The dynamic brakes on the SD70ACe/M-2 are located on the rear of the hood behind the radiators. This arrangement is a radical departure from the SD50/60/70M/MAC series. I think EMD introduced this placement with the SD80/90MAC? IIRC, GE U-boats and most Dash 7s had dynamic brakes placed near the rear of the hood too before GE opted for the box-arrangment behind the cab on Dash 8 and later?
Lyon,
You are correct. Early GE's through the 'Dash-7' engines have the D/B grids mounted in the rear of the engine(you can see the grids though the screening on eary 'U Boats'). The 'Dash-8' series moved them to an area behind the cab.
EMD normally mounted them on 'blisters' over the prime mover. The SD50 was the first domestic production locomotive with the D/B behind the cab. The SD80/90MAC engines moved the D/B behind the radiators. The SD60/70/75 series kept the D/B equipment behind the cab. The new SD70ACe engines have moved the D/B to the area behind the radiators. From the 'crew comfort' perspective, this makes sense as all of the blower noise is not right behind the crew. The 'down side' is that extra long cables have to be run back to the new D/B location.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Indeed they are better for crew comfort I love the db location on the acs's, it took a little to get used to because I was so used to hearing the whine of the db cooling fan.
Rodney
The SD90mack has this configuration to. I think that this is silly, the erlier EMD's didn't have this configuration and they looked better I think. So what you are saying is is that the U-boats had this configuration to?
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I believe the Conrail SD80MACs were the first to have this arrangement, they were quite a departure in style from what was around up til then.
GE uses 1 large cooling fan. Early U-boats had the dynamic grids under this fan as well. The EMD SD80-90-70ACe has a separate fan for the dynamics.
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
As has been stated earlier they are back there for the noise reduction and safety. I have seen several grid blowers that have oversped and shot off all their blades. with the grid blower in the back of the hood they are kept away from the crew.
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