Canadian Pacific 4-8-2 Locomotives in Canada

The Canadian Pacific Railway chose the 4-6-2 "Pacific" for its passenger service and built or bought 205 of them between 1900 and 1914.

In 1914, the CPR built two 4-8-2 "Mountain" type locomotives in its Angus Shops. These two locomotives were designated Class I1a and assigned road numbers 2900 and 2901.

After World War I the CPR reconfirmed its commitment to the 4-6-2 "Pacific" by adding another 293 to its roster without building or buying another "Mountain" type locomotive.


Class Details by Steve Llanso of Sweat House Media

Class H-1-a (Locobase 4528)

Data from table in May 1916 of Railway Mechanical Engineer (RME), p. 346 and W H Winterrowd, "Canadian Pacific Mountain Type Locomotives", Railway Age Gazette (5 November 1915), pp.862-864. See also "4-8-2 Express Passenger Locomotive, Canadian Pacific Ry", Locomotive Magazine, Volume XXII [22] (15 July 1916), pp. 130-131; and a silent documentary from 1928 showing all the steps to building the British Empire's most powerful steam locomotive at [], last accessed 17 January 2019. (Thanks to Chris Hohl for his 15 June 2019 email correcting the overall wheelbase.)

The H-1s were the only Mountains delivered to the CP and were in fact smaller than the G4 Pacifics that would enter service a few years later. The pair was virtually identical except for the provision of a Gaines combustion chamber firebox in 2900. (For a full description of the Gaines combustion chamber's intended effect on combustion, see the next paragraph and Locobase 4228; and for the rival 2901, see Locobase 9641.)

At the front of the grates lay the 10"(254 mm)-thick vertical brick wall that formed the back end of a combustion chamber. It had five 3"(76.2 mm) -diameter vertical air passages. The installation of a combustion chamber resulted in much shorter tubes, which meant a smaller heating surface area all around. 44 sq ft (4.1 sq m) of arch tubes contributed to firebox heating surface area. A booster added 12,000 lb (5,443 kg or 53.38 kN) to starting tractive effort.

Both of the locomotives had cast-iron cylinders that Winterrowd claimed were designed with "...particular attention ...given to the steam and exhaust passages, which are unusually direct and of liberal cross-sectional area." They were served by 12" (305 mm) piston valves.

LM reported that the H-1 design was "quite typical of modern American practice, and there are no point calling for special comment, save, perhaps, the unusually short connecting (main, in North American parlance) rods, due to the drive being taken to the second coupled axle."

Both of them had an equalizing system developed by H A Hoke, assistant engineer of the Pennsylvania Railroad. The leading truck was equalized with the first & second driving axles and the trailing truck was equalized with the third & fourth driving axles.

The 2900 later teamed up with much larger tenders that weighed 123,500 lb (56,019 kg) tare and 283,000 lb (128,367 kg) when loaded with 12,000 Imperial gallons (14,400 US gallons) of water and either 21 tons (23.1 short tons) of coal or 4,000 Imp gal (4,800 US gal) of fuel oil.

2901 was retired in 1944, 2900 followed a year later.


Class H-1-b (Locobase 9641)

Data from W H Winterrowd, "Canadian Pacific Mountain Type Locomotives", Railway Age Gazette (5 November 1915), pp. 862-864. (Thanks to Chris Hohl for his 15 June 2019 email correcting the overall wheelbase.)

These were the only Mountains delivered to the CP and were in fact smaller than the G4 Pacifics that would enter service a few years later. The 2900 had a Gaines wall; it's described in Locobase 4528.

Both of the locomotives had cast-iron cylinders that Winterrowd claimed were designed with "...particular attention ...given to the steam and exhaust passages, which are unusually direct and of liberal cross-sectional area." They were served by 12" (305 mm) piston valves. 30 sq ft (2.8 sq m) contributed to firebox heating surface are.

2901 had a more conventional firebox and two sizes of fire tubes: 43 2 1/4" and 136 2 1/2". They extended more than 25 feet, a length only exceeded in Locobase (or anywhere else, most likely) by the Pennsy's HH-1s 2-8-8-2. So long were the tubes, says Winterrowd, then the CP's Assistant Chief Mechanical Engineer, that they "...were beaded into place before the boiler was applied to the frames, with the boiler turned upside down. The center sag of the tubes was then toward the top of the boiler and when it was righted the tubes tended to straighten out." Winterrowd claimed that the long tubes gave more trouble to the maintenance group than did those of the 2900.

Like the 2900, the 2901 later teamed up with much larger tenders carrying 12,000 Imperial gallons (14,400 US gallons) of water and either 21 tons (23.1 short tons) of coal or 4,000 Imp gal (4,800 US gal) of fuel oil. For some reason, the H-1-b's tender weighed 7 1/2 short tons more empty (138,000 lb/62,596 kg), which boosted its loaded weight to 298,000 lb (135,171 kg).

Principal Dimensions by Steve Llanso of Middle Run Media

ClassH-1-aH-1-b
Locobase ID4528 9641
RailroadCanadian Pacific (CPR)Canadian Pacific (CPR)
CountryCanadaCanada
Whyte4-8-24-8-2
Number in Class11
Road Numbers29002901
GaugeStdStd
Number Built11
BuilderCanadian PacificCanadian Pacific
Year19141914
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)18.25 / 5.5618.25 / 5.56
Engine Wheelbase (ft / m)39.50 / 12.0439.50 / 12.04
Ratio of driving wheelbase to overall engine wheelbase 0.46 0.46
Overall Wheelbase (engine & tender) (ft / m)66.50 / 20.2466.42 / 20.24
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)192,000 / 87,090192,000 / 87,090
Engine Weight (lbs / kg)286,000 / 129,728286,000 / 129,728
Tender Loaded Weight (lbs / kg)157,000 / 71,214157,000 / 71,214
Total Engine and Tender Weight (lbs / kg)443,000 / 200,942443,000 / 200,942
Tender Water Capacity (gals / ML)7200 / 27.277200 / 27.27
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)12 / 1112 / 11
Minimum weight of rail (calculated) (lb/yd / kg/m)80 / 4080 / 40
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)70 / 177870 / 1778
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)23.5" x 32" / 597x81323.5" x 32" / 597x813
Tractive Effort (lbs / kg)42,918 / 19467.3042,918 / 19467.30
Booster (lbs)12,000
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.47 4.47
Heating Ability
Tubes (number - dia) (in / mm)210 - 2.25" / 57181 - 2.25" / 57
Flues (number - dia) (in / mm)30 - 5.25" / 13330 - 5.25" / 133
Flue/Tube length (ft / m)20.61 / 6.2825.37 / 7.73
Firebox Area (sq ft / m2)309 / 24.63251 / 20.54
Grate Area (sq ft / m2)59.60 / 5.5459.60 / 5.54
Evaporative Heating Surface (sq ft / m2)3711 / 340.804180 / 385.69
Superheating Surface (sq ft / m2)760 / 70.63943 / 87.64
Combined Heating Surface (sq ft / m2)4471 / 411.435123 / 473.33
Evaporative Heating Surface/Cylinder Volume231.07260.27
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation11,92011,920
Same as above plus superheater percentage13,94614,066
Same as above but substitute firebox area for grate area72,30659,236
Power L117,57420,227
Power MT807.17929.02

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