While researching the Milwaukee Road's roster I noticed many of their 1st generation road switchers; SD7, SD9, H16-66 etc, have very small fuel tanks. Why is this? Does it have something to do with locomotive weight? I know the SDL39 was built specifically for branch line service and it also has a small fuel tank.
Almost any time you see a small tank, it’s weight.
The exception is that if the unit has a steam generator there needs to be water tankage too (and water is relatively heavy) and if both tanks are slung between the trucks the fuel tank may be shorter or narrower than it could be in a freight-only unit.
You should have seen some of the WSOR tracks before they were upgraded to 40-50 mph. Milwaukee in the 1970's and into the 1980's would operate Geeps and later MP15AC's on some of the worst track you ever saw loaded with 5 and 10 mph limits. Ties sunk below the mud with weeds up almost waist high. They would run 25-50 miles on a branch line like that and if it was 100 miles they would have the switching patrols meet in the middle.....as long as everything stayed on the track, they kept running.
One would think they could have used regular sized tanks but just filled them part way.......
Could it be that engineers were still paid by max weight on drivers?
Bruce FrierdichOne would think they could have used regular sized tanks but just filled them part way.......
So you want a guy that is filling the tank to be responsible when the now overweight engine for the particular segment of track derails?
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blue streak 1 Could it be that engineers were still paid by max weight on drivers?
Couldn't they modify the fuel filler pipes to limit capacity? I believe Union Pacific went that route to drop the fuel capacity of their SD9043MAC's to help address frame stress that was causing cracks.
Although in the Milawaukee's case, it makes more sense that they went down this route. Yields a slightly cheaper locomotive to acquire and if they're just planning to run the locomotive on branches and such with bad track, there's little reason to be concerned about the possibility of one day upping a unit's fuel capacity.
Don't forget that the Milw began as a Granger and was cursed with miles of branch lines that had track that was put down before (in some cases long before) the Great War.
Second, IIRC, the size of fuel tank was an option that the buyer could pick and I would expect a smaller tank was cheaper than a larger. You might say, "but that's such a small difference", but don't forget, the MILW wasn't exactly swimming in cash post WW2.
Also, smaller fuel tanks were at least several hundred pounds lighter than large ones. If you're trying to reduce as much weight as you can, that's an obvious place to start.
The Milw only put a 3200 gallon tank on them IIRC that is the same size that came on the GP series. The standard tank for a SD40-2 was 5K gallons just in fuel alone they saved 5 tons in weight and maybe another 2-3 tons in the tank. Minimal savings on a locomotive that large but it also meant that they could have one set point for their 40 series of locomotives.
BEAUSABREDon't forget that the Milw began as a Granger and was cursed with miles of branch lines that had track that was put down before (in some cases long before) the Great War.
Yes, in fact the Milwaukee had a fair number of branch lines in Minnesota and Iowa that were originally built in the 1880s - as 3' narrow gauge lines. Even when they were converted to standard gauge (some stayed narrow into the 1930s), things like old bridges restricted the weight of the engines that could run on the lines.
Shadow the Cats owner The Milw only put a 3200 gallon tank on them IIRC that is the same size that came on the GP series. The standard tank for a SD40-2 was 5K gallons just in fuel alone they saved 5 tons in weight and maybe another 2-3 tons in the tank. Minimal savings on a locomotive that large but it also meant that they could have one set point for their 40 series of locomotives.
I believe 4,000 Gal was the max fuel tank you could get on a SD40-2.
I think the only SDs with 5000gal fuel tanks were the Erie Lackawanna's SDP45s, that were ordered as "P's" just because they had a longer frame that would accommodate the larger tank.
The 18 SD40A's for Illinois Central were constructed on the SDP45's longer 71' 8" frame in order to accomodate a 5,000 gallon fuel tank.
Erie Lackawanna's SD45-2's also had 5,000 gallon fuel tanks. Quite noticeable on those still on Norfolk Southern's roster (The NSDash9 roster page also quotes 5,000 gallon tanks in the specs for them).
Unless my recollections are inaccurate, the SD45-2 and SD40-2's frame were of the same length. So if a SD45-2 can accomodate a 5,000 gallon tank, I don't see why a SD40-2 couldn't?
The Erie Lackawanna SD45-2 had the air tanks moved into the carbody under the radiators. This allowed for the extra 600 gallons over the SD40-s or regular SD45-2.
For reference standard SD40 and SD45 locomotives had 4000 gallon capacity max. The SD38 and SD39 were similar. The Dash-2 versions had a maximum of 4400 gallons unless something was done like to the E-L locomotives. With the production 50 and 60 series locomotives and their longer frame 5000 gallon tanks could be accomodated.
Thought of more examples. The SD40 and SD40-2 fleet for Quebec North Shore & Labrador have oversize fuel tanks of ~5,000 gallon capacity, with the air reservoirs tucked away presumably in the long hood somewhere.
Weight, the branchlines off the mainline had original rail from when it was first laid in 1918 (Montana branch lines) They ran GP38s with the small fuel tank.
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"Stock" SD7s and SD9s had two 1200 gallon tanks, one fuel, one water (for steam generator). If the "delete steam generator" option was chosen, the SD7/9 came with a single 1200 gallon tank. Soo Line 2381 is an example. SP converted the water tank to fuel on some, but not all of their SD7/9s as the steam generators were removed. On a few of them, they just removed the water tank. Some were built with dual fuel tanks at "customer option".
GP7/GP9 passenger units often had the air tanks moved to the roof ("Torpedo boats") to make fuel and/or water space.
Their SD40-2s were also delivered with small fuel tanks. I think there might have been weight restrictions imposed by some of the Milwaukee's spindly steel bridges in places out west (Washington in particular) on the PCE that led to those smaller fuel tanks. I can't seem to find the reference.
I don't think the mainline bridges would call for weight restrictions, but the Milwaukee had a number of branch lines with 60 to 75 pound rail.
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