DTT HGV Vehicle Weights 2 — Questions and Answers
Question 1: What is the maximum weight permitted on a tandem axle (two axles in a bogie) with air suspension?
- 20,000 kg for a driven tandem axle with air suspension (Correct answer)
- 18,000 kg
- 16,000 kg
- 22,000 kg
Correct answer: 20,000 kg for a driven tandem axle with air suspension
A tandem (bogie) drive axle with air suspension or equivalent is permitted up to 19,000 kg under standard EU rules, with some Irish permits allowing up to 20,000 kg on certain configurations. The air suspension allowance is higher than mechanical suspension.
Question 2: What are the consequences of driving an overloaded vehicle in Ireland?
- Fixed charge penalties, court prosecution, increased insurance risk, and the vehicle may be immobilised until the excess load is removed (Correct answer)
- A verbal warning only
- No consequences for a first offence
- A small fine with no further action
Correct answer: Fixed charge penalties, court prosecution, increased insurance risk, and the vehicle may be immobilised until the excess load is removed
Overloading offences can result in fixed charge penalties, prosecution in court with significant fines, penalty points, vehicle detention until excess load is removed, and increased insurance premiums. Repeat offences carry heavier penalties.
Question 3: How does overloading affect a vehicle's braking performance?
- Braking distances increase significantly as the brakes must absorb more kinetic energy, and brakes may overheat and fade (Correct answer)
- Overloading has no effect on braking
- Heavier vehicles actually stop faster due to more grip
- Braking only improves if the load is over the rear axle
Correct answer: Braking distances increase significantly as the brakes must absorb more kinetic energy, and brakes may overheat and fade
An overloaded vehicle has more momentum and kinetic energy, requiring greater braking force and longer distances to stop. Brakes can overheat under the additional strain, leading to brake fade. Overloading also affects steering and vehicle stability.
Question 4: What is the 'unladen weight' of a vehicle?
- The weight of the vehicle when empty of payload, including the body, fuel, oil, water, spare wheel, and standard equipment (Correct answer)
- The weight of the load only
- The maximum weight the vehicle can carry
- The weight of the chassis without the body
Correct answer: The weight of the vehicle when empty of payload, including the body, fuel, oil, water, spare wheel, and standard equipment
Unladen weight (also called 'kerb weight' or 'tare weight') is the weight of the vehicle in its normal operating condition without any payload. It includes the vehicle body, full fuel tank, oils, coolant, spare wheel, and standard equipment.
Question 5: What is the maximum permitted weight for a tri-axle group (three axles in a bogie)?
- 24,000 kg (Correct answer)
- 22,000 kg
- 26,000 kg
- 20,000 kg
Correct answer: 24,000 kg
Under EU and Irish regulations, the maximum permitted weight for a tridem axle group (three axles) is 24,000 kg (24 tonnes), subject to minimum axle spacing requirements between the outer axles.
Question 6: Why is it important to distribute the load evenly across all axles of a truck?
- Uneven distribution can cause individual axle overloading, affect steering, reduce braking efficiency, and make the vehicle unstable (Correct answer)
- Load distribution does not matter as long as total weight is within limits
- The load should always be concentrated over the rear axle
- Even distribution is only important for tanker vehicles
Correct answer: Uneven distribution can cause individual axle overloading, affect steering, reduce braking efficiency, and make the vehicle unstable
Even load distribution ensures no individual axle exceeds its permitted weight, maintains proper steering response (especially on the front axle), ensures effective braking on all wheels, and prevents instability from a high or unbalanced centre of gravity.
DTT HGV Vehicle Weights 2
What is the maximum weight permitted on a tandem axle (two axles in a bogie) with air suspension?