FS Class E.424

FS E.424

Company type	Electric locomotive series
Industry	Railway transportation
Predecessor	FS Class E.326, FS Class E.428
Founded	1943
Defunct	2008
Successor	FS Class E.646 (experimental basis)
Area served	Italy
Products	Electric locomotives

Template:Unreferenced Template:Infobox locomotive The FS E.424 represents a series of Italian electric locomotives produced between 1943 and 1951, which were officially withdrawn from service in 2008.

History

During the early 1930s, engineer Giuseppe Bianchi conceptualized a compact multi-purpose Bo′Bo′ locomotive capable of reaching speeds up to 90 km/h (56 mph). However, this initiative was shelved following the introduction of the FS Class E.326 and FS Class E.428. Later, after the development of the six-axle FS Class E.636, the project was revisited and modernized by incorporating components such as engines, bogies, and suspension systems derived from the E.636 design.

The initial trio of E.424 prototypes was constructed by the Società Italiana Ernesto Breda workshops between 1943 and 1944. Full-scale manufacturing commenced only post-World War II, supported in part by funding from the United Nations Relief and Rehabilitation Administration.

Series

File:Locomotiva E424.075.jpg

Unit 075 (non "N") in its original paint scheme, preserved by FerAlp Team museum in Bussoleno

Production of these locomotives occurred across four distinct series starting from 1943:

• 001-003: Prototype models equipped with 32R-200 motors featuring a gear ratio of 21/65, enabling a peak speed of 100 kilometres per hour (62 mph) and fitted with two field shunts; unit 003 differed by having a 20/65 gear ratio allowing up to 120 kilometres per hour (75 mph), and utilized compound-type motors (model 92-250).
• 004-013: These units incorporated compound-type 92-250 motors similar to unit 003, maintained a maximum velocity of 100 kilometres per hour (62 mph), and employed a gear ratio of 19/65.
• 014-038 and 057-078: Among these, units numbered from 017 to 020 as well as units 022 and 024 mirrored the design of units 001 and 002; units numbered 014, 023, 025, 057, and 060 used a gear ratio of 19/65 allowing speeds up to ; the remainder featured compound-type motors (92-250), two field shunts, a gear ratio of 16/65, and could reach ; notably, unit 068 was converted between November 1954 and May 1974 into unit E434-068 with four double-wound motors (82-333), two shunts, and a gear ratio of 20/69 supporting speeds up to , serving as an experimental platform for future FS Class E.646 locomotives.
• 039-056 and 079-158: These units were equipped with compound-type motors (92-250), five field shunts, and had a gear ratio of 16/65 for a maximum speed of , except for unit number136 which had a gear ratio of19/65 allowing it to reach .
• Series200 units: Between1986 and1993,105 locomotives were upgraded with features including an automatic fire suppression system, anti-slip technology, red and green signal lights, and a78-wire cable system enabling remote operation for commuter train service; their top speed was increased to . These upgraded models are designated E.424N—where "N" signifies "Navetta" (push-pull)—and received an additional200 added to their original serial numbers (for example,E.424.116 becameE.424.316).

Technical

File:Cabina di Guida 424.075.jpg

Original E.424 driver console.

The E.424 class, equipped with direct current motors typical of Italian locomotives from that era, operates as a rheostatic locomotive. At startup, a rheostat is placed in series with the motors and is progressively bypassed as the locomotive accelerates, allowing increased current to reach the motors. Unlike other rheostatic locomotives of its time, this process is not controlled by the traditional lever (Maniglione), but instead managed by an automatic mechanism known as the Avviatore Automatico, which was adapted from the first-generation ALe 790/880/883 electric multiple units.

The operator only needs to choose the motor configuration (either series or parallel), and the system automatically and smoothly closes the rheostat contactors. Should the automatic system fail, a dedicated handwheel—normally turning automatically during operation—can be manually rotated by the driver to continue the rheostat exclusion.

Once the rheostat is fully bypassed in series mode, field shunts may be applied, or the driver can switch to parallel mode. This transition is facilitated by a device named 'CEM', which automatically manages motor connections by closing the appropriate contacts.

File:Volantino avviatore E424.JPG

The Avviatore Automatico handwheel rotates during rheostatic exclusion and can be manually operated if necessary.

Initially, it was possible to couple multiple units and control them remotely from the lead locomotive through a system called Comando Multiplo. A door located centrally in the cab allowed crew members to move between locomotives if needed. However, due to safety concerns and limited reliability—particularly because there were no indicators confirming whether the slave unit had successfully completed transitions—this feature was eventually discontinued and dismantled.

A subset of eleven locomotives were fitted with compound-type motors, which provided exceptionally precise speed regulation within ranges of approximately 25 and 50 km/h (16 and 31 mph) in series mode and 50–100 km/h (31–62 mph) when operating in parallel.

See also

• FS Class E.646
• FS Class E.636

External links

• Detailed history of the group (Italian)