• 1st Generation SD-series official thread (all variations)

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

  by pablo
Golden Arm, I was tightening the bolt on the + on top of the battery when the head of the wrench touched the side of the compartment as it tighetned the bolt. God bless the rubber handles...

I tried to track down a 70 tonner a few years ago. Two in fact. One vaoprized, apparently; no one knows after it got to A. Merilees. The other was scrapped mere months before I started looking.

Good luck...

Dave Becker

Not much you can do about that, other than use rubberized tools, or place a fender protector on the lip of the battery box. The hot will always go to ground, when the opportunity presents itself........... :P

  by mxdata
So has anyone posting on this forum run one of these new locomotives yet? Is the selection of the number of running engines done manually by the engineer, or is there a sensing circuit that brings them on line as needed?

  by pablo
Everything I've seen says it's autmoatic on such units, but I don't know if an engineer could manually bring online more than were needed.

Dave Becker

  by mxdata
If it is automatic, one question would be whether the fuel economy that is being quoted is based on the manufacturers BSFC data for the engines (done on a test stand) or the actual operation of the locomotive. If the system is automatic and it takes a couple seconds to start and load another engine when it is needed (starting into a grade, for example), you need to anticipate that and do the start before the one on line gets overloaded. This uses fuel in the starting and restoring the air or charging the battery after the start, this usage would not be reflected in manufacturers fuel consumption figures. If they have layover heaters powered by the running unit to keep the others up to temperature that consumes fuel too. It will be interesting to see how the engines stand up to constant thermal cycles of starting and stopping, there are relatively few other diesel applications that operate this way. The closest service to this that I have seen is backup generators at server farms or nuke plants, but they have a minimum run time once they start to keep from doing very short thermal cycles, maybe this does too.

On the other hand, if the engineer can override the system, there is the possibility for all the engines to end up on line all the time. I hope that somebody who has actually run one will post and let us know how it is arranged.

  by BR&P
Golden Arm, speaking in the context of automobiles, you always disconnect the negative terminal from the battery. Since on an auto (and on small GE locos for that matter) the ground is to the frame, by doing so you have removed the possibility of closing a circuit. Once that negative is off you can touch positive to anything and it won't do a thing. If you disconnect the positive it does essentially the same thing, but in Pablo's case, he was tightening the +. If the neg had been off there would have been no circuit, and if the wrench hit the fender when tightening the negative no problem as it is already ground.

Larger locos have separate wires for positive and negative. When one shorts out and touches something metal it does not necessarily draw an arc because (in theory) there is no ground to the frame. It gets interesting if you happen to get a negative AND a positive wire grounded at the same time, as it is possible to feed currect in strange ways. George Hockaday told of a unit on the Monon which had multiple grounds. They could not shut the loco down as long as the steam generator control circuit was ON, as there was also a ground in one of the governor circuits as well and the gov was fed current through the steam gen.

That's why one of the things you are required to do on a 92-day test on a loco is checking for grounds, both + and -.

  by tominboise
The multi engine switchers are certified wth the EPA using a microprocessor to start and stop the engines, to a rather exotic scheme calculated to reduce the NOx emissions to the lowest possible levels, when tested on the locomotive switch and line haul duty cycles. There are no provisions for the engineer to start all the engines and have them on line, as this would be considered by the EPA as a "defeat device", in other words, you could operate the locomotive outside the control system that it was certified under. This is illegal.
  by uhaul
What was the weight limit (in tons per axle) of the trackage the SDL39s were designed to run on?

  by NHRDC121
The SDL39's weighed in at 250,000 lbs for an axle loading of 20.8 tons per axle, which was still within the loading range of the track and bridges of the branches they were intended to be used on, if that's any help.

  by uhaul
Thank you.

  by Otto Vondrak
[moved to the EMD Forum - omv]

  by uhaul
Thank you moving it Otto Vondrak. (I thought it was in the EMD forum in the first place.)

  by VITO
Didnt WC buy some ? I forget who first owned them.Maybe Milwaukee Road.

  by charlie6017
Vito is right...........there were only 10 built and the first owner was the Milwaukee Road. Here is some info from Wikipedia!


  by MEC407
What the Wikipedia article doesn't tell you is that CN got rid of the SDL39s after they took over Wisconsin Central.
  • 1
  • 4
  • 5
  • 6
  • 7
  • 8