Questions about diesel switchers

[AltonFan]

AIUI, new emissions standards being phased in over the next ten or so years is forcing the railroads to start considering purchasing new switchers to meet those standards.

[CSSHEGEWISCH]

QUOTE: Originally posted by AltonFan

AIUI, new emissions standards being phased in over the next ten or so years is forcing the railroads to start considering purchasing new switchers to meet those standards.

California and Texas are just leading the way on this issue. The Houston metro area is under an EPA order to clean up their emissions drastically (Houston rivals Los Angeles for dirty air) and this also involves industry, such as railroads, construction, factory and refinery emissions, etc. Hence the need for low-emission switchers and light road switchers. California has long been ahead of the rest of the country on emissions issues.

[LVJJJ]

For switching up here in the extreme pacific northwest (up against the Canadian border Blaine, Bellingham, etc.), BNSF uses old GP-38's, GP-30's, even seen some GP-9's, all rebuilt of course. Haven't seen a "real" switcher in this area for decades. (been here since 1961). Whereas before the merger, all we got to see up here was green & black, now we have a rainbow of colors which makes for some very interesting lash-ups. In fact, I have a GP-30, N gage loco with the same road number as one of the old GP-30's running around up here (2817 I think). Now that's exciting, huh!! Larry in Blaine.

[dbradley]

Just a couple cents worth. The cyclopedia volume 2 states that and SW-1200 has was no lighter than a GP-9, but tighter turning. The New Haven, which I model, had souped up SW-1200's with full length hand rails, MU and flexicoil trucks for higher speeds and tracking over the road. One other thing that I understand restricted there use, was there lack of toilet facilities on board. I don't know if that was a state or railroad mandate.
I know more than a couple of cents worth, Sorry.

[f14aplusfl]

First off, its your railroad so you can do whatever you want. [:P] It also depends on what your modeling.

A number of railroads used SD38s for hump yard power thanks to their tractive effort for pushing frieght cars over the hump to be sorted via switches moved by our friend Issac Newton (gravity). At other times, a railroad might used what's readily available and on hand. Granted you probably won't want to use (or see often) a 9-44CW or SD70M for yard service but if thats what's available and there are cars that need to be switched, then the railroad will use them. Some railroads like the Florida East Coast Railway no longer operate switchers, in their place, you can find either GP38-2s or GP40/-2/-3s in there place. Statistically speaking you're more likely to get a GP40 model... and I think there is a GP40 outfitted with remote control equipment. I don't know if CSX uses remote control equipment but sometimes a switcher due to its smaller size, doesn't have the space for it.

Side note: To save money or due to the the length of the run in which a railroad bought a locomotive.... they might not have toliets on board.

[Anonymous]

Another perspective on the answers here...

Steam switchers usually had only coupled wheels in order to put all of the loco's weight into the tractive effort.
(When non-driven wheels are added they reduce the tractive effort by the amount of weight they carry...
so why have them?
At the front end it mostly relates to easing transition into curves and also supports some of the front end weight of the design - but some of the front end weight is put onto the leading wheels to ensure they stay on the track... but, contra to what might be inferred from one of the above, leading wheels do not make something more that can be derailed... okay they tend to derail more often than drivers.. that's because they get there first.
Trailing non-driven wheels usually result from boiler and firebox size and design... without a trailing axle or two there would be too much overhang and an imbalance of weight to the rear of the drivers...
why not more drivers to support the back end?
Some firebox designs don't leave space for more drivers. There is a limit to the number of drivers a combination af boiler/cylinders can usefully drive. There is a limit to the number of drivers that can work in a rigid frame on curves of different radii.
The other alternative is to go for an articulated loco... where the designers think this is appropriate... even there you often end up with leading and trailing non-powered axles)

Meanwhile ... back at switchers etc...

If you look at steamers you will see that as a general rule there were four classes of loco. Switchers, Freight, Mixed Traffic and Express.

Switchers had least non-driven axles and (generally) the smallest drivers. They could be pretty massive (I think 0-10-0 was the biggest non-artic) but they were designed for shifting heavy weight slowly. They also rarely went far from their home yard and fuel water supply.

Freight, from local to long distance heavy drag came next in wheel size. Locals tneded to have leading and trailing trucks so that they didn't have to be turned on long spurs. Long haul would turn or Y between trips. Both increased in size to fit their home range/division.

Mixed Traffic (more rare in the US I believe) came between freight and express - I use the word express rather than passenger because there were many smaller branch and suburban passengers that mix things up... and because some freight... reefers especially ran express - A mixed Traffic would haul perishables, milk, mail and reefers but could be bumped up to passenger express for Thanksgiving and other heavy holiday traffic periods.

