Najran General Dept. of Traffic - Saudi Heavy Vehicle Skills Test 1

Q: How many questions is the Najran General Dept. of Traffic truck & bus theory test?

The official General Dept. of Traffic truck & bus theory test in Najran has 35 questions and you need 26 correct (75%) to pass. This practice test has 22 questions.

Q: Is this the real exam?

These are original practice questions to help you revise. They are not the official Saudi exam and the real question bank, format, fees and pass mark are set by the General Department of Traffic (Moroor) and the driving schools, and can change. Always confirm the current requirements with your driving school or the traffic department.

Q: Is this practice test free?

Yes. It is completely free, with no signup or payment, and you can retake it as many times as you like.

Q: What does the Najran truck & bus theory test cover?

Road signs, traffic signals, right of way, roundabouts, speed limits, seat belts, penalties and safe-driving rules, plus the handling and safety topics specific to your vehicle.

Question 1

What document must a driver of a dangerous-goods vehicle carry at all times during transport?

Accepted Answer

A transport document listing the UN number, proper shipping name, hazard class, packing group, and emergency response information for each dangerous good carried. Drivers of dangerous-goods vehicles must carry a transport document (also called a consignment note or declaration) that identifies each substance by UN number, proper shipping name, hazard class, packing group, and quantity. Emergency information panels or written instructions must also be on board so that emergency services know what they are dealing with if an incident occurs.

Answer

Only the vehicle registration and driving licence are required, the same as for any other truck

Answer

A letter from the loading company confirming that the cargo has been checked

Answer

A certificate of insurance covering the dangerous goods

Question 2

A truck carrying flammable liquids is involved in an accident and the tank begins to leak. What is the driver's immediate priority?

Accepted Answer

Move away from the vehicle, warn other road users, call the emergency services, provide the transport document to rescuers, and prevent ignition sources from approaching. When a dangerous-goods vehicle leaks, the driver's immediate priority is to move to a safe distance, prevent other people from approaching, eliminate ignition sources, and call emergency services. The transport document must be handed to the emergency services so they know what they are dealing with. Attempting to repair the leak is extremely dangerous.

Answer

Attempt to repair the leak using tools from the cab to prevent spillage

Answer

Drive the vehicle to the nearest fire station at reduced speed

Answer

Cover the leak with a tarpaulin and wait for the operator to send a recovery vehicle

Question 3

Which dangerous goods class covers compressed gases such as LPG and oxygen cylinders carried on a heavy truck?

Accepted Answer

Class 2, which covers compressed, liquefied, or dissolved gases including flammable, non-flammable, and toxic gases. Class 2 of the UN dangerous goods classification covers gases. This includes flammable gases (such as LPG), non-flammable non-toxic gases (such as compressed nitrogen), and toxic gases. The specific sub-division is indicated by the division number after the class number on the hazard diamond.

Answer

Class 3, which covers flammable liquids

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Class 5, which covers oxidising substances and organic peroxides

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Class 8, which covers corrosive substances

Question 4

What is the purpose of the range-change (hi/lo) splitter on a heavy truck gearbox?

Accepted Answer

It doubles the number of available gear ratios by providing a high and low range for each main gearbox position, giving the driver finer control of engine speed and tractive effort. A range-change or splitter gearbox doubles (or further multiplies) the gear ratios available. In low range the gearbox provides high torque multiplication suitable for starting from rest or climbing hills; in high range the same lever positions give higher road-speed ratios for highway driving. This gives the driver precise control over engine revs and wheel torque across a wide range of conditions.

Answer

It selects four-wheel drive for off-road driving conditions

Answer

It controls the differential lock on the rear axle

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It changes the fuel map between economy and power modes

Question 5

When should a heavy truck driver engage the differential lock on the drive axle?

Accepted Answer

Only when one or more drive wheels are spinning on a slippery or soft surface and the vehicle cannot move; it must be disengaged as soon as traction is regained. The differential lock forces both wheels on an axle to rotate at the same speed, preventing one spinning wheel from losing all drive force. It should only be engaged when a wheel is already spinning on a low-traction surface (sand, mud, gravel) and must be disengaged immediately on regaining traction. Driving with the diff lock engaged on a firm surface at speed causes severe driveline stress and makes steering unpredictable.

