
  3. Allow the hook to carry load on its tip for short lifts
  4. Keep the sling from coming out of the bowl when the line goes slack Correct answer.

Explanation

The latch is not a load-bearing part; it exists to keep slings and fittings captured in the bowl when tension is released. Load must always sit in the bowl of the hook, and latch condition is an inspection item.

Question 43Rigging Selection and Configuration

Which marking identifies a chain sling that is acceptable for overhead lifting?

  1. Transport grade
  2. A color tag only
  3. Grade 80 or Grade 100 Correct answer.
  4. The letters HT only

Explanation

Alloy chain intended for overhead lifting is identified by grade, most commonly 80 or 100, along with size, reach, working load limit and the manufacturer's identification. The letters HT only indicate that the chain was heat treated and do not establish a lifting grade.

Question 44Rigging Selection and Configuration

A spreader beam is used instead of a plain two-leg bridle mainly because it:

  1. Weighs less than any other below-the-hook device
  2. Increases the rated capacity of the crane
  3. May be used only with four-leg slings
  4. Keeps the sling legs vertical and eliminates horizontal squeezing of the load Correct answer.

Explanation

A spreader beam is loaded in compression and holds the sling legs vertical or nearly vertical above the lift points. This avoids the horizontal squeeze that a wide bridle imposes on a load, which matters for loads that can be crushed or whose lifting points are not designed for side loads.

Question 45Rigging Selection and Configuration

A wire rope sling has a tight, permanently distorted kink in one leg. The sling should be:

  1. Used only in a vertical hitch
  2. Used at one-half its rated capacity
  3. Straightened and returned to service
  4. Removed from service Correct answer.

Explanation

A permanent kink shows that the strands have been distorted and the rope's strength is no longer predictable. Such a sling is removed from service; it cannot be restored by straightening and is not permitted to be used at a reduced rating.

Question 46Rigging Selection and Configuration

A tag line is attached to a load to:

  1. Allow the lift to be made without a hook latch
  2. Raise the capacity of the lifting sling
  3. Control rotation and swing without the rigger touching the load Correct answer.
  4. Share part of the load's weight

Explanation

A tag line lets a rigger steer and steady the load from a safe distance outside the fall zone. It is never used to support weight, and it does not change the capacity of any lifting component.

Question 47Rigging Selection and Configuration

The rated capacity of an alloy steel chain sling is based on a design factor of:

  1. 4 to 1 Correct answer.
  2. 5 to 1
  3. 2 to 1
  4. 3 to 1

Explanation

Chain slings are rated on a 4 to 1 ratio of breaking force to working load limit. Wire rope slings, synthetic slings and most rigging hardware are rated on 5 to 1.

Question 48Rigging Selection and Configuration

To lift a load level, the hook must be positioned:

  1. Directly above the heaviest lifting lug
  2. Directly above the load's center of gravity Correct answer.
  3. At the midpoint between any two lifting points
  4. At the end of the load nearest the crane

Explanation

A suspended load hangs so that its center of gravity is directly below the hook. Placing the hook over the center of gravity therefore produces a level lift with predictable leg loads.

Question 49Rigging Selection and Configuration

A 6,000 lb load is lifted with a symmetric two-leg bridle in which each leg makes a 60 degree angle with the horizontal. What is the approximate tension in each leg?

  1. 1,730 lb
  2. 3,460 lb Correct answer.
  3. 6,000 lb
  4. 3,000 lb

Explanation

Leg tension equals load divided by two times the sine of the leg angle from horizontal: 6,000 / (2 x 0.866), which is about 3,460 lb. Note that this is well above the 3,000 lb an equal vertical split would suggest.

Question 50Rigging Selection and Configuration

A single-leg wire rope sling rated 8,000 lb in a vertical hitch is used in a choker hitch. Its approximate capacity is:

  1. 6,000 lb Correct answer.
  2. 8,000 lb
  3. 12,000 lb
  4. 4,000 lb

Explanation

A choker compresses the sling and bends it sharply through its own eye, so the capacity is derated, commonly to about 75 percent of the vertical rating. Here that is about 6,000 lb, and the sling identification tag should be consulted for the exact figure.