Great Northern 4-6-6-4 "Challenger" Locomotives in the USA

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The Great Northern Railway bought two 4-6-6-4s from its subsidiary, the Spokane, Portland & Seattle Railroad These two ALCO-built, former SP&S road numbers 903 and 904, were designated Class Z-6 and were given road numbers 4000 and 4001 on the Great Northern. They had four 23 x 32 cylinders, 69" drivers, a boiler pressure of 250 psi, a tractive effort of 104,500 lbs and weighed 621,000 pounds.

The two Great Northern "Challengers" were sold back to the SP&S, number 4000 in 1946 and 4001 in 1950.


Roster by Richard Duley

ClassQty.Road NumberYear Built Builder Notes
Z-6 24000-40011937ALCOThese locomotives were bought from the SP&S. Ex SP&S numbers 903 & 904. Number 4000 sold back to the SP&S in 1946 and number 4001 sold back to the SP&S in 1950.
Specifications for Class Z-6
Wheel Arrangement:4-6-6-4
Length:119' - 8"
Drivers:69" dia.
Weight on Drivers:436,000 lbs
Locomotive Weight:621,000 lbs
Locomotive & Tender Weight:1,014,700 lbs
Grate Area:152.3 sq ft
Cylinders (dia. x stroke):(4) 23" x 32"
Boiler Pressure:250 psi
Tractive Effort:104,500 lbs
Tender Capacity:
Water:20,000 gals.
Fuel Oil:6,000 gals.

Reference