In the early 1900's, more agricultural machinery was being transported to service areas where wheat and other grain crops were being developed. To provide transport with wider doors and better access, some _I__ wagons were constructed with 'falling doors'.
In the 1920's there was a suggestion placed for these vehicles to be utilised in ballast traffic. However this was not done as the vehicles were still in use hauling agricultural equipment.
The 12 ton wagons entered service coded I and were coded to IG between March and July 1904. The 16 ton 'falling door' wagons were issued to service with the IG class letters.
There were two main types:
IX wagons were converted ex 12 ton IG wagons between 1935 and 1937. The number group was 6499, 7097 - 7196.
These wagons were scrapped between 1944 and 1954.