China Clay CDA

Modellers are taking more of an interest in modern freight traffic because there is more of it about and Enterprise has seen a return in short freights operating as feeders into hub yards for trunk haul Enterprise services. Short trains of eight or ten differing wagons sit very nicely on most layouts, I think you will agree.

What I really wanted was a quick, simple, "glue together" CDA covered hopper conversion for the Hornby MGR model, and that is precisely what Appleby Model Engineering (AME) produced. Stick the kit together in about ten minutes and bingo! You may wish to keep the original underframe or replace it, as I have, with a white metal kit also from the AME catalogue.

Prototype notes: the CDA china clay hopper:
The history of the CDA covered hopper is quite simple with little in the way of detail changes between the builds. Two main batches were produced: 375000-123 constructed during 1987/88. They replaced elderly china clay hoods of 1950s vintage, instantly modernising clay transport on the intense but short MGR type circuits to Fowey Docks.

The 1987/88 build was constructed to design code CD002B. They followed the HDA MGR wagon design with platform mounted brake cylinder and distributor equipment. A second batch appeared in 1989 constructed as conversions applied to existing HAA MGR coal hopper wagons. They differ from the first batch in the location of the brake equipment. That is now located under the floor.

The CDA covered hopper wagon slipped into traffic with little fuss until wear and tear saw degradation of an internal coating that started to contaminate the clay. An expensive exercise to remove this was done at the former CCE tip site at St. Dennis Junction prior to removal of the track and connection.

The wagon is characterised by the flexible hood fitted to the hopper top that protects the load from water ingress. The livery is also striking: black underframe, aluminium hopper and blue fittings including the hood. Add a liberal dusting of china clay and the distinctive ECCI logo and you have a pleasing modelling project.

CDA Covered Hopper constructed by BREL Doncaster.CDA CD002B Tare 15.45t GLW 47.00t 375000 - 375123 Total 124.

CDA Covered Hopper constructed by RFS Doncaster.CDA CD001B Tare 15.4t GLW 47.00t 375124 - 375137 Total 14. (Prototype CDA 353224 built to design code CD001A, a MGR conversion).

Modelling the CDA hopper wagon
The CDA conversion kit from AME is simply designed as a quick glue together conversion which must rate as one of the simplest I have ever completed. Things may be made a little more challenging by including a cast white metal underframe kit to add some really exquisite detail. A joint venture between Alan Gibson and AME makes the correct wheels for MGR type underframes available for the first time. To model the CDA, several options are available depending on your budget...

A simple conversion to the Hornby MGR model. The conversion kit includes all of the hopper parts and the additional details required to super detail the underframe.

Add the AME white metal underframe to the basic conversion project and reduce the expense a little by obtaining spare MGR hoppers and cradles from Model Spares of Blackburn.  Add an underframe kit and CDA conversion kit for a finescale model at reasonable cost.

The basic conversion kit consists of all the parts to convert the Hornby MGR into a CDA covered hopper. Included are the hopper vents, flexible hood and bar, correct buffers and airbrake equipment. Before fitting the parts, wash them thoroughly in warm soapy water to remove the mould release agent. Then file the thin edge carefully to remove excess material and achieve a tight fit in the top of the hopper.  Secure with a tiny quantity of superglue. The cast metal details fit neatly to the top with superglue too, but use it sparingly.  Modellers who wish to keep the original Hornby underframe are supplied with some detailing parts in the kit to super detail it, including buffers and airbrake parts which may be glued into place.

Resin is used to advantage on the hopper cover to replicate the effect of a wrinkled sheet to perfection.  However, it is important that safety notes in the instructions are followed when preparing resin parts for use.

Modellers who find the original Hornby underframe unsatisfactory may wish to consider replacing it with an AME cast metal kit.  Whilst complex on first inspection, it is quite straight forward to build either by soldering with Carrs low melt solder or gluing together with Araldite. Superglues are far from ideal for this type of kit

To fit the Hornby MGR wagon hopper moulding to the cast metal underframe, some cutting of the cradle is required so the hopper fits tight to the underframe floor.

Aluminium coloured paint is quite tricky to apply to models either with an airbrush or by hand painting. Try Tamiya X-11 chrome paint, which I have found effective at producing a smooth even finish. Tamiya paints are acrylic based, so it is vital to use the correct thinners (X-20A) and take particular care to clean airbrushes and other equipment immediately after painting.

Alternatives:
The recent supply problems from AME has me looking for alternative ways of building CDA hoppers.  Whilst the Hornby MGR wagon is a good base and the CDA version marginally better, it is possible to detail one by using individually purchased components from InterCity Models (brake equipment) and A1 Models for axleguards and buffers.

The finished models:
Applications of ECCI blue to the flexible hood and hopper cradle is done by hand. Weathering is done in a unique manner: by dusting white etching primer onto the model using an airbrush. The airbrush was held a good two feet away from the model during spraying to achieve a dusty rather than streaked effect. Some dry brushing with white primer and light rust colour from Railmatch completes the picture. The correct wheels for MGR type wagons are available from AME for OO and EM modellers. The models may be fitted with instanter couplings, Kadee No.5 couplers or left with the original Hornby tension lock couplings.

Useful Addresses:
Appleby Model Engineering
PO Box 104, Worcester, WR5 2YZ.
Telephone: 01905 351952

Please note that supplies from AME have dwindled in recent times.  Recent correspondence has not been answered.   SAEs at your own risk.

Railmatch Products c/o Howes
12 Banbury Road, Kidlington OXON OX5 2BT.
Telephone: 01865 848000

Modelspares
65 Burnley Road, Hapton Burnley,
LANCS, BB11 5QR.
Telephone 01282 771109

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