Northern Pacific 2-6-6-2 Type Locomotives

Class Z (Locobase 1046)

Identical to the Great Northern's L-1s (Locobase 819) and fitted with a Belpaire firebox. Placed in helper service where they were rated at 850 tons up 2.2% grades. These were slow-speed engines, held by the railroad to 15 mph or less.

Data confirmed by locomotive diagrams from 1900 hosted on http://www.nprr.org/Steam%20Diagrams/Forms/AllItems.aspx (7 Feb 2004) and Tom Farin's http://www.ironhorse129.com/Prototype/Mallet/Baldwin65/NP_Mallett.jpg

Class Z-1 (Locobase 821)

Follow-ons to the Zs (record 1046), but significantly lighter and fitted with smaller cylinders. As with the Zs, these were a copy of a Great Northern design, in this case the L2 (Locobase 3554).

Data confirmed by locomotive diagrams from 1900 hosted on http://www.nprr.org/Steam%20Diagrams/Forms/AllItems.aspx (7 Feb 2004).

Specifications
ClassZZ-1
Locobase ID1046821
RailroadNorthern Pacific (NP)Northern Pacific (NP)
Whyte2-6-6-22-6-6-2
Road Numbers3000-30153100-3105
GaugeStdStd
BuilderBurnham, Williams & CoBaldwin
Year19071910
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase10' 9.83'
Engine Wheelbase44.83'43.75'
Ratio of driving wheelbase to overall engine wheebase 0.22 0.22
Overall Wheelbase (engine & tender)73.17'
Axle Loading (Maximum Weight per Axle)57000 lbs
Weight on Drivers316000 lbs250000 lbs
Engine Weight355000 lbs305150 lbs
Tender Light Weight152700 lbs154700 lbs
Total Engine and Tender Weight507700 lbs459850 lbs
Tender Water Capacity8000 gals8000 gals
Tender Fuel Capacity (oil/coal)3449 gals13 tons
Minimum weight per yard of rail on which locomotive could run87.78 lb rail69.44 lb rail
Geometry Relating to Tractive Effort
Driver Diameter55"55"
Boiler Pressure200 psi210 psi
Cylinders (dia x stroke)21.5" x 32"20" x 30"
Low Pressure Cylinders (dia x stroke)33" x 32"31" x 30"
Tractive Effort64193 lbs54999 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.92 4.55
Heating Ability
Firebox Area225 sq. ft214 sq. ft
Grate Area78 sq. ft53.42 sq. ft
Evaporative Heating Surface56084007
Superheating Surface
Combined Heating Surface56084007
Evaporative Heating Surface/Cylinder Volume417.07367.33
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1560011218.20
Same as above plus superheater percentage1560011218.20
Same as above but substitute firebox area for grate area4500044940
Power L13896.693729.21
Power MT163.12197.32

Reference

Credits

Introduction and specifications provided by Steve Llanso of Sweat House Media.

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