Permis de Conduire Catégorie C — Poids Lourds (Mali)

What component serves as the primary source of compressed air in a heavy vehicle pneumatic braking system?

• AThe engine-driven air compressor
• BThe vehicle electrical alternator
• CThe hydraulic steering pump
• DThe exhaust turbocharger wastegate

What is the primary function of the air dryer desiccant cartridge in an air brake system?

• ATo lubricate the brake drums and shoe friction surfaces
• BTo extract moisture and oil aerosols from compressed air before it enters the reservoirs
• CTo increase compressed air pressure above 15 bar
• DTo cool the engine coolant before it reaches the radiator

What minimum operating pressure must typically be reached in the air reservoirs before driving a heavy vehicle equipped with full pneumatic brakes?

• AApproximately 1 to 2 bar
• BApproximately 3 to 4 bar
• CApproximately 6 to 7 bar
• DAt least 15 to 20 bar

Why should manual drain valves on pneumatic air reservoirs be purged daily by the driver?

• ATo expel accumulated water condensate and oil residue from the bottom of the tanks
• BTo depressurize the fuel delivery system before parking
• CTo bleed air bubbles out of the hydraulic brake fluid lines
• DTo adjust the tension of the engine alternator serpentine belt

What is the primary function of the spring brake (maxi-brake / frein à ressort) on a heavy truck?

• ATo provide hydraulic power steering assistance at slow speeds
• BTo cool the turbocharger after the engine is switched off
• CTo actuate the windshield wipers under heavy rainfall
• DTo provide parking braking and automatic emergency braking upon total loss of air pressure

What is the role of the pressure regulator (governor) in a heavy vehicle air brake circuit?

• ATo measure the vehicle road speed and display it on the tachograph
• BTo control compressor pumping by governing cut-in and cut-out pressure limits
• CTo regulate diesel fuel injection pressure in the common rail
• DTo distribute electrical current to the trailer exterior lights

If air pressure drops below the critical safety threshold (typically below 4.5 to 5 bar) while driving, what will occur?

• AThe engine will instantly accelerate to maximum governor speed
• BThe headlights will automatically switch off to conserve battery charge
• CVisual and audible warning devices will trigger, and the spring brakes will begin to apply
• DThe differential lock will permanently engage without warning

How do the service brake (frein de service) and parking brake (frein de stationnement) differ in their actuation mechanism on an air brake truck?

• AService brakes use compressed air to apply force; parking brakes use compressed mechanica…
• BService brakes use mechanical springs; parking brakes use hydraulic fluid lines
• CService brakes apply to the transmission shaft only; parking brakes apply to the front st…
• DBoth systems rely exclusively on electric solenoids without mechanical components

How does an engine exhaust brake (ralentisseur sur échappement) create braking torque to slow a heavy vehicle?

• ABy injecting water directly into the diesel exhaust manifold
• BBy closing a butterfly valve in the exhaust pipe, creating cylinder backpressure that res…
• CBy disengaging the clutch automatically during descents
• DBy reversing the rotation of the engine crankshaft

How does an electromagnetic retarder (such as a Telma retarder) generate retarding torque on a heavy truck's driveline?

• ABy forcing friction brake shoes against rotating iron drums
• BBy spraying pressurized engine oil against the drive axle differential gears
• CBy compressing air into a specialized high-pressure auxiliary storage tank
• DBy energizing electromagnets in a stator to induce eddy currents (courants de Foucault) i…

How does a hydrodynamic/hydraulic retarder (intarder or retarder hydraulique) dissipate kinetic energy during deceleration?

• ABy discharging hydraulic fluid out onto the roadway beneath the rear wheels
• BBy using an electric heating element to vaporize excess fuel in the tank
• CBy pumping transmission oil between a spinning rotor and a stationary stator, transferrin…
• DBy locking the planetary gearsets inside the gearbox simultaneously

What causes brake fade (évanouissement des freins) during prolonged descent of a steep hill, and how is it prevented?

• AFriction linings and drums overheat, causing loss of braking grip; prevented by using low…
• BCompressed air leaks through the exhaust valve; prevented by accelerating periodically do…
• CTyre tread separates from the casing; prevented by inflating tyres past their maximum sid…
• DEngine oil overheats and dilutes brake fluid; prevented by coasting downhill in neutral

What is the primary safety purpose of the four-circuit protection valve (valve de protection à quatre circuits) in a commercial vehicle air system?

