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Vehicle dimension fields and measurement methods

Definitions and measurement method for heavy vehicle dimension fields

Updated over 2 years ago

The vehicle dimension field definition and measurement methods are based on the Australian Design Rules and definitions in the Heavy Vehicle (Mass, Dimension and Loading) National Regulation.

Vehicle configuration fields

Field

Definition

Width

The maximum width of the configuration measured from the widest point on each side of the configuration.

Length

The overall length of the configuration measured from the forward most point of the configuration to the most rear point of the configuration.

Height

The maximum height of the configuration measured from the ground to the highest point of the configuration.

Forward projection

The forward projection of the configuration measured from the front of the configuration to the front any loads or equipment projecting from the front of the configuration.

Vehicle unit fields

Field

Definition

Width

The width of the vehicle measured from the widest points between each side of the vehicle.

Length

The length of the vehicle measured from the forward most point of the vehicle to the most rear point of the vehicle.

Front overhang

The distance between the centre line of the vehicle's foremost axle and the front of the vehicle.

Swing radius

The front overhang swing radius of the vehicle defined as the maximum radius from the front articulation point.

Wheelbase

The wheelbase of the vehicle measured from the centre line of the vehicle’s foremost axle to the rear overhang line.

Rear overhang

The rear overhang of the unit measured from between the rear of the vehicle unit and the rear overhang line of the vehicle.

Tow coupling overhang

The tow coupling overhang of the unit measured from between the drawbar at the rear of the vehicle unit and the rear overhang line of the vehicle.

Drawbar length

The drawbar length of the vehicle measured from the centre of the axle or axle group to the centre of the drawbar coupling pivot point with the drawbar level.

S dimension

The s dimension of the vehicle measured as the distance between the front articulation point and the rear overhang line.

Fifth wheel offset

The fifth wheel offset of the vehicle measured as the distance between the front articulation point of a semi-trailer and the center of the drive axle group.

Height front

The front height of the vehicle measured from the ground to the highest point at the front of the vehicle.

Height rear

The rear height of the vehicle measured from the ground to the highest point at the rear of the vehicle.

Floor height front

The front height of the vehicle floor measured from the ground to the highest point at the front of the vehicle floor.

Floor height rear

The rear height of the vehicle floor measured from the ground to the highest point at the rear of the vehicle floor

Drawbar height

The drawbar height of the vehicle measured from the ground to the centre of the drawbar coupling pivot point with the drawbar level.

Vehicle axle group fields

Field

Definition

Axle spread

The spacing from the foremost axle to the last axle in an axle group measured from between the centre of the foremost axle to the centre of the last axle in an axle group.

Tyre size section width

The tyre section width size of tyres in the axle group.

Tyre size

The tyre size of tyres in the axle group eg) radial: 385/95R25 or bias belted: 10.00-20 *If Bias belt tyre multiply by 25.4 and round up to whole mm.

Track width

The track width measured from between the centerline of two wheels on the same axle. In the case of an axle with dual wheels, the centerline of the dual wheel assembly is used.

Dual tyre spacing

The dual tyre spacing measured from the centerline of one tyre rim to the centerline of the other tyre rim.

Ground contact width

The ground contact width measured between the outermost point of ground contact of the outside tyres on each end of the axle. Does not include any tyre bulge.

Vehicle axle fields

Field

Definition

No. Tyres

The number of tyres on the axle. Allowable numbers include 2, 4, 6, 8, 12, and 16.

Spacing

The spacing from the previous axle within the axle group or from the last axle within the previous axle group. Measured from between the centre of the axle to the centre of the next axle.

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