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CACES R487 study materials
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CACES R487 practice questions

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Question 1Tower-crane types, mechanisms and R487 scope

Under French occupational safety standards, who is authorized to carry out the structural erection, climbing, and dismantling (*montage, télescopage et démontage*) of a tower crane?

  1. A specialized crane assembly team (*équipe de monteurs spécialisés*) trained and equipped according to the manufacturer's erection manual and site erection plan Correct answer.
  2. The crane operator working alone during weekend overtime
  3. Any team of general construction laborers using standard hand tools
  4. The truck driver who transported the mast sections to the site

Explanation

Erection, climbing and dismantling need appropriate specific competence, equipment and the actual manufacturer/site method. Operator assessment alone does not establish that separate competence. No assembly, structural change or live operation is authorized by recognizing the appropriate specialist role in this written item.

Question 2Inspection, signals, controlled operation and handover

Under CNAM Recommandation R487, what is the maximum validity period of the CACES R487 certificate for tower crane operators in France?

  1. 3 years
  2. 10 years
  3. 5 years Correct answer.
  4. Permanent (lifetime validity once issued)

Explanation

The published R487 framework uses a five-year knowledge-and-skill updating and reassessment cycle for the relevant category. Confirm the actual current certificate, scope and issuer procedure rather than treating a practice score as authorization. CACES and the employer’s operating authorization are distinct, and administrative profile facts remain unasserted here.

Question 3Tower-crane types, mechanisms and R487 scope

Which major structural component of a top-slewing tower crane carries the hoisting winch machinery, electrical control cabinets, and counterweight ballast blocks?

  1. The distribution trolley (*chariot de distribution*)
  2. The counter-jib (*contre-flèche*) Correct answer.
  3. The undercarriage chassis (*châssis de base*)
  4. The hook block (*moufle de levage*)

Explanation

The counter-jib (*contre-flèche*) extends rearward from the crane tower top or slewing ring. It houses the heavy counterweights (*lest de contre-flèche*), the main hoist winch, and electrical enclosures, balancing the overturning moments created by the forward working jib (*flèche*).

Question 4Tower-crane types, mechanisms and R487 scope

What is the primary mechanical function of the slewing ring (*couronne d'orientation*) on a tower crane?

  1. Allowing continuous 360-degree rotation of the crane superstructure while transmitting immense vertical loads and overturning bending moments into the mast Correct answer.
  2. Spooling the main hoist rope smoothly onto the winch drum
  3. Locking the crane jib in a fixed position during violent storm winds
  4. Measuring the dynamic weight of the suspended concrete bucket

Explanation

The slewing ring is a large-diameter heavy-duty bearing with internal or external gear teeth driven by one or two electric slewing motors. It must safely transmit the massive vertical, axial, and overturning bending moments from the jib and counter-jib down into the stationary mast while providing smooth rotational motion.

Question 5Tower-crane types, mechanisms and R487 scope

How is the horizontal movement of the distribution trolley (*chariot de distribution*) along the crane jib accomplished?

  1. By gravitational rolling controlled by friction disc handbrakes
  2. By hydraulic fluid pumped directly through telescopic jib cylinders
  3. By manual ropes pulled by the slinger on the ground
  4. By an electric trolley travel winch (*treuil de chariot*) driving opposing steel wire ropes connected to the front and rear of the trolley Correct answer.

Explanation

The trolley travel mechanism uses a dedicated electric winch drum that pulls continuous steel wire ropes routed through sheaves at the jib tip and mast, allowing positive mechanical travel both outward (*chariot avant*) and inward (*chariot arrière*).

Question 6Tower-crane types, mechanisms and R487 scope

What is the mechanical purpose of the sheaves (*poulies*) housed inside the hook block (*moufle*) and distribution trolley?

  1. To measure ambient air temperature aloft
  2. To lock the hook rotation whenever the wind exceeds 50 km/h
  3. To guide the hoist wire rope and provide mechanical advantage through multiple falls of reeving (*mouflage*) Correct answer.
  4. To inject lubricating grease continuously onto the electrical cables

Explanation

The sheaves in the trolley and hook block guide the steel hoist rope and form a pulley block system (reeving / *mouflage*). Reeving with multiple falls (e.g. 2 or 4 falls) provides mechanical advantage, multiplying lifting capacity while reducing line tension on the winch drum.

Question 7Tower-crane types, mechanisms and R487 scope

In a supplied ideal line-pull-limited model with unchanged rope speed and no other capacity limit, changing from two to four supporting rope parts doubles support and halves hook speed. Which listed change matches that stated model, rather than every real crane rating?