• ATo equalize tire pressures across all four corners of the vehicle automatically
• BTo blend diesel fuel from four different auxiliary fuel tanks into the engine
• CTo switch between four different audio frequencies on the vehicle radio
• DTo isolate a ruptured circuit so that failure in one circuit does not depressurize the re…

What is the function of a quick release valve (valve de purge rapide) installed in an air brake line?

• ATo rapidly vent fuel from the tank in case of a rollover fire
• BTo discharge air pressure rapidly from brake actuators when the driver releases the brake…
• CTo release trailer coupling pins automatically during high-speed driving
• DTo purge engine coolant when temperature exceeds 100°C

Why is a relay valve (valve relais) installed near the rear axles of a long heavy goods vehicle?

• ATo mechanically shift the differential gear ratios between high and low range
• BTo allow the driver to steer the rear wheels using pneumatic switches
• CTo rapidly deliver and exhaust air to rear brake chambers directly from a dedicated rear…
• DTo charge the electrical storage batteries during regenerative braking

What is the correct procedure for testing pneumatic system leakage during a static pre-trip inspection on a rigid heavy truck?

• AShut off the engine at full pressure, fully apply the foot brake, hold for one minute, an…
• BRun the engine at high idle and pump the brake pedal continuously for five minutes
• CLoosen the drain plug on the primary reservoir while driving at 40 km/h
• DDisconnect all pneumatic hoses and check for audible whistling with the engine running

Why should a driver exercise caution or reduce the stage of an auxiliary retarder on wet or slippery road surfaces?

• ARetarders consume excess diesel fuel when operated in wet weather
• BExcessive retarding torque applied only to the drive axle can break tyre adhesion and ind…
• CRetarders cause rainwater to boil and burst the engine radiator hoses
• DUsing a retarder in the rain automatically disables the vehicle steering wheel

What is the primary function of a one-way check valve (clapet anti-retour) positioned at the inlet of each air reservoir?

• ATo allow compressed air to vent directly to atmosphere when pressure exceeds 2 bar
• BTo mix lubricating motor oil with the incoming compressed air
• CTo redirect air to the turbocharger intake manifold under full acceleration
• DTo allow air to enter the reservoir from the supply line while preventing backflow if ups…

What is the function of the safety relief valve installed on the wet (primary) air reservoir of a heavy vehicle?

• ATo vent excess air to atmosphere (typically at 10 to 11 bar) if the compressor governor f…
• BTo regulate tire inflation automatically while driving at highway speeds
• CTo inject pressurized air into the cabin air conditioning ducts
• DTo lock the transmission in neutral whenever air pressure rises above 5 bar

What is the primary role of an automatic slack adjuster (rattrapeur automatique de jeu) on an S-cam drum brake system?

• ATo vary the brake fluid viscosity as operating temperatures change
• BTo automatically apply the trailer parking brakes when disconnecting from the tractor
• CTo maintain proper pushrod stroke and lining-to-drum clearance as the friction brake lini…
• DTo disconnect the drive axle from the differential during tight cornering

Why is repeatedly pumping the foot brake pedal ('fan braking') on a long mountain descent particularly dangerous with full air brakes?

• AIt causes the steering wheel to vibrate and overturn the front axle
• BIt discharges compressed air faster than the compressor can replace it, depleting reservo…
• CIt causes engine diesel fuel to backflow into the cabin heater matrix
• DIt completely discharges the electrical starter battery within thirty seconds

In a dual-chamber spring brake actuator (cylindre combiné / vase double), how are the service and parking sections configured during normal driving?

• AThe parking section is constantly pressurized with air to compress the spring, while the…
• BBoth sections are filled with hydraulic oil under high pressure from the steering pump
• CThe service section is kept at constant pressure while the parking section is vented to a…
• DNeither section contains air until the driver operates the dashboard parking brake control

When and why would a technician or recovery driver use the mechanical caging bolt (vis de desserrage manuel) on a spring brake chamber?

