Southern Pacific 4-8-4 "Northern" Type Locomotives

Class GS-1 (Locobase 279)

Data from SP 7-1951 locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

First of the Golden State (or General Service) wheel arrangement. Four delivered to the Texas & Louisiana Lines.

Locobase is puzzled by the Menke book, which shows 2,565 sq ft for the superheater of all of the early GS series of 4-8-4s. Each of them also has a page with a lower area -- 1,866 sq ft in this case -- and a revision date of 3/1/1950 or later. Locobase suspects that some of the superheater was blocked off in the late 1940s to lower maintenance costs.

Class GS-2 (Locobase 280)

Data from SP Menke All Time Steam locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

The oil-fired GS-2 is essentially a streamlined GS-1 and was the first of a series of streamliners that became steadily more colorful and powerful. The GS-3 (4416-4429) class was completed the same year.

Locobase is puzzled by the Menke book, which shows 2,565 sq ft for the superheater of all of the early GS series of 4-8-4s. Each of them also has a page with a lower area -- 1,834 sq ft in this case -- and a revision date of 3/1/1950 or later. Locobase suspects that some of the superheater was blocked off in the late 1940s to lower maintenance costs.

Class GS-3 (Locobase 1404)

Data from SP 7-1951 locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

Took the GS-2 and juggled the cylinder dimensions and boiler pressure. These were part of the well-known series of 4-8-4s that pulled most Espee long-haul passenger service.

Class GS-4 (Locobase 281)

GS-4s were an expansion of the basic SP 4-8-4 needed to handle the 12-car Daylight over a hilly route between San Francisco andLos Angeles. Although they had 80-in drivers, the great bulk of the engine, especially with the air-smoothing casing, dwarfed the running gear. These huge engines had a broad orange valence overthe wheels below a smaller red trim band that came halfway up the cab windows. They were oil-fired, used rapid-responding electro-pneumatic braking, and a trailing-truck booster that raised starting and hill-climbing tractive effort by 13,000 lb.

Locobase notes that the the restored 4449 is credited with 1,834 sq ft of superheating surface. Locobase suspects that some of the superheater was blocked off in the late 1940s to lower maintenance costs.

Class GS-5 (Locobase 6680)

Data from SP Menke All Time Steam locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

The two GS-5s were additions to the GS stud in 1942. They differed from the previous locomotives in the smaller amount of superheat. They also had Timken roller bearings.

Class GS-6 (Locobase 282)

Data from SP Menke All Time Steam locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

These last 10 engines in the GS series reverted to the GS-2/3 cylinder proportions and driving-wheel diameter for dual-service (freight and passenger) work. They were oil-fired (as were virtually all SP locomotives) and had neither streamlining nor color.

Specifications
Class	GS-1	GS-2	GS-3	GS-4	GS-5	GS-6
Locobase ID	279	280	1404	281	6680	282
Railroad	Southern Pacific (SP)	Southern Pacific (SP)	Southern Pacific (SP)	Southern Pacific (SP)	Southern Pacific (SP)	Southern Pacific (SP)
Whyte	4-8-4	4-8-4	4-8-4	4-8-4	4-8-4	4-8-4
Road Numbers	4400-4409, 700-703	4410-4415	4416-4429	4430-4457	4458-4459	4460-4469
Gauge	Std	Std	Std	Std	Std	Std
Builder	Baldwin	Lima	Lima	Lima	Lima	Lima
Year	1930	1937	1937	1941	1942	1943
Valve Gear	Walschaert			Walschaert	Walschaert	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	20'	20'	21.50'	21.50'	21.50'	20'
Engine Wheelbase	45.83'	45.83'	47.67'	47.66'	47.66'	45.83'
Ratio of driving wheelbase to overall engine wheebase	0.44	0.44	0.45	0.45	0.45	0.44
Overall Wheelbase (engine & tender)
Axle Loading (Maximum Weight per Axle)	67000 lbs	67000 lbs	67000 lbs	69000 lbs	69600 lbs	67900 lbs
Weight on Drivers	262000 lbs	266500 lbs	267300 lbs	275700 lbs	278700 lbs	283200 lbs
Engine Weight	442300 lbs	448400 lbs	460000 lbs	475000 lbs	483200 lbs	468400 lbs
Tender Light Weight	291000 lbs	373000 lbs	358880 lbs	313730 lbs	313730 lbs	317800 lbs
Total Engine and Tender Weight	733300 lbs	821400 lbs	818880 lbs	788730 lbs	796930 lbs	786200 lbs
Tender Water Capacity	16150 gals	22000 gals	22000 gals	23300 gals	23300 gals	23200 gals
Tender Fuel Capacity (oil/coal)	4690 gals	6275 gals	6010 gals	6275 gals	6275 gals	6080 gals
Minimum weight per yard of rail on which locomotive could run	109.17 lb rail	111.04 lb rail	111.38 lb rail	114.88 lb rail	116.12 lb rail	118 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	73.50"	73.50"	80"	80"	80"	73.50"
Boiler Pressure	250 psi	250 psi	280 psi	300 psi	300 psi	260 psi
Cylinders (dia x stroke)	27" x 30"	27" x 30"	26" x 32"	25.5" x 32"	25.5" x 32"	27" x 30"
Tractive Effort	63230 lbs	63230 lbs	64355 lbs	66326 lbs	66326 lbs	65759 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.14	4.21	4.15	4.16	4.20	4.31
	Heating Ability
Firebox Area	356 sq. ft	356 sq. ft	388 sq. ft	385 sq. ft	388 sq. ft	451 sq. ft
Grate Area	90.20 sq. ft	90.20 sq. ft	90.40 sq. ft	90.40 sq. ft	90.40 sq. ft	90.20 sq. ft
Evaporative Heating Surface	4858	4858	4890	4887	4890	4852
Superheating Surface	2565	2565	2565	2086	1834	2086
Combined Heating Surface	7423	7423	7455	6973	6724	6938
Evaporative Heating Surface/Cylinder Volume	244.36	244.36	248.68	258.37	258.52	244.06
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	22550	22550	25312	27120	27120	23452
Same as above plus superheater percentage	30342.10	30342.10	34020.96	35233.05	34517.10	30503.15
Same as above but substitute firebox area for grate area	119753.74	119753.74	146019.15	150052.27	148148.60	152515.75
Power L1	45787.17	45787.17	56795.37	54107.31	49349.18	41463.46
Power MT	1541.12	1515.10	1873.73	1730.66	1561.48	1291.12

Some of the Last Runs of the GS Class
Jan 22, 1957	SP GS-4 4430, San Fransisco -> San Jose, last commuter run assigned to steam
May 4, 1958	SP GS-6 4460 pulled the "Oakland-Sacramento Senator" over Sutter Basin branch north of Sacramento
Jul 27, 1958	SP GS-6 4460 deadheaded to San Fransisco then pulled the "Suntan Special" to Watsonville Jct. A diesel finished the trip to Santa Cruz over lighter rail.
	The above trip was repeated three weeks later.
Oct 12, 1958	SP GS-6 4460, San Fransisco -> Fresno and return over the Dumbarton Bridge, through Niles Canyon, and down the west side of the San Joaquin Valley.
Oct 18, 1958	SP GS-6 4460, excursion from Sacramento -> Donner Pass -> Reno.
Oct 19, 1958	SP GS-6 4460, excursion from Reno -> Sacramento.