Up until 1902 the few tank wagons were old tenders or small capacity water trucks.
Tanks for use as petroleum transports entered service in 1902 and were simply called 'Oil Tanks'.
The numbers started at 1 and by the early 1950's were up to the high 500's.
This single number block was unusual for two reasons
The 'Oil Tank' ( OT ) wagons were given the new lettering of _TW_ and TWF_ from 1961. The wagons kept the same numbers.
The numbers were extended to this single list as new tank wagons were added through to the 1980's.
A break was made in the early 1970's when new gas tank wagons were placed into service. The numbers were started at '1'. Gas and fertiliser traffic took the numbers to about 12.
Four wheel wagons in the Oil Tank group were originally between 1 and 83. Bogie vehicles started at number 84. The introduction of water tank wagons in the mid 1950's saw some wagons use numbers in the 400's and 500's.
Before 1961 some of the classes that used the Oil Tank group were:
After 1961, wagons were frequently transposed between TW and TWF as traffic demanded.
A tank wagon list from 1977 shows all the numbers, class, owner and capacity. The list was typed up from an internal VR memo and includes an introduction by me:
Note:missing numbers indicate vehicles out of service by 1977 or a vehicle that never entered service
File 'aTank' compiled by Peter J. Vincent, updated 20/1/2007