What does the "G" mean in the GM-EMD export locomotive line, e.g., G12

[LOREN AANDAHL]

i did not see your original posting. Thank you for the detailed explanation.

[M636C]

I provided a detailed answer to this question on 11 January in the JT42CWR thread...

 

I think "G" stood for General Purpose, just as it did for domestic GP units, but "G" alone was used to avoid confusion. Certainly the original drawings for the G12 and G8, which shared the same body, showed a scaled down GP 7 with shaped hood ends and an arched cab roof that emphasised the similarity in both purpose and appearance. I'm pretty sure the words "General Purpose" appeared in the early advertising.

 

The letters were allocated more or less as GDRMCo indicated...

 

A - standard and broad gauge cab units

B - narrow gauge cab units

 

G - general purpose hood units

GA - frame mounted motors with gear drive

GL - light weight units

GT - turbocharged units

 

J - double end cab unit either cab or hood body

 

K - Egypt only double end cab unit with twin eight cylinder engines model KK

 

R - six motor hood unit (later GR in model GR12, later still the R was dropped)

 

T - Tropical (for Africa only verandah hood unit with two streamlined cabs model TT)

 

Suffixes

 

W - standard gauge motors as in G12W

U - narrow gauge motors as in G8U4 (4 is number of axles) an A1A-A1A would be G8U6

 

So for the class 66 in the thread title

 

J = double end cab unit

T = turbocharged

42 = 12 cylinder 710 engine = 12+30 (12+10 + 645E, 12+20 = 645F)

C = six motor trucks

W = standard gauge (although the D43 motors used are really universal)

R = radial trucks

 

That's about it for export designations...

Why did you ask it again?

M636C

[NorthWest]

Probably general purpose, but without the P to indicate an export unit.

[LOREN AANDAHL]

The GM-EMD 567 powered export locomotive series developed in the 1950s had a "G" designation for their models. G8, G12, G16, etc. In the mid-1960s this changed with the introduction of the 645 engine to be G18, G22, G26, etc. The designation is still used in the latest 710 engine offerings, e.g., GT46.

What does the "G" designation mean? Global? General?