Reading 4-4-2 "Atlantic" Type Locomotives

Class P1-e (Locobase 9449)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Class P1-f (Locobase 9450)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Class P2-a (Locobase 9451)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Class P2-b (Locobase 9452)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Later reduced to 276 tubes (for 2,088.7 sq ft of tube surface vs 2,139) and boiler pressure dropped to 190 psi.

Class P3-a/P3-c (Locobase 9453)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

P3-a engines weighed 99,325 lb on the drivers, but added more than 9,000 lb to the engine weight and totalled 185,800 lb. The boiler in this class later was reconfigured with fewer, but larger-diameter tubes resulting in much less heating surface; see Locobase 9454..

Class P3-a/P3-c - 2"" tubes (Locobase 9454)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Apparently the idea of squeezing a lot of relatively small-bore (1 3/4") tubes into a boiler didn't work out well in practice, so the Reading reconfigured the boiler to a more conventional layout. In the process, the engine lost about one-quarter of its heating surface.

Class P4-d - 80"" (Locobase 9456)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Class P4-d - 84 1/4"" (Locobase 9455)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Class P4-e/P4-f - 80"" (Locobase 9457)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Other locomotives of this design had 84 1/4" drivers; see Locobase 9458. P4-f adhesion weight was 101,625 lb.

Class P4-e/P4-f - 84 1/4"" (Locobase 9458)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

P4-e engines had adhesion weights of 105,350 lb each.

Class P5-c (Locobase 4100)

It's hard to believe one could fit a larger grate on a camelback Atlantic that this one. Add to the novelty a three-cylinder layout and you have the third of three experiments by Edward Elliott of the Philadelphia & Reading.

Data from Paul T. Warner (RLHS Bulletin #58). Note that the BP is slightly lower than that of 303. Also, Warner notes that the heating surface includes the Schmidt superheater. Warner's best time behind any locomotive came one morning when 344 clipped off 12 miles of descending grade in the Lehigh Valley in 8 min 4 sec or 89 mph.

Class P5-sd/e (Locobase 6453)

Data from Philadelphia & Reading 9 Sept 1914 erecting diagram for this more conventional Atlantic camelback. The two piston valves each measured 13" in diameter and had 7" travel with 5/16" lead and 1 3/8" lap. The diagram notes that the P-5d has 23" x 26" cylinders with 80" drivers while the P-5e had the 23" x 27" and 86" drivers shown in the specs.

The EHS dropped when the locomotives were superheated. Axle loadings ranged from 63,650 lb to the 68,125 lb shown in the specs. At a later date, the boiler saw the removal of 28 tubes and a drop in tube & flue heating surface area to 2,707 sq ft. Total EHS then came to 2,981 sq ft.

The RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection do not show superheater area. The figure given in the specs is an estimate based on installations of similar flue count and length.

Class P6-a (Locobase 2809)

Another unusual Reading design, this one conceived by chief draftsman Edward O. Elliott. Add to the camelback with its enormous firebox (108" wide) a 3-cylinder layout that originally was compound, later simpled as depicted here. Edwin Alexander (1950) observes that this were the first Reading engines to have Walschaerts valve gear.

Paul T. Warner (RLHS Bulletin #58) supplied the heating surface and weights information, noting that the former included a Taylor superheater. This was a chamber some 3 feet long in the front boiler course. Warner concluded that it was probable " that the device ...gave only a very moderate degree of superheat." He notes that a later upgrade included the Schmidt type of superheater.

Class P6-b (Locobase 4099)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

The second of three trial 3-cylinder camelback Atlantics (talk about an exclusive club!), this engine had a surprisingly high boiler pressure for the time. It was likely reduced soon after the 303 entered service. Data from Paul T. Warner (RLHS Bulletin #58), who notes that the heating surface area includes a Taylor superheater. (See notes for engine 300, Locobase 2809)

Later superheated with a more conventional boiler; see Locobase 9459.

Class P6-sb (Locobase 9459)

Locobase 4099 describes the second of three trial 3-cylinder camelback Atlantics built by the Reading in the early teens. As with the other experiments, operational reality soon dictated a conversion to a more conventional, but still camelback, layout. An oddity in this engine's boiler, however, is the provision of 18 1 3/4" tubes in addition to the 154 2" tubes shown in the specs. The superheater flues were slightly narrower than the conventional as well.

Class P7-a (Locobase 9448)

Data from RDG 11 - 1926 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Few railroads managed to make the 4-4-4 wheel arrangement work and the Reading fit the majority mold. Within a year of introducing its C1-a, the company rebuilt the quartet as 4-4-2s.

