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NCCCO Mobile Crane study materials
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NCCCO Mobile Crane practice questions

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Question 1Site and Equipment Inspection

Who is required to perform the shift inspection of a mobile crane before it is used?

  1. The site superintendent for the project
  2. The operator assigned to run the crane Correct answer.
  3. The crane owner's maintenance technician
  4. The rigging crew foreperson on shift

Explanation

A competent person, normally the assigned operator, must inspect the crane before each shift it is used. The inspection covers controls, safety devices, wire rope, and the items listed in the operator's manual. Any defect affecting safe operation must be corrected before the crane is put to work.

Question 2Site and Equipment Inspection

What is the primary purpose of the latch on a crane hook?

  1. To show that the hook has been load tested
  2. To keep slings and rigging from slipping off the hook Correct answer.
  3. To let the hook swivel freely under load
  4. To increase the hook's rated load capacity

Explanation

The latch keeps slings, shackles, and other attachments from slipping off the hook when the line goes slack or the load shifts. It is not a load-bearing component and does not change the hook's rated capacity. A hook with a missing or broken latch is removed from service.

Question 3Site and Equipment Inspection

What is the minimum portable fire extinguisher rating required on a mobile crane?

  1. 20 BC
  2. 10 ABC
  3. 5 BC Correct answer.
  4. 2 A

Explanation

Mobile cranes must carry a portable fire extinguisher rated at least 5 BC. Class BC units are effective on the energized electrical and flammable-liquid fires most common around crane operations. A higher rating is acceptable; a lower one is not.

Question 4Site and Equipment Inspection

Which hand signal tells the crane operator to stop?

  1. Both arms extended forward, palms up, raised and lowered
  2. Arm extended, palm down, moved back and forth horizontally Correct answer.
  3. One arm extended out with hand open, moved in a circle
  4. Arm extended upward with fist closed, moved in small circles

Explanation

The standard stop signal is the arm extended with the palm down, moved back and forth horizontally. Standard signals must be used consistently by every signal person so the meaning is never in doubt. Any signal person may give the stop signal at any time.

Question 5Site and Equipment Inspection

Why is a tag line used when handling a load?

  1. To increase the lifting capacity of the crane
  2. To measure how far the load has traveled
  3. To control load rotation and swinging without touching the load Correct answer.
  4. To add a second point of support to the load

Explanation

A tag line lets a worker outside the fall zone steady and guide the load as it moves. It does not support any of the load weight or change the crane's capacity. Workers must never wrap a tag line around a hand or body.

Question 6Site and Equipment Inspection

What does the anemometer mounted on a crane measure?

  1. The hydraulic pressure in the boom circuit
  2. The radius from the crane to the load
  3. The angle of the boom above horizontal
  4. The wind speed at the crane Correct answer.

Explanation

An anemometer measures wind speed so the operator can compare it with the manufacturer's limit and stop lifting when that limit is reached. Wind limits are found in the operator's manual and load chart notes. Boom angle and radius are shown by separate indicators.

Question 7Site and Equipment Inspection

When must rigging slings be inspected for damage?

  1. Only when the annual crane inspection is done
  2. Once each month by a qualified person
  3. Before each use, by the person using them Correct answer.
  4. Only after a load has been dropped

Explanation

Slings must be inspected before each use by the person who will use them, in addition to documented periodic inspections. Frequent inspection catches cuts, broken wires, and stretched links before a load is committed. Damaged slings are tagged out and removed from service.

Question 8Site and Equipment Inspection

A running wire rope of 6x19 classification must be removed from service when it shows:

  1. Two randomly distributed broken wires within one full lay
  2. Six broken wires randomly distributed in one lay Correct answer.
  3. Any single broken wire found anywhere along the rope
  4. Two broken wires in a single strand within one full lay

Explanation

For 6x19 and 6x37 running ropes, removal is required at 6 randomly distributed broken wires in one lay, or 3 broken wires in one strand in one lay. Isolated single wires are recorded and watched but do not by themselves require removal. These criteria apply to running ropes, not to rotation-resistant or standing ropes.

