Pere Marquette 4-6-2 "Pacific" Locomotives of the USA


Class Details by Steve Llanso of Sweat House Media

Class P2 (Locobase 9286)

Data from PM 3 1929 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. Roster information developed by Art Million and Tom Dixon and presented on the Pere Marquette Historical Society website (http://www.pmhistsoc.org/stmrostr.shtml, accessed 1 March 2008).

This quintet of high-drivered Pacifics (works #48001-48005) went into service with saturated boilers, Locobase is almost certain. They were pretty small in comparison to other US 4-6-2s when delivered and among the express-passenger sub-group they were perhaps the smallest to go into service. Near-cousins were the Harriman Pacifics delivered to several lines, but these had bigger grates.


Class SP (Locobase 7604)

Data from reproduction of 1913 Alco Bulletin 1016 on Richard Leonard's http://www.railarchive.net/alcopacifics/index.html (accessed 16 June 2006).

These were the second quintet of Pacifics (works #50044-50048) to come on the PM. Compared to other 4-6-2s of the time, the design was relatively small and light. But useful, apparently, and so in service until 1948.


Class SP2 (Locobase 9288)

Data from PM 3 1929 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. See also DeGolyer, Volume 50, pp. 175+. Roster information developed by Art Million and Tom Dixon and presented on the Pere Marquette Historical Society website (http://www.pmhistsoc.org/stmrostr.shtml, accessed 1 March 2008).

Works numbers ran 41310-41314 in April 1914.

This set of Pacifics was so like those of the Chicago Great Western (Locobase 4175) that they might as well have been built as a single batch. They were the biggest Pacifics on the PM and were comparatively large for the time, as were their 15" (381 mm) inside adminssion piston valves. When delivered, their tenders had the same capacity but weighed 144,000 lb (65,317 kg). The locomotives had Gaines combustion chambers, which divided a large firebox into two sections using a half wall.

Presumably they were intended for similar service as mainline passenger engines, a service doubtless responsible for the injunction: "Particular attention to be given to make tender ride easily and smoothly.".

Like the PM's other 4-6-2s, these locomotives operated into the late 1940s. In the last two years of their careers, they wore the colors of the Chesapeake & Ohio and fell in the F-12 class as 405-409. 406 was scrapped in April 1948; the others went in April 1949 (405, 407) and May (408-409).


Class SP3 (Locobase 9287)

Data from PM 3 1929 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. Roster information developed by Art Million and Tom Dixon and presented on the Pere Marquette Historical Society website (http://www.pmhistsoc.org/stmrostr.shtml, accessed 1 March 2008).

Works numbers ran 62582-62593. Sized to meet the PM's express-passenger needs, these were relatively small and light Pacifics. Firebox heating surface, which included 25 sq ft of arch tubes, was surprisingly low, yet the whole heating system seems appropriately sized for the cylinder volume.

They remained in service until 1950.

Specifications by Steve Llanso of Sweat House Media
ClassP2SPSP2SP3
Locobase ID9286 7604 9288 9287
RailroadPere Marquette (PM)Pere Marquette (PM)Pere Marquette (PM)Pere Marquette (PM)
CountryUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-2
Number in Class55512
Road Numbers701-705706-710725-729711-722
GaugeStdStdStdStd
Number Built55512
BuilderAlcoAlcoBaldwinAlco-Brooks
Year1910191119141921
Valve GearWalschaertWalschaertWalschaertBaker
Locomotive Length and Weight
Driver Wheelbase13.33'13.33'13'13.33'
Engine Wheelbase33.83'33.83'35.33'34.50'
Ratio of driving wheelbase to overall engine wheebase 0.39 0.39 0.37 0.39
Overall Wheelbase (engine & tender)65.27'63.27'66.03'69.06'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers139000 lbs142500 lbs156000 lbs149000 lbs
Engine Weight216000 lbs220000 lbs257000 lbs243000 lbs
Tender Light Weight144000 lbs141700 lbs153000 lbs172900 lbs
Total Engine and Tender Weight360000 lbs361700 lbs410000 lbs415900 lbs
Tender Water Capacity7000 gals7000 gals8000 gals8000 gals
Tender Fuel Capacity (oil/coal)14 tons14 tons11 tons14 tons
Minimum weight of rail (calculated)77 lb/yard79 lb/yard87 lb/yard83 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter77"77"73"77"
Boiler Pressure200 psi200 psi190 psi190 psi
Cylinders (dia x stroke)22" x 26"22" x 28"25" x 28"23" x 28"
Tractive Effort27783 lbs29920 lbs38716 lbs31067 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.00 4.76 4.03 4.80
Heating Ability
Firebox Area185 sq. ft152 sq. ft258.20 sq. ft185 sq. ft
Grate Area43.90 sq. ft43 sq. ft56 sq. ft50.20 sq. ft
Evaporative Heating Surface2762 sq. ft2733 sq. ft3746 sq. ft2803 sq. ft
Superheating Surface557 sq. ft557 sq. ft794 sq. ft648 sq. ft
Combined Heating Surface3319 sq. ft3290 sq. ft4540 sq. ft3451 sq. ft
Evaporative Heating Surface/Cylinder Volume241.45221.85235.48208.18
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation87808600106409538
Same as above plus superheater percentage10273100621244911350
Same as above but substitute firebox area for grate area43290355685739841829
Power L119521177221770417313
Power MT928.84822.53750.59768.50

Reference


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