The Alsthom 705 belongs to a series of over one hundred locomotives built by this French manufacturer that were perfectly suited for underdeveloped infrastructure. In Spain, the transition from steam to diesel traction practically saw this model as the universal locomotive, and for this reason, various private or public narrow-gauge companies have owned forty-two units that have yielded great results. Between 1955 and 1967, Alsthom France built twenty-eight units, and the rest were produced under license in 1958 by Babcock & Wilcox (seven units) and by Euskalduna (the other seven). The electrical components were supplied by General Eléctrica Española. Locomotives built after 1965 have better power performance.
In the case of those intended for the C.G.F.C., eleven machines have been in circulation; five were leased by the state-owned company EFE. The rest were part of the 700 series and the rest were of the 1000 series, which were intended for the former Manresa - Olvan concession, although they circulated indiscriminately throughout the Catalans network. The first unit, the 1001, arrived in September 1955 and over the following months most of them did the same. In January 1966, the last three units, the 705, 706 and 1009, arrived. When FGC was created, they were numbered as series 251.
From the outset, they replaced steam locomotives, both for passengers and for goods. With the arrival of diesel locomotives and the progressive extension of electrification with a fleet of electric units, the diesels were progressively relegated to the transport of goods, with the exception that until it was completed in 1985, the electrification between Monistrol and Manresa continued to haul the passenger trains on these sixteen kilometers. At the end of 1990, with the arrival of the new 254 locomotives, the transport of goods was restructured, and the Alsthom locomotives, the old 700/1000, were relegated to maneuvers at the Port of Barcelona, Martorell, and at the mines of Sallent and Súria, and exceptionally as reserves for the new 254 locomotives. At the same time, some are purchased by railway companies to be used for work trains, and in 2026, some are still in service, remaining in FGC until 2018, of which the 705, 706, 1003 and 1009 are still operational; the company preserves the 1003 and 1009 for the future Narrow Gauge Museum in Martorell-Central. In 2021, it hands over the 706 to the City Council of Sant Vicenç de Castellet for its preservation and the same happens with the 705, which the City Council of Guardiola de Berguedà places in front of the old station. Transferred to this town, where the Museum of the Railway of Móra la Nova begins its restoration in situ in 2025, which is expected to be completed in 2026.
Technical data sheet
| Any construction | 1966 |
| Constructor | Alstom France |
| Track width (mm) | 1.000 |
| Length (mm) | 11.200 |
| Height (mm) | 3.700 |
| Box width (mm) | 2.600 |
| Pes | 44 terameters |
| Axis layout | Bo' Bo' |
| Transmission | Diesel-electric |
| Diesel engine | 1 x SACM type MGO V12 |
| Power | 925 hp (680 kW) |
| Maximum speed | 90 km/h |
Client: Guardiola de Berga City Council
Types of Restoration: Aesthetic
Any: 2025
