Missouri-Kansas-Texas 4-6-2 "Pacific" Locomotives of the USA


Class Details by Steve Llanso of Sweat House Media

Class H-1 (Locobase 7081)

Data from MKT 1941 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

The first of the Alcos for the Katy, these had 12" diameter piston valves with 1 1/16" lap, 1/4" lead, 6" total travel. They were followed a year later with very similar engines with larger cylinders.


Class H-2a (Locobase 7080)

Data from MKT 1941 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Following the H-1s by a year, these Katy H-2a had 14" diameter piston valves with 1 1/8" lap, 1/4" lead, 6 1/2" total travel. This resulted in a useful increase in power while the boiler and grate remained essentially unchanged.


Class H-2b (Locobase 7082)

Data from MKT 1941 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Following the H-1s by a year, these Katy H-2a had 14" diameter piston valves with 1 1/8" lap, 1/4" lead, 6 1/2" total travel. This resulted in a useful increase in power while the boiler and grate remained essentially unchanged.


Class H-3a (Locobase 5462)

Data from MKT 1941 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

These were express Pacifics for the Katy supplied in two batches by Alco - 5 in each of 1915 & 1916. By 1941, all but two had Baker gear -- 377, 385 had Walschaert gear. As with the H-2bs, these had 14" diameter piston valves with 1 1/8" lap, 1/4" lead, 6 1/2" total travel.


Class H-3b/3c (Locobase 7083)

Data from MKT 1941 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Following the H-3a by a couple of years, these express Pacifics had slightly higher boiler pressure and thus more tractive effort. They were otherwise essentially identical to the H-3a. Alco delivered the first 10 in 1917. Lima followed with 10 more in 1920.


Class H-3d (Locobase 7084)

Data from MKT 1941 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. Works numbers were 6477-6481 in April 1923.

Other than deleting five boiler tubes from the H-3's total, these Limas were virtually identical to the earlier locomotives. Some of these Pacifics were later fitted with Boxpok drivers and slotted-steel pilot, but the basic dimensions remained the same.

Specifications by Steve Llanso of Sweat House Media
ClassH-1H-2aH-2bH-3aH-3b/3c
Locobase ID7081 7080 7082 5462 7083
RailroadMissouri-Kansas-Texas (MKT)Missouri-Kansas-Texas (MKT)Missouri-Kansas-Texas (MKT)Missouri-Kansas-Texas (MKT)Missouri-Kansas-Texas (MKT)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class97101220
Road Numbers358-366350-356367-376377-388389-408
GaugeStdStdStdStdStd
Number Built97101220
BuilderAlco-SchenectadyAlco-SchenectadyAlco-SchenectadyAlco-Schenectadyseveral
Year19101911191219151917
Valve GearWalschaertWalschaertWalschaertBakerWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)1313131313
Engine Wheelbase (ft)33.2533.5033.5034.3334.33
Ratio of driving wheelbase to overall engine wheebase 0.39 0.39 0.39 0.38 0.38
Overall Wheelbase (engine & tender) (ft)68.0868.2568.2569.3769.43
Axle Loading (Maximum Weight per Axle) (lbs)54,800
Weight on Drivers (lbs)147,000147,000155,000165,000165,000
Engine Weight (lbs)242,000242,000254,000272,000272,000
Tender Loaded Weight (lbs)158,000158,000159,500160,000160,000
Total Engine and Tender Weight (lbs)400,000400,000413,500432,000432,000
Tender Water Capacity (gals)80008000800080008000
Tender Fuel Capacity (oil/coal) (gals/tons)37603760376012.504033
Minimum weight of rail (calculated) (lb/yd)8282869292
Geometry Relating to Tractive Effort
Driver Diameter (in)7373737373
Boiler Pressure (psi)210200200200210
High Pressure Cylinders (dia x stroke) (in)22" x 28"24" x 28"24" x 28"25" x 28"25" x 28"
Tractive Effort (lbs)33,13737,55837,55840,75342,791
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.44 3.91 4.13 4.05 3.86
Heating Ability
Firebox Area (sq ft)230200200245245
Grate Area (sq ft)49.5049.5049.5057.5057.50
Evaporative Heating Surface (sq ft)29772948328038383824
Superheating Surface (sq ft)719597688870870
Combined Heating Surface (sq ft)36963545396847084694
Evaporative Heating Surface/Cylinder Volume241.66201.08223.73241.26240.38
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10,3959900990011,50012,075
Same as above plus superheater percentage12,37011,58311,58313,57014,369
Same as above but substitute firebox area for grate area57,47746,80046,80057,82061,226
Power L121,98015,47117,38119,72220,685
Power MT988.93696.08741.65790.54829.14

Specifications by Steve Llanso of Sweat House Media
ClassH-3d
Locobase ID7084
RailroadMissouri-Kansas-Texas (MKT)
CountryUSA
Whyte4-6-2
Number in Class4
Road Numbers409-412
GaugeStd
Number Built4
BuilderLima
Year1923
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)13
Engine Wheelbase (ft)35.25
Ratio of driving wheelbase to overall engine wheebase 0.37
Overall Wheelbase (engine & tender) (ft)71.10
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)165,000
Engine Weight (lbs)271,000
Tender Loaded Weight (lbs)201,500
Total Engine and Tender Weight (lbs)472,500
Tender Water Capacity (gals)10,000
Tender Fuel Capacity (oil/coal) (gals/tons)4033
Minimum weight of rail (calculated) (lb/yd)92
Geometry Relating to Tractive Effort
Driver Diameter (in)73
Boiler Pressure (psi)210
High Pressure Cylinders (dia x stroke) (in)25" x 28"
Tractive Effort (lbs)42,791
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.86
Heating Ability
Firebox Area (sq ft)245
Grate Area (sq ft)57.50
Evaporative Heating Surface (sq ft)3824
Superheating Surface (sq ft)870
Combined Heating Surface (sq ft)4694
Evaporative Heating Surface/Cylinder Volume240.38
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation12,075
Same as above plus superheater percentage14,369
Same as above but substitute firebox area for grate area61,226
Power L120,685
Power MT829.14


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