Answer

On all motorway driving to improve stability at high speed

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When descending steep hills to improve braking

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Whenever the vehicle is loaded to maximum gross weight

Question 6

A driver is climbing a steep grade in a split gearbox truck and needs to change from 5-Hi to 6-Lo. What is the correct sequence?

Accepted Answer

At the correct engine rev for the upshift, move the main lever to position 6 while simultaneously pre-selecting Lo on the range switch; the change completes cleanly mid-shift. On most split or range gearboxes the range switch is pre-selected before the shift, and the actual range change occurs as the clutch is depressed and the main lever moved. The exact procedure varies by gearbox make and model; always follow the manufacturer's instructions. Correct technique keeps engine revs in the right band and prevents crunching or missed shifts.

Answer

First move the range switch to Lo, then wait for the gearbox to change range automatically before moving the main lever

Answer

Fully depress the clutch, select neutral, change the range switch, release the clutch, then re-depress the clutch and select 6

Answer

Range changes should never be made on uphill gradients; pull over and stop first

Question 7

What is the kingpin on an articulated trailer?

Accepted Answer

A steel pin on the underside of the trailer's front skid plate that locks into the fifth wheel of the tractor unit to form the articulation joint. The kingpin is a hardened steel pin on the underside of the trailer's front (turntable) plate. When the tractor reverses under the trailer, the kingpin enters the jaw of the fifth wheel and is locked by the fifth wheel's jaw mechanism, creating the pivot point around which the tractor and trailer articulate.

Answer

The central locking pin that holds the trailer's cargo doors shut during transit

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A safety pin that prevents the landing legs from accidentally folding while the trailer is coupled

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The pin that connects the service brake air line to the trailer brake system

Question 8

A driver notices that the kingpin has visible wear and cracks after coupling. What action must be taken?

Accepted Answer

Do not move the vehicle; the trailer must be taken out of service for inspection and repair of the kingpin before it is used. A cracked or severely worn kingpin is a critical safety defect. If the kingpin fails at speed, the trailer separates from the tractor and becomes an unguided projectile. The vehicle must be taken out of service immediately for inspection and repair by a qualified technician. Never drive with a defective kingpin.

Answer

Drive only at low speed to the nearest workshop, because the kingpin is unlikely to fail completely on a short journey

Answer

Lubricate the kingpin with grease and tighten the fifth wheel jaw to compensate for the wear

Answer

Complete the current delivery and report the condition at the next scheduled maintenance

Question 9

Why are high-sided curtain-sided trailers especially vulnerable on exposed sections of Saudi highways during windy conditions?

Accepted Answer

The large flat surface of the trailer acts as a sail, and strong crosswinds can generate enough lateral force to push the trailer sideways or cause rollover, especially when lightly loaded. A curtain-sided trailer has a very large flat vertical surface. Crosswinds act on this surface like a sail, generating significant lateral forces. An empty or lightly loaded high-sided trailer is at greatest risk because there is less ballast weight resisting the sideways push and the centre of gravity is relatively high. Drivers must reduce speed and steer with both hands in strong crosswind conditions.

Answer

Wind vibrates the curtain fabric and loosens the load restraints

Answer

Wind reduces the air pressure in the tyres, lowering traction

Answer

High-sided vehicles are not vulnerable to wind because their aerodynamic shape deflects air over the roof

Question 10

A driver is crossing an exposed bridge in a high-sided empty trailer when a sudden strong gust hits from the side. What is the correct immediate response?

Accepted Answer

Reduce speed smoothly, grip the steering wheel firmly with both hands, steer gently to counteract the push, and do not make sudden swerving corrections. In a sudden crosswind gust, the driver must reduce speed smoothly (not brake suddenly), keep a firm two-handed grip on the steering wheel, and make gentle corrective steering inputs. Sharp braking or overcorrection can cause the trailer to sway or roll. The priority is to reduce speed to a level where aerodynamic forces are manageable.

Answer

Accelerate to pass the exposed section of bridge as quickly as possible

Answer

Apply the trailer brakes sharply to stabilise the trailer

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Steer sharply into the wind to prevent the trailer from blowing off course

Question 11

How does extreme heat in Saudi Arabia affect truck tyre pressure during a long journey?

