This Act does not apply to the following motor vehicles--
(a) a crane, hoist or conveyor,
(b) an excavator, road grader, road roller, bulldozer or forklift truck or other machinery (other than a tractor), that is not constructed on a chassis of a type normally used in the construction of a truck,
(c) a motor vehicle that is constructed or adapted for road construction or maintenance (including cleaning, sweeping or watering).
Note : Other motor vehicles, persons or other things may be exempted from provisions of this Act by the regulations (see section 186 (2) (a)).