ALCO RSD-4

Infobox Locomotive
name=ALCO RSD-4
powertype=Diesel-electric

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caption=Kennecott Copper Corporation locomotive 201 on display at Snoqualmie Depot, Snoqualmie, Washington
builder=ALCO
builddate=1951–1952
totalproduction=36
buildmodel=RSD-4 (Specification E1663)
gauge=RailGauge|ussg|lk=on
primemover=Alco 244
cylindercount=V12
cylindersize= convert|9|x|10.5|in|mm|0|abbr=on
displacement=convert|8016|cuin|L|abbr=on|lk=on
poweroutput=convert|1600|hp|MW|abbr=on|lk=on
aarwheels=C-CThe ALCO RSD-4 was a diesel-electric locomotive of the road switcher type rated at convert|1600|hp|MW|lk=on, that rode on three-axle trucks, having an C-C wheel arrangement.

Used in much the same manner as its four-axle counterpart, the ALCO RS-3, though the six-motor design allowed better tractive effort at lower speeds. Due to the inadequate capacity of the main generator, this model was later superseded in production by the ALCO RSD-5

Original owners

Preserved units

The only ALCO RSD-4 that has survived is Kennecott Copper Corporation #201. As of 2007, it resides in fully restored condition at the Northwest Railway Museum (formerly known as the Puget Sound & Snoqualmie Valley Railway) in Snoqualmie, Washington, wearing a coat of bright orange paint.