Philadelphia & Reading 2-8-2 "Mikado" Locomotives in the USA

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The Reading Company was established in the 1890s as a holding company with its major holding being the Philadelphia & Reading Railroad and The Philadelphia & Reading Coal and Iron Co. Its operations included coal mining, iron making, canal and sea-going transportation and shipbuilding. In 1924, the P&RC&I became a separate corporation and the Philadelphia & Reading Railroad became simply the Reading Company. With its great complex of shops for locomotive and car building and repair, the railroad held a position of leadership in the railroad industry.

In 1912, the Philadelphia & Reading Railroad built an experimental "Mikado" locomotive at the Reading shops. This locomotive had 61.5" diameter drivers, 24" x 32" cylinders, a 215 psi boiler pressure, it exerted 54,772 pounds of tractive effort and it weighed 329,310 pounds. The firebox was 326 square feet, the evaporative heating surface was 4,224 square feet and with the superheater the combined heating surface was 5,217 square feet. The design of this 2-8-2 which was given road number 1700 was deemed to be a success

In1917, the Baldwin Locomotive Works was given an order to build 56 locomotives based on this design in two subclasses. The first 26 of these "Mikados" had 61 ½" diameter drivers and were classified as Class M1-sa and assigned road numbers 1701-1726. The other 30 were built with 55 ½" diameter drivers and classified as Class M1-sb and assigned road numbers 1727-1756. All 56 of these 2-8-2s had 24" x 32" cylinders, they were delivered with a 215 psi boiler pressure and the M1-sa class exerted 54,772 pounds of tractive effort and the M1-sb class exerted 60,693 pounds of tractive effort.

These Class M1-sa and M1-sb locomotives used superheated steam and had Wootten boilers and a grate area of 108 square feet. The Wootten boiler was designed in 1877 to burn small sizes of cheap anthracite coal. Slow burning anthracite required a very large grate area to achieve the same heat as a much smaller one that burned bituminous coal. The firebox was extremely wide and shallow at the bottom and had a crown sheet curved with a large radius. The design permitted a thin fire and a light draft, which avoided blowing fuel out of the stack. The firebox was 298 square feet, the evaporative heating surface was 3,803 square feet and with the superheater the combined heating surface was 4,640 square feet.

There are no surviving Reading 2-8-2 .Mikado. type locomotives.

Roster by Richard Duley

ClassQty.Road NumbersYear BuiltBuilderNotes
M1-sa 117001912Reading1
  1. All steam locomotives were gone by 1950.

Class Details by Steve Llanso of Sweat House Media

Class M-1 (Locobase 11023)

Data from Record of Recent Construction #98 (Baldwin Locomotive Works, 1920), p. 31 and Proceedings of the Annual Convention of the International Railway Fuel Association (Published by The Association, 1914), p. 346. See also DeGolyer, Volume 49, pp. 318+ and Volume 51, p. 186. Baldwin works numbers were


December 41029-41030, 41052


January 41089, 41094, 41106


November 42673-42686, December 42728-42733

Known as "Big Dutch Mikes", these had the enormous Wooten boiler in a conventional-cab arrangement. The first of the class was built in the Reading shops and had a saturated boiler with a heating surface area of 5,508 sq ft, of which 298 sq ft came from the firebox and combustion chamber. The remaining 2-8-2 were produced in two versions: this one, with the 61 1/2" drivers and the M1sb with smaller drivers and a lower boiler pressure (see Locobase 9548).

The M1s had a 36"(914 mm) high wall separating the firebox proper from the 81 sq ft (7.53 sq m) combustion chamber and 14" (356 mm) piston valves. They burned a mixture of hard (fine anthracite) and soft coal.

In the mid-1920s, the Reading reworked the boilers considerably while increasing the cylinder volume; see Locobase 9547.

Class M1-sa (Locobase 9547)

Data from Reading 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

In the mid-1920s, the Reading rebuilt its stud of Mikados delivered with 61 1/2" drivers (Locobase 11023), principally by removing 39 of the boiler tubes from the original layout. At the same time, the railroad increased cylinder volume by boring out the cylinder by 1". It's possible that the Reading determined that the original design had too much heating surface in the relatively underperforming tube bundle. Another flaw may have been lack of steaming space, which the deletion of three or four rows of tubes may have alleviated.