  1. Maximum lifting capacity doubles, while maximum hoisting speed is halved Correct answer.
  2. Maximum lifting capacity is halved, while maximum hoisting speed doubles
  3. Both maximum capacity and hoisting speed double simultaneously
  4. Capacity remains unchanged, but motor electrical power consumption is tripled

Explanation

In accordance with basic pulley physics, doubling the number of rope falls supporting the hook block from 2 to 4 doubles the mechanical advantage, doubling the crane's maximum allowable gross load (e.g. from 4 tonnes to 8 tonnes). In return, the hoist drum must spool twice as much rope to raise the hook by the same distance, halving the linear hook speed.

Question 8Tower-crane types, mechanisms and R487 scope

What is the primary safety purpose of the load moment limiter (*limiteur de moment / couple*) on a tower crane?

  1. Preventing the trolley from traveling backwards toward the mast
  2. Preventing structural collapse or tipping by automatically halting outward trolley travel and hoisting when the overturning moment reaches safe limits Correct answer.
  3. Preventing electrical short circuits in the generator set
  4. Limiting the maximum slewing speed during strong tailwinds

Explanation

The specified load-moment protective function responds to relevant load and radius conditions under the actual design. It is not a guarantee against every structural failure, ground problem, side force or incorrect configuration. Understand its actual behavior without bypassing it or treating the display as a complete lift approval.

Question 9Tower-crane types, mechanisms and R487 scope

How does the maximum gross load limiter (*limiteur de charge maximale*) differ from the moment limiter?

  1. It only operates when the trolley is positioned at the extreme tip of the jib
  2. It measures the wind speed acting against the counterweight blocks
  3. It cuts off power to the slewing motors during rotational acceleration
  4. It cuts off hoisting power immediately whenever the suspended mass exceeds the crane's structural maximum capacity (e.g. 6.0 t), regardless of radius Correct answer.

Explanation

The defined gross-load function addresses the selected maximum load condition, while moment-related limits also depend on radius and configuration. Actual stopping actions and settings are product-specific. Neither device alone establishes that all rope, hook, support, wind and structural conditions are suitable.

Question 10Tower-crane types, mechanisms and R487 scope

When the moment limiter (*limiteur de moment*) trips due to excessive load at a given radius, what automatic kinematic actions occur?

  1. All crane movements including slewing and lowering are permanently locked out
  2. The slewing brake disengages into free weathercocking while the load drops
  3. The hoist line is cut by an emergency pyrotechnic guillotine
  4. Hoisting up (*levage montée*) and outward trolley travel (*chariot avant*) are disabled; lowering (*descente*) and inward trolley travel (*chariot arrière*) remain enabled Correct answer.

Explanation

The listed movement restrictions correspond to the described product response to its load-moment condition. Actual controllers can differ, and not every enabled motion is automatically safe in the real situation. Follow the actual approved response and competent plan rather than improvise recovery from an overload.

Question 11Tower-crane types, mechanisms and R487 scope

What is the critical safety function of the upper hoist travel limit switch (*fin de course haut de levage*)?

  1. Stopping the upward motion of the hook block before it strikes the distribution trolley or jib structure, preserving a mandatory safety clearance buffer Correct answer.
  2. Preventing the hoist cable from unwinding completely off the winch drum
  3. Cutting off electrical power whenever wind speed exceeds 72 km/h
  4. Locking the hook safety latch automatically during hoisting

Explanation

The upper hoist limit switch (equivalent to an anti-two-block device) stops upward travel before the hook block crashes into the trolley sheaves (*choc sous chariot*). An impact would snap the hoist cable and cause the suspended load and hook block to plunge to the ground.

Question 12Tower-crane types, mechanisms and R487 scope

How do trolley travel limit switches (*fins de course chariot avant et arrière*) protect the crane jib and mast?

  1. They weigh the load on the trolley wheels at every meter of travel
  2. They trigger automatic deceleration before cutting travel power prior to the trolley striking mechanical end buffer stops Correct answer.
  3. They automatically drop the hook whenever the trolley approaches the jib tip
  4. They lock the trolley in a fixed position whenever rain is detected

Explanation

Appropriate trolley travel limits prevent the intended movement beyond the designed operating range. Actual deceleration, stops and safety behavior depend on the crane and configuration. This concept does not authorize a live limit test, override or assumption that every end condition is protected by one device.

Question 13Tower-crane types, mechanisms and R487 scope

How does an electronic anti-collision system (*système anticollision*) function on construction sites with multiple overlapping tower cranes (*grues en interférence*)?

  1. It continuously tracks real-time 3D positions, trolley radii, and slewing angles via radio telemetry, automatically slowing and stopping conflicting movements before collision zones are breached Correct answer.
  2. It blows an audible siren but leaves all motor controls under full manual operator authority
  3. It shuts off primary electrical power to the entire construction site simultaneously whenever two jibs come within 10 meters
  4. It forces the lower crane to drop its load immediately to avoid collision

Explanation

A suitable configured anti-collision arrangement can use actual position information and defined boundaries to restrict conflicting movements. Sensor errors, changes, communications and unmodeled obstacles can affect protection. It supplements the coordinated actual plan rather than guaranteeing that every possible collision is prevented.

