N&W class M

N&W M class
N&W #450, the very first M, in its 1906 Baldwin portrait.
Power type	Steam
Builder	Baldwin Locomotive Works (50); ALCO-Richmond (75)
Build date	1906
Total produced	125
Configuration	4-8-0
Gauge	4 ft 8 1⁄2 in (1,435 mm)
Leading wheel diameter	27 in (686 mm)
Driver diameter	56 in (1,422 mm)
Length	74 ft 11 3⁄4 in (22.85 m)
Height	15 ft 5 in (4.70 m)
Weight on drivers	160,000 lb (73 tonnes)
Locomotive weight	200,000 lb (90.7 tonnes)
Fuel type	Coal
Fuel capacity	40,000 lb (18.1 tonnes)
Water capacity	12,000 US gal (45,000 l; 10,000 imp gal)
Boiler pressure	200 lbf/in² (1.38 MPa)
Heating surface: Total	2,940 sq ft (273.1 m2)
Cylinders	Two
Cylinder size	21 × 30 in (533 × 762 mm)
Valve gear	Stephenson (inside); Some later coverted to Baker
Valve type	12-inch (300 mm) piston valves
Tractive effort	40,163 lbf (178.65 kN)
Career	Norfolk & Western Railway
Class	M
Number	375–499
Preserved	4

N&W M1 class
Power type	Steam
Only differences from class M above are shown
Builder	Baldwin (50), ALCO-Richmond (50)
Build date	1907
Total produced	100
Valve gear	Walschaerts
Career	Norfolk & Western Railway
Class	M1
Number	1000–1099

N&W M2 class
N&W #1138 in its Baldwin portrait.
Power type	Steam
Builder	Baldwin (50); N&W Roanoke Shops (11)
Serial number	Roanoke 182–192
Build date	1910
Total produced	61
Configuration	4-8-0
Gauge	4 ft 8 1⁄2 in (1,435 mm)
Driver diameter	56 in (1.422 m)
Boiler pressure	200 psi (1.38 MPa)
Heating surface: Total	4,041 sq ft (4,315 if superheater fitted)
Cylinders	Two
Cylinder size	24×30 in (540×762 mm)
Valve gear	Walschaerts (Baldwin built); Baker (Roanoke built)
Tractive effort	52,457 lbf (233.34 kN)
Career	Norfolk & Western Railway
Class	M2
Number	1100–1160

The Norfolk and Western Railway's M, M1 and M2 classes (also known as the "Mastodon-class") were a series of 4-8-0 steam locomotives owned and operated by the Norfolk and Western Railway. These were the last significant deliveries of 4-8-0s in the United States. The N&W needed to get coal shipments over a mountain range, and powerful locomotives were needed. 4-8-0s were chosen over 2-8-2s because the 4-8-0 had better adhesive weight. Thus, in 1906, the first of the most numerous American class of 4-8-0 was contracted and built by Baldwin. The M1 class only differed from the M in valve gear. Because the M1's valve gear was poorly designed, there was excessive wear, making it impossible to keep them in alignment and valves properly set. Unsurprisingly, the M1's were the first to be retired.

Survivors

Several locomotives survive. The most well known is No. 475, part of the 1906 order, which is currently operating on the Strasburg Rail Road in Pennsylvania. No. 433, also of the 1906 order, is an outdoors static exhibit in a park Abingdon, Virginia, with a basic roof to protect it from rain. There are also two M2 locomotives, numbers 1118, 1134, and one M2c, 1151, which have resided in the Virginia Scrap Iron & Metal yard since the early 1950s until 2009. M2c #1151 was moved on 21 August 2009, M2 #1134 moved on 24 August, and M2 #1118 on 26 August. 1134 will receive cosmetic restoration and move to Portsmouth, Virginia. 1118 was traded for 0-6-0T no. 34 and will remain at NRHS chapter's 9th Street facility. 1151 was moved to the Virginia Museum of Transportation in Roanoke.

See also

4-8-0

4-8-0 475

References

• Carling, D. Rock (1972). 4-8-0 Tender Locomotives. Drake Publishers Inc.. ISBN 87749-150-X. 
• Rosenberg, Ron; Archer, Eric H. (1973). Norfolk & Western Steam (The Last 25 Years). New York, NY: Quadrant Press, Inc.. pp. 11–16, 77–78. ISBN 0-915276-00-3. 
• The Lost Engines Of Roanoke Maintained by Richard Jenkins
• The Western Virginia Railroad Preservation Society
• Photos of 1151's move.
• Photos of 1118's move.
• Norfolk & Western 4-8-0 "Mastodon" Type Locomotives. (Steamlocomotive.com)