Dumb Newby Questions

[Anonymous]

1. What's a Tunnel Motor?
2. Why are "slugs" so rare? Seems like they would have to be a lot cheaper than a unit with a full cab.
3. Why are there so few pictures of the insides of engines? Both in the cab and elsewhere. Seems like there are never pictures with any of the many hoods or access hatches open.

[daveklepper]

Tunnel motor: Term also used elsewhere, such as electric locomotives used on electrifications limited to tunnels and approaches, such as Cascade Tunnel (1st electrifcation), Hoosack, Baltimore-B&O, but more recent and better remembered application of the term concerned some EMD locomotives built for the SP and the D&RGW that had air-intakes for all cooling (engine, dynamic brake grids, etc) relocated low instead of high to prevent overheating by proximity to exhaust stacks that would result when regular diesels with high intakes are operated in snowsheds and tunels . Someone can expand further.

Don't confuse calves and slugs. Calves are complete diesel electrics without regular controls, also some have very limited "hostler" controls for low-speed movement. They are rare because their use limits flexibility. The cost saving is not that great as to overcome the limitation of not being able to use them on the head end when the total power lashup is positioned to make that desireable. Slugs don't have diesel prime movers but draw power for the electric motors from an adjacent regular locomotive. They can add tractive effort in low speed service. They are rare because diesel locomotives are already a balanced design with the right combination of motors and diesel engine for the intended service. Thus slugs use is restricted mainly to low speed transfer service and pushing cuts of cars up humps in classification yards.

Railfans don't have much access to the repair shops where the hoods are open. Some picures do exist from open house tours . Watch for a railroad "open house" in your area. If you live in the New York metropolitan area, Metro North has an open house at Harmon once a year (or did, anyone know if they still do?) Dave Klepper

[Anonymous]

Just got my latest TRAINS mag which stated that GE's 4400CW is available in two weights: a standard weight unit of 416,000 lbs and a hi-traction Heavy unit of 432,000 lbs.

Does anyone know how they add some 8 tons of weight to what seems an already crowded chassis?

Thanks,
Bobby

[dehusman]

In modern parlance a tunnel motor is a type of diesel locomotive built by EMD (General Motors) for service in the mountains of the western US. The rear of the hood has the radiator intakes mounted just above the walkway and the radiator fans mounted internally (as opposed to on the top of the hood). Normally the engines would have the radiator air intakes near the top of the hood. However in the long tunnels in the Western US the air at thte top of the tunnel was so hot that the radiators couldn't keep the motors cool, the engines would overheat and stop working. By lowering the intakes the air pulled into the radiators would be significantly lower in temperature and provide better cooling of the radiators, allowing the locomotive to provide full horsepower. I believe that SD40-2 and SD45-2's were built as tunnel motors, primarily for the SP and DRGW (now both UP). All GP15-1's and some MP15AC's had "tunnel motor" style radiators, but that was more consistancy of design issue than to keep them from overheating.
2. Slugs use the power form the attached unit (a slug has no diesel engine in it) so the best applications are slow speed, high drag ones. Also since only certain specific engines are set up to power a slug if the power unit goes down, you lose both the slug and the master unit.
If you are talking about "B" units, engines that are full engines, just with no cab, the aren't used as much because of the limitations on how they can be used. One of the successes of diesel engines is their interchangability, so the abilty to be a leader is inportant. In reality, many units end up as defacto "B" units. Un-rebuilt SP C44AC's are essentially "B" units on the UP since they are not equipped with DP (distributed power i.e. remote control) or cab signals. C44AC's are the mainstay of the UP's coal fleet so a coal train leader has to have DP and cab signals to get to any of the utilities east of Colorado or Wyoming.
3. Because they are so small. Go into a typical half bath or laundry room set a full size 4 drawer vertical filing cabinet in the middle of the room and try to take good pictures of it without a fisheye lens. Pretty damn tough.

Dave H.

[CSSHEGEWISCH]

Added weight for ballast is often achieved by using heavier structural members in the frame than otherwise necessary. BRC is noted for its heavily ballasted locomotives, especially GP38-2's 490-495, which were hump engines.

As mentioned above, slugs are rare because of their limited applicability. Outside of yard limits, they can primarily be found on low-speed secondary lines or mine runs. SCL used its MATE's , which were factory-built slugs, in phosphate service in Florida paired with U36B's.

[JoeKoh]

JB
first welcome to the forums!
I have seen both yard slugs (in switching) and road slugs on csx trains.if you want to see the engineers side of a dash 8 email me.
stay safe
joe

[Mookie]

Gentlemen: To put this into something I can remember, since I always mix the two up, would I be safe in saying that a slug is like a parasite - it draws power from the locomotive it is attached to and a calf would be just that - a smaller version of an engine without the necessary controls - hasn't grown into them yet?

Mookie

[Anonymous]

There are a number of slug units, resplendent in the new BNSF "Pumpkin
& Green" livery operating in Northtown Yard. I've seen them hooked-up to
GP40s quite often.

[tree68]

Crowded as they may seem, there are places to put weight. Most of the "superstructure" of a slug is just weight, often concrete I believe, since it's cheap and easy to put where you want it. Adding extra steel between the frame members of a loco probably isn't all that hard to do, though I have to admit, I've never done it. Certainly different from adding Babbitt metal to the inside of the hood or boiler of an HO loco....