Question 14Tower-crane types, mechanisms and R487 scope

What is the function of an electronic forbidden zone flyover system (*système de gestion des zones d'interdiction de survol*) installed on a tower crane?

  1. Preventing birds from perching on the jib lattice structure
  2. Restricting slewing and trolley movements to prevent the hook and load from entering designated 3D protected airspace over schools, public streets, or railways Correct answer.
  3. Locking the anemometer cups whenever the wind blows from the east
  4. Preventing the operator from listening to commercial music in the cab

Explanation

Configured restricted-zone control can limit relevant movements against the defined envelope. The actual hook, load, swing and obstruction geometry must be considered; a stored boundary is not proof of every current site condition. Maintain competent coordination and do not defeat a protective function for convenience.

Question 15Tower-crane types, mechanisms and R487 scope

A supplied rotation-resistant hoist rope uses opposing lay directions to reduce net torsional tendency. Which listed construction purpose explains that design, without asserting the same rope is required on every tower crane?

  1. They are constructed with opposing lay directions in outer and inner strand layers, balancing torsional torque under load to prevent unguided hook spinning Correct answer.
  2. They are made from flexible Kevlar fibers that never require lubrication
  3. They can be knotted together by the operator if snapped without loss of strength
  4. They stretch by 30% under peak load to cushion dynamic shocks

Explanation

Opposing rope-layer lay can reduce the net torsional tendency in the intended rotation-resistant design. It does not guarantee no hook rotation or mean the same rope is suitable for every crane. Use the actual manufacturer selection, reeving and termination basis.

Question 16Tower-crane types, mechanisms and R487 scope

What is the structural distinction between base ballast (*lest de base*) and counter-jib ballast (*lest de contre-flèche*)?

  1. Base ballast is made of lead while counter-jib ballast is made of water tanks
  2. Base ballast is adjusted during every lift while counter-jib ballast is fixed permanently
  3. Base ballast is placed only on mobile cranes while tower cranes have no base ballast
  4. Base ballast stabilizes the stationary mast against overturning at ground level; counter-jib ballast balances the moments of the rotating jib and load aloft Correct answer.

Explanation

Base ballast consists of heavy precast concrete blocks placed on the cross-chassis (*châssis en croix*) at the ground to prevent overturning of the entire mast structure. Counter-jib ballast consists of concrete blocks placed at the tail of the rotating superstructure to counterbalance the horizontal jib and live loads.

Question 17Tower-crane types, mechanisms and R487 scope

What severe hazard occurs if an operator allows slack rope (*mou de câble*) to develop on the hoist winch drum?

  1. The cable can jump drum grooves, cross-wind, and become crushed under subsequent heavy tension, leading to severe wire deformation and sudden failure Correct answer.
  2. The electric motor immediately reverses polarity and catches fire
  3. The counterweights on the counter-jib slide backward off the crane
  4. The anemometer reading drops to zero

Explanation

Slack can permit poor winding, displacement or crushing when tension returns, creating actual rope and control hazards. The severity depends on the arrangement and conditions, not a guaranteed failure on every occurrence. Stop and use the appropriate competent assessment rather than hide or repeatedly load a damaged condition.

Question 18Tower-crane types, mechanisms and R487 scope

On luffing-jib tower cranes (*grues à tour à flèche relevable*), how is the working radius changed during lifting operations?

  1. By extending hydraulic telescopic cylinder sections inside the horizontal boom
  2. By shifting the counterweights forward and backward along the counter-jib
  3. By rolling a standard distribution trolley along the upper chord of the jib
  4. By luffing the entire inclined lattice jib up or down using a heavy-duty luffing winch and tie cables Correct answer.

Explanation

Luffing-jib cranes (often used in congested urban centers with air-rights constraints) have no trolley. The working radius is varied by changing the angle of inclination of the entire jib, pulling it up toward vertical (minimum radius) or lowering it outward (maximum radius) via the luffing winch.

Question 19Tower-crane types, mechanisms and R487 scope

What is the primary structural function of foundation anchor stools (*pieds de scellement*) embedded in a concrete crane base?

  1. Anchoring the lowest mast section directly into a massive reinforced concrete footing block to transmit dynamic overturning moments, shear loads, and deadweight into the ground Correct answer.
  2. Allowing the crane to slide smoothly on railway tracks during windstorms
  3. Providing spring-loaded shock dampening to prevent crane vibrations from affecting adjacent buildings
  4. Acting as sacrificial electrical fuses to ground lightning strikes safely

Explanation

Stationary tower cranes without ground ballast chassis use foundation anchor stools (*pieds de scellement*). These four high-strength steel legs are precisely cast into a massive reinforced concrete foundation pad, transferring all overturning moments (P x R) and wind forces directly into the earth.

