FS Class 680

FS Class 680

Company type	Steam locomotive class
Industry	Rail transport
Founded	1907
Headquarters	Italy
Products	Express steam locomotives (2-6-2 wheel arrangement)
Parent	Ferrovie dello Stato Italiane (Italian State Railways)

The FS Class 680 (Italian: Gruppo 680) is an express steam locomotive with a 2-6-2 wheel arrangement, operated by the Ferrovie dello Stato Italiane (FS; Italian State Railways). It served as the direct predecessor to the highly regarded and successful FS Class 685.

Design and construction

Conceived as the standardized replacement for the renowned fast locomotives of the Rete Adriatica, specifically the FS Class 670 (originally classified as Class 500 before FS reclassification), the Class 680's development began even prior to the RA's incorporation into FS in 1905. Early plans, including a proposed designation of RA 550, outlined a fast 2-6-2 locomotive sharing numerous characteristics with what later became the FS Class 680.

This class incorporated the widely adopted Italian bogie and utilized the same Plancher compound engine system found in the Class 500. This configuration paired two high-pressure (HP) cylinders on one side and two low-pressure (LP) cylinders on the other, each pair controlled by a single piston valve through crossed ports. While this design was elegant and straightforward, it resulted in some imbalance and instability at higher velocities.

Manufactured between 1907 and 1909, a total of 151 units were produced by Ernesto Breda, Gio. Ansaldo & C., and Berliner Maschinenbau. The final two locomotives were completed by Ansaldo in 1909 and Breda in 1911 respectively.

Originally equipped with three-axle tenders holding up to 20,000 litres (4,400 imp gal; 5,300 US gal) of water, these tenders exhibited derailment issues at elevated speeds, notably on the route between Genoa and Ventimiglia. To address this, they were replaced with bogie tenders from the FS Class 625, which offered increased water capacity of 22,000 litres (4,800 imp gal; 5,800 US gal) and improved stability.

A brief success

When the first locomotive rolled out of the Ernesto Breda factory in 1907, it was initially designated as FS 6401, but within a few days, it was reclassified as FS 6801. Over subsequent years, the classification system evolved to include five and eventually six digits, separated by a period between the class and running numbers, ultimately settling on the format 680.XXX.

The Class 680 demonstrated excellent performance, effectively replacing the Class 670 on key routes such as Rome-Naples and Florence-Rome. During a test run, locomotive 6801 (later renumbered 680.001) hauled a special train weighing 210 tonnes (210 long tons; 230 short tons) from Parma to Piacenza, reaching a maximum speed of 118 km/h (73 mph).

Despite its initial success, the Class 680's prominence was short-lived. By 1912, the introduction of the Class 685, essentially a superheated and simple-expansion variant, rendered the earlier model obsolete. The newer Class 685 offered greater power and smoother operation, leading to the rapid decline of the Class 680's relevance.

Rebuilds and conversions

The final two units produced, numbered 680.150 and 680.151, were experimentally equipped with superheaters from their inception. However, this modification yielded disappointing outcomes; the anticipated performance gains were negated by diminished steaming capacity. Nevertheless, this trial set the stage for a comprehensive rebuilding program aimed at matching the capabilities of the Class 685.

Between 1918 and 1924, seventy-three locomotives underwent reconstruction with a new small-tube superheater. Initially categorized under subclass 680.2XX, these were later reclassified as Class 681. Additionally, fifteen locomotives—plus two more converted from Class 681 units—were fitted with larger high-pressure cylinders (measuring 400 mm [15+3⁄4 in] compared to the original 360 mm [14+3⁄16 in]). These were first assigned to subclass 680.4XX before being redesignated as Class 682. This class represented the pinnacle of the Plancher compound engine's development for passenger service.

In 1924 and 1925, locomotives from Class 682 were stationed at Ancona shed for comparative testing against Class 685 units. The trials revealed that although Class 682 engines delivered slightly higher power output (around 1,270 hp (950 kW) versus 1,250 hp (930 kW)), they consumed more water and coal and exhibited less stable high-speed performance than the Class 685s. Consequently, further rebuilds were halted in favor of fully converting not only remaining Class 680 locomotives but also those in Classes 681 and 682 into Class 685 configurations.

These conversion efforts spanned from 1925 until 1933. By their conclusion, only four locomotives from Class 680, twelve from Class 681, and fifteen from Class 682 remained unmodified. The vast majority—120 units—were reclassified into subclasses 685.3XX and 685.5XX within Class 685, along with a separate designation as Class S.685.5XX.

Final Years

The locomotives that were never rebuilt continued to operate in less demanding capacities throughout the remainder of their service lives. Prior to the outbreak of World War II, their use had already become intermittent; however, during the war, they were reinstated for active duty. Following the conclusion of the conflict, the process of phasing them out commenced, culminating in their complete withdrawal by 1955.

Preservation

Among the Class 680 units, only one example, number 680.037, has been preserved. After spending an extended period in Merano, this locomotive was ultimately relocated to the Pietrarsa railway museum for conservation.

References

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