Free Practice Questions for Iran Heavy Vehicle Driving Theory

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Sample Iran Heavy Vehicle Driving Theory Practice Questions

Try these sample questions to review concepts for the Iran Heavy Vehicle Driving Theory exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1What is the primary function of the air compressor governor (گاورنر کمپرسور باد) in a heavy vehicle's pneumatic brake system?

A.To control when the air compressor pumps air into the storage reservoirs based on system pressure

B.To lubricate the brake drums and slack adjusters during continuous operation

C.To automatically apply the spring parking brakes if the driver falls asleep

D.To equalize hydraulic fluid pressure between front and rear drive axles

Explanation: In commercial vehicle compressed air brake systems, the governor controls the compressor's pumping cycle. When reservoir pressure reaches the cut-out level (typically 120–130 psi), the governor stops the compressor from pumping air. When pressure drops to the cut-in level (typically 85–100 psi), the governor allows the compressor to resume pumping.

2On the European-specification trucks and buses that make up most of Iran's heavy fleet, what is the typical governor cut-out (working) pressure of the compressed air brake system?

A.About 3 to 4 bar

B.About 8 to 8.5 bar

C.About 5 to 6 bar

D.About 12 to 13 bar

Explanation: European-specification air brake systems, which is what Mercedes-Benz, Volvo, Scania and Iranian-built heavy vehicles use, run a nominal working pressure of roughly 8 to 8.5 bar. When reservoir pressure reaches the cut-out setting the governor unloads the compressor so the tanks and lines are not over-pressurised; it cuts the compressor back in roughly 1 bar lower. Always read the pressure gauges in bar, as fitted, rather than converting from another country's figures.

3Why must air storage tanks (مخازن باد) in a pneumatic brake system be drained of water and oil sludge regularly?

A.To maintain proper lubrication on the exterior of the slack adjuster pushrods

B.To increase the octane rating of diesel fuel circulating in the injector pump

C.To prevent moisture from freezing in valves during cold weather and oil from degrading rubber brake seals

D.To allow ambient air to cool the transmission planetary gearset

Explanation: Air compressed by the compressor contains moisture and atomized oil. If not drained, water accumulates in the reservoirs, causing rust, contaminating relay valves, freezing and blocking lines in winter, and deteriorating internal rubber diaphragms and seals.

4What does the low air pressure warning device (a red lamp plus an audible buzzer) on a heavy vehicle tell the driver, and what must the driver do?

A.That the compressor has reached cut-out pressure; keep driving normally

B.That reservoir pressure has fallen to the manufacturer's warning threshold and braking performance can no longer be guaranteed; stop safely as soon as possible

C.That the reservoirs are over-pressurised; brake hard to bleed air out of the system

D.That the parking brake has already applied and the vehicle has stopped itself

Explanation: The warning device is calibrated to operate while there is still enough stored air for a controlled stop — well before the spring brakes apply on their own. Treat it as a command to get off the road and stop, not as an advisory. Read the actual trigger value from the gauge markings and the vehicle handbook for the model you are driving; the figure varies between vehicle standards and must never be assumed from another country's rulebook.

5What is the mechanical operating principle of spring parking brakes (ترمز فنری / ماکسی‌بریک) on heavy commercial vehicles?

A.They are held in the released position by air pressure, and powerful mechanical springs apply the brakes if air pressure is lost

B.They are applied by hydraulic fluid pressure pumped directly from the steering reservoir

C.They rely exclusively on magnetic solenoids wired to the commercial vehicle battery

D.They engage only when the driver manually rotates a mechanical screw handle located on the rear axle

Explanation: Spring parking brakes contain powerful mechanical coil springs. When driving, air pressure is supplied to the spring chamber to compress and hold back the spring. When parking or if air pressure fails completely (typically below 20–45 psi), air exhausts and the heavy spring expands, forcefully applying the foundation brakes.

6What is 'brake fade' (کاهش اثر ترمز / داغ کردن لنت‌ها) in heavy commercial vehicles, and what causes it?

A.Excessive moisture freezing inside the air dryer desiccant bed

B.Overheating of brake linings and drums from prolonged or severe braking, causing friction loss and drum thermal expansion

C.An electrical alternator malfunction that cuts power to the ABS modulator valves

D.Overfilling the engine oil pan causing hydraulic oil migration into the wheel hubs

Explanation: Brake fade occurs when excessive friction generates extreme heat in brake drums and linings. Overheated friction material loses its coefficient of friction, and brake drums expand outward away from the shoes. This drastically increases pushrod stroke and stopping distance, potentially causing total brake failure.

7What is the primary role of the air dryer (خشک‌کن هوا) installed between the compressor and primary reservoir in a heavy vehicle?

A.To heat the compressed air so that it reaches operating temperatures faster

B.To cool the engine turbocharger intercooler during uphill mountain climbs

C.To remove moisture, oil vapor, and contaminants from the compressed air stream before it enters the storage tanks

D.To compress ambient air using auxiliary electric turbines

Explanation: The air dryer collects and removes moisture and oil droplets from compressor discharge air using a desiccant cartridge. When the governor cuts out, the air dryer automatically purges water and oil to atmosphere, preventing moisture from entering reservoir tanks and brake valves.