Question 20Chart interpretation, load geometry and rigging calculations

A supplied capacity model has only a 120 tonne-metre moment cap and a separate 6.0 tonne gross cap. At a radius of 30 metres, what maximum load follows under those stated caps, before other real-world conditions?

  1. 4.0 tonnes Correct answer.
  2. 6.0 tonnes
  3. 3.0 tonnes
  4. 2.5 tonnes

Explanation

For the supplied two-limit model, the moment allowance gives 120 divided by 30 = 4 tonnes, below the separate 6 tonne gross cap. This answers that stated comparison only; a real lift still needs the actual chart, deductions, configuration, wind and competent plan.

Question 21Chart interpretation, load geometry and rigging calculations

For a supplied moment-only exercise, divide 160 tonne-metres by a 50 metre radius. What load quantity follows from that stated model, rather than a complete actual crane capacity?

  1. 1.6 tonnes
  2. 4.0 tonnes
  3. 3.2 tonnes Correct answer.
  4. 5.0 tonnes

Explanation

Under the supplied moment-only model, 160 tonne-metres divided by 50 metres gives 3.2 tonnes. This is not a complete capacity chart or safe-lift authorization. Other line, structural, accessory and environmental limits remain outside the simplified calculation.

Question 22Chart interpretation, load geometry and rigging calculations

A tower crane's load chart indicates a rated moment of 100 tonne-meters (t.m) and a maximum gross hoist capacity of 5.0 tonnes. At a radius of 15 meters, what is the maximum allowable load the crane can lift?

  1. 6.67 tonnes
  2. 5.0 tonnes Correct answer.
  3. 3.33 tonnes
  4. 7.5 tonnes

Explanation

The supplied moment ratio is 100 divided by 15, about 6.67 tonnes, but the separate gross cap is 5 tonnes. The more restrictive stated limit gives 5 tonnes before other applicable deductions and conditions. A real complete chart and competent assessment remain necessary.

Question 23Chart interpretation, load geometry and rigging calculations

A tower crane has an allowable gross lifting capacity of 4,000 kg at a radius of 28 meters. The hook block weighs 180 kg, the concrete bucket has a tare weight of 320 kg, and the chain slings weigh 50 kg. What is the maximum net payload of wet concrete that can be loaded into the bucket?

  1. 3,820 kg
  2. 3,450 kg Correct answer.
  3. 3,500 kg
  4. 3,250 kg

Explanation

The supplied deductions total 180 + 320 + 50 = 550 kilograms. From the 4,000 kilogram gross allowance, the net object allowance is 3,450 kilograms under that model. Actual chart interpretation and every other lift condition still require verification.

Question 24Chart interpretation, load geometry and rigging calculations

What does the abbreviation *CMU (Charge Maximale d'Utilisation)* stamped on lifting accessories (slings, shackles, spreader beams) indicate?

  1. The ultimate tensile breaking strength at which the accessory will snap
  2. The deadweight mass of the lifting accessory itself
  3. The maximum mass that the accessory is legally certified to support under normal specified lifting conditions Correct answer.
  4. The proof test load applied in a factory testing bench

Explanation

CMU (Working Load Limit - WLL) is the maximum payload that a lifting accessory (sling, shackle, eyebolt, lifting beam) is authorized to lift in routine service. It incorporates a safety factor (e.g. 4:1 for steel chains, 5:1 for steel cables, 7:1 for synthetic webbing) relative to ultimate breaking strength.

Question 25Chart interpretation, load geometry and rigging calculations

What is the primary function of the spring-loaded safety latch (*linguet de sécurité*) mounted on a crane hook?

  1. Preventing slings, master links, or eyebolts from accidentally jumping out of the hook bowl when the hoist rope goes slack or during transit Correct answer.
  2. Increasing the hook's maximum lifting capacity by 20%
  3. Measuring the exact weight of the suspended load
  4. Preventing the hook from rotating on its axial bearing

Explanation

The latch helps retain appropriately seated loose rigging in the hook throat under its actual design. It is not the primary load-bearing surface or permission for tip loading. The complete hook, rigging configuration, condition and manufacturer criteria remain necessary.

Question 26Chart interpretation, load geometry and rigging calculations

Why is diagonal lifting or dragging loads sideways (*tirage en biais*) strictly prohibited when operating a tower crane?

