Locomotive Phases - GE Dash 8-40C, Dash 8-40CW

These detail differences are based largely on my own observations. For the changes that occurred in prior six-axle GE Dash 8 production, see the GE C32-8 and C39-8 phases.

Phases: Dash 8-40C

Production variations

There were a few minor production variations but no major changes. The last units were built concurrently with early Dash 8-40CW units, and they adopted the anticlimber design of Phase 1b Dash 8-40CW units (two angled braces lining up with the ditch lights, if present). Additionally, around the time the Dash 8-40CW was introduced, the dynamic brake intakes were moved from the top of the hood behind the cab to the right side of the hood; this design was used on late Dash 8-40C's and all Dash 8-40CW's. Some earlier Dash 8-40C's were upgraded with the revised dynamic brake intakes.

Most Dash 8-40C's rode on trucks cast by Rockwell International (later Atchison Casting), which assumed the FB-3 design previously cast by GSC. This version of the FB-3 truck can be identified by holes centred between the axles and smoothly curved side frame edges. Some earlier Dash-8 units rode on trucks cast by Adirondack Foundries, which went out of business in 1987 near the beginning of Dash-8 production. Some units (notably UP Dash 8-40C's) rode on trade-in trucks from older Universal series units.

Transition: Dash 8-40C to Dash 8-40CW

CN #2173, a former ATSF Phase 1c Dash 8-40CW seen in 2015. The raised sections on top of the radiators are a modification.

The GE wide-nosed cab was just over 5" taller above the walkway than the standard cab. Since installing the taller cab on the standard Dash 8-40C frame would have caused clearance problems (with the roof approaching 16 feet) GE lowered the frame on the Dash 8-40CW from a nominal 75" to 69.75", in the process maintaining the same overall cab height.

Based on photo measurements I've made, the bottom of the main frame also appears to ride about 1" higher off the trucks on the Dash 8-40CW than on earlier units (which, together with the lower walkway, results in a roughly 6" thinner main frame overall). This increase may have been made to accommodate a taller fuel tank, as the lower walkway height resulted in the air reservoirs taking up a larger notch in the fuel tank. The bottom chord of frame was also significantly thicker than on either the Dash 8-40C or the later Dash 9 series.

As a result of the dimensional changes to the frame, the most obvious visual differences on the Dash 8-40CW compared to the Dash 8-40C are the following:

• A thinner walkway side frame - the handrail stanchions cover the side frame's entire height.
• A lower walkway height, which is most evident when a Dash 8-40CW is coupled with an earlier standard-cab GE unit. As the central engine compartment and radiators remained essentially unchanged from the Dash 8-40C, they too reached a lower overall height.
• Lower-mounted air reservoirs required a larger notch in the fuel tank. This may have been the reason for the slightly taller overall tank height (to maintain the same fuel capacity as the Dash 8-40C).
• The front hood section was raised higher above the walkway to match the taller cab roof, creating a larger bump up from the central hood section. The added height is most visible above the central air intakes, although the intakes themselves were also moved up slightly.
• The air conditioner was moved from the cab roof to a cabinet on the left side behind the cab, with the initial version mostly replaced by revised designs as the units aged.

Phases: Dash 8-40CW

The most visible difference between the early and late Dash 8-40CW is the radiators. Later units adopted a split cooling system that manifested itself externally as thicker edges on the radiator wings and rooftop grills in 2 (rather than 3) sections. The thicker wings resulted a nearly flat (rather than angled) lower edge to the wings, and the wings were slightly longer overall. However, the proportions of the radiator section—the overall height of the "wings" and the dimensions of the intakes underneath—were otherwise unchanged. The revised radiator design (but not the hood section underneath) was carried over to Dash-9 production.

ATSF and UP ordered a number of units rated at 4135 horsepower, classified as Dash 8-41CW. They were visually identical to other Dash 8-40CW units save for 6 corner steps on UP units (in place of 5). These steps were not the same as the steps on Dash-9 units since they still used the slanted side sheet, rectangular kick plates and lower walkway height of the Dash-8 series. Some Dash 8-40CW units were later uprated to the higher horsepower rating as well.

The last two batches of CSX units (9000-9002 and 9003-9052) were built with 4400 horsepower engines and split cooling. For some reason, CSX classified 9003-9052 (and later 9000-9002) as Dash-9 units, but whatever changes prompted that designation were internal as the units were visually the same as other Dash 8 units. They were neither the last Dash-8 units built nor the only ones built with split cooling, and since they used Dash-8 frames they lacked the high-adhesion bolsterless trucks of the Dash 9 series (the biggest mechanical change between the two series).

References