Question 9Site and Equipment Inspection

What is the main purpose of placing crane mats under outrigger floats?

  1. To keep the floats from scratching the pavement
  2. To raise the crane so the boom can reach higher
  3. To spread the outrigger load over a larger ground area Correct answer.
  4. To shorten the time needed to set up the crane

Explanation

Mats increase the area over which each outrigger force acts, reducing soil pressure and helping prevent settlement or punch-through. They do not change the crane's load chart or allow longer boom. Mat size and type are chosen from the actual ground bearing capacity.

Question 10Site and Equipment Inspection

For power lines rated up to 50 kV, the minimum required clearance between any part of the crane or load and the line is:

  1. 10 feet Correct answer.
  2. 20 feet
  3. 15 feet
  4. 4 feet

Explanation

The clearance table requires 10 feet for lines rated up to 50 kV, with greater distances as voltage rises. The clearance applies to the crane, boom, load line, and load. A signal person or dedicated spotter is used when the operator cannot see the clearance.

Question 11Site and Equipment Inspection

What does the anti-two-block device on a crane do?

  1. It prevents the hook block from contacting the boom tip Correct answer.
  2. It limits the crane to a preset load moment
  3. It stops the boom from being lowered too far
  4. It locks the outriggers while lifting

Explanation

The anti-two-block device senses when the hook block or headache ball approaches the boom tip and stops the hoist before the parts contact. Contact would part the hoist line and drop the load. The device must be functional before lifting begins.

Question 12Site and Equipment Inspection

A polyester web sling has a deep cut across its width. What is the correct action?

  1. Use it, but only for loads under half its rated capacity
  2. Use it only if the cut is shorter than one inch
  3. Wrap the cut area with tape before use
  4. Remove it from service and tag or destroy it Correct answer.

Explanation

Web slings with cuts, snags, burns, or holes must be removed from service no matter how much of the sling appears intact. Cutting load-bearing fibers reduces strength unpredictably, and the rated capacity no longer applies. Damaged slings are tagged and destroyed so they cannot return to service.

Question 13Site and Equipment Inspection

When installing wire rope clips to form an eye, the clip saddle must be placed:

  1. Against the short dead end of the rope
  2. Against the live, load-bearing end of the rope Correct answer.
  3. On the side of the rope that faces the load
  4. Alternating between the live and dead ends

Explanation

The saddle, the wide part of the clip, goes on the live load-bearing end, and the U-bolt straddles the dead end. Reversing this crushes the live rope and greatly reduces splice efficiency. Clips are spaced and torqued per the manufacturer, then retorqued after the first load.

Question 14Site and Equipment Inspection

In a correctly installed wedge socket, the live end of the wire rope should:

  1. Run in a straight line from the socket pin Correct answer.
  2. Be bent sharply around the wedge to lock it
  3. Pass around the wedge and exit the socket barrel
  4. Be secured with at least two wire rope clips

Explanation

The live end must leave the socket in line with the pin so the load pulls straight through the wedge. A side-loaded live end can let the wedge work loose. The dead-end tail is left long enough beyond the socket to meet the manufacturer's requirement.

Question 15Site and Equipment Inspection

A sheave groove is worn so badly that the wire rope bottoms out in the groove. What is required?

  1. Replace the sheave before further use Correct answer.
  2. Install a larger-diameter rope on the crane
  3. Fill the groove with weld and grind it smooth
  4. Continue using it if the rope is new

Explanation

When the rope bottoms out, the sheave pinches and abrades the strands and can flatten the rope. A sheave worn beyond the manufacturer's limits must be replaced, not repaired by welding. Groove diameter is checked during periodic inspection.

Question 16Site and Equipment Inspection

A screw-pin shackle shows wear at the bow measuring more than 10 percent of the original dimension. What should be done?

  1. Swap the pin for a new one and continue
  2. Use it only in a vertical, non-side-loaded hitch
  3. Return it to service after a visual check
  4. Remove it from service Correct answer.