  1. Because it causes the hoist motor to draw too little electrical current
  2. Because it exerts dangerous lateral forces on the jib and mast, inducing high torsional stresses that can buckle the mast and collapse the crane Correct answer.
  3. Because it makes the concrete set too quickly inside the bucket
  4. Because it causes the anemometer cups to spin backwards

Explanation

Side pulling can introduce lateral forces, uncontrolled release and loading outside the intended tower-crane design. The apparent object mass does not bound the force of dragging or freeing a restrained load. Use the actual approved lifting method; this written recognition authorizes no maneuver.

Question 27Chart interpretation, load geometry and rigging calculations

A symmetrical 2-leg chain sling lifts a precast concrete beam weighing 4.0 tonnes. The angle between the two sling legs at the hook is 60° (each leg is 30° from the vertical). What is the tensile force in each sling leg?

  1. Approximately 2.31 tonnes Correct answer.
  2. Exactly 2.00 tonnes
  3. Exactly 4.00 tonnes
  4. Approximately 3.46 tonnes

Explanation

Under the supplied ideal static equal-leg model, each leg carries 4 divided by (2 × cos 30 degrees), approximately 2.31 tonnes-force equivalent. The answer uses a mass-equivalent force convention; a tonne is not an SI force unit. Actual equipment, dynamics and configuration remain separate.

Question 28Chart interpretation, load geometry and rigging calculations

A 2-leg sling lifts a generator weighing 6.0 tonnes. The included angle between the two legs is 90° (each leg is 45° from the vertical). What is the tension acting on each individual sling leg?

  1. Exactly 3.00 tonnes
  2. Exactly 2.12 tonnes
  3. Approximately 4.24 tonnes Correct answer.
  4. Approximately 6.00 tonnes

Explanation

Each ideal leg force is 6 divided by (2 × cos 45 degrees), about 4.24 tonnes-force equivalent. This assumes the stated equal geometry and static load. It is not a complete sling rating, dynamic assessment or authorization to perform the lift.

Question 29Chart interpretation, load geometry and rigging calculations

A 2-leg chain sling lifts a container weighing 5.0 tonnes. Due to excessively short slings, the angle between the two legs opens to 120° (each leg is 60° to the vertical). What is the tension in each sling leg?

  1. 2.50 tonnes
  2. 5.00 tonnes (each leg carries 100% of the entire load weight) Correct answer.
  3. 3.54 tonnes
  4. 10.00 tonnes

Explanation

With each leg at 60 degrees from vertical, 5 divided by (2 × cos 60 degrees) equals 5 tonnes-force equivalent per leg. The horizontal force components matter even though the total vertical load is shared. Actual rated gear and other conditions still require the complete plan.

Question 30Chart interpretation, load geometry and rigging calculations

When rigging an asymmetrical precast concrete component where the center of gravity is offset toward one end, how must the crane hook be positioned before lifting?

  1. Directly above the geometric center of the object regardless of mass distribution
  2. Positioned over the lightest corner to make it lift first
  3. Positioned 2 meters to the side to induce a balancing swing
  4. Positioned vertically directly above the center of gravity, with sling leg lengths adjusted so the load lifts level Correct answer.

Explanation

A suspended load always rotates until its center of gravity hangs vertically directly below the crane hook. If the hook is not aligned directly over the center of gravity before lifting, the load will violently tilt and swing as it leaves the ground, potentially striking personnel or overloading rigging legs.

Question 31Chart interpretation, load geometry and rigging calculations

What is the primary function of a tagline (*corde de guidage*) attached to a long load, and what is the mandatory safety rule when holding it?

  1. To guide and prevent rotation of the load from a safe distance, while strictly never wrapping the line around the hands, wrists, or waist Correct answer.
  2. To drag the load horizontally so the crane operator does not have to slew
  3. To tie the load to the ground scaffolding during windy lunch breaks
  4. To wrap the rope tightly around the wrist to get maximum mechanical pulling force

Explanation

Taglines allow ground personnel to control load rotation and orientation while maintaining a safe standoff distance outside the drop zone. The line must NEVER be wrapped around hands, wrists, or body; if the load shifts or catches a wind gust, a wrapped line will drag the worker off their feet.

Question 32Chart interpretation, load geometry and rigging calculations

The crane's load chart permits a maximum gross load of 3.20 tonnes at a 38-meter radius. Rigging gear comprises a 150 kg hook block, a 50 kg 4-leg chain sling, and a 300 kg concrete bucket tare. What is the maximum mass of concrete that can be loaded into the bucket?

  1. 3.20 tonnes
  2. 2.70 tonnes Correct answer.
  3. 2.90 tonnes
  4. 2.45 tonnes

Explanation

The stated deductions are 0.15 + 0.05 + 0.30 = 0.50 tonne, leaving 3.20 minus 0.50 = 2.70 tonnes for concrete under the supplied gross model. Do not mistake this arithmetic for full lift permission or ignore actual chart notes and environmental conditions.