Express. Not the biggest (that was the big freight) but usually the smartest with the biggest wheels for speed and frame/truck design for getting round the curves smoothly at speed. These were the least good at small moves... like setting cars into a terminal station... they tended to eat fuel and water... so again you didn't want them messing about getting their train out of a carriage yard and hanging about in the terminal. Much better for a switcher to do the donkey work and have the thoroughbred drop onto the train at almost the last minute fully stocked for the journey.

OKAY...

SO DIESELS.

people tend to design by what they know.

So the first express diesels (that developed into the E8s and E9s) were streamlined throroughbreds. Suitable gearing for getting there in a hurry.
It's interesting to notice that right from the start they were effectively "cab ahead" units despite the fact that early freight soon switched from the "cab ahead" F and similar units to long-hood forward hood units. I mention this because we tend to assume that diesels ran long-hood forward following the usual order of boiler-cab on a steamer.... but the Covered Wagons broke this convention right at the start.
There was another advantage to the big passenger diesels... they could run through saving journey time taken by changing steamers. (For newbies steam engines were like stage-coach horses... they could only be run so far before they had to be serviced).

I'm not an expert on what came where, when from whom but my first thoughts on this subject were that Alco distinguished between its "S" switchers, "RS" road switchers and Passenger classes (The DL109s were really fast passenger but called Mixed Traffic to get them by war time building restrictions - same thing happened in the UK with at least the Merchant Navy Class "Spam Cans").

I think that Road Switcher goes a long way to explain what went on and what has developed. The RSs and later GPs - General Purpose - were mules, oxen or medium carthorses. They could switch most yards, work on the main and work the lighter branch lines They were exactly general purpose for switching and road use.

EMD decided that the big diesels with six axles were "SD" = Special Duties... hauling coal and ore... the big stuff needing muscle.
Alco fought back with their Century series but GE pulled the master stroke by designating all their locos "U" = Universal... go anywhere, do anything. One basic breed of locos, one basic set of spares...

Then things got BIGGER... so size for size an early SD now compares to one of the big AC things in the way that a GP used to compare to it.

As has been noted there is still demand for the small switchers or small GPs. The locos not much mentioned here are the small industrials and critters. They still quietly do their bit where appropriate.

Also, a completely different issue... passenger diesels have seperated off into a completely different line of development.

Q2 People have covered where switchers appear. the simple answer is "where they are most suitable and available.
Q3 Horse Power... Also answered.But it's not just raw horsepower... it's getting the power on the rail... so there have been devekopments in traction control and there are slugs. There are also DPUs (Distributed Power Units)... which also factor into the whole equation of what sort of loco to do the job.

BUT Qs 2&3... what happens is a mix of what is available (including what cash is available), what is best suited ... and that means what power is needed, track conditions, loads and all sorts. The solution is not just switchers, GPs, SDs or modern big power but what will get the right amount of power down most cost effectively.

If a job is best haued by a pair of ACs... say a unit coal train... it may also be appropriate for them to stay on the train for the slow crawl to load or unload on the move. Elsewhere it may be appropriate for a switcher to dawdle off along the main with a couple of cars.

Then there's cow-calf combination, slugs and things...

Hope this helps.

Er... what I haven't said but others have commented on is that diesels get different wheel sizes to a small degree but lots of different gear ratios and turbos or not turbos. these don't show up in the same way that different sized drivers and wheel arrangements did on steamers. This led very rapidly to steam fans saying that diesels were boring because they all looked the same. The biggest give away is often in special trucks... and that gets knobbled by RRs trading in trucks... Fuel tank size and dynamic brakes make a difference... but never as much as between a heavy freight and a light passenger steamer.

[Anonymous]

Speaking of Cows and Calfs.... what exactly was the purpose of a calf? Were the just a cab-less switcher designed for MU lashups in areas where more horsepower was needed, but not the extra cab? Or were they more like today's modern slugs? Lots of weight for extra tractive effort for switching manuevers, but not much else in the way of usefulness?

I notice very few roads use 'calfs' anymore, unless you consider slugs, so they must've been an idea that was outgrown in time.

[DanRaitz]

Calfs were just that "cab-less switchers", you could call them the "B-unit" of the switcher world.
Slugs are a different matter, as they do not have any prime-mover (diesel engine) installed or any means of self-propulsion. They recieve power to run it's traction motors from another diesel.

Dan

[CSSHEGEWISCH]

Slugs are strictly low-speed designs that allow additional horsepower to become useful at low speeds. Because of adhesion limits, a high-horsepower design like a GP40 is no more useful in yard service than a GP7. A slug raises the adhesion limit by putting additional weight over additional drivers at the same horsepower. At low speeds, a GP40/slug set becomes the functional equivalent of 2 GP7's. Because a slug has no prime mover, it serves no useful purpose at speeds where the horsepower produced by the slug mother can be used without being affected by adhesion limits.