 In 1923-4, DD 1022 was experimentally fitted with Pulverised Brown Coal (PBC) burning equipment.In 1922 a complex renumbering and reclassing of VR locomotives saw the DD class split into two subclasses, the D1 class (comprising all the original saturated steam locomotives with 18 in.cylinders) and the D2 class (comprising superheated locomotives with either 18 or 19 in.