Accepted Answer

Tyre pressure rises significantly as the air inside heats up; tyres must be checked cold before departure, and pressure must never be released from hot tyres to bring the reading down. As tyre temperature rises, the air inside expands and pressure increases. This is normal and expected. Tyres must be inflated to the manufacturer's cold specification before the journey. If you check a hot tyre and the pressure is high, do not release air; that elevated pressure is needed for the tyre to carry the load safely at operating temperature. Releasing pressure from a hot tyre leads to dangerous underinflation once the tyre cools.

Answer

Heat causes tyres to deflate gradually, so pressure should be topped up at every fuel stop

Answer

Tyre pressure is unaffected by temperature changes in a tubeless tyre

Answer

Hot weather tyres should be inflated 50% above the cold specification to prevent overheating

Question 12

During a summer crossing of a Saudi desert highway, a driver notices that one tyre on the trailer feels unusually hot compared with the others when checked at a fuel stop. What could this indicate and what should the driver do?

Accepted Answer

A binding or dragging brake, underinflation, or internal tyre damage causing heat build-up; the driver must not continue until the cause is identified and rectified to prevent tyre blowout or fire. A significantly hotter-than-normal tyre is a warning sign of a binding brake calliper or drum, underinflation, or internal structural damage (broken belt or ply). All of these generate heat that can cause a catastrophic blowout or tyre fire, especially in summer desert heat. The vehicle must not continue until the cause is found and fixed. Pouring cold water on a hot tyre can cause the rubber to crack.

Answer

It is normal for one tyre to run hotter than others due to variation in road surface; continue the journey

Answer

Inflate the hot tyre to maximum sidewall pressure and continue, as extra pressure will reduce heat generation

Answer

Pour water over the tyre to cool it and then continue immediately

Question 13

Why does a fully loaded articulated truck require a much greater stopping distance than a private car travelling at the same speed?

Accepted Answer

Greater mass gives the truck far more kinetic energy, so the brakes must absorb much more energy before the vehicle stops. A fully loaded truck has far greater mass than a car, which means far more kinetic energy at any given speed. The brakes must absorb all that energy before the vehicle stops, so the stopping distance is significantly longer. Always allow a large gap to the vehicle ahead.

Answer

Truck air brakes are slower to react than a car's hydraulic brakes

Answer

Truck tyres are wider and create more wind resistance, which slows the braking

Answer

A loaded truck sits lower, reducing tyre contact and grip

Question 14

Compared with the same truck when empty, a fully laden heavy truck travelling at 80 km/h will have a stopping distance that is

Accepted Answer

Considerably longer, because higher mass requires more braking force over a greater distance. A laden truck has considerably longer stopping distance than the same truck when empty. Higher mass means more kinetic energy, and the brakes must work much harder over a greater distance. This effect is even more pronounced on wet or sandy roads.

Answer

Roughly the same, because the brakes are identical on the laden and unladen vehicle

Answer

Slightly shorter, because added weight presses the tyres harder onto the road

Answer

Shorter only on wet roads, due to the extra mass improving tyre adhesion

Question 15

When following another vehicle on a Saudi highway in a fully loaded 40-tonne articulated truck, what following distance approach should you use?

Accepted Answer

A gap well beyond the two-second rule, because heavy vehicles need far more distance to stop safely. A fully loaded articulated truck needs a following distance far greater than the two-second rule designed for light vehicles. A gap of at least four to five seconds in dry conditions is widely recommended; confirm the current requirement with the General Department of Traffic (Moroor).

Answer

The same two-second rule used for a light vehicle at the same speed

Answer

A fixed 20-metre gap regardless of speed

Answer

One vehicle length for every 10 km/h of speed

Question 16

You are driving a laden heavy truck at 90 km/h on a dry Saudi highway when the vehicle in front stops suddenly. Which factor most increases your stopping distance compared with a light vehicle?

Accepted Answer

The high kinetic energy of the truck's greater mass, which requires much more braking force and distance to dissipate. Kinetic energy increases with the square of speed and linearly with mass. A fully laden truck has far more mass than a car, so at the same speed it carries far more kinetic energy. That energy must all be converted to heat by the brakes before the vehicle stops, dramatically increasing the stopping distance.

Answer

The longer wheelbase, which forces the rear wheels to travel further before locking

Answer

The elevated driving position, which reduces the driver's ability to judge distance accurately

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Air resistance acting against the front of the cab, which pushes the truck forward

Question 17

What type of braking system is fitted to most heavy trucks and buses operating in Saudi Arabia?

