This is a placeholder for all information on OTA wagons, as written up in Update, and on the old Forum, plus additional new material.
BR has a history of converting wagons to convey logs: the Timber-P (TOPS code UUV) had previous lives on the Condor freight service, and as Plate wagons. These of course were not appropriate for the air-braked era.
In the 1980’s log timber was being moved around by unconverted OBA wagons, and by bogie wagons such as the BSW and BTA conversions. These were not always totally suitable. In particular the OBA wagons were not able to take the volume of the cargo to be efficient. As a result, various OCA wagons were converted, and then with the changes in contracts, further conversions were undertaken.
Surplus VDA vans were used as donors in the 1990’s, along with the VHA. Finally some OBA wagons were also modified. The position was complicated by transfers between wagon pools, as contracts were won or lost and some OTAs were then used as reach wagons, or as engineers stock. Additionally wagons were written off in incidents, and even then they were sometimes rebuilt and reinstated.
This created a varied fleet as lessons were learnt about what was really required. For example the original timber floors didn’t stand up to the unloading machinery, and so steel decking was introduced. Indeed wagons were rebuilt during their career as OTAs, with ends extended (to increase capacity), or had stanchions taken out, again probably modified to meet the requirements of the handling
machinery in each contract.
There were also trials with experimental ‘one-offs’. 112292 was apparently the test bed for the later ExTe stanchions, and 200944 had a cradle between the stanchions to keep the handling grabs free of the wooden floor.
There were three main sets of donor wagons: OCAs, Vans (VDA/VHA), and OBAs, to the following design codes: (and I’ve included the original Update article references)
|Design code||Tops Code||Number range*||UpDate article|
|OT001A||OTA-A||112067-112399||71, 76, 78, 79||Ex OC001A|
|OT001B||OTA-B||112292 ?||75||Not definitive|
|OT001C||OTA-C||112184-112386||69||Ex OC001A Thames|
|OT002B||OTA-D||201029-201093||73||Ex VDA, experimental suspension|
|OT002F||OTA-E||200944||70||Ex VDA. Revised stanchions for Forestry Commission|
|OT003C||OTA-B||200651-200997/210107-210332||74||Ex ZRA (VDA)|
|OT003D||OTA-D||200995||74||Ex VDA experimental suspension|
|OT004A||OTA-F||110010-110797||68||Ex ZDA (OBA)|
*the actual numbers will be set out later when going through the design codes