Explanation

Wear exceeding 10 percent of the original bow or pin dimension is a removal criterion for shackles, along with cracks, nicks, and bent pins. The worn shackle is tagged out and destroyed so it cannot be reused. Pin replacement does not correct body wear.

Question 17Site and Equipment Inspection

What does the boom angle indicator on a mobile crane show?

  1. The angle of the outrigger beams to the ground
  2. The angle between the boom and the crane's axis
  3. The angle between the boom and horizontal Correct answer.
  4. The angle of the load line away from vertical

Explanation

The boom angle indicator shows the boom's angle above horizontal. That angle, with boom length, is used to determine radius and read the load chart. It indicates angle only and does not itself limit the load.

Question 18Site and Equipment Inspection

During inspection you find a crack in a load-bearing weld on the boom. The crane should be:

  1. Marked with paint and monitored for growth
  2. Operated only with the boom fully retracted
  3. Operated at reduced capacity until the next annual inspection
  4. Removed from service until repaired per the manufacturer Correct answer.

Explanation

Cracks in structural welds or boom sections can propagate quickly once the boom is loaded. The crane is removed from service until the manufacturer or a qualified person approves and completes a repair. Reduced capacity or monitoring does not make a cracked boom safe.

Question 19Site and Equipment Inspection

Which tire condition requires the crane to be taken out of service?

  1. Tread depth that is slightly uneven across the tire
  2. Cords or fabric visible through the tread Correct answer.
  3. Mud packed into the tread grooves
  4. A small amount of sidewall scuffing

Explanation

Tires with cord or fabric showing, deep cuts, bulges, or improper inflation are unsafe because a blowout during a lift can upset the crane. Tires and rims are part of the shift inspection. Cosmetic scuffing or packed mud does not by itself condemn a tire.

Question 20Site and Equipment Inspection

Crane load charts assume the crane is level. Unless the manufacturer specifies otherwise, the crane must be leveled to within:

  1. 0.5 percent of level
  2. 3 percent of level
  3. 1 percent of level Correct answer.
  4. 5 percent of level

Explanation

The setup requirements call for the crane to be leveled within 1 percent of level grade, unless the manufacturer requires a tighter tolerance. An out-of-level crane swings the load, side-loads the boom, and no longer matches the load chart. Level is verified with a bubble level or inclinometer on the crane.

Question 21Site and Equipment Inspection

The load moment indicator fails during setup on a lift that is about to begin. What is the correct action?

  1. Stop operation until the LMI is repaired and recalibrated Correct answer.
  2. Continue if the operator calculates loads manually
  3. Continue at 50 percent of charted capacity
  4. Continue if a second person watches the boom

Explanation

The LMI is a required operating aid, and the crane must be taken out of service when it is not functioning. Work resumes only after repair and recalibration by a qualified person. Manual calculations or reduced capacity do not substitute for a functioning LMI.

Question 22Site and Equipment Inspection

A crane is used in severe service. What is the minimum interval for its documented inspection?

  1. Every six months
  2. Annually
  3. Monthly Correct answer.
  4. Quarterly

Explanation

Cranes in severe service, such as high-cycle or harsh-environment use, must receive documented inspections at least monthly. All cranes still receive the annual periodic inspection. The severity of use determines whether the shorter interval applies.

Question 23Site and Equipment Inspection

For rotation-resistant wire rope, the crane must be removed from service when the rope shows:

  1. Two broken wires in 6 rope diameters Correct answer.
  2. Two broken wires in 30 rope diameters
  3. One broken wire in 30 rope diameters
  4. One broken wire in 6 rope diameters

Explanation

Rotation-resistant ropes have stricter criteria because broken wires concentrate and the rope can fail with less visible damage. Removal is required at 2 randomly distributed broken wires in 6 rope diameters or 4 in 30 rope diameters. Different criteria apply to standard 6x19 and 6x37 running ropes.

