What is the roof bulge with with vents on it just behind the cab on some C36-7s? From looking at many photos, and from comparisons to this roster http://www.thedieselshop.us/GE_C36-7.HTML it seems that only engines delivered to MP and NS (not N&W) have the bulge. These are later in the production run, but Conrail's units, as well as the export units for China, are from the same time frame and don't have the bulge. It's not a production phase difference, then. An option? Maybe dynamic brakes? Whatever it was, was it offered from the start of production, or only starting in 1984? Anyway, the important question: http://www.railpictures.net/viewphoto.php?id=119924 The lead engine is one of N&W's first order of C36-7s in 1981. And it has the bulge. Except it doesn't have vents on it. In fact, it distinctly looks like plated-over vents. What's going on with this unit? Was it rebuilt sometime in its first 4 years in service?
High-capacity extended-range dynamic brakes... Yes, 8501 was rebuilt with the high-capacity extended range dynamic brakes, it was the test unit for these. As for the vents, they're up top.
There's a similar distinction between BN's two orders of B30-7A(B)s. The second order had bulges similar to those on C36-7s, so I assume those are extended-range dynamics as well? Another question regarding C36-7s... how do you distinguish units without the extended-range dynamics from C30-7s?
Yep... The first six C36-7 built, N&W 8500-8505, are alomst identical to the C30-7s... they have one difference though... on the engineers side, the first access hatch is vented. On the C30-7s, this access hatch does not have vents. As well as the above vetned hatch... for other C36-7s, look at the nose. It'll have access hatches on the front of the short hood (on the bottom, much like an EMD), and it also will not have a headlight casting. The conductors side of the nose will not have vents as well.
