At lunch today from about 1:00 PM to 1:15 PM, I had an opportunity to walk pretty close to a pair of road diesels - a WB NS freight on the Reading Line had stopped at about MP 32 - presumably for a red signal ahead - which is paralleled about 30 ft. away on the south by Industrial Ave. Specifically, they were NS 9509, a GE D9-40CW leading, back-to-back with NS 8760, a GE D8-40C, trailing.
What I noticed right away was that the entire frame and perimeter walkway of the D8 was a good 9 or 10 inches higher than that of the D9 (perhaps Kootenay Central’s recent post with the links to the FM Trainmaster photos and comment about how high their vertical ladders were, was still on my mind). It wasn’t just a temporary or one-end-only thing such as unusual trucks underneath, either - at both ends, the D8 had a single step-down and notch cut into the walkway so that it matched at about the same height as the D9’s entire walkway and top of frame. After further study, it seemed to me that the hood sections were all about the same relative height and ‘steps’ up and down, so it is likely that the D8’s overall height difference is that much higher than the D9’s. And that is compounded by the air conditioner unit on top of the D8’s cab, which the D9 didn’t have - althogether, then, the D8 might need about 2 ft. more vertical clearance than the D9. Of course, my wife ha
That’s a detail I wasn’t too explicit on, for those not familiar with the model codes and designations - this Dash-9 is a wide-cab, and the Dash-8 is a standard cab.
The dash 9’s A/C unit is on the conductors side, just behind the cab, the entire unit is changeable quite quickly, it even has fork lift slots/pallet built in.
.
The height difference is because of the cab differences, the Dash 9 also has a few inches less head room, but the cab layout and seat placement are a lot better than the 8 series.
If you look a little more closely, you will also find the Dash 8 has one more step in the pilot and rear side steps, and the steps are more vertical than on the Dash 9.
In the dash 9, the toilet and some electronics occupy the nose, with the center walkway and interior steps leading up to the cab, both the engineers and conductor/fireman seat are on raised platforms, 8 to 10" high, with a depresses walkway in-between, where as on the Dash 8s, the cab floor is even all the way across, with a door leading down into the cab nose toilet.
Also note there is a two step down in the engineers side walk way, about 3 feet behind his door, with an intermediate single step directly outside the door.
On the 7 and 8s with a standard cab, you had 2 steps just outside the rear door.
Because both the Dash 8 and 7 series used the older style tricycle type suspension and ridged trucks as opposed to the “steer able” trucks on the Dash 9, the 8s frame sits taller on the truck bolster.
Ed - Thanks for pointing out all those subtle details. I was only able to walk along 1 side of the locomotive consist, which was the engineer’s side of the Dash 9, but the conductor’s side of the Dash 8. I did notice that each side had what seemed to be a symmetrical bend in the handrail for the steps down, but I wasn’t counting them. I also wondered about the trucks, and looked at them long enough to see that the brake cylinder piston rods were pretty far out on each - but not much else - i.e., ''You look, but do not see". Well, next time I’ll have a better idea of what to look at, and what to look for. I haven’t seen many of the standard-cab Dash 8’s over here until recently,but in the last couple weeks they seem to be about 50 % plus of the locomotives that I see, so hopefully I’ll have some more opportunities to do that. Thanks again. - Paul North.
The 6-axle Dash 8 frame are also 2.4 ft shorter at 70.8 ft than the Dash 9’s 73.2 ft frame. I wonder if the C40/44-9Ws frame is longer than the C40-8/8W series because of commonality with the AC-traction AC44CW, or is it because of the D9’s HiAd trucks? IIRC, EMD lengthened the frame of the SD40-2 from that of the SD40 because of the SD40-2’s HT-C trucks. I guess GE could have lengthened the frame of the Dash 9 from the 6-axle Dash 8 for the same reason since the Dash 9 too introduced a new type of truck? Then again maybe the AC440CW required a longer frame than that of a C40-8W to easily accommodate it’s AC-traction equipment?
The DC motored Dash9s came out well before their AC motored cousins, and GE’s self steering trucks didn’t appear until about two years after the first AC4400CW appeared.
The change from the “thick” side sills to the thinner ones occurred when GE introduced the wide cab. The first wide cab models on CR were the C40-8Ws.
There isn’t anything under the walkways on the C40-8’s other than cabling for the traction motors, control wiring and air piping. It’s all still there on the wide cabs…so ???
The radiator cab is higher height on the Dash 9s due to the split cooling system (aftercoolers on their own cooling system loop = lower NOx), but I’m pretty sure that came much later than the early wide cabs.
Looking at some pix of NS std cab Dash 9s, they have the “thin” side sills like the wide cabs do.
Look at the engineers side walk way, it is about 6 inches thick, and it serves 2 purposes.
One is of course as a walk way, the other is as the rear traction motor(s) blower duct.
Same on the 7, 8 and 9s, and on EMDS as well.
Older locomotives had blowers for each set of trucks, from the GP30 on EMD used the walk way as a duct and filtered the air in from just behind the cab.
Don’t know when GE started, but do know its that way as far back as the 7 series.
We keep getting Dash 9 frames in here for export to Brazil, just the frames on flat cars with the trucks on another, they install the prime mover and all the rest, so I will try and get a few photos of a nude frame for yall.
EMDs vary as to whether or not there is ducting on top of the frame for traction motor cooling, SD70MACs have the ducting, SD70Ms do not. If they have the laundry chute blower duct, then they have ducts on top of the frame, if they don’t then no ducts either. The current SD70M-2 and SD70ACes lack ducting.
You are right about EMD locos GP30 up through 60 series, but not the GEs. GE’s Dash 8 and newer have a separate front and rear electric motor driven traction motor blowers. Dash 7s and older used the area between the frame rails as a blower duct.
Had an opportunity to take some photos of a lash-up of various Norfolk Southern locomotive models to illustrate these differences on this past Monday afternoon, 18 April 2011, at the west end of the NS Allentown Terminal (Yard). Note that all photos were taken from the City of Allentown, PA’s adjoining Canal Park. Unfortunately, I forgot about the depressed step at the ends of the standard cab Dash 8, so that doesn’t appear here (yet - maybe next time !).
Paul North.
Data is on the sides of the cabs - NS D8-40C 8692 on left;
NS D8-40CW 8374 on right:
My ignorance of the engineering of locomotives not withstanding, I wonder if raising of the walkway beside the long hood serves multiple purposes. Seems to me they could be used for MU cables and cooling air for the traction motors. Another purpose could be train crew protection in the event the prime mover pukes a lot of oil onto the frame. It would drain overboard while leaving the crew a safe place to walk.
I’ve never taken notice of the steps being higher in back than in front.
As it happened, I saw 2 (only) of the pictured units heading WB again early this afternoon at MP 32. The 9017 - a D9-40CW - was again leading, and the 8692 - a D8-40C - was facing the other way. But even though they were coupled “tail-to-tail”, from about 200 ft. away I couldn’t discern any noticeable differences in their frame heights.