Question 33Chart interpretation, load geometry and rigging calculations

What is the physical effect of a sudden acceleration shock (*à-coup de levage*) when an operator engages high-speed hoisting with loose, slack slings?

  1. The dynamic force generated (F = m * (g + a)) can instantaneously double or triple the static load, risking hoist cable rupture, sling failure, or tripping the moment limiter Correct answer.
  2. The motor automatically draws zero electrical current during sudden shocks
  3. The crane counter-jib tilts downward to cushion the shock automatically
  4. The hook safety latch opens to release the load safely

Explanation

Abrupt acceleration or taking up slack can produce dynamic force beyond a static weight comparison. Its magnitude depends on the actual acceleration, elasticity and transient response; no fixed doubling or tripling applies universally. Avoid shock through the appropriate actual controlled method rather than test the claim on equipment.

Question 34Site support, wind, interference and environmental hazards

A supplied crane/site plan has a wind pre-alarm at 50 km/h. Which listed response best uses that scenario-specific warning rather than treating the number as a universal French legal threshold?

  1. Evaluate wind-sensitive loads with large sail areas (such as formwork shutters), anticipate stopping work, monitor gusts continuously, and prepare for safe parking Correct answer.
  2. Immediately drop all suspended loads onto the nearest scaffolding
  3. Lock the slewing brake tightly to prevent the jib from rotating
  4. Disconnect the anemometer buzzer so it does not distract the operator

Explanation

A supplied wind pre-alarm is a cue to evaluate the actual load, gusts, manufacturer/site limits and required actions. The stated 50 km/h is this scenario’s trigger, not a universal threshold. Plan the appropriate stop or parking before conditions make the task unsafe.

Question 35Site support, wind, interference and environmental hazards

What is the "sail effect" (*prise au vent*) in crane operations, and why does it represent a major hazard?

  1. Wind aerodynamic pressure acting against large surface area loads, producing massive horizontal forces that can displace the load, twist the crane jib, and cause loss of control Correct answer.
  2. Wind blowing into the cabin windows causing excessive cooling of the operator
  3. Wind whistling through the mast lattice structure causing acoustic noise violations
  4. Wind pushing rainwater into the hydraulic brake fluid reservoir

Explanation

The sail effect (*prise au vent*) refers to aerodynamic drag exerted by wind on loads with a large surface-to-weight ratio (such as formwork shutters, large cladding panels, or prefabricated walls). The resulting horizontal forces push the load sideways, causing severe swinging, twisting of the jib, and potential structural overload.

Question 36Site support, wind, interference and environmental hazards

For the supplied aerodynamic model q = 0.5 × density × speed², hold density, projected area and drag coefficient fixed. How does modeled pressure and force change when wind speed doubles?

  1. Wind pressure increases linearly with wind velocity (doubling speed doubles pressure)
  2. Wind pressure is inversely proportional to wind velocity
  3. Wind pressure is proportional to the square of wind velocity (V^2), meaning that doubling the wind speed quadruples the aerodynamic force Correct answer.
  4. Wind pressure remains constant regardless of wind speed

Explanation

For the stated fixed density, area and drag coefficient model, wind pressure and resulting force scale with speed squared. Doubling speed therefore gives four times the modeled pressure or force. Actual gust, orientation and aerodynamic effects still need the relevant design basis.

Question 37Site support, wind, interference and environmental hazards

Why can a large vertical panel require stopping at wind conditions acceptable for a different smaller-area load, using the actual manufacturer and site limits rather than a universal 50 or 72 km/h rule?

  1. Because formwork panels produce radio interference that blocks remote controls
  2. Because the formwork steel alloy weakens when exposed to cool breezes
  3. Because the concrete release agent evaporates too quickly in moderate wind
  4. Because their large sail area creates unmanageable lateral aerodynamic forces, causing severe load drift and risk of crushing personnel or overloading the crane structure Correct answer.

Explanation

A broad panel can impose substantial lateral wind action despite a modest mass, so its actual permissible conditions may be more restrictive than those for another load. No universal 50 or 72 km/h limit is asserted here. Use the actual load, machine, site and planned response.

Question 38Site support, wind, interference and environmental hazards

What ground condition hazard around the tower crane base must be verified prior to and during operations, particularly following prolonged heavy rainfall?

  1. Soil bearing capacity, differential ground settlement, water pooling undermining footing pads, and slope instability near adjacent trenches Correct answer.
  2. Soil acidity levels affecting the rubber tires of transport vehicles
  3. Earthworm activity around the crane chassis
  4. Ambient soil moisture levels remaining strictly below 5%

Explanation

A tower crane concentrates immense point loads onto its foundation pads or outriggers. Heavy rain can saturate the subsoil, wash away supporting backfill, or cause nearby excavation embankments to collapse, leading to differential settlement (*tassement différentiel*) and catastrophic crane tilt.

