DTT HGV Vehicle Inspection and Load Securing 3

Question 1

How should a truck driver check the coupling between a tractor unit and trailer?

Accepted Answer

Check the fifth-wheel lock engagement, safety catch is secured, trailer kingpin seated correctly, and perform a 'pull-test' by moving forward gently against the brakes

Answer

Coupling check: confirm the kingpin is locked in the fifth wheel, the safety catch is engaged, airlines and electrical connections are correctly made, and perform a pull-test with the trailer brakes applied to confirm lock.

Question 2

What is the tyre tread depth minimum for a commercial vehicle (truck or bus)?

Accepted Answer

At least 1mm across 75% of the tread width and around the full circumference

Answer

Commercial vehicles (trucks and buses) require a minimum tread depth of 1mm across at least 75% of the tread width and around the entire circumference of the tyre.

Question 3

What must a driver check regarding the trailer air lines (susie hoses) before moving off?

Accepted Answer

That both red (emergency) and yellow (service) airlines are correctly coupled, undamaged, and secure — not dragging on the ground

Answer

Both the red (emergency/supply) and yellow (service/brake) airlines must be correctly connected to the trailer, not damaged or kinked, and positioned so they do not drag or snag when turning.

Question 4

During a walkaround check, a driver notices the trailer's tail lights are not working. What should they do?

Accepted Answer

Report the defect and do not depart until tail lights are repaired — operating without tail lights at night or in poor visibility is dangerous and illegal

Answer

Non-functioning tail lights make the vehicle invisible from behind at night or in poor visibility — an extreme danger and a serious roadworthiness defect. The vehicle must not be driven until repaired.

Question 5

What is the correct procedure for checking a bus's emergency exits before starting a service?

Accepted Answer

Check all emergency exits open easily from inside and outside, are unobstructed, and have visible emergency exit signs and working emergency hammers

Answer

All emergency exits (doors, roof hatches, windows) must open freely from inside and outside, not be obstructed by luggage or equipment, have visible signage, and emergency hammers must be present and accessible.

Irish DTT Truck/Bus Practice Test

Irish DTT Truck/Bus Practice Test

DTT HGV Vehicle Inspection and Load Securing 3