8Article 63 of the Iranian Traffic Regulations sets a specific performance requirement for the hand (parking) brake. What must it be able to do?

A.Hold the vehicle stationary, loaded or carrying passengers, on a 16 per cent uphill or downhill gradient

B.Stop the vehicle from 80 km/h within 20 metres on a wet surface

C.Act on the front steering axle only, leaving the drive axles free to roll

D.Release automatically whenever the engine is started

Explanation: Article 63(b) of the Iranian Traffic Regulations requires the hand brake to hold the vehicle — however it is loaded or however many passengers it carries — stationary on a 16 per cent uphill or downhill gradient. The same article requires the foot brake to slow and stop the vehicle quickly, effectively and safely on any gradient, and Article 64 requires the foot brake to act on all wheels (with a concession for one axle on vehicles with more than two axles).

9Under Article 176 of the Iranian Traffic Regulations, what must the driver of a heavy vehicle arrange before driving on a narrow road or reversing?

A.An assistant (کمک راننده) must accompany the driver so that the manoeuvre can be made without danger

B.The vehicle must be escorted by a traffic police patrol car

C.The trailer must be uncoupled and towed separately

D.The driver must obtain a written permit from the local municipality each time

Explanation: Article 176 of the Iranian Traffic Regulations requires drivers of heavy vehicles to have an assistant driver with them when passing along narrow roads or when reversing, so that any danger can be avoided. The assistant acts as a banksman for the blind areas the mirrors cannot cover — the single largest of which lies along the right-hand side of the vehicle.

10What is the function of an S-cam (بادامک S شکل) in heavy vehicle foundation drum brakes?

A.To compress air and feed it into the steering booster reservoir

B.To rotate and force the brake shoes outward against the inner surface of the brake drum

C.To lock the differential gears during low-traction mud operation

D.To cool the wheel hub bearings using engine coolant circulation

Explanation: The S-cam is a camshaft with S-shaped lobes at the wheel end. When the brake chamber pushrod moves the slack adjuster, it twists the S-cam shaft. The rotating S-cam lobes force the rollers and brake shoes outward against the rotating brake drum, creating braking friction.

About the Iran Heavy Vehicle Driving Theory Exam

The Grade 1 driving licence (گواهینامه پایه یکم) is Iran's highest commercial driver credential, issued under the Executive Regulations of the Council of Ministers (آیین‌نامه صدور انواع گواهینامه‌های رانندگی مصوب هیئت وزیران، ماده ۲). It entitles the holder to operate heavy goods vehicles exceeding 6 tonnes cargo capacity, multi-axle articulated trucks, and passenger transport vehicles carrying more than 26 passengers (buses). The theoretical examination evaluates specialized mechanical knowledge of dual-circuit pneumatic air brake systems, vehicle dynamics, off-tracking, fifth-wheel coupling, axle load distributions, retarders, and commercial fleet safety rules under the Sepahtan monitoring system. This practice bank is an independent English-language multiple-choice study adaptation by OpenExamPrep; the official examination is administered in Persian (Farsi), and this bank is not an official translation or simulator.

Exam sponsor: Iranian Traffic Police (پلیس راهنمایی و رانندگی فراجا — پلیس راهور / Rahvar Faraja). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Computerized multiple-choice theory test (30 questions, 20 minutes, 26/30 pass mark), followed by closed-circuit maneuvering tests and an extensive on-road driving examination on heavy commercial trucks (such as Mercedes-Benz 1921/2624) or large passenger buses.

Time Limit

20 minutes

Passing Score

87% (26 of 30 questions)

Exam / Certification Fees

Commercial Grade 1 training and testing packages quoted in 2026 (1405) typically run from IRR 160,000,000 to 250,000,000 (16 to 25 million tomans) depending on city and school, covering practical driving hours on heavy trucks and buses, classroom instruction, drug screening, and licensing stamps.

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

23% of our practice bank

Compressed Air Brake Systems and Mechanical Components

Compressors, governors, reservoirs, moisture drain valves, air dryers, low-pressure warnings, spring brakes, and brake fade.

27% of our practice bank

Heavy Vehicle Dynamics, Articulation, and Safe Maneuvering

Center of gravity, off-tracking, button-hook right turns, jackknifing prevention, commercial blind spots, and downhill retarder control.

20% of our practice bank

Combination Vehicles, Fifth Wheel Coupling, and Air Lines

Fifth wheel and kingpin inspection, coupling sequences, glad hands (service and emergency lines), and tractor-trailer stability.

15% of our practice bank

Cargo Securement, Axle Weight Limits, and Commercial Regulations

Iran's axle load and gross weight ceilings, width/height/overhang limits, traffic-load permits, cargo distribution, waybills, and Sepahtan fleet monitoring.

