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Locomotive Phases - EMD SD70M-2, SD70ACe

The SD70M-2 and SD70ACe were a redesign of the EMD SD70 series aimed at meeting new emissions standards that took effect in 2005. While they shared many mechanical components with the previous SD70M and SD70MAC models, they received a substantially altered carbody and underframe that borrowed some features previously used in the SD80MAC and SD90MAC series. The air reservoirs and associated piping were all moved to the engineer's side while the traction motor cables were moved to the conductor's side, as on contemporary GE units. The dynamic brakes were moved from the front to the rear of the hood, and a wider radiator section was located behind a lowered and tapered central hood. The underframe was several inches taller than on earlier SD70 models and resulted in a shorter cab being adopted from the late-model SD90MAC. The radial-steering HTCR trucks were carried over and a new, simpler HTSC truck was introduced that lacked radial steering and rode on a shorter wheelbase.

Unlike the SD70M and SD70MAC (which rode on different underframes) the SD70M-2 and SD70ACe were nearly identical. The main differences were the substantially thicker and more numerous DC traction motor cables, smaller traction motors and absence of inverter cabinet vents on the SD70M-2. Visual changes over the production run were numerous but relatively minor, and as the SD70ACe outsold the SD70M-2 by a wide margin, the latter had fewer variations.

These phases are of my own making. They do not include EMD's new Tier-4 version of the SD70ACe.

Phases

Phase 1a 1b 2a 2b1 2b2 2c 2d1 2d2 2e1 2e2 2f
Jacking pads open flat plate (except early Phase 2a SD70M-2) curved plate
Panels above d.b. intakes 3 rows of vertical louvers 3 columns of horizontal louvers short doors medium-height doors shorter columns of louvers
Cab sub-base panels hinged bolted
Inverter cabinets surface-mounted grills flush grills no grabirons on panel edges, no slot at top right corner
Rear sand fill step No Yes No
Rear hood end grabirons engineer's side conductor's side
Rearmost conductor's side hood door bolted on all sides hinged with 4 bolts hinged with 2 latches
Frame and side sill open sill under cab continuous sill, slightly narrower under cab (1)narrower section extended toward fuel tank,
removable sill section under inverter cabinets,
shorter vertical extension behind front steps,
2 additional vertical ribs on underframe (above & behind fuel tank)
Air reservoirs strap supports end support brackets
Dynamic brake intakes open at bottom corners notched bottom corners
  1a 1b 2a 2b1 2b2 2c 2d1 2d2 2e1 2e2 2f
Rear hood end bottom panels 2 latches 1 latch
Engineer's side handrail   6th stanchion from rear moved forward
Conductor's side underframe cable shroud yes no
Conductor's side handrail straight (SD70ACe) or zig-zag (SD70M-2) vertical section behind inverter cabinet zig-zag vertical section behind inverter cabinets, stanchions moved rearward
Side sill handrail stanchion supports vertical angled sides
Panel behind inverter cabinet solid (SD70ACe) or square grill intake (SD70M-2) small (SD70ACe) or large (SD70M-2) louvered section rectangular grilled intake (SD70ACe)
Fuel system narrow cutoff switch housing, separate gauge wider combined gauge and cutoff switch housing Revised fuel sensor (near bell)
Air piping revised piping ahead of reservoirs revised piping behind reservoirs
Small front hood panel on conductor's side 2 bolted panels 1 bolted panel, 8 bolts 1 larger bolted panel, 10 bolts
Traction motor cable shroud (SD70M-2)   yes   no
Hand brake 5-spoke or 8-spoke stamped wheel 3-spoke welded wheel, new housing wider notch above wheel
Isolated cab seam notch around door latch
Sand hose supports narrow wide
Phase 1a 1b 2a 2b1 2b2 2c 2d1 2d2 2e1 2e2 2f

Notes

  1. Frame and side sill, Phase 2c: Same as Phase 2b2 except narrower sill section extended rearward, farther than on later phases and without removable section.

Other details

 Copyright © Michael Eby - Page code last updated 2016-10-09