Question 39Site support, wind, interference and environmental hazards

On a construction site where two tower cranes operate in mutual interference, what determines crane movement priority when their operating zones overlap?

  1. The larger crane always possesses absolute priority over the smaller crane
  2. The crane operator with the longest trade experience always takes priority
  3. Strict adherence to the automated anti-collision system interlocks and the predetermined priority protocol established in the site safety plan (*PPSPS*) Correct answer.
  4. The crane that is slewing faster always forces the slower crane to yield

Explanation

Actual overlapping-crane operation needs the coordinated priority, communication and protective arrangements defined for that site. An anti-collision interlock supports but does not replace the complete plan or correct every unmodeled change. Resolve conflicts through the authorized process rather than force a movement.

Question 40Site support, wind, interference and environmental hazards

What are "forbidden flyover zones" (*zones d'interdiction de survol*) on a construction site?

  1. Areas where the crane operator cannot see because of sun glare
  2. Designated parking spaces reserved exclusively for the general contractor's management vehicles
  3. Material storage areas dedicated solely to gravel and aggregate piles
  4. Designated off-site or on-site zones (such as public streets, pedestrian sidewalks, occupied school buildings, and railway tracks) over which loads must never be transported Correct answer.

Explanation

French regulations strictly forbid hoisting loads over public roadways, active sidewalks, neighboring residential properties, or schools without specialized municipal permits, protective overhead tunnels, or street closures. These perimeters are defined as *zones d'interdiction de survol* and are enforced by electronic limiters.

Question 41Site support, wind, interference and environmental hazards

How does severe freezing weather and ice formation (*givre / verglas*) endanger tower crane operations?

  1. It adds substantial deadweight to the jib and counter-jib lattices, creates severe slip hazards on access ladders, freezes limit switch actuators, and impairs brake lining friction Correct answer.
  2. It causes the electric motors to overspeed by 50%
  3. It causes the hydraulic oil to boil inside the lines
  4. It increases the structural tensile strength of steel cables beyond safety limits

Explanation

Ice accumulation adds tons of uncalculated deadweight to the long lattice structures, increasing overturning moments. Furthermore, ice can freeze limit switch levers in the closed position, cause brake pads to slip, freeze anemometer cups into immobility, and create deadly slip hazards for the operator climbing the mast.

Question 42Site support, wind, interference and environmental hazards

A vertical formwork shutter has a projected surface area of 18 m² and a shape drag coefficient Cx = 1.2. At a wind velocity of 15 m/s (54 km/h), the dynamic pressure is q is approximately 138 N/m². What is the approximate horizontal aerodynamic force pushing against the shutter?

  1. Approximately 150 N
  2. Approximately 650 N
  3. Approximately 12,000 N
  4. Approximately 2,980 N (approx 3.0 kN or ~300 kgf) Correct answer.

Explanation

The supplied aerodynamic model gives 138 × 18 × 1.2 = 2,980.8 newtons, about 3.0 kN. This uses the stated pressure, projected area and coefficient, not a universal wind allowance or safe operating limit. Actual gusts, orientation and the complete system still matter.

Question 43Site support, wind, interference and environmental hazards

If dense fog or heavy snowfall severely restricts visibility so the crane operator cannot see the load or landing zone, and two-way radio communication becomes intermittent or fails, what must the operator do?

  1. Continue operating by guessing landing coordinates based on the building floor markers
  2. Slew the crane while sounding the horn continuously to warn ground workers
  3. Immediately halt all crane movements, land the load safely if possible or hold it stationary, and suspend operations until clear visibility or reliable communications are restored Correct answer.
  4. Instruct the ground slinger to climb onto the load to guide it visually

Explanation

Operating 'blind' requires uninterrupted, crystal-clear communication with a qualified banksman. If visibility is zero and radio communication fails, operating is strictly illegal and immediately hazardous. The operator must cease all movement and wait for conditions to improve.

Question 44Site support, wind, interference and environmental hazards

How does an electronic anti-collision system prevent an operator from inadvertently swinging the crane jib or load into site scaffolding or mobile construction hoists?

  1. By continuously comparing actual sensor coordinates against pre-programmed 3D geometric envelope boundaries, automatically overriding joysticks to decelerate and halt drives before buffer margins are crossed Correct answer.
  2. By ejecting the operator's seat from the cabin if a boundary is crossed
  3. By sounding an exterior horn while allowing the operator to steer through the scaffolding
  4. By shutting down the job site's electrical transformer substation

Explanation

The specified protection compares appropriate actual sensor information with configured boundaries and can restrict movement under its designed logic. It cannot guarantee every coordinate, obstacle or current site change is correctly represented. Competent planning, checks and controlled response remain essential.