Specifications
Class	P1-e	P1-f	P2-a	P2-b	P3-a/P3-c	P3-a/P3-c - 2"" tubes	P4-d - 80""	P4-d - 84 1/4""	P4-e/P4-f - 80""	P4-e/P4-f - 84 1/4""	P5-c	P5-sd/e	P6-a	P6-b	P6-sb	P7-a
Locobase ID	9449	9450	9451	9452	9453	9454	9456	9455	9457	9458	4100	6453	2809	4099	9459	9448
Railroad	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading
Whyte	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2	4-4-2
Road Numbers	311-314		304-317		322-327	322-327	329	328	330-332, 335-338	333-334, 339	344	340-343, 345-349	300	303	303	350-353
Gauge	Std	Std	Std	Std	Std	Std	Std	Std	Std	Std	Std	Std	Std	Std	Std	Std
Builder	Reading	Reading	Reading	Reading	Burnham, Williams & Co	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading	Reading
Year	1900	1900	1907	1900	1900	1900	1900	1900	1900	1900	1912	1912	1909	1911	1911	1916
Valve Gear	Stephenson	Stephenson	Stephenson	Stephenson	Stephenson	Stephenson	Stephenson	Stephenson	Stephenson	Stephenson	Walschaert	Walschaert	Walschaert	Walschaert	Walschaert	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	7.25'	7.25'	7.17'	7.17'	7.25'	7.25'	7.25'	7.25'	7.25'	7.25'	7.25'	7.75'	7.25'	7.25'	7.25'	7.25'
Engine Wheelbase	26.58'	26.58'	27.08'	27.08'	26.58'	26.58'	26.58'	26.58'	26.58'	26.58'	28'	29.25'	28'	28'	28'	29.25'
Ratio of driving wheelbase to overall engine wheebase	0.27	0.27	0.26	0.26	0.27	0.27	0.27	0.27	0.27	0.27	0.26	0.26	0.26	0.26	0.26	0.25
Overall Wheelbase (engine & tender)
Axle Loading (Maximum Weight per Axle)												68125 lbs
Weight on Drivers	93200 lbs	95750 lbs	104900 lbs	102050 lbs	100450 lbs	100450 lbs	107825 lbs	107825 lbs	105350 lbs	101625 lbs	128300 lbs	134500 lbs	106150 lbs	108000 lbs	122000 lbs	129210 lbs
Engine Weight	166000 lbs	175950 lbs	192000 lbs	192400 lbs	176750 lbs	176750 lbs	192700 lbs	192700 lbs	196175 lbs	196500 lbs	233200 lbs	220500 lbs	205400 lbs	208000 lbs	217450 lbs	231925 lbs
Tender Light Weight
Total Engine and Tender Weight	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
Tender Water Capacity
Tender Fuel Capacity (oil/coal)
Minimum weight per yard of rail on which locomotive could run	78 lb rail	80 lb rail	87 lb rail	85 lb rail	84 lb rail	84 lb rail	90 lb rail	90 lb rail	88 lb rail	85 lb rail	107 lb rail	112 lb rail	88 lb rail	90 lb rail	102 lb rail	108 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	74"	84"	78"	78"	84.30"	84.30"	80"	84.30"	80"	84.30"	80"	86"	80"	80"	80"	80"
Boiler Pressure	200 psi	200 psi	205 psi	205 psi	220 psi	220 psi	225 psi	225 psi	225 psi	225 psi	230 psi	200 psi	225 psi	240 psi	215 psi	215 psi
Cylinders (dia x stroke)	20" x 26"	20" x 26"	20.5" x 26"	20.5" x 26"	21" x 24"	21" x 24"	21" x 24"	21" x 24"	21" x 24"	21" x 24"	19" x 24" (3)	23" x 27"	18.5" x 24" (3)	19" x 24" (3)	22" x 26"	23.5" x 26"
Tractive Effort	23892 lbs	21048 lbs	24410 lbs	24410 lbs	23478 lbs	23478 lbs	25302 lbs	24012 lbs	25302 lbs	24012 lbs	31759 lbs	28234 lbs	29455 lbs	33140 lbs	28747 lbs	32800 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	3.90	4.55	4.30	4.18	4.28	4.28	4.26	4.49	4.16	4.23	4.04	4.76	3.60	3.26	4.24	3.94
	Heating Ability
Firebox Area	183 sq. ft	175 sq. ft	245 sq. ft	245 sq. ft	219 sq. ft	219 sq. ft	182 sq. ft	182 sq. ft	180 sq. ft	180 sq. ft	266 sq. ft	274 sq. ft			260 sq. ft	292 sq. ft
Grate Area	76 sq. ft	76 sq. ft	85.50 sq. ft	85.50 sq. ft	80.70 sq. ft	80.70 sq. ft	79.30 sq. ft	79.30 sq. ft	79.30 sq. ft	79.30 sq. ft	94.50 sq. ft	94.50 sq. ft	90 sq. ft	90 sq. ft	90 sq. ft	94.50 sq. ft
Evaporative Heating Surface	1583	2425	2384	2384	2550	1851	2944	2944	3043	3043	3097	2854	2846	3345	2957	3509
Superheating Surface												461
Combined Heating Surface	1583	2425	2384	2384	2550	1851	2944	2944	3043	3043	3097	3315	2846	3345	2957	3509
Evaporative Heating Surface/Cylinder Volume	167.44	256.51	240.02	240.02	265.04	192.39	305.99	305.99	316.28	316.28	262.15	219.82	254.10	283.15	258.50	268.84
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	15200	15200	17528	17528	17754	17754	17843	17843	17843	17843	21735	18900	20250	21600	19350	20318
Same as above plus superheater percentage	15200	15200	17528	17528	17754	17754	17843	17843	17843	17843	21735	20790	20250	21600	19350	20318
Same as above but substitute firebox area for grate area	36600	35000	50225	50225	48180	48180	40950	40950	40500	40500	61180	60280	0	0	55900	62780
Power L1	6518	9774	9683	9683	11710	9465	12017	12663	12295	12956	11492	18487	0	0	10668	10913
Power MT	308.36	450.09	407.00	418.37	514.01	415.46	491.41	517.82	514.59	562.13	394.94	606.05	0	0	385.56	372.40