The G8, GA8 and GL8 were standard EMD export models.
The G8C and GL8C were built by EMD’s Australian associate, Clyde Engineering, to meet specific Australian railway system requirements.
The G8 road switcher dated from 1953-54, and used the same frame, body and running gear as the more powerful G12 model, but with the 8-567C (later 8-567CR) engine rather than the 12-567 of the G12. Both the G8 and G12 were available with B-B or A1A-A1A running gear.
The GA8 and GL8 end-cab units were part of the 1958 expanded export range. Both used the 8-567C(R) engine. The GA8, with B-B running gear, was by design very simple, with freight car-type trucks and longitudinal, frame-mounted traction motors and shaft drive. The GL8 was lighter and shorter than the G8. Initially it was offered only with B-B running gear, but an A1A-A1A option was soon added. Although the G8 remained in the catalogue, it was largely displaced by the GL8, with few built after 1959-60. The last G8 batch, built for New Zealand Railways c.1965, were significantly modified.
Clyde initially (1955) built the G8 and the G12 on a longer frame, 44’6” (the same as had been used for the EMD B12) rather than the standard 43’0”. Then it separated the two models, the G8 (with B-B) running gear being built for Victorian Railways on a significantly shorter frame, and soon renamed as the G8B. This went through several iterations, at some stage incorporating some GL8 features.
The Clyde G8C was built for New South Wales Railways (NSWGR) as its 49 class) from 1960. This was essentially a six-motor (C-C) derivative of the Clyde G8B variant of the time, necessarily on a longer frame. Effectively this model competed with the Alco-Goodwin DL531G, which constituted the majority of NSWGR’s branchline fleet.
The Clyde GL8C (C-C) was built for Queensland Railways from 1963 as its 1700 class, for branchline service. To some extent it was a GL8 derivative, but not simply a reshod version of the latter. It looks to have been of lighter overall construction than the standard GL8, being built to a total weight target of 61.5 long tons (roundly 138 000 lb). It was notable for using CD36 traction motors (designed for the 3 ft gauge) as a weight-saving measure.
Note that Clyde started using A (A1A-A1A), B (B-B) and C (C-C) suffixes in its models in the later 1950s, before EMD did the same. For example, its version of the GR12 (which it built before EMD built its version) was soon renamed as the G12C. In general, EMD did not apply these letter suffixes to its export models until the 645 engine era, and even then, mostly used only the C suffix, e.g. G22C for the six-motor (C-C) version but G22 (without suffix) for the four-motor version, whether B-B or A1A-A1A. But it had alphanumeric suffixes to show the number of axles and whether narrow or standard gauge traction motors were fitted. Thus, G22U6 was a G22 with A1A-A1A running gear and narrow gauge (U for universal) motors. Clyde did not appear to use this system. One exception for EMD in the 567 era was the GA12C of 1963, derived from the earlier GA12, which in turn was derived from the GA8. I am not sure of the significance of the intermediate “A” in the GA8 (and GA12) models. It was not related to wheel arrangement, but it was associated with very simple locomotives with shaft drive.
These export locomotives used the same engines and generators as the domestic model range, but in different frames, usually with different running gear and often with different auxiliary systems. Standard gauge traction motors, where used, were the domestic models. Control systems were generally similar to domestic practice, although where fitted, export models used potential wire type dynamic braking from the start. Thus, there was seldom direct correlation between export and domestic models.
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