The use of Tractor 11 in the Charentes having produced excellent results, the C.F.D. considered upgrading to higher power by converting a locomotive to a thermal engine. This decision was prompted by the particular case of the Saône-et-Loire network, where the most important traffic was confined to the 10 km section between Digoin and Gueugnon, from where the Forges shipped a very important tonnage to this transhipment point. The short distance and the special reduced rates applied militated in favour of using a more economical traction system. The Charente example naturally paved the way for this operation. Mr. Strobino, Head of the Toulon-sur-Arroux depot was therefore asked to present a project and to choose a locomotive for which the scale of the work involved in its refurbishment would be an inconsiderate expense. Machine 204 was chosen and dismantled, the chassis shortened and the front bissel removed. These operations were carried out in 1936.
Description of the prototype tractor No. 204 from Saône-et-Loire
The layout of this tractor was identical to that of the 11 tractor, i.e. engine hood at the front, central cab and fuel tank and auxiliaries at the rear, the principle adopted for the entire construction of the C.F.D. workshops.
The engine chosen was a special type manufactured by the C.L.M. Of the DV 85 Diesel type with 6 cylinders of 150 HP, it was delivered with an important delay delaying the exit of the machine until 1939. The transmission, of the MINERVA type, controlled the central axle, connected by connecting rods to the two others, through a drive axle and a 6-speed gearbox with reverser.
The cab was larger than that of the 11th and had a set of 10 bays (3 on the front and rear sides and 2 on the sides, including one on the swing door) allowing a very wide vision.
The larger engine space did not permit the cabin access doors to be located on the front face, and they were located aft of the side faces. Handrails and a handrail at the front protected the access platform to the engine cowling access doors. The engine hood had a right grille.
The decoration was identical to that of Tractor 11 and the licence plates and sleeper markings of the original locomotive had been retained. The company monogram had been placed at the top of the grille.