Boston & Maine 2-8-0 "Consolidation" Type Locomotives

Class K-5 (Locobase 4123)

A batch of simple-expansion consolidations that roamed all over the system. They were retired during the 1926-1936 decade.

Class K-6 (Locobase 3274)

These cross-compounds ran for the better part of two decades before being rebuilt as simples. See Railway Age (21 Jan 1921 - Vol 70, # 3).

Class K-6 simpled (Locobase 3275)

As Railway Age (21 Jan 1921 - Vol 70, # 3) noted in its coverage of rebuilding programs on the Boston & Maine, "It can easily be imagined just how unsatisfactory a saturated steam cross-compound Consolidation type locomotive of these dimensions would prove under modern conditions, both from an operating and maintenance standpoint."

Notice where the changes were made: Cylinder stroke was shortened by 2 inches, and both now had piston valves actuated by Walschaerts radial gear. Total heating surface shrank by 370 sq ft, but the steam was now superheated when it reached the cylinders. Weight grew only slightly and the grate was untouched.

The rebuild added about 10-15 years to the design's life and the class retired between 1928 and 1935.

Class K-7 (Locobase 2382)

Data from 1927 and 1947 Boston & Maine Description of Locomotives books supplied in May 2005 by Allen Stanley from his extensive collection.

This was the smaller of the two main Consolidation classes operated by the B & M. Those that were not superheated (see Locobase 6627) were scrapped in the 1920s and 1930s.

Class K-7b/c - superheated (Locobase 6627)

Data from 1927 and 1947 Boston & Maine Description of Locomotives books supplied in May 2005 by Allen Stanley from his extensive collection.

When the K-7 engines shown in Locobase 2382 were superheated, this was the result. Drier steam more than made up for the 16% loss in overall heating surface.

Class K-8/original (Locobase 3276)

A notably large class of Consolidations using piston valves, but saturated steam. Firebox heating surface included 25 sq ft of arch tubes.

This class, delivered from Alco-Schenectady, Alco-Brooks, and Baldwin over a 5-year period, was superheated in a 1916 rebuild; see K-8/superheated. Railway Age (21 Jan 1921 - Vol 70, # 3)

Class K-8/superheated (Locobase 3277)

Data from 1927 and 1947 Boston & Maine Description of Locomotives books supplied in May 2005 by Allen Stanley from his extensive collection.

Railway Age (21 Jan 1921 - Vol 70, # 3) reveals the subtle differences that went into superheating this large class of Consolidations. Cylinder size grew by 2 inches. The boiler was rearranged to accept 30 superheater elements, while working boiler pressure was eased by 40 psi. The designers obviously felt that the more potent dry steam would allow them to back off on the pressure to improve reliability.

The 1947 books show 8 fewer boiler tubes than the 204 counted in the 1921 article. The discrepancy is explained by noting that by that time, the firebox had been reworked with 62.5 sq ft of thermic syphon and only 1 arch tube of 12.6 sq ft; these areas are included in the firebox heating surface.

The rebuilds ran on for years, with the first retirements beginning in 1937, but not ending until 1954. Bangor & Aroostook bought 2 in 1946.

Specifications
ClassK-5K-6K-6 simpledK-7K-7b/c - superheatedK-8/originalK-8/superheated
Locobase ID4123327432752382662732763277
RailroadBoston & MaineBoston & MaineBoston & MaineBoston & MaineBoston & MaineBoston & MaineBoston & Maine
Whyte2-8-02-8-02-8-02-8-02-8-02-8-02-8-0
Road Numbers2310-23432350-23592350-23592360-24292360-24292600-27342600-2734
GaugeStdStdStdStdStdStdStd
BuilderAlco-SchenectadyAlco-SchenectadyB & MAlco-SchenectadyAlco-SchenectadyseveralB & M
Year190119011920190519111916
Valve GearStephensonStephensonWalschaertWalschaertWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase17'17'17'17'17'17'17'
Engine Wheelbase25.50'25.50'25.50'25.50'25.50'26'26'
Ratio of driving wheelbase to overall engine wheebase 0.67 0.67 0.67 0.67 0.67 0.65 0.65
Overall Wheelbase (engine & tender)53.86'53.86'58.06'58.06'
Axle Loading (Maximum Weight per Axle)37900 lbs37900 lbs52500 lbs
Weight on Drivers142000 lbs150000 lbs153000 lbs148000 lbs151600 lbs182000 lbs197100 lbs
Engine Weight162000 lbs175000 lbs178000 lbs170000 lbs176600 lbs206000 lbs222500 lbs
Tender Light Weight118000 lbs118000 lbs163000 lbs152900 lbs
Total Engine and Tender Weight000288000 lbs294600 lbs369000 lbs375400 lbs
Tender Water Capacity5000 gals5000 gals5000 gals7300 gals7300 gals
Tender Fuel Capacity (oil/coal)10 tons tons tons14 tons14 tons16 tons16 tons
Minimum weight per yard of rail on which locomotive could run59.17 lb rail62.50 lb rail63.75 lb rail61.67 lb rail63.17 lb rail75.83 lb rail82.12 lb rail
Geometry Relating to Tractive Effort
Driver Diameter60"61"61"61"61"61"61"
Boiler Pressure200 psi200 psi200 psi200 psi200 psi220 psi180 psi
Cylinders (dia x stroke)20" x 30"22" x 32" (1)20" x 30"20" x 30"20" x 30"22" x 30"24" x 30"
Tractive Effort34000 lbs30939 lbs33443 lbs33443 lbs33443 lbs44512 lbs43342 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.18 4.85 4.57 4.43 4.53 4.09 4.55
Heating Ability
Firebox Area143 sq. ft143 sq. ft143 sq. ft158 sq. ft158 sq. ft205 sq. ft247.10 sq. ft
Grate Area46.51 sq. ft46.04 sq. ft46.04 sq. ft46.50 sq. ft46.50 sq. ft53.24 sq. ft53.24 sq. ft
Evaporative Heating Surface2860286020602860204631892369
Superheating Surface431437520
Combined Heating Surface2860286024912860248331892889
Evaporative Heating Surface/Cylinder Volume262.19406.28188.85262.19187.56241.61150.82
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation9302920892089300930011712.809583.20
Same as above plus superheater percentage9302920810801.19930010936.7711712.8011308.11
Same as above but substitute firebox area for grate area286002860033548.453160037161.504510052483.73
Power L16554.644079.9312403.216803.6812617.577140.909651.56
Power MT407.06239.86714.89405.39733.96346.00431.82

Credits

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

This page last modified: . [Contact] All material © 1999-2008 SteamLocomotive.com