Connelly's Baldwin list shows that all of the M1s were rebuilt in 1924 and again (?) in 1943. The M1-sb that had 55 1/2" drivers were converted to M1-sa in two batches: the last 10 delivered were rebuillt by 1929, the first 20 were rebuilt in 1941-1943.

All of the M1s were scrapped in the late 1940s.

Class M1-sb (Locobase 9548)

Data from Reading 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Vol 58, pp. 366+. Baldwin works were


January 42799-42801, 42823-42825; February 42906-42908, 42939; October 44329-44330; November 44443-44445, 44474-44475; December 44577-44581, 44619-44621, 44674


January 44814-44816, 44870

After the first 26 Baldwin Big Dutch Mikes were delivered to the Reading (Locobase 9547), the railroad changed the specification by reducing the driver diameter by 6 1/2" and dropping the boiler pressure. Firebox heating surface area included 82 sq ft (7.6 sq m) in the combustion chamber; the latter was separated from the firebox by a brick half wall. Piston valves measured 14" (356 mm) in diameter. Apparently the Reading found the exhaust nozzle diameter a touch too large at 7" (178 mm); a handwritten "Hereafter" note states that exhaust nozzles were to measure 6 1/2" (165 mm).

Although the tractive effort remained about the same, the M1sb alosmst certainly proved sluggish. In any event, the last 10 were converted to M1sa (Locobase 9547) by 1929. The other 20 were converted to the M1sa standard in 1941-1943.

Specifications by Steve Llanso of Sweat House Media
Locobase ID11,023 9547 9548
RailroadPhiladelphia & ReadingPhiladelphia & ReadingPhiladelphia & Reading
Number in Class265630
Road Numbers1701-17261701-1726 (& 1727-1756)1727-1756
Number Built2630
Valve GearWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)16.50 / 5.0316.50 / 5.03
Engine Wheelbase (ft / m)35 / 10.6735 / 10.67
Ratio of driving wheelbase to overall engine wheebase 0.47 0.47
Overall Wheelbase (engine & tender) (ft / m)68.46 / 20.8750.32 / 15.3468.37 / 20.84
Axle Loading (Maximum Weight per Axle) (lbs / kg)65,427 / 29,67761,580 / 27,932
Weight on Drivers (lbs / kg)246,600 / 111,856249,700 / 113,262248,734 / 112,824
Engine Weight (lbs / kg)329,300 / 149,368334,425 / 151,693332,225 / 150,695
Tender Loaded Weight (lbs / kg)155,700 / 70,624162,000 / 73,482122,000 / 55,338
Total Engine and Tender Weight (lbs / kg)485,000 / 219,992496,425 / 225,175454,225 / 206,033
Tender Water Capacity (gals / ML)8000 / 30.308000 / 30.308000 / 30.30
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12.80 / 11.6012.90 / 11.7012 / 10.90
Minimum weight of rail (calculated) (lb/yd)103104104
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)61.50 / 156261.50 / 156255.50 / 1410
Boiler Pressure (psi / kPa)225 / 15.50220 / 15.20215 / 14.80
High Pressure Cylinders (dia x stroke) (in / mm)24" x 32" / 610x81325" x 32" / 635x81324" x 32" / 610x813
Tractive Effort (lbs / kg)57,319 / 25999.4960,813 / 27584.3560,693 / 27529.91
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.30 4.11 4.10
Heating Ability
Firebox Area (sq ft / m2)326 / 30.30298 / 27.70327 / 30.38
Grate Area (sq ft / m2)108 / 10.04108 / 10.04108 / 10.03
Evaporative Heating Surface (sq ft / m2)4224 / 392.573803 / 353.443803 / 353.31
Superheating Surface (sq ft / m2)993 / 92.29993 / 77.79837 / 77.76
Combined Heating Surface (sq ft / m2)5217 / 484.864796 / 431.234640 / 431.07
Evaporative Heating Surface/Cylinder Volume252.10209.18226.97
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation24,30023,76023,220
Same as above plus superheater percentage28,91728,75027,400
Same as above but substitute firebox area for grate area87,28779,32882,960
Power L120,35917,65015,396
Power MT728.04623.33545.84