Treno ad alta frequentazione

Infobox Locomotive
name = ALe 426/502 TAF
powertype = Electric

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caption = An FNM TAF in Milan Cadorna station
builder = Ansaldobreda, ABB, Firema
serialnumber =
buildmodel =
builddate = 1996-2000
totalproduction = 100
whytetype =
aarwheels = Bo2+22+22+2Bo (EMU4)
uicclass =
gauge = 1435 mm
leadingsize =
driversize =
trailingsize =
wheelbase =
length = 103.970 mm
width = 2.820 mm
height = 4.300 mm
framesize =
weightondrivers =
weight = 273 t
locotenderweight =
fueltype =
fuelc

tenderc

consumption =
watercons =
electricsystem = 3000 V DC
collectionmethod = Pantograph
primemover =
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displacement =
boiler =
boilerpressure =
feedwaterheater =
firearea =
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fluearea =
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fireboxarea =
totalsurface =
superheatertype =
superheaterarea =
cylindercount =
cylindersize =
rearcylindersize =
hpcylindersize =
lpcylindersize =
valvegear =
transmission = 20/101
topspeed = 140 km/h
poweroutput = 3640 kW
tractiveeffort = 214 kn
factorofadhesion =
locobrakes = Oerlikon FV4E
trainbrakes =
railroad = Trenitalia, FNM
railroadclass =
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officialname =
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deliverydate =
firstrundate = 1997
lastrundate =
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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,

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.

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.