Accepted Answer

Pneumatic (air) brakes, which use compressed air to actuate the brake chambers. Most heavy trucks and buses use pneumatic (air) brakes. Compressed air from an onboard compressor actuates brake chambers to apply the wheel brakes. Understanding air-brake operation and the fail-safe spring-brake system is essential for every heavy-vehicle driver.

Answer

Hydraulic disc brakes identical to those fitted on light vehicles

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Electric regenerative brakes that charge the battery on every stop

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Cable-operated drum brakes similar to those used on motorcycles

Question 18

What is brake fade, and which situation most commonly causes it on a heavy truck?

Accepted Answer

A reduction in braking power caused by overheated brake drums or discs, most commonly on long downhill descents when brakes are applied repeatedly. Brake fade is the loss of braking effectiveness that occurs when brake components overheat. On long downhill gradients, repeatedly applying the service brakes heats the drums or discs until they can no longer absorb heat effectively. Always use engine or exhaust brakes to control speed on descents and avoid relying solely on the service brakes.

Answer

A sudden increase in braking force caused by air pressure building up too quickly in the chambers

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The delay between pressing the brake pedal and the air reaching the rear axle chambers

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The locking of the rear wheels caused by excessive brake pedal pressure on a slippery surface

Question 19

What does the low air-pressure warning light or buzzer on a heavy truck indicate?

Accepted Answer

The air pressure in the braking system has fallen below a safe level and you must stop safely as soon as possible. A low air-pressure warning on a heavy truck means the compressed air reservoir pressure has dropped below the minimum threshold for safe brake operation. You must stop the vehicle safely as soon as possible and not move it until the fault is investigated. Driving with low air pressure risks complete brake failure.

Answer

The air conditioning system has lost refrigerant and needs servicing

Answer

The tyre pressures need to be checked at the next fuel stop

Answer

The air suspension has deflated and must be re-inflated before driving

Question 20

A heavy truck fitted with spring-brake actuators is left parked on a slope without connecting the hand-brake control. What happens to the spring brakes if the air pressure in the system drops to zero?

Accepted Answer

The spring brakes apply automatically, holding the vehicle stationary because the springs are released by air pressure and engage when pressure is lost. Spring-brake actuators are a fail-safe device. Compressed air holds the large internal spring in a compressed, released position. When air pressure drops to zero (or below a set threshold), the spring extends and forces the brake on. This is why air-brake equipped trucks automatically apply their parking brakes if the air supply fails.

Answer

The spring brakes release fully, allowing the vehicle to roll freely down the slope

Answer

Nothing changes because spring brakes are independent of air pressure

Answer

The service brakes apply instead, but only on the front axle

Question 21

Why should a driver use the engine brake or exhaust brake on a long downhill gradient rather than relying on the service (foot) brakes alone?

Accepted Answer

To prevent the service brakes from overheating and fading, which could lead to brake failure. Using engine or exhaust brakes on long descents removes the braking load from the service brakes, preventing them from overheating and fading. Brake fade on a descent can lead to complete loss of braking ability. The service brakes should be reserved for supplementary slowing or emergency stops.

Answer

To save fuel because using the engine brake charges the air compressor

Answer

Because service brakes are not permitted on downhill gradients under Saudi regulations

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To keep the engine revs high enough for the alternator to charge the batteries

Question 22

Before descending a long steep grade, a heavy truck driver should select an appropriate gear. What is the correct principle?

Accepted Answer

Select a low gear before reaching the descent so engine braking can hold the truck at a safe speed throughout. The correct principle is to select the appropriate low gear before reaching the descent. Engine braking in a low gear will hold the truck at a safe speed without requiring constant service-brake application. Changing down mid-descent or descending in neutral are dangerous and can lead to runaway speed and brake fade.

Answer

Descend in a high gear to keep engine revs low and reduce noise

Answer

Descend in neutral so the engine does not drag and overheat

Answer

Begin the descent in any gear and change down only if speed rises above the limit

Najran General Dept. of Traffic - Saudi Heavy Vehicle Skills Test 1

Najran General Dept. of Traffic - Saudi Heavy Vehicle Skills Test 1

What this test covers

Frequently asked questions