Treno ad alta frequentazione

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ALe 426/502 TAF

An FNM TAF in Milan Cadorna station
Power type	Electric
Builder	Ansaldobreda, ABB, Firema
Build date	1996-2000
Total production	100
AAR wheel arr.	Bo2+22+22+2Bo (EMU4)
Gauge	1435 mm
Length	103.970 mm
Width	2.820 mm
Height	4.300 mm
Locomotive weight	273 t
Electric system(s)	3000 V DC
Curent collection method	Pantograph
Transmission	20/101
Top speed	140 km/h
Power output	3640 kW
Tractive effort	214 kn
Locomotive brakes	Oerlikon FV4E
Career	Trenitalia, FNM
First run	1997
Disposition	In service

ALe 426/506 TAF (acronym of Treno ad Alta Frequentazione) is an Italian Electric Multiple Unit (EMU) used mainly on commuter regional trains.

Two different companies employ them: Trenitalia and Ferrovie Nord Milano (FNM).

Concept design has been made by Italian designer Pininfarina.

Recently some slightly modified version of the EMU have been purchased by Moroccan Railways,

[edit] Description

Each train is formed by fixed sections of four bi-level pieces: two motorized units (ALe 426/506) and two coaches between them (Le 736). Two sections can be coupled togheter, but by now it is not possible on Trenitalia units (on FNM ones is common practice).

The total capacity of the train is of 469 seated and 372 standing passengers.

[edit] Technique

ALe 426/506 employs asynchronous three-phase traction motors feed by the 3000 V DC catenary, which produce a characteristic sound while accelerating and dynamically braking.

Motors are mounted on one bogie per motorized unit, for a total of two motorized bogies per section.

This choice, however, has not proven too wise: first of all the power is very high in respect of the weight (3640 kW for 273 tons.), and the poor distribution of traction power along the train (only on the edges) induces poor performances in case of poor adhesion.

In fact TAFs are known for their frequent wheel slippage.

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