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 Wheelbase13'13'13'13'13'
Engine Wheelbase33.25'33.50'33.50'34.33'34.33'
Ratio of driving wheelbase to overall engine wheebase 0.39 0.39 0.39 0.38 0.38
Overall Wheelbase (engine & tender)68.08'68.25'68.25'69.37'69.43'
Axle Loading (Maximum Weight per Axle)54800 lbs
Weight on Drivers147000 lbs147000 lbs155000 lbs165000 lbs165000 lbs
Engine Weight242000 lbs242000 lbs254000 lbs272000 lbs272000 lbs
Tender Light Weight158000 lbs158000 lbs159500 lbs160000 lbs160000 lbs
Total Engine and Tender Weight400000 lbs400000 lbs413500 lbs432000 lbs432000 lbs
Tender Water Capacity8000 gals8000 gals8000 gals8000 gals8000 gals
Tender Fuel Capacity (oil/coal)3760 gals3760 gals3760 gals12.5 tons4033 gals
Minimum weight of rail (calculated)82 lb/yard82 lb/yard86 lb/yard92 lb/yard92 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter73"73"73"73"73"
Boiler Pressure210 psi200 psi200 psi200 psi210 psi
Cylinders (dia x stroke)22" x 28"24" x 28"24" x 28"25" x 28"25" x 28"
Tractive Effort33137 lbs37558 lbs37558 lbs40753 lbs42791 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.44 3.91 4.13 4.05 3.86
Heating Ability
Firebox Area230 sq. ft200 sq. ft200 sq. ft245 sq. ft245 sq. ft
Grate Area49.50 sq. ft49.50 sq. ft49.50 sq. ft57.50 sq. ft57.50 sq. ft
Evaporative Heating Surface2977 sq. ft2948 sq. ft3280 sq. ft3838 sq. ft3824 sq. ft
Superheating Surface719 sq. ft597 sq. ft688 sq. ft870 sq. ft870 sq. ft
Combined Heating Surface3696 sq. ft3545 sq. ft3968 sq. ft4708 sq. ft4694 sq. ft
Evaporative Heating Surface/Cylinder Volume241.66201.08223.73241.26240.38
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10395990099001150012075
Same as above plus superheater percentage1237011583115831357014369
Same as above but substitute firebox area for grate area5747746800468005782061226
Power L12198015471173811972220685
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 Wheelbase13'
Engine Wheelbase35.25'
Ratio of driving wheelbase to overall engine wheebase 0.37
Overall Wheelbase (engine & tender)71.10'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers165000 lbs
Engine Weight271000 lbs
Tender Light Weight201500 lbs
Total Engine and Tender Weight472500 lbs
Tender Water Capacity10000 gals
Tender Fuel Capacity (oil/coal)4033 gals
Minimum weight of rail (calculated)92 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter73"
Boiler Pressure210 psi
Cylinders (dia x stroke)25" x 28"
Tractive Effort42791 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.86
Heating Ability
Firebox Area245 sq. ft
Grate Area57.50 sq. ft
Evaporative Heating Surface3824 sq. ft
Superheating Surface870 sq. ft
Combined Heating Surface4694 sq. ft
Evaporative Heating Surface/Cylinder Volume240.38
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation12075
Same as above plus superheater percentage14369
Same as above but substitute firebox area for grate area61226
Power L120685
Power MT829.14


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