Question 24Site and Equipment Inspection

If the required power line clearance cannot be maintained, work may proceed only after:

  1. A dedicated signal person is posted beside the line to warn the operator
  2. The operator has completed an electrical hazard awareness course
  3. A warning flag has been attached to the boom tip by the rigger
  4. The line is de-energized and visibly grounded Correct answer.

Explanation

When the table clearance cannot be kept, the line must be de-energized and visibly grounded at the site, or the utility must confirm the line is isolated, before the crane works near it. Training, flags, and spotters do not make contact safe. Encroachment procedures must be documented in the lift plan.

Question 25Crane Setup and Configuration

What is the primary purpose of placing cribbing under a mobile crane's outrigger floats?

  1. To level the crane regardless of how uneven the ground is
  2. To spread the concentrated outrigger force over a larger area of ground Correct answer.
  3. To reduce the amount of counterweight needed for the lift
  4. To lengthen the effective reach of the outrigger beam

Explanation

Cribbing or mats increase the contact area beneath a float so the same force produces a lower bearing pressure on the soil. The goal is to keep that pressure below what the ground can support without settlement. Cribbing does not correct an out-of-level crane; the crane must already be level before lifting.

Question 26Crane Setup and Configuration

Before making a lift, a mobile crane on outriggers must be leveled to what standard?

  1. Leveling is unnecessary once all outriggers are fully extended
  2. Within 5 percent of level in any direction
  3. Within the manufacturer's stated tolerance, commonly about 1 percent of grade Correct answer.
  4. Within 10 degrees of level in any direction

Explanation

Load charts assume the crane is level within a small tolerance, typically around 1 percent of grade, because even a slight tilt changes radius and loads the outriggers unevenly. The manufacturer's published tolerance governs, and the level indicator must be checked before the lift. Full outrigger extension does not by itself make a crane level.

Question 27Crane Setup and Configuration

With boom length held constant, what happens to a crane's rated capacity as the working radius increases?

  1. Rated capacity depends only on the boom angle and not on radius
  2. Rated capacity decreases Correct answer.
  3. Rated capacity stays the same until the boom is nearly horizontal
  4. Rated capacity increases because the boom is steeper

Explanation

A larger radius increases the overturning moment produced by the load, so the charted capacity is reduced to keep the crane within its stability and structural limits. Boom angle and radius are directly related for a fixed boom length, but the chart itself is organized by radius. Capacity therefore falls as radius grows.

Question 28Crane Setup and Configuration

On a mobile crane, boom angle is measured from what reference?

  1. The crane's longitudinal axis
  2. Horizontal to the centerline of the boom Correct answer.
  3. The tip of the boom to the load line
  4. The vertical centerline of the boom

Explanation

Boom angle is the angle between horizontal and the centerline of the boom, so a horizontal boom reads zero degrees and a vertical boom reads ninety. This value is used with boom length to determine radius. Angle indicators must be set for the actual boom being used.

Question 29Crane Setup and Configuration

How must the counterweight on a mobile crane be set for a lift?

  1. It must be varied according to the weight of the load being lifted
  2. It must be removed any time the boom is swung over the side
  3. It must always be the maximum weight the crane can physically carry
  4. It must match the configuration on which the selected load chart rating is based Correct answer.

Explanation

Each load chart is published for a specific counterweight configuration, and the chart is invalid if the actual counterweight differs. The operator confirms the counterweight matches the chart before picking. Counterweight is not adjusted lift by lift according to load weight.

Question 30Crane Setup and Configuration

For a normal lift using the outrigger chart, how should the outrigger beams be positioned?

  1. Extended only on the side toward which the load will swing
  2. Left retracted whenever the boom works over the rear
  3. Fully extended with the floats set on firm, prepared bearing Correct answer.
  4. Extended halfway to reduce tail swing

Explanation

Load charts are normally published for fully extended outriggers, and capacities depend on that stance. Partial extension is only permitted when a chart specifically covers it. Setting only some beams also creates unequal loading and voids the rating.

