- Terminology
- What does HVO consider a Heavy Vehicle?
- What is a Restricted Access Vehicle (RAV)?
- What is a General Access (as of right) Vehicle ?
- What is an Axle Group?
- What are the Regulated Dimension Limits?
- What are the Regulation Mass Limits?
- What is a Road Train?
- What is a Turntable/Fifth Wheel?
- What is a Semi-Trailer?
- What is a Converter Dolly?
- What is a Pig Trailer?
- What is a Dog Trailer?
- What is a B-Double?
- What is a Block Truck?
- What is a Trailer Drawbar?
- Do I need brake testing certification?
- Who can I contact for more information?
- GCM: Gross Combination Mass
- GVM: Gross Vehicle Mass
- ATM: Aggregate Trailer Mass
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- a vehicle with a GVM exceeding 4.5t;
- a combination that includes a vehicle with a GVM exceeding 4.5t; and
- a load on a vehicle described above.
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- is a vehicle that alone or together with any load, exceeds one or more of the following limits:
- a mass limit prescribed in Part 3 of the Road Traffic (Vehicle Standards) Regulations 2002; or
- one of the following dimension limits:
- a width of 2.5m;
- a height of 4.3m;
- a length of 12.5m in the case of a motor vehicle that is not part of a combination; or
- a length of 19m in the case of a combination;
- any other dimension limit specified in the:
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- is any vehicle that is not a Restricted Access Vehicle (RAV)
- These vehicles generally do not require any permits or exemptions from regulatory requirements
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- is a single axle group, tandem (bogie) axle group, twinsteer axle group, tri-axle group or a quad axle group
- Different axle groups have certain requirements in relation to minimum and maximum axle spacings
- Definitions for each type of axle group are located in Schedule 1 Road Traffic (Vehicle Standards) Regulations 2002
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- Vehicles can be built to various dimensions, which are controlled by the:
- Regulation dimensions should not be confused when a vehicle requires a permit
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|
Axles and Tyres |
Maximum axle group load |
|
Single Steer 2 Tyres |
6.0t |
|
Twin steer axle group 4 tyres |
10.0t for non load sharing suspension 11.0t for load sharing suspension |
|
Single axle 4 tyres |
9.0t 9.0t when fitted to a pig trailer |
|
Tandem axle group Single tyres (4) |
14.0t (tyre section width >450mm) 13.3t (tyre section width <450mm but >375mm) 11.0t (tyre section width <375mm) |
|
Tandem axle group Dual tyres (8) |
16.5t 16.5t when fitted to a pig trailer |
|
Tri-axle group Single tyres (6) |
20.0t (tyre section width >375mm) 18.0t fitted to a pig trailer (tyre section width >375mm) 15.0t (tyre section width <375mm) |
|
Tri-axle group Dual tyres (12) |
20.0t 18.0t fitted to a pig trailer |
- Vehicles must not exceed any manufacturers limit
- The least value should be noted for components such as:
- tyre pressure;
- tyre rating;
- axle rating;
- axle spacing;
- gross vehicle mass (GVM)
- gross trailer mass (GTM)
- aggregate trailer mass (ATM); and
- gross combination mass (GCM)
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Means a combination, except a B-Double, consisting of a motor-vehicle towing at least 2 trailers (counting as a single trailer a converter dolly supporting a semi-trailer).
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A device (except the upper rotating element and the king pin, which are parts of a semi trailer) used with a prime mover semi-trailer, or converter dolly
- Device allows quick coupling and uncoupling and provides for articulation
- Turntable is a load-bearing plate that supports vertical and horizontal loads, and is coupled to the semi-trailer"s kingpin and locked into place by a set of jaws
turntable/fifth wheel

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- Is a load carrying trailer that has its axle group towards the rear of the trailer
- Its forward connection is by means of a kingpin to either a prime-mover, converter dolly or lead semi-trailer, this arrangement allows up to half of the trailers load to be carried by the prime-mover/convertor dolly/lead semi-trailer
semi-trailer road train with two (2) semi-trailers and one (1) converter dolly

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- Is a short trailer with its forward connection by a drawbar, the drawbar normally pivots vertically
- Dollys are only equipped with a turntable
- Dollys are designed to carry some of the load of an attached semi-trailer rather than a load itself
- Road trains are an example of where a converter dolly is used as part of the combination
converter dolly

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- Is a load carrying trailer that has an axle group near its centre
- Forward connection is by a drawbar, which is normally rigid
pig trailer rigid truck and pig trailer combination

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- Is a combination for a fixed or converter dolly with a semi-trailer
dog trailer triple road train with 2 dog trailers

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- Is a prime-mover towing two semi-trailers
- First trailer is a lead semi-trailer ("A trailer"), second is a conventional semi-trailer ("B trailer")
- Lead semi-trailer (A trailer) has a turntable at its rear, this means another semi-trailer can connect without the use of a converter dolly
- B-triple are variations of this concept where three semi-trailers are connected
lead semi trailer b-double
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- I a haul unit expressly designed to tow other vehicles by means of a drawbar (rather than using a turntable)
- Often used to tow platforms, or a dog trailers in situations where road trains are required to break up (split) at assembly areas
block truck

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16. What is a Trailer Drawbar and it"s length requirements?
- Can be either a single rigid bar or an a-frame which is part of a trailer (except a semi-trailer) connecting the trailer body to a coupling for towing purposes
- Distance between the coupling pivot point on the drawbar of a dog trailer, and the centre of the front axle group or of the front single axle of the trailer, must not be:
- over 5m; and
- under 3m, if the trailer is used in a road train over 19m long
- Distance between the coupling pivot point on a drawbar, and the centre of the axle group or single axle on a trailer with only one axle group or single axle (except a semi-trailer), must not be over 8.5m
drawbar

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Heavy vehicle Operations Help Desk