For the introduction of electrification a new type of suburban carraiage was placed into service from 1910.
The new carriages featured sliding doors and seating down each side of the carriage with an aisle down the centre. These carriages were introduced with gas lighting on steam hauled suburban trains with plans for eventual conversion to electric service.
These AP class carriages were introduced to service between 1910 and 1913 with car numbers 1 - 62.
Between 1919 and 1922 the carriages were converted to electric service. This involved replacing the gas lighting with electric lighting circuits and the fitting of a through jumper cable connections for traction control in trains sets.
Upon conversion most of the cars were reclassed to APT_ with the same numbers.
AP conversions to electric service done late 1921/early 1922 were reclassed to _T__ with new numbers.
These cars were: AP 27 to T 227, AP 31 to T 231, AP 33 - 36 to T 233 - 236, AP 38 - 40 to T 238 - 240, AP 42 - 44 to T 242 - 244, AP 47 - 49 to T 247 - 249, AP 51 to 56 to T 251 - 256, AP 58 - 62 to T 258 - 262.