Chicago Great Western 4-6-2 "Pacific" Type Locomotives

Class K1s (Locobase 4171)

See http://www.geocities.com/zvwrr/chicago_great_western_steam.html for the original 1917 railroad diagrams. Firebox heating surface includes 11 sq ft of arch tubes. Originally delivered as F6 Prairies, these were converted to Pacifics in the 'teens. They used Vauclain superheaters and decreased boiler pressure. As K1s, this group ran for years, the last retiring only in 1950.

Class K2/K3s (Locobase 4173)

See http://www.geocities.com/zvwrr/chicago_great_western_steam.html for the original 1917 railroad diagrams. Firebox heating surface includes 11 sq ft of arch tubes.

When the K3s conversions (from F6 Prairies) were superheated, this is what resulted. K3s engines had a slightly lower boiler pressure and less heating surface, but a high ratio of superheat offset the difference. As K3s engines, the original F6 remained in service for decades, some even seeing the end of steam on the CGW.

Class K3 (Locobase 4172)

See http://www.geocities.com/zvwrr/chicago_great_western_steam.html for the original 1917 railroad diagrams. Firebox heating surface includes 11 sq ft of arch tubes.

When these F6 Prairies were converted to Pacifics, they received 3' longer boilers and four more tubes as well as the bogie truck replacing the Bissell. Otherwise, they were essentially similar.

See K3s (Locobase 4173) for the superheated variety.

Class K4s (Locobase 4174)

See http://www.geocities.com/zvwrr/chicago_great_western_steam.html for the original 1917 railroad diagrams. Firebox heating surface includes 11 sq ft of arch tubes.

Originally delivered as F6 Prairies, these were converted to Pacifics in the 'teens. They used Vauclain superheaters and decreased boiler pressure. As K4s, this group ran for years, the last retiring only in 1950.

Class K5s (Locobase 4175)

See http://www.geocities.com/zvwrr/chicago_great_western_steam.html for the original 1917 railroad diagrams. Firebox heating surface includes 33 sq ft of arch tubes.

These were the first CGW Pacifics to be built as such. Five were produced by Baldwin in December 1913 (works #41000-41004), 3 more followed in 1916 (43781-43783). Steam admission came through capacious 15" piston valves with a lap of 1", lead of 3/16", and an exhaust clearance of 1/8"..

At least one was fitted with a thermic syphon (in 1928), which raised the total direct heating surface to 338 sq ft.

The first three were scrapped in 1932 while the others carried on until 1950.

Class K6s (Locobase 4176)

See http://www.geocities.com/zvwrr/chicago_great_western_steam.html for the original 1917 railroad diagrams. Firebox heating surface includes 13 sq ft of arch tubes. Superheating surface isn't clear on the diagrams; could be 854 sq ft (although that results in a higher than usual percentage of superheater area).

These engines started out as F3 Prairies, but were converted in the 'teens. Three had an intermediate existence as 2-6-6-2 Prairie Mallets, but by 1918 all were 4-6-2s. In the process, they received boilers that were 3 ft longer.

With the scaling back of the CGW in the early 1930s, the entire class became redundant and was scrapped in 1932.

Specifications
Class	K1s	K2/K3s	K3	K4s	K5s	K6s
Locobase ID	4171	4173	4172	4174	4175	4176
Railroad	Chicago Great Western	Chicago Great Western	Chicago Great Western	Chicago Great Western	Chicago Great Western	Chicago Great Western
Whyte	4-6-2	4-6-2	4-6-2	4-6-2	4-6-2	4-6-2
Road Numbers	902-905, 920	906, 912, 914-917		921-923	925-932	950-955
Gauge	Std	Std	Std	Std	Std	Std
Builder	CGW	CGW	CGW	CGW	Baldwin	CGW
Year	1910	1918	1910	1911	1913	1915
Valve Gear	Stephenson	Walschaert	Stephenson	Walschaert	Walschaert	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	12.50'	12.50'	12.50'	13'	13'	11.33'
Engine Wheelbase	33.50'	33.80'	33.80'	34.50'	35.33'	32'
Ratio of driving wheelbase to overall engine wheebase	0.37	0.37	0.37	0.38	0.37	0.35
Overall Wheelbase (engine & tender)	53.80'	59.80'	59.80'	63.33'	66'	59.09'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers	121500 lbs	124800 lbs	125700 lbs	140000 lbs	152400 lbs	136950 lbs
Engine Weight	191200 lbs	197600 lbs	190700 lbs	216000 lbs	256450 lbs	211170 lbs
Tender Light Weight	122560 lbs	122560 lbs	122560 lbs	144200 lbs	158000 lbs	118080 lbs
Total Engine and Tender Weight	313760 lbs	320160 lbs	313260 lbs	360200 lbs	414450 lbs	329250 lbs
Tender Water Capacity	6125 gals	6125 gals	6125 gals	8000 gals	8000 gals	6000 gals
Tender Fuel Capacity (oil/coal)	11 tons	11 tons	11 tons	11 tons	13 tons	9 tons
Minimum weight per yard of rail on which locomotive could run	67.50 lb rail	69.33 lb rail	69.83 lb rail	77.78 lb rail	84.67 lb rail	76.08 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	68"	68"	68"	73"	73"	63"
Boiler Pressure	175 psi	190 psi	200 psi	180 psi	190 psi	200 psi
Cylinders (dia x stroke)	22" x 26"	20.5" x 26"	20" x 26"	24" x 26"	25" x 28"	21.5" x 28"
Tractive Effort	27528 lbs	25950 lbs	26000 lbs	31388 lbs	38716 lbs	34926 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.41	4.81	4.83	4.46	3.94	3.92
	Heating Ability
Firebox Area	157 sq. ft	157.80 sq. ft	157 sq. ft	191.80 sq. ft	260 sq. ft	167 sq. ft
Grate Area	40.10 sq. ft	40.10 sq. ft	40.10 sq. ft	49.30 sq. ft	56 sq. ft	49.30 sq. ft
Evaporative Heating Surface	2506	2325	2600	3171	3732	2981
Superheating Surface	446	494		615	794	654
Combined Heating Surface	2952	2819	2600	3786	4526	3635
Evaporative Heating Surface/Cylinder Volume	219.07	234.08	275.02	232.93	234.60	253.37
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	7017.50	7619	8020	8874	10640	9860
Same as above plus superheater percentage	8077.73	8954.15	8020	10315.50	12506.58	11633.99
Same as above but substitute firebox area for grate area	31626.03	35236.03	31400	40132.10	58066.28	39409.24
Power L1	12665.46	16389.88	8115.90	15547.98	17696.48	17316.87
Power MT	689.45	868.59	427.03	734.52	767.99	836.30