WA Heavy Vehicle Theory Test key terms

In Western Australia, a motor vehicle with a gross vehicle mass over 4.5 tonnes, or a combination, that is licensed and driven under heavy vehicle rules rather than light vehicle rules.

A category printed on a driver licence that states which vehicle types the holder may legally drive, such as car, light rigid, medium rigid, heavy rigid, heavy combination or multi-combination.

A licence class covering a rigid vehicle of up to 8 tonnes gross vehicle mass, or a bus seating more than 12 adults including the driver, with a towed load of no more than 9 tonnes.

A licence class for a rigid vehicle with two axles and a gross vehicle mass over 8 tonnes, or a three-axle rigid vehicle up to 8 tonnes, towing no more than 9 tonnes.

A licence class covering a rigid vehicle with three or more axles and a gross vehicle mass over 8 tonnes, towing a load of no more than 9 tonnes, such as a typical tipper or garbage truck.

A licence class for a heavy rigid vehicle towing a trailer with a gross vehicle mass over 9 tonnes, including prime movers pulling semi-trailers and trucks pulling dog trailers.

The licence class allowing a heavy combination vehicle towing two or more trailers, such as a B-double or road train, and requires holding a heavy combination licence first.

A truck or bus whose cab and load-carrying body sit on a single chassis that cannot articulate at a joint, as distinct from an articulated combination where a prime mover pulls a trailer.

A combination in which a prime mover is coupled to a semi-trailer by a turntable, so the two units pivot relative to each other when steering and turning.

The powered towing unit of an articulated combination, fitted with a turntable or coupling that supports and pulls a semi-trailer or similar trailer.

A trailer with one or more axles at the rear and no front axle, supported at the front by the towing vehicle's turntable so part of its weight rests on the prime mover.

A trailer with a fixed drawbar and its own axle group at the front and rear, towed behind a rigid truck or prime mover rather than supported on a turntable.

A trailer whose front axle group is mounted on a dolly or converter that attaches to the towing vehicle, used to convert a semi-trailer for towing behind a rigid truck.

A combination of a prime mover and two semi-trailers, where the first trailer's rear is supported on a turntable mounted on the second trailer rather than on a separate dolly.

A heavy combination of a prime mover and two or more trailers, used on long-distance routes, and requiring a multi-combination licence and often route-specific approvals.

The maximum total mass a vehicle is designed and rated to carry, including its own tare weight plus fuel, driver, passengers and payload, as specified by the manufacturer.

The maximum total mass permitted for a towing vehicle plus all trailers and their loads combined, as rated by the manufacturer and recorded on the vehicle's compliance plate.

The unladen weight of a vehicle as built, including standard equipment and full fuel and fluids but excluding driver, passengers and any payload.

The weight of goods, passengers and other contents a vehicle may legally carry, found by subtracting the tare mass from the gross vehicle mass or the relevant axle limits.

The total mass carried by all wheels on a single axle or axle group, which must not exceed the manufacturer's rating or the statutory mass limits for that axle configuration.

The maximum weight legally allowed for a vehicle, combination, axle or axle group on a road, set by national heavy vehicle rules and sometimes reduced by local road or bridge restrictions.

The system of straps, chains, binders and headboards that stops a load moving, sliding or falling from a vehicle, and must meet the performance standards for the load type carried.

The maximum permitted width, height and length of a vehicle or combination and its load, which if exceeded requires an oversize permit or pilot and escort arrangements.

A written authority allowing a vehicle or load that exceeds standard dimension or mass limits to travel on specified roads, usually with conditions on times, speeds, signage and escorts.

A escort vehicle driven ahead of or behind an oversize load to warn other road users, fitted with warning signs and lights and operated by a trained pilot under permit conditions.

A state of physical or mental weariness that slows reaction time, reduces attention and impairs judgement, and which must be managed by rest, sleep and limits on driving hours.

The planning and recording of work and rest so a driver stays alert, including complying with regulated driving hours, taking minimum rest breaks and recording them correctly.

A record kept by a heavy vehicle driver showing work time, rest time and other activities across each day, used to show compliance with fatigue management rules.

A minimum period of non-work time a driver must take between blocks of driving or work, during which the driver is free of all work duties and able to recover.

The legal principle that parties such as employers, schedulers, consignors and loaders share responsibility with the driver for complying with heavy vehicle mass, dimension, loading and fatigue rules.

A device fitted to a heavy vehicle that restricts its maximum speed, commonly to 100 km/h for heavy trucks and buses, to improve safety and reduce crash severity.

The gap a driver keeps behind the vehicle ahead, which for heavy vehicles should be at least three seconds in good conditions and more in rain, darkness or when fully loaded.

The total distance travelled from when a hazard is seen until the vehicle stops, made up of reaction distance plus braking distance, and much longer for loaded heavy vehicles.

A retarding system that uses engine compression or exhaust restriction to slow a heavy vehicle without using the foot brakes, helping prevent brake fade on long descents.

The loss of braking power caused by overheating of brake drums, discs or linings during repeated or prolonged braking, often on long downhill grades, and prevented by using lower gears.

The technique of selecting a low gear before a steep downhill run so engine braking controls speed, avoiding continuous service braking that can overheat and fade the brakes.

An area around a heavy vehicle that the driver cannot see in the mirrors, especially close beside and behind the trailer, where other road users may be hidden.

The sideways movement of a heavy vehicle's rear wheels or trailer as it turns, which can strike kerbs, poles or nearby road users and requires wide, slow turns.