Question 31Crane Setup and Configuration

How close may an outrigger float be placed to the top edge of an unshored excavation?

  1. On the excavated spoil pile beside the hole, for extra height
  2. Directly over the opening on steel plates spanning the excavation
  3. Directly at the edge, so the crane can work at the shortest radius
  4. Far enough back that the excavation slope cannot undermine the float's support Correct answer.

Explanation

An excavation removes lateral support from the soil beside it, so the ground near the edge may not carry the outrigger load. The float must be set back beyond the zone of influence of the slope, and a qualified person should confirm the setback or provide shoring. Spoil piles and plates spanning the opening are not acceptable substitutes.

Question 32Crane Setup and Configuration

What primarily determines the required size of the pad placed under an outrigger float?

  1. The length of the outrigger beam
  2. The weight of the load being lifted alone
  3. The crane's travel speed on the site
  4. The allowable ground bearing pressure at the setup location Correct answer.

Explanation

Pad area is selected so the outrigger force divided by the contact area stays below the soil's allowable bearing pressure. Softer ground or higher float loads require larger pads or mats. Load weight alone is not enough, because the crane's own weight also reaches the outriggers.

Question 33Crane Setup and Configuration

One outrigger float of a crane carries 48,000 lb and rests on a 4 ft by 4 ft pad. What bearing pressure does that pad apply to the ground?

  1. 3,000 pounds per square foot Correct answer.
  2. 12,000 pounds per square foot
  3. 48,000 pounds per square foot
  4. 750 pounds per square foot

Explanation

The pad area is 4 ft times 4 ft, or 16 square feet. Dividing the 48,000 lb reaction by 16 square feet gives 3,000 pounds per square foot. That value is then compared with the allowable soil bearing pressure for the site.

Question 34Crane Setup and Configuration

Wind at the boom tip is rising and approaching the manufacturer's limit for the lift. What should the operator do?

  1. Add counterweight to counteract the wind force
  2. Raise the boom to reduce the wind's effect on the crane
  3. Stop the lift and follow the manufacturer's procedure for securing the crane Correct answer.
  4. Continue as long as the load is under half of chart capacity

Explanation

Manufacturers publish maximum permissible wind speeds because wind loads on the boom and load can exceed the chart's allowances regardless of load weight. When the limit is reached, lifting stops and the boom is handled as the manufacturer directs. Reducing load weight does not reduce the wind area of the boom.

Question 35Crane Setup and Configuration

During boom assembly, when must the connecting pins between boom sections be fully driven and secured with their retainers?

  1. Only when the boom is fitted with a jib
  2. After the first test lift has been completed
  3. After the boom has been raised to working angle
  4. Before the boom is raised, using the retainers specified by the manufacturer Correct answer.

Explanation

Boom sections must be positively pinned and retained before any raising occurs, because a partially pinned joint can separate under the boom's own weight as it lifts. Retainers are required to prevent pins from walking out in service. Pins are never left to be installed later.

Question 36Crane Setup and Configuration

A jib is erected and the load chart contains a separate rating for jib work. How is capacity determined?

  1. The jib rating is used, along with any counterweight and boom configuration that rating requires Correct answer.
  2. Capacity increases because the jib shortens the working radius
  3. The main boom chart applies unchanged
  4. The anti-two-block device may be bypassed to gain boom angle

Explanation

Jib ratings are published separately because a jib adds weight and offset to the boom tip and changes structural limits. The operator selects the jib chart and matches the counterweight, boom length, and offset called for by that chart. Safety devices remain functional in every configuration.

Question 37Crane Setup and Configuration

What must be done with the area swept by the crane's rotating counterweight?

  1. It must be barricaded or kept clear of personnel while the crane is operating Correct answer.
  2. It only needs to be clear during the first lift of the shift
  3. It only needs marking when the boom is over the front
  4. It should be covered with plywood to prevent damage to the deck

Explanation

Tail swing is a crushing hazard because the operator cannot see the entire rear swing path from the cab. The swing radius is barricaded or controlled so no one can enter it. The hazard exists for every swing, not only the first lift or one direction.

