21 Ton Diamonds - MDO and MDV in OO/4mm! — Accurascale Skip to content
21 Ton Diamonds - MDO and MDV in OO/4mm!

21 Ton Diamonds - MDO and MDV in OO/4mm!

Our latest announcement in OO/4mm is the British Railways unfitted 21 Ton mineral wagon diagram 1/107 (later classed as MDO under the TOPS system) and the British Railways vacuum braked 21 Ton mineral wagon diagram 1/120 (later classed as MDV under the TOPS system), two much needed wagons in ready to run form!

We revealed these wagons at the Festival of Railways virtual show following own now usual practice of announcing new models with complete tooling samples, showing both models well-advanced in development.

Announcing models with tooling samples already completed reduces the waiting times for the modeller considerably and makes a firm commitment that the models will be released in a timely manner, with expensive and time consuming tooling already carried out and paid for. It also demonstrates that the models have been in development for a significant period of time, with research, surveys, CAD development and tooling creation already completed.

These wagons form part of our “Powering Britain” plan of recreating the wagons through the ages that fuelled Britain by rail. This began with the 24.5 Ton HUO hopper wagons and will be represented by the forthcoming HYA bogie hoppers, IIA biomass hoppers, these 21 Ton mineral wagons and other forthcoming, but as yet unannounced, Accurascale models.

As can be seen in the photographs, these ubiquitous wagons have received the full Accurascale treatment, featuring an underframe consisting of unparalleled levels of detail and tooling crispness to create a true scale model of some long missing prototype wagons in ready-to-run form. A wealth of separately applied parts have been employed and full chassis detail is represented, along with 26mm over pinpoint axles and kinematic couplings with NEM pockets at correct height to allow simple coupling changes for modellers and easy conversion to EM/P4 standards if desired. Provision has been made to represent the MDW variant as well as other wagons on this chassis in future production runs.

These wagons primarily conveyed coal but were sometimes used to carry scrap metal, rock salt and gypsum. Both the MDO and MDVs saw widespread use but are most often associated with coal trains on the Midland Region and the South Wales coalfields, supplying coal to power stations, steel works, and docks for export. They were also used to supply coal concentration depots. MDVs could also be seen in use in other areas such as Kent, East Anglia, West Midlands, The Potteries and Central Valley of Scotland.

The unfitted 21 Ton mineral wagons (later MDO) were introduced in 1950 building on from previous GWR wagon designs. A total of 1,500 wagons were built to diagram 1/107 and featured oil axle boxes, two doors either side with another at one end only for end tipping. These wagons remained in service until 1987, running in block trains and mixed with other coal wagons such as 16 Ton minerals, 21 Ton hoppers, 24.5 Ton hoppers and others. The last outpost for MDOs was on workings between Llanelli and Swansea Docks as the unloading facility could not end-tip vacuum-fitted wagons at the time.


Meanwhile the vacuum braked 21 Ton mineral wagon (later MDV) began service in 1961 as a development of diagram 1/107 platform, featuring additional flap doors over the side doors, roller bearings and vacuum braking. A total of 3,950 wagons were built to the 1.120 that our model represents. Once again these wagons ran both in block trains and mixed with other coal wagons such as 16 Ton minerals, 24.5 Ton minerals (later MEO) and hopper wagons like the 21 Ton BR hoppers. The MDVs soldiered on in service until 1992, representing an interesting traditional wagon throwback in the exciting railfreight sectorisation era.


As ever, we will be offering both wagons in packs of three wagons with multiple running numbers across several packs in both pre TOPS and TOPS guises, with grey and bauxite liveries represented. Price per three wagon pack is £74.95 with bundle deals available as always, giving you further savings! Delivery is slated for Q3 2021 and are available to pre-order direct right here or via one of our 90 local stockists. 

(Please note that tweaks and improvements will be made to these pre-production samples before production)

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