(3) 2-8-8-2 Q's

Discussion in '2-8-8-2 Mallet' started by trainchaser007 (Brandon Adams RIP 9/22/2017), May 13, 2010.

  1. trainchaser007 (Brandon Adams RIP 9/22/2017)

    trainchaser007 (Brandon Adams RIP 9/22/2017) Passed away September 22, 2017

    #1. Are there any surviving SLSF 2-8-8-2's?
    #2. If so, are there any SLSF 2-8-8-2's in operation - OR - retired but operational if it wasn't for those dang required boiler inspections...kind of like SLSF 1522?
    #3. Did the SLSF ever own a locomotive with a wheel arrangement larger than 2-8-8-2? According to wikipedia (which I know isn't fool proof by a long shot), UP was the only RR to own 4-8-8-4 Big Boys. I'm assuming that since I can't find any mention of anything larger than 2-8-8-2 on frisco.org, such SLSF's never existed... but I want to know for sure.
  2. klrwhizkid

    klrwhizkid Administrator Staff Member Administrator Frisco.org Supporter

    The seven Mallets that Frisco (#2000 - #2007) were built in 1910 by ALCo. Numbers 2000 - 2005 were originally assigned to the Kansas City, Fort Scott, & Memphis and #2006 & 2007 were assigned to the St Louis - San Francisco Ry Co. All were intended for service climbing the steep grades between Springfield and Thayer. Their tractive effort was directly linked to speed, so they were most powerful at a dismal 5 mph and fell off quickly with increasing speed. Their ridiculously small fireboxes for the size of the boiler and overall engine (despite compound steam operation) doomed them all to be scrapped in Birmingham from 1935 to 1937.
    These were the largest of all the Frisco steam locomotives, just ahead of the 2-10-2s.

    Both the 2-8-8-2s and the 2-10-2s were hard on the rails and roadbed with their small drivers and heavy linkages. The maximum speed allowed for the faster of the two series, the 2-10-2s was 35 mph due to the pounding they gave the rails. Ultimately the 2-10-2s met the same fate. All but two of the 2-10-2s were gone by 1940, with two serving on the Ft Leonard Wood branch for a few years before succumbing.

    Sources: Frisco Power, Collias and Steam Locomotives of the Frisco Line, Stagner
    Last edited by a moderator: May 14, 2010
  3. frisco1522

    frisco1522 Staff Member Staff Member

    My Dad remembered them and told me they leaked so badly that in the winter is was like running in a dense fog all the time.
    I think they all got cut up in the '30s after finishing out their days around Birmingham on the coal branches.
  4. Karl

    Karl 2008 Engineer of the Year Frisco.org Supporter

    The Grate Area of the Mallets compared favorably with that of the spot engines. Even with an ample GA, when compared to the spot engines, the engines "fell short" in all other areas used to transfer heat to the water/steam.

    Values are ft^2
    GA=Grate Area
    HSFB=Heating Surface Firebox
    HSF=Heating Surface Flues
    THS=Total Heating Surface
    SHS=Super Heating Surface
    EHS=Equivalent Heating Surface

    Three of the locomotives (2001, 2004, & 2007) received 39" piston valves on the low pressure steam chest. Locomotive 2007 received betterments to its tender or it may have received a new tender; it carried 21 tons of coal and 9125 gallons of water.

    Banwart's Ft Scott book shows the 2001 in Ft Scott

    2001 retired Apr 1939
    2002 retired July 1935
    2003 retired July 1935
    2004 retired Apr 1939
    2005 retired Dec 1929
    2006 retired July 1935
    2007 retired Apr 1936

    Last edited: Mar 26, 2019
  5. JamesP

    JamesP James Pekarek

    I did some more seat of the pants calculations just for fun to compare the spots to the mallets. At 15 mph, the spots would have had a swept cylinder volume of 3854 ft^3/min, compared to the mallet's effective swept volume (high pressure engine only) of 2896 ft^3 per min (compound). This means the mallets would have used just 75% of the steam as a spot engine, making the boiler stats look pretty good in favor of the mallets (86% of THS vs spots, but used only 75% of the steam). Tractive Effort for the mallets was 83500 lbs (compound) vs 71480 lbs for the spots (no booster) giving 16.8% more TE in normal operation (thanks to compounding).