Question 38Crane Setup and Configuration

A crane must be set up on ground that slopes. What is the correct approach?

  1. Set the outriggers on the slope and check the level indicator only while swinging
  2. Lower the outriggers until the tires just touch the ground
  3. Prepare a level, stable pad with matting or cribbing so the crane is within the manufacturer's tolerance Correct answer.
  4. Extend the uphill outriggers farther than the downhill outriggers

Explanation

The crane must be level before lifting, so the ground itself is built up or cut down and matted rather than relying on outrigger stroke. Unequal beam extension individually changes the stance and invalidates the chart. Level is verified on the indicator before the load is applied.

Question 39Crane Setup and Configuration

Site conditions prevent fully extending the outrigger beams. How should the lift proceed?

  1. Use the fully extended chart and deduct 10 percent from the capacity
  2. Restrict the lift to boom angles above 60 degrees
  3. Use the load chart published for the outrigger extension that is actually achieved Correct answer.
  4. Compensate by installing additional counterweight

Explanation

Manufacturers publish separate ratings for mid-extend or non-fully-extended stances because the stability envelope changes. The chart matching the actual beam extension must be used. Arbitrary deductions and added counterweight are not substitutes for a published rating.

Question 40Crane Setup and Configuration

What is required of the rated capacity limiter before a lift is made?

  1. It must be switched off when working near power lines
  2. It must be set for the crane's actual configuration and checked as functioning before the lift Correct answer.
  3. It needs calibration only once, at the factory
  4. It must be set by the rigger at the start of each shift

Explanation

The rated capacity limiter computes allowable load from the boom length, angle, radius, and configuration, so it must be set to the configuration actually in use. It is verified for function as part of the pre-lift inspection. It is never disabled to complete a lift.

Question 41Crane Setup and Configuration

What is the purpose of a boom-mounted anemometer on a mobile crane?

  1. To verify outrigger float pressure
  2. To record the weight of each load lifted
  3. To indicate wind speed at the boom so it can be compared with the manufacturer's limit Correct answer.
  4. To measure the slope of the setup ground

Explanation

Wind speed at the boom tip can be significantly higher than at ground level, so the anemometer gives the operator the value used against the manufacturer's wind limit. When the limit is reached, lifting stops. The device does not measure ground conditions, outrigger pressure, or load weight.

Question 42Crane Setup and Configuration

Before an outrigger is set, what should the ground beneath it be checked for?

  1. Drainage grates only
  2. Underground utilities, voids, uncompacted fill, and previous excavations Correct answer.
  3. The color and texture of the surface soil
  4. Whether the surface has been painted or marked

Explanation

An outrigger concentrates a large force on a small area, so hidden voids, buried utilities, or loose backfill can collapse and drop the float. Site drawings, utility locates, and a visual survey are used before setup. Surface appearance alone gives no information about subsurface support.

Question 43Crane Setup and Configuration

A crane is to be set up on an elevated concrete slab. What is required?

  1. Nothing, provided the slab appears to be in good condition
  2. Spreading the load with a single layer of plywood under each float
  3. Only that all outriggers be fully extended
  4. Verification by a qualified person that the slab can carry the outrigger loads, with shoring if needed Correct answer.

Explanation

Elevated slabs are designed for distributed floor loads, not for the concentrated point loads an outrigger applies. A qualified person evaluates the slab and specifies shoring or load spreading as necessary. Plywood alone does not provide the required structural capacity.

Question 44Crane Setup and Configuration

What is the rule about working beneath a boom that is being assembled or disassembled?

  1. It is permitted if all workers wear hard hats
  2. It is permitted once the boom is pinned at both ends
  3. Workers must stay out from under the boom, which is supported on stands or blocking Correct answer.
  4. It is required so workers can guide the connecting pins

Explanation

A boom being assembled is supported only by the crane's cylinders or by temporary stands, and a loss of hydraulic pressure can drop it. Personnel stay clear and the boom is lowered onto suitable supports before work continues. Hard hats and pinning do not protect against a falling boom.

