Philadelphia & Reading 4-6-2 "Pacific" Locomotives in the USA

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The first 30 of Reading class G1sa Pacifics were built at the Reading shops from 1916-1922. The last five of this class were built by Baldwin in 1924. With 40,900 lbs starting te and 80 inch drivers, these were certainly not light Pacifcs. They had a Wootten type firebox, designed for burning an anthracite waste product, "culm", and anthracite coal in general. Similar Pacifics were to be found on the Central New Jersey, the Lehigh Valley the Delaware, Lackawanna & Western

In 1948, Reading Shops built Class G3 (no more "s", just as on the Pennsy)) 210-219. Basically, these were developments of a later version of 124, class G2sa. They had higher boiler pressure, and such details as a Worthington SA feedwater heater and cast steel engine beds. Under the combined onslaught of diesels and the debilitating effect of declining passenger traffic, they were all gone within nine years. One of the places where they worked was on the Pennsylvania- Reading Seashore Line, during the summer rush. Actually, on PRSL runs which served PRR 30th Street, they may well have been the last steam locomotives to haul passenger trains in Philadelphia.


Class Details by Steve Llanso of Sweat House Media

Class G1-sa (Locobase 445)

Data from Railway Age Gazette (21 July 1916), pp 107-109. See also DeGolyer, Vol 74, pp. 89 + and RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Wooten type boiler

First Pacifics (five in the order) bought by the Philadelphia and Reading. RA's report commented that the valve gear and reciprocating parts had been made as light as possible to "reduce the ill effects from the counterbalancing." The piston load per pound of reciprocating parts was 79 lb (35.8 kg) and 65% of the reciprocating parts was balanced. The result was a dynamic augment of 41.5% of the static weight at 80 mph (129 kmh). Inside-admission piston valves measured 12" (306 mm) in diameter.

Used on the Boardwalk Flyer between Philadelphia and Atlantic City. Reading built 25, Baldwin the last five in a batch (works #57756-57760) in April 1924. Baldwin built another five in 1925 with 74" drivers; see Locobase 9411.


Class G1-sb (Locobase 9411)

Data from Reading 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 74, pp. 102+. (Thanks to Chris Hohl for his 26 November 2015 email reporting the original tender capacity.) Works numbers were 58264-58266, 58291-58292 in March 1925.

Locobase 445 shows the lion's share of this design, the version that rolled on 80" (2,032 mm) drivers. To finish the class in 1925, the Reading bought five from Baldwin with smaller drivers. Otherwise they were repeats of the G1-sa down to the 12" (305 mm) inside-admission piston valves and wide Wootten fireboxes in a conventional-cab layout. The combustion chamber contributed 78 sq ft (7.25 sq m) to firebox heating surface area.

Original tender coal capacity was 15 tons. The entire class added brick arch and arch tubes and a Standard MB automatic stoker. 204 was later equipped with thermic syphons.


Class G2-sa (Locobase 158)

Data from tables in 1930 Locomotive Cyclopedia, supplemented by Reading 11 - 1926 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See a lso DeGolyer, Volue 76, pp. 46+. Works numbers were 59226, 59254-59258 in May 1926.

Built ten years after the first Pacifics on the Reading (Locobase 445), these Baldwins differed only in small details. They were fitted with the large Wootten firebox fitted to most Reading engines and gained another 80 sq ft (7.43 sq m) from the combustion chamber. 12" (305 mm) piston valves supplied the cylinders.

Westcott (1960) says these engines "were carefully designed so they could run as fast as the Reading's Atlantics". Used on the Boardwalk Flyer between Philadelphia and Atlantic City. 178 was semi-streamlined in September 1936.


Class G3 (Locobase 16279)

Data from C B Peck, 1950-52 Locomotive Cyclopedia of American Practice, 14th Edition (New York: Simmons-Boardman Publishing Company, 1950), p.526. See also the driver thread begun 17 August 2014 on the"Model Railroader"Forums"Prototype information for the modeler"Reading G3 Pacifics, at http://cs.trains.com/mrr/f/13/t/231790.aspx, last accessed 25 April 2017 (Many thanks to Chris Hohl for his 18 March 2017 email with spreadsheet supplying details of the late-arriving G3s, thus filling a hole in the Reading motive power roster.) Reading's shops produced 210-214 in May 1948 and 215-219 in June.

