The exemption under clause 8 of a person using, or causing or permitting the use of, a truck and dog trailer combination is subject to the following conditions:(a) if the combination is being used on a road other than a road specified in Schedule 1 , the combination must not (i) exceed, inclusive of its load, 21 metres in length, or 21.3 metres in length if it is fitted with a guard to prevent logs from shifting rearwards; or(ii) exceed the aggregate axle load calculated in accordance with the allowable axle group loads of the axles of the combination, or 50 tonnes, whichever is the lesser;(b) if the combination is being used in accordance with Schedule 1 , the combination must not exceed (i) 25 metres in length, inclusive of its load; or(ii) subject to clause 12 , the aggregate axle load calculated in accordance with the allowable axle group loads of the axles of the combination, or 60.5 tonnes, whichever is the lesser;(c) the mass of the dog trailer must not exceed the mass of the truck by more than 50%;(d) if the combination has an aggregate axle load in excess of 50 tonnes, the trailer couplings must have a coupling strength with a D value of at least 13.5 kilo Newtons;(e) all the axles of the combination except for the steer axle of the truck must be equipped with air suspension or road-friendly suspension;(f) if the combination exceeds 22 metres in length, it must display a long vehicle warning sign specified in Division 4 of Part 2 of Schedule 3 to the Vehicle Operations Regulations;(g) the combination must comply with Schedule 2 .