15% of our practice bank

Passenger Transport, Bus Safety, and Emergency Protocols

Passenger bus emergency exits, fire equipment standards, tachograph driving-rest cycles, and accident response.

Preparing for the Iran Heavy Vehicle Driving Theory Exam

What You Need to Know

Passing score: 87% (26 of 30 questions)
Assessment: Computerized multiple-choice theory test (30 questions, 20 minutes, 26/30 pass mark), followed by closed-circuit maneuvering tests and an extensive on-road driving examination on heavy commercial trucks (such as Mercedes-Benz 1921/2624) or large passenger buses.
Time limit: 20 minutes
Exam / certification fees: Commercial Grade 1 training and testing packages quoted in 2026 (1405) typically run from IRR 160,000,000 to 250,000,000 (16 to 25 million tomans) depending on city and school, covering practical driving hours on heavy trucks and buses, classroom instruction, drug screening, and licensing stamps. Official sources

Using Our Practice Resources

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Iran Heavy Vehicle Driving Theory: Suggested Study Strategy

1Study the pneumatic brake cycle in the units the vehicle actually uses: European-specification trucks and buses run a nominal 8 to 8.5 bar working pressure, with the governor cutting the compressor back in roughly 1 bar lower. Learn the reservoir draining procedure and the point at which the spring brakes apply on their own.

2Understand heavy vehicle downhill driving techniques: always select a low gear before initiating a descent, utilize the engine exhaust brake or hydraulic retarder to control speed, and avoid continuous service brake friction that causes dangerous brake fade.

3Memorize fifth wheel coupling safety checks: verify that the fifth wheel jaws are completely closed around the kingpin shank, the safety release lever is locked, and there is zero visible space between the tractor fifth wheel and trailer apron.

4Learn commercial vehicle blind spots (the four No-Zones): the largest and most hazardous blind spot is located along the right side of the vehicle, extending across multiple lanes.

5Memorise Iran's weight and dimension ceilings: 6 tonnes on a two-wheel steering axle, 13 tonnes on a four-wheel single axle and 20 tonnes on an eight-wheel tandem; 40 tonnes gross for a five-axle eighteen-wheel articulated rig; 2.6 m wide and 4.5 m high (3.8 m on the Chalus and Haraz roads). Anything beyond those figures needs a traffic-load permit and carries its own reduced speed limits.

Frequently Asked Questions

What is the minimum age and prerequisite for obtaining a Grade 1 heavy vehicle licence in Iran?

Under the Driver Licensing Executive Regulations as applied by Rahvar Faraja in 2026, candidates must be at least 25 years old — raised from 23 in the recent amendments — and must have held a valid Grade 2 (پایه دوم) licence for at least 2 full years, with at least 6 months of validity still remaining. Applicants must also pass physical and psychological examinations and provide a certificate of non-addiction.

Does the Grade 1 licence cover both heavy trucks and passenger buses in Iran?

Yes. In Iran, the First Grade licence (گواهینامه پایه یکم) is a unified heavy vehicle credential that entitles the holder to drive cargo vehicles with a capacity exceeding 6 tonnes (including multi-axle and articulated trucks) as well as passenger transport vehicles carrying more than 26 passengers (buses). There is no separate Category D or bus-only theory examination.

What is the format and passing score of the Grade 1 theory examination?

The computerized theory examination administered by Rahvar Faraja contains 30 multiple-choice questions administered over 20 minutes. Candidates must answer at least 26 questions correctly (86.7%) to pass.

How does the pneumatic air brake system warning device operate?

Compressed air brake systems carry a low air pressure warning device — a red lamp plus an audible buzzer — set to operate while there is still enough stored air for a controlled stop, and well before the spring parking brakes (maxi-brakes) apply on their own. Read the actual trigger pressure from the gauge markings and handbook for the vehicle you are driving: Iran's fleet is largely European-specification and works in bar, so a figure taken from another country's rulebook should not be assumed.

What is off-tracking and why is it critical for heavy vehicle drivers?

Off-tracking refers to the phenomenon where the rear wheels of a turning heavy truck or bus follow a shorter radius and track inside the path traveled by the front steering wheels. Drivers must execute wide turns (such as button-hook turns) to prevent rear wheels from mounting curbs or colliding with pedestrians and obstacles.

What is the Sepahtan system in Iran's commercial transport sector?

Sepahtan (سامانه پایش هوشمند تردد ناوگان حمل و نقل جاده‌ای) is the national intelligent fleet monitoring platform run by the Road Maintenance and Transportation Organization (سازمان راهداری و حمل و نقل جاده‌ای), working alongside the highway police. Onboard telematics and driver smart cards verify driver identity, track speed and position, and measure time at the wheel against the 9-hour daily driving ceiling. Tachographs are separately compulsory on intercity trucks and trailers, and tampering with either system can mean a fine, cancellation of the driver smart card, and impoundment of the vehicle.

In which language is the official Grade 1 test administered?

The official computerized theory examination is conducted in Persian (Farsi) by Rahvar Faraja. This practice question bank is an independent English-language multiple-choice study adaptation by OpenExamPrep.