The 64xx class was created in 1932, a throughly modernised locomotive deisgn specifically created to replace older, but generally similar locomotives on branchline and suburban passenger duties. All forty of the 6400 class were fitted for auto-train working, the 0-6-0 panniers being able to handle up to four trailers when needed, a load which would have taxed the capailities of the smaller 0-4-2 'auto tanks'. The similar 54xx class being built around the same time had larger driving wheels and were sent to the London division for suburban branchlines, while the smaller wheeled 64xx was intended for the more steeply graded lines of the Welsh valleys, Devon and Cornwall.
Following the 64xx series in 1936 came the 74xx class, identical locomotives but omitting the auto train control gear. These engines were used on light goods duties and on branchlines operated in the conventional manner with rolling stock like the 2-coach 'B-set'.
Three of these useful and ecconomical locomotives have been preserved, with all three having been restored to service.
Great care has been taken to produce a model as accurate as possible to the prototype locomotives, incorporating the many detail changes and alterations made during production and at overhauls.
The main construction of the chassis is die-cast metal, which is strong and reproduces details well. This material is used for the frames, wheel centres, gearbox casing, motor support and ashpan, while the wheel tyres and axles are steel, running in brass bearings. Plastic is used for the brake shoes to avoid any electrical short circuits.
The locomotive body is again mainly die-cast, metal being used for the footplate, complete with valances and buffer beams, boiler, smokebox, firebox, tanks and buffer shanks, providing useful additional weight.
The cab is moulded in plastic to show fine rivet details.
The lower boiler/tank moulding houses the PC boards and speaker for the sound equipped versions.
Details such as the chimney, dome, safety valve casing and buffer heads are turned metal components, vacuum pipes, screw couplings, handrail knobs and handrails are all metal parts.
Cabside number plates are photo-etched brass with black background.
The motor has a balanced, skewed armature and drives the rear wheels via a toothed belt to a separately fitted gearbox. The two front axles are connected by equalising beams to provide better tracking with electrical current being collected via the wheel bearings, whilst the rear axle uses sprung plungers.
All locomotives are fitted with a PCB that includes an 8 pin socket for decoder installation by the customer to upgrade to DCC. Sounds for the DCC sound fitted locomotives were recorded from number 6435 now resident on the Bodmin & Wenford Railway
All 64xx locomotives have the auto coach control gear added to front/rear buffer beams and screw reverse handle assembled in the cab. All 74xx locomotives have later cab with bunker steps and handrail to cab roof. A lever reverse handle is fitted in the cab.
All Great Western decorated models have their pannier tanks showing weld seams All British Railway decorated models have top feed added to the boiler, and large whistle shield fitted.