Locobase hasn't pinned down an explanation for why the Reading built ten new Pacifics at a time when the trend was strongly toward diesel power. But the railroad needed passenger power and its youngest 4-6-2s were over twenty years and hard used. So it took the basic power dimensions and wide Wootten firebox, put 80" drivers under a cast steel frame, juiced the boiler so it would withstand a high operating pressure, and added a Worthington 5A feed water heater.

The shops also adopted a pair of Boxpok disc drivers for the center coupled axle. The thread mentioned above consisted of a question about why and a couple of reasons offered. "Charlie 9" noted the high boiler pressure, which increased strain on the main driver, as well as the need to balance the main rod's effect. "Overmod" agreed, but added" "It's not just the added strength in the main driver, it's the added space for both the principal and the angled balance mass for low augment at high speed, and better seating and securement in the wheel for the main pins.".

Like all of the late-model North American steam locomotives, the G3s enjoyed relatively brief careers before being supplanted by diesels. Some were leased to the Pennsylvania-Reading Seashore Lines, where they hauled main-line commuter trains between Atlantic City and Philadelphia.

The official retirement dates for all ten fell in June 1957.

Specifications by Steve Llanso of Sweat House Media
ClassG1-saG1-sbG2-saG3
Locobase ID445 9411 158 16,279
RailroadPhiladelphia & ReadingPhiladelphia & ReadingPhiladelphia & ReadingPhiladelphia & Reading
CountryUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-2
Number in Class305510
Road Numbers105-134200-204175-179210-219
GaugeStdStdStdStd
Number Built305510
BuilderseveralseveralBaldwinReading
Year1916192519261948
Valve GearWalschaertWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.83 / 4.2213.83 / 4.2213.83 / 4.2213.83 / 4.22
Engine Wheelbase (ft / m)35.58 / 10.8435.58 / 10.8435.92 / 10.9536.58 / 11.15
Ratio of driving wheelbase to overall engine wheebase 0.39 0.39 0.39 0.38
Overall Wheelbase (engine & tender) (ft / m)67.98 / 20.7267.98 / 20.7272.20 / 22.0178.31 / 23.87
Axle Loading (Maximum Weight per Axle) (lbs / kg)61,000 / 27,66959,120 / 26,81664,860 / 29,420
Weight on Drivers (lbs / kg)176,900 / 80,241177,210 / 80,381192,540 / 87,335197,184 / 89,441
Engine Weight (lbs / kg)273,600 / 124,103288,120 / 130,689306,360 / 138,963329,450 / 148,075
Tender Loaded Weight (lbs / kg)160,000 / 72,575183,000 / 83,008154,000 / 69,853257,540 / 116,818
Total Engine and Tender Weight (lbs / kg)433,600 / 196,678471,120 / 213,697460,360 / 208,816586,990 / 264,893
Tender Water Capacity (gals / ML)8000 / 30.309000 / 34.099000 / 34.0912,500 / 47.35
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12.90 / 11.7016 / 14.5015 / 13.6019 / 17.30
Minimum weight of rail (calculated) (lb/yd / kg/m)98 / 4998 / 49107 / 53.50110 / 55
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)80 / 203274 / 188080 / 203280 / 2032
Boiler Pressure (psi / kPa)220 / 15.20220 / 15.20230.60 / 15.90260 / 17.90
High Pressure Cylinders (dia x stroke) (in / mm)25" x 28" / 635x71125" x 28" / 635x71125" x 28" / 635x71125" x 28" / 635x711
Tractive Effort (lbs / kg)40,906 / 18554.6744,223 / 20059.2442,877 / 19448.7048,344 / 21928.50
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.32 4.01 4.49 4.08
Heating Ability
Firebox Area (sq ft / m2)282 / 26.21282 / 26.21314 / 29.18431 / 40.04
Grate Area (sq ft / m2)94.50 / 8.7894.50 / 8.7895 / 8.8395 / 8.83
Evaporative Heating Surface (sq ft / m2)2926 / 271.932926 / 271.933045 / 282.992981 / 276.94
Superheating Surface (sq ft / m2)652 / 60.59652 / 60.59745 / 69.24770 / 71.53
Combined Heating Surface (sq ft / m2)3578 / 332.523578 / 332.523790 / 352.233751 / 348.47
Evaporative Heating Surface/Cylinder Volume183.93183.93191.41187.39
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation20,79020,79021,90724,700
Same as above plus superheater percentage24,53224,53226,28829,887
Same as above but substitute firebox area for grate area73,20773,20786,890135,593
Power L118,81617,40421,87926,294
Power MT703.48649.55751.56881.94

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