Denver & Rio Grande Western 2-8-8-8-2/4 "Triplex" Locomotives of the USA


Class Details by Steve Llanso of Sweat House Media

Class Centipede 28 62 62/62 1/4 EEE (Locobase 6823)

In Locobase 3300, we profile the famous Erie P-1s, the helper engines that couldn't boil tea water because the vast capacity of their 6 equal-sized cylinders proved more than a match for the boiler and grate.

In the same year that Erie was testing the Matt Shay, Baldwin prepared a proposal for the Rio Grande. The diagram, preserved in a later diagram book (D&RGW 12 - 1937 Folio 10 supplied in May 2005 by Allen Stanley from his extensive Raildata collection), shows a locomotive whose design has been toned down. The cylinders are 2" smaller in diameter, but most of the other details were repeated.

This engine's firebox heating surface, which included 108 sq ft of combustion chamber and 88 sq ft of arch tubes, almost matched that of the Erie. The grate itself was deliberately limited to 80 sq ft through a "Gaines wall" such as that used in the Yellowstones (see Locobase 331), which was expected to raise interior temperatures. In the Erie's, which originally had a similar setup, the Gaines wall was removed when the grate proved much too small. Doubtless the same fix would have been resorted to had this locomotive ever entered service.

In the event, the Erie's experience probably dampened enthusiasm and the locomotive was not built.

Specifications by Steve Llanso of Sweat House Media
ClassCentipede 28 62 62/62 1/4 EEE
Locobase ID6823
RailroadDenver & Rio Grande Western (D&RGW)
CountryUSA
Whyte2-8-8-8-2
Number in Class
Road Numbers
GaugeStd
Number Built
BuilderBaldwin
Year
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase16.50'
Engine Wheelbase71.50'
Ratio of driving wheelbase to overall engine wheebase 0.23
Overall Wheelbase (engine & tender)90'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers720000 lbs
Engine Weight805000 lbs
Tender Light Weight
Total Engine and Tender Weight805000 lbs
Tender Water Capacity9500 gals
Tender Fuel Capacity (oil/coal)15 tons
Minimum weight of rail (calculated)100 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter58"
Boiler Pressure210 psi
High Pressure Cylinders (dia x stroke)34" x 32"
Low Pressure Cylinders (dia x stroke)34" x 32" (4)
Tractive Effort170769 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.22
Heating Ability
Firebox Area459 sq. ft
Grate Area80 sq. ft
Evaporative Heating Surface6198 sq. ft
Superheating Surface1436 sq. ft
Combined Heating Surface7634 sq. ft
Evaporative Heating Surface/Cylinder Volume184.32
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation16800
Same as above plus superheater percentage19992
Same as above but substitute firebox area for grate area114704
Power L16465
Power MT237.55

Reference


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