Question 45Crane Setup and Configuration

An outrigger float applies 60,000 lb to the ground and the soil is rated for 2,000 pounds per square foot. What contact area must the cribbing provide at the soil surface?

  1. At least 4 square feet
  2. At least 30 square feet Correct answer.
  3. No additional area beyond the float itself
  4. At least 15 square feet

Explanation

Required area equals force divided by allowable pressure, so 60,000 lb divided by 2,000 pounds per square foot is 30 square feet. The cribbing must also be thick enough for the load to spread across that full area, roughly at 45 degrees through the material. A pad smaller than this will exceed the soil's capacity.

Question 46Crane Setup and Configuration

Working radius for load chart purposes is measured from what point to what point?

  1. From the front bumper of the carrier to the load
  2. From the boom tip to the hook block
  3. From the boom pivot pin to the boom tip
  4. From the crane's center of rotation to the center of gravity of the load Correct answer.

Explanation

Radius is a horizontal distance measured from the crane's axis of rotation to the vertical line through the load's center of gravity. This is why the rigging height and load position affect the radius that must be used. Measuring along the boom or from the carrier gives a different, incorrect value.

Question 47Crane Setup and Configuration

After the outriggers are set on compacted fill, the crane drifts out of level as the load comes onto the hook. What is the correct action?

  1. Increase engine speed so the outriggers hold pressure
  2. Continue if the level indicator is still close to center
  3. Stop, land the load, and reset the outriggers with adequate support before continuing Correct answer.
  4. Swing to the high side to compensate for the tilt

Explanation

Movement during loading means the ground or blocking is yielding, which shifts load onto other outriggers and changes the stability condition the chart assumed. The lift must stop and the setup be rebuilt on adequate support. Continuing or compensating by swinging keeps the crane outside its rated condition.

Question 48Crane Setup and Configuration

A light but very large, solid load presents a big sail area, and the site is near the chart's wind limit. How does this affect the lift?

  1. Capacity is unaffected because the chart is based on weight alone
  2. The chart's wind allowance covers any shape of load
  3. The lift should simply be made at a longer radius
  4. Wind force on the load's sail area can overload the boom even though the load weight is below chart capacity Correct answer.

Explanation

Load charts account for wind on the boom and a limited allowance for the load, but a large sail area catches far more wind than a compact load of the same weight. The added force increases boom loading and can also cause the load to drift. Operators must consider sail area and stop when the manufacturer's wind limit is reached.

Question 49Crane Setup and Configuration

If the ground beneath an outrigger is softer than the bearing pressure assumed for the setup, what is the likely consequence?

  1. The float settles, tilting the crane and transferring load to other outriggers, which can lead to tipping Correct answer.
  2. The rated capacity of the crane increases
  3. There is no effect, because outrigger floats are made of steel
  4. Swing speeds become faster and more consistent

Explanation

Bearing pressure that exceeds the soil's capacity causes settlement under the float. The crane then tilts, the load shifts onto the remaining outriggers, and the machine can progress toward a tipping failure. This is why pad size and ground preparation are treated as part of the lift plan.

Question 50Crane Setup and Configuration

A mobile crane with outriggers is being set up for a lift on a firm, prepared surface. How level must the crane be before the lift is made?

  1. Level enough that the crane does not creep or walk while swinging.
  2. Within the manufacturer's specified tolerance. Correct answer.
  3. Leveled only when the load exceeds 75 percent of the chart capacity.
  4. Within 5 degrees of horizontal, which is the industry-wide maximum.

Explanation

Load charts are based on the crane being level, so the machine must be brought within the tolerance stated in the manufacturer's operating manual, commonly 1 percent or less. Out-of-level setups shift load between the outriggers and reduce the tipping margin, which the chart does not reflect. A crane that merely feels stable or does not creep is not necessarily within tolerance.