• ADuring routine pre-trip inspections to verify parking brake holding power
• BTo increase the vehicle's maximum road speed on the highway
• CTo bleed moisture out of the brake linings after driving through heavy rain
• DTo mechanically compress and cage the internal spring to move a disabled vehicle when air…

How does an Anti-lock Braking System (ABS) control braking pressure at the wheels of a pneumatic-braked heavy goods vehicle during an emergency stop?

• ABy disengaging the rear differential and shifting the transmission into reverse
• BBy shutting down the engine air compressor to prevent any air pressure from reaching the…
• CBy using electronic wheel speed sensors and solenoid modulator valves to hold, release, a…
• DBy spraying pressurized engine coolant onto the brake drums to cool them rapidly

How does a compression-release engine brake (commonly termed a Jake Brake) differ mechanically from a standard exhaust butterfly brake?

• AIt opens the exhaust valves near top dead center of the compression stroke, dumping compr…
• BIt injects engine oil into the combustion chamber to extinguish the diesel flame
• CIt relies on friction pads rubbing directly against the engine flywheel ring gear
• DIt reverses the polarity of the vehicle alternator to create electromagnetic driveline dr…

In road transport regulations and vehicle registration documents, what does the abbreviation PTAC represent?

• AThe total power produced by the turbocharger air cooler
• BPoids Total Autorisé en Charge: the maximum legal authorized laden mass of the vehicle in…
• CThe unladen empty weight of the truck chassis without fuel or driver
• DPression Totale d'Air Comprimé: the maximum operating pressure of the air brake reservoirs

How is the maximum legal payload (charge utile - CU) of a commercial goods vehicle determined?

• ABy subtracting the unladen tare weight (Poids à Vide - PV) from the maximum authorized gr…
• BBy multiplying the engine cylinder capacity by the number of drive axles
• CBy adding the unladen weight (PV) directly to the gross weight rating (PTAC)
• DBy measuring the physical length of the cargo platform in meters

Under the axle-load table incorporated into Décret n° 2023-0509/PT-RM, what is the maximum load for a single intermediate or rear axle fitted with dual wheels?

• A6 tonnes
• B11.5 tonnes
• C12 tonnes
• D20 tonnes

Under UEMOA Regulation 14/2005/CM/UEMOA, what is the maximum legal load permitted on a single non-drive steering axle (essieu directeur simple)?

• A3.5 tonnes
• B4.5 tonnes
• C11.5 tonnes
• D6.0 tonnes

What is the primary objective of roadside weigh stations (postes de pesage) deployed on Malian national roads and UEMOA transit corridors?

• ATo protect road infrastructure from premature destruction caused by overloaded axles and…
• BTo inspect the validity of tourist visa stamps for passengers on international coaches
• CTo test engine exhaust sound levels and calibrate vehicle horns
• DTo collect agricultural property taxes from rural crop producers

In cargo transport terminology, what is 'calage' (blocking/chocking) and how is it used?

• AUsing bright paint to mark the dimensions of oversized loads on the road surface
• BPlacing robust timber blocks, wedges, or purpose-built chocks firmly against the base of…
• CTying down cargo exclusively with flexible synthetic ropes tied to door handles
• DCovering the load completely with waterproof tarpaulins to prevent dust infiltration

What is 'arrimage' (cargo lashing/securing) in heavy road haulage operations?

• AThe administrative registration of freight bills at customs offices
• BThe mechanical alignment of the truck steering wheels during alignment checks
• CSecuring the load to certified anchor points on the vehicle using approved straps, chains…
• DThe process of painting the exterior cab panels with heat-reflective coatings

Under standard Malian and UEMOA road traffic regulations, what is the maximum legal width for a standard rigid heavy goods vehicle (excluding refrigerated bodies)?

• A2.55 meters
• B3.20 meters
• C1.90 meters
• D4.00 meters

What maximum load does the current Malian axle table assign to a Type 3 intermediate or rear tandem group?

• A11.5 tonnes
• B16 tonnes
• C22 tonnes
• D20.0 tonnes

What maximum load does the current Malian axle table assign to a type 2 tridem axle group?

• A20 tonnes
• B25 tonnes
• C31 tonnes
• D44 tonnes

What is the maximum authorized gross vehicle weight (PTAC) for a standard rigid 2-axle heavy goods vehicle under UEMOA Regulation 14?

