Chicago and North Western Z Class

C&NW class Z Omaha Road class Z
C&NW 1455, the first of the class Z (Alco 46607 of 1909)
Type and origin Power type Steam Builder American Locomotive Company (226) Baldwin Locomotive Works (25) Serial number see table Build date 1909–1913 Total produced 251
Specifications Configuration: ​  • Whyte 2-8-0  • UIC 1′D n2, later 1′D h2 Gauge 4 ft 8+1⁄2 in (1,435 mm) Driver dia. 61 in (1.549 m) Wheelbase 36 ft 5 in (11 m) Loco weight 235,000–243,500 pounds (106,600–110,400 kg) Firebox: ​  • Grate area 52.68 sq ft (4.894 m2) (108 in × 70+1⁄4 in or 2.743 m × 1.784 m) Boiler: ​  • Diameter 81+1⁄2 in (2.070 m) Boiler pressure 170 lbf/in2 (1.17 MPa) Cylinders Two, outside Cylinder size 25 in × 32 in (635 mm × 813 mm) Valve gear Walschaerts or Baker Valve type 14 in (360 mm) piston valves Valve travel 6 in (150 mm)
Performance figures Tractive effort 47,500 lbf (211.29 kN)
Career Operators Chicago and North Western Railway Omaha Road Number in class CNW: 249 CMO: 2 Numbers CNW: 1455–1494, 1700–1910 CMO: 219–220 Disposition All scrapped

The Chicago and North Western Railway class Z (and Omaha Road class Z) was a class of 251 American 2-8-0 locomotives. They were built between 1909 and 1913, when production switched to the larger class J 2-8-2 locomotives. The class letter spawned their nickname amongst C&NW and Omaha Road crews: "Zulu".^[1]

The locomotives has boiler pressed to 170 pounds per square inch (1.2 MPa) feeding steam to two cylinders that had a 25-inch (640 mm) bore and a 32-inch (810 mm) stroke. These were connected to 61-inch (1,500 mm) driving wheels buy Walschaerts valve gear, although the last 47 were built with Baker valve gear. They had 14-inch (360 mm) piston valves with 6 inches (150 mm) travel. The firebox was of the radial-stay pattern, 108 inches (2,700 mm) deep by 70+1⁄4 inches (1,780 mm) wide. The resulting 52.68 square feet (4.894 m²) was 14 per cent larger than the class R-1.

Apart from a batch of 25 built by the Baldwin Locomotive Works, all the locomotives were built by the American Locomotive Company at their Schenectady plant. Baldwin classified their locomotives as 10-48-E

On the C&NW, they were used system-wide on freight trains, and were the principle freight-hauling locomotive on the railway until the arrival of the class J Mikados. The extra power over the existing freight locomotives enabled running 75-car trains; unfortunately, older wooden-framed freight cars could not stand the punishment and a large number of "bad-ordered" cars required repairs.^[1] The Omaha Road used its pair, like all its 2-8-0s, in switching, transfer and helper service.^[4] They had in fact been delivered a week after the Omaha Road's first class J 2-8-2 locomotives.^[5]

When new all had been built as hand-fired coal-burning locomotives. The large grates were tricky to fire and several firemen resigned as a result.^[1] At least 17 were fitted-up for oil-firing for use in Wyoming, where fuel oil was readily available. Twelve others received mechanical stokers during World War II.

In 1942, several locomotives were leased out to other operators; by war's end, these had either been purchased or returned. Sales included five to American Smelting and Refining Company (ASRCo), five to the Seaboard Air Line Railroad (SAL), two to the St. Louis Southwestern Railway (Cotton Belt or SSW), 25 to the Ferrocarriles Nacionales de México (NdeM) directly, and another seven via a dealer. They also later acquired ASRCo's five.

The first retirement was in 1936; fifty were still in service in mid-1948. The Omaha Road retired both of its Zulus in June 1956.^[3]

No locomotives of this class have been preserved.

• Cole, F.A. (1938). Locomotives of the Chicago & North Western Railway. Boston: The Railway & Locomotive Historical Society.
• Chicago and North Western Railway (1948). Locomotives of the Chicago & North Western Railway, supplement. The Railway & Locomotive Historical Society.
• Drury, George H. (1985). The Historical Guide to North American Railroads. Milwaukee, Wisconsin: Kalmbach Publishing Company. ISBN 0-89024-072-8. LCCN 85080107.
• Mailer, Stan (2004). The Omaha Road: Chicago, St. Paul, Minneapolis & Omaha. Mukilteo, Washington: Hundman Publishing. ISBN 0-945434-04-9. OL 8448884M.
• Barrie, Wes. "Chicago & North Western / Chicago, St Paul, Minneapolis & Omaha 2-8-0 "Consolidation" Locomotives in the USA". steamlocomotive.com. Retrieved 2020-05-01.