    Now for the HOWEVER. The mallets could run simple, boosting their TE to an astounding 100000 lbs. Just as astounding is that this increased the swept volume of the cylinders to 10234 ft^3 per min! The actual steam usage wouldn't have increased 353% like the figures suggest, since the mallets would have had a pressure reducing valve for the LP engine while in simple operation. However, even if the steam usage doubled, the boiler would have been woefully undersized. A spot engine with the booster cut in could generate 80230 lbs of TE, although I don't know how much steam the booster would have used. This come's close to the mallets compound TE.

    Tweaking could have resulted in a more successful mallet, but only if they weren't operating as a simple engine at very low speeds trying to drag the tonnage over the hills. If they were operating as a compound on the hills, they should have been just as successful as a spot, assuming they weren't leaking away their efficiency. I also can't really quantify the effects of a mallet's softer exhaust blast on steaming ability due to lowered draft for the firebox.

    Regardless, both series of engines were doomed to be obsolete as the drag era came to an end. The mallets had a 57" driver diameter that was going to limit their top speed regardless of boiler capacity. Compare that to the 1500's 69" drivers, the 4300 & 4400's 70" drivers and the 4500's 74" drivers. Even the rebuilt 180 series Americans had 69" drivers. The mallet drivers were just 6" bigger than many of the 0-6-0 switchers. I bet the sight of a mallet going faster than 10 mph would make a section gang break out in a cold sweat!

    - James
  6. trainchaser007 (Brandon Adams RIP 9/22/2017)

    trainchaser007 (Brandon Adams RIP 9/22/2017) Passed away September 22, 2017

    OK, I get this much:
    1. Larger diameter driver = greater circumference = greater distance per revolution = increased speed. (It's sort of like gear ratios)
    2. Larger boilers needed larger fireboxes (right?)
    3. 2-8-8-2's small driver size and small fire boxes led to their downfall (right?)

    So why were the 4-8-8-4's seamingly so much more successful relative to the 2-8-8-2's? I understand that boiling water produces steam and steam pressure was used to move trains but even though I had an "A" in Physics 101, I was a music ed. major, not a steam engineering major so, please, put it in laymans terms.

    They must have increaed the firebox. Larger box = more fire = more heat = more steam.
    They also must have increased the driver diameter to increase speed.
  7. meteor910

    meteor910 2009 Engineer of the Year Staff Member Frisco.org Supporter

    There were many very successful 2-8-8-2 locomotives - one good example: N&W Y-class.

    The UP 4-6-6-4 (Challenger) and 4-8-8-4 (Big Boy) types had huge fireboxes and large, high pressure boilers, plus the ability to run at relatively high speed.

    The wheel arrangement isn't really the issue - it's steam capacity and pressure, plus the mechanical ability to turn that into TE, HP and speed.

    I have just run past the limit of my knowledge of successful steam locomotive design characteristics! :confused: There are many such experts here in frisco.org who could explain better than I.

  8. JamesP

    JamesP James Pekarek

    Ken, I think you summed it up very well. Now I'll do my best to muddy the waters...:D

    So why do 4-8-8-4's seem more successful than 2-8-8-2's? The UP articulates (they weren't mallets, since by definition a mallet is compound and the UP Big Boy and Challenger locos were simple) were a much more modern design than our beloved Frisco Mallets. The UP engines were designed to be fast freight (and passenger) locomotives - products of the school of Super Power design, while the Frisco locos were designed to be drag engines - who cares about speed, just give me the maximum tractive effort! Other railroads also had early compounds that suffered from not enough boiler - the Erie Triplex is an example that springs to mind.

    Lima pioneered the Super Power concept with a 2-8-4. The Berkshire was targeting fast freight, so it had to have a high TE and horsepower. For horsepower production at speed, an extra large firebox was needed so the four wheel trailing truck was used to support the weight. An appropriate driver diameter was used to keep rotational speed down at high speeds. The development of lightweight disc drivers and lighter reciprocating parts also helped with balance at high speed to minimize the tendency of the steam locomotive to pound the track out of alignment. Higher boiler pressures were used for greater power and efficiency. All of these design refinements found their way into the later engines, such as the Big Boy and Challenger.

    Comparing the UP articulateds to the Frisco Mallets is like comparing my 2009 Silverado to my Dad's 1946 Chevy 1/2 ton - two different schools of design from two different eras for two very different uses. Nevertheless, I wish I could have seen a Frisco Mallet in action!


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