• A12 tonnes
• B15 tonnes
• C18 tonnes
• D26 tonnes

What is the maximum legal gross vehicle weight (PTAC) for a rigid 3-axle heavy truck under UEMOA Regulation 14?

• A26 tonnes
• B18 tonnes
• C32 tonnes
• D40 tonnes

Under the current Malian Highway Code, what is the maximum PTAC for an isolated rigid vehicle with four or more axles?

• A18 tonnes
• B26 tonnes
• C31 tonnes
• D38 tonnes

What legal consequences and penalties occur when a heavy goods vehicle is weighed and found overloaded at an official weigh station in Mali?

• AThe driver is issued a complimentary fuel coupon and allowed to proceed immediately
• BHeavy monetary fines per overloaded tonne are levied, and the vehicle is immobilized unti…
• CThe truck is permanently confiscated and destroyed by the regional transport authority on…
• DThe vehicle registration is upgraded automatically to an exceptional convoy status

How does concentrating heavy cargo toward the very rear of a rigid truck's platform affect vehicle dynamics?

• AIt improves fuel economy and shortens stopping distances on wet roads
• BIt stabilizes the front axle and prevents high-speed jackknifing
• CIt acts as a lever over the rear axle, lifting weight off the front steering axle and cau…
• DIt locks the differential automatically and doubles maximum payload capacity

What is the primary danger of placing too much cargo weight at the front bulkhead of a rigid truck?

• AOverloading the steering axle, causing heavy steering, rapid tyre wear, component failure…
• BCausing the rear drive tyres to spin constantly on dry asphalt
• COverheating the rear differential and melting the brake fluid lines
• DTriggering automatic emergency braking whenever the headlights are switched on

What is the operating principle of frictional top-over lashing (arrimage par friction / arrimage plaquant)?

• ATying straps between the truck tyres and the chassis frame
• BConnecting the load directly to the vehicle engine cooling fan belt
• CUsing adhesive glue sprayed on the truck bed to bond cargo permanently
• DApplying downward clamping tension across the top of cargo to press it into the deck, mul…

How does direct lashing (arrimage direct / haubanage) differ from frictional top-over lashing?

• ADirect lashing uses only plastic zip ties, whereas top-over lashing uses steel chains
• BLashings connect directly from vehicle anchor points to dedicated lashing eyes on the car…
• CDirect lashing requires the driver to hold the tension cables by hand while driving
• DDirect lashing is permitted only on agricultural tractors towing timber logs

Why is the vehicle's center of gravity (centre de gravité) critical when loading, and how should it be positioned?

• AIt should be placed as high as possible to improve passenger visibility
• BIt should be positioned as far to the right side as possible to clear road gutters
• CIt must be kept as low as possible and aligned near the vehicle centerline to minimize bo…
• DIt has no influence on heavy vehicle handling as long as the engine has sufficient horsep…

When loading heavy, high-density concentrated cargo (such as steel dies, stone blocks, or machinery) on a flatbed truck, how must it be positioned and supported?

• APlaced directly over the longitudinal chassis main beams on load-spreading timbers, cente…
• BPlaced on the extreme outer edge of the sideboards to facilitate rapid forklift unloading
• CSuspended by nylon ropes from the roof frame of the canvas body
• DPiled at the extreme rear bumper to minimize air resistance behind the cab

What is the primary operational hazard of 'liquid surge' (effet de vague) when driving a tanker truck with partly filled compartments?

• ALiquid surge causes the fuel to freeze inside the tank at ambient tropical temperatures
• BLiquid sloshing creates an electrical voltage that disables the truck alternator
• CLiquid surge cleans the internal tank walls and increases fuel consumption by 50%
• DThe shifting momentum of the sloshing liquid creates severe longitudinal thrust during br…

A rigid 3-axle truck has an unladen empty mass (PV) of 9,800 kg and a registered PTAC of 26,000 kg. If 15,500 kg of cargo is loaded, what is the actual total laden mass and the remaining legal payload margin?

• ATotal mass is 25,300 kg; remaining margin is 700 kg
• BTotal mass is 26,000 kg; remaining margin is 0 kg
• CTotal mass is 24,500 kg; remaining margin is 1,500 kg
• DTotal mass is 27,200 kg; the truck is overloaded by 1,200 kg