Question 45Site support, wind, interference and environmental hazards

What is the operational definition and purpose of placing a tower crane into "free weathercocking" (*mise en girouette libre*)?

  1. Releasing the slewing mechanism brakes completely, allowing the crane jib and counter-jib to rotate freely like a weathervane and align with the path of least wind resistance Correct answer.
  2. Locking the slewing brakes with maximum hydraulic force to prevent any rotation during storms
  3. Running the slewing motors continuously at 1 rpm all night to prevent bearing seizure
  4. Tying the crane hook to a concrete foundation anchor block with a steel wire rope

Explanation

Weather-vaning describes the intended ability to align with wind in the actual approved out-of-service configuration. It is not a universal instruction to release every brake in every crane state. Follow the manufacturer method and clear-envelope plan rather than operate a release from this written definition.

Question 46Site support, wind, interference and environmental hazards

What catastrophic structural failure can occur if an operator leaves the tower crane's slewing brake locked (*frein d'orientation serré*) overnight or during gale-force winds?

  1. The slewing motor gearbox oil will overheat and boil
  2. The cabin radio batteries will discharge completely
  3. Wind striking the side of the locked jib exerts massive bending and torsional twisting moments on the mast, which can buckle lattice chords and overturn the crane Correct answer.
  4. The anemometer cups will spin in reverse

Explanation

A crane left in a condition incompatible with its actual wind design can face severe bending, torsional and stability consequences. The actual risk depends on the machine and conditions; it is not proof that every locked slewing brake always causes collapse. Use the approved out-of-service arrangement.

Question 47Inspection, signals, controlled operation and handover

Which of the following checks is a mandatory part of the crane operator's daily pre-use inspection (*prise de poste*) before starting lifting operations?

  1. Visual and functional inspection of ground stability, foundation pins/bolts, ballast blocks, wire ropes, hook latch, travel limit switches, and anemometer operation Correct answer.
  2. Taking laboratory oil samples from the slewing gearbox
  3. Disassembling the hoist motor brake shoes using hand wrenches
  4. Repainting any minor cosmetic paint scratches on the mast sections

Explanation

Pre-use inspection addresses the actual crane, site and operating instructions and relevant accessible checks. It is not a substitute for specialist inspection or permission to access hazardous areas. Record defects and use the competent controlled process rather than assume a signed checklist establishes full readiness.

Question 48Inspection, signals, controlled operation and handover

During blind lifting operations where the load is hidden from the operator's view, what is the mandatory radio communication protocol between the slinger and the crane operator?

  1. The slinger speaks only once when the load touches the ground
  2. The operator continues moving for 60 seconds after radio contact is lost
  3. Radio communication is only needed during initial lift-off
  4. Continuous verbal commentary (*signal continu* / *parole continue*); if voice communication stops for any reason, the operator must immediately halt all movements Correct answer.

Explanation

Required reliable agreed communication is essential when the operator cannot directly observe the load. The actual site and signaling method govern the specific protocol. A loss or ambiguity in the required control link calls for a controlled stop rather than guessing or relying on a generic phrase alone.

Question 49Inspection, signals, controlled operation and handover

For rail-mounted tower cranes (*grues sur voies*), what mandatory mechanical securing operation must be performed during end-of-shift parking?

  1. Draining the hydraulic oil from the rail travel bogies
  2. Welding the wheels to the rails with an arc welder
  3. Engaging and tightening the rail clamping jaws (*griffes d'ancrage / pinces de rail*) and positioning wheel chocks (*sabots d'arrêt*) Correct answer.
  4. Jacking the entire crane off the rails using pneumatic air bags

Explanation

A rail-mounted crane needs the actual specified restraint and parking arrangement to address unintended movement and wind. Clamps and chocks are relevant only as designed for that equipment and condition. This concept is not a complete universal parking sequence or permission to improvise restraints.

Question 50Inspection, signals, controlled operation and handover

If an operator discovers a broken strand or localized birdcage deformation on the hoist rope during the morning pre-use check, what immediate action is required?

  1. Wrap industrial tape around the damaged section and operate only with light loads
  2. Lock out the crane immediately (*mise à l'arrêt et consignation*), record the defect in the logbook, notify site management, and do not operate until the cable is replaced Correct answer.
  3. Lubricate the broken strand with grease and continue operating as normal
  4. Increase the hoist speed to pass the damaged section through the sheaves faster

Explanation

Severe rope distortion is a reason to remove the crane from normal operation and use the actual competent inspection, discard and restoration process. Do not hide the defect or test it with another load. The correct replacement and release require actual manufacturer and applicable requirements.