Canadian Pacific 4-6-2 "Pacific" Type Locomotives

Class Details by Steve Llanso

Class G1 (Locobase 4519)

Data from table in June 1907 issue of American Engineer & Railroad Journal (AERJ).

A relatively small batch of tall-drivered Pacifics built over an 8-year period by the Canadian Pacific and the Montreal Locomotive Works.

The boiler had a coned second course and the steam dome on the first course. As delivered, the class was fitted with the 22-element Vaughan-Horsey superheater, which is very similar in basic design to the much-better-known Schmidt smoke-tube design. The data in the specifications reflect that installation.

At a later date, the CPR replaced the Vaughan-Horsey superheater with the more widely used Schmidt Type A in many of its early Pacifics. Locobase 4518, although it describes the G2a, has data exactly the same as the G1 after the change.

Class G2 - Vaughan-Horsey - 1st mod (Locobase 6556)

Data from "Standardizing Locomotive Equipment - Canadian Pacific", American Engineer and Railroad Journal (May 1906), p. 161-165.

Locobase divides this class into several variants depending on the superheater and the cylinder volume. In the present entry, the class refers to the version using the Vaughan-Horsey superheater that was orginally installed when these engines were delivered in 1906-1907. They had 11" (279 mm) piston valves. Arch tubes added 16 sq ft to the firebox heating surface.

The principal difference between the Vaughan-Horsey and the Schmidt or Cole smoke-tube superheater was that the Vaughan-Horsey's superheater tubes were connected "separately and individually to the headers", as Vaughan put in his report to the 40th Annual Convention of the American Railway Master Mechanics' Association in 1906. (See pp. 286-287 for his comments on initial problems with the design.)

In later days, the tubes were shortened by 6" and most G2s had only 189 2" (15156) or 175 2 1/4" boiler tubes. (See Locobases 15156 and 10809, respectively.

For the Schmidt Type A variant, see Locobase 4518. Firebox heating surface for both versions included 24 sq ft of arch tubes.

Similar in most respects to the G1s of the same span (1906-1914), this much larger class had 70" drivers. They were supplied by Alco-Schenectady, Canadian Pacific shops, and Montreal Loco Works.

They stayed in service until 1940-1961.

Class G2d - Vaughan-Horsey (Locobase 15156)

Data from CP 2 - 1947 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See Locobase 6556 for the original 1906 Vaughan-Horsey version of this Pacific.

As the G2's service career wore on, many of the locomotives were altered in one way or another. This entry shows the later version of the Vaughan & Horsey subtype fitted with larger-diameter tubes and pistons, but still using the 5" diameter flues. Firebox heating surface included 24 sq ft of arch tubes.

Class G2f - Vaughan-Horsey (Locobase 10809)

Data from CP 2 - 1947 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection. See Locobase 6556 for the original 1906 Vaughan-Horsey version of this Pacific.

As the G2's service career wore on, many of the locomotives were altered in one way or another. This entry shows the later version of the Vaughan & Horsey subtype fitted with fewer tubes, larger-diameter flues, and more cylinder volume. Firebox heating surface included 24 sq ft (2.2 sq m) of arch tubes.

Class G2p-u Type A - 30 unit (Locobase 4518)

Data from 1947 Canadian Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. (Thanks to Chris Hohl, whose inquiries led to a review of the several G2 entries.)

Locobase divides this class into two variants depending on the superheater that was added to the design some time after they were put in service in 1906-1914. This entry applies to those upgraded with the Schmidt Type A superheater. Unlike the upgraded Ten-wheelers, most Schmidt engines retained their 200-psi setting. Firebox heating surface for both versions included 24 sq ft of arch tubes.

Almost all of the conversions used the 30-flue Type A installation shown in the specs. Two were fitted with a 28-tube Type A with 5 1/2" flues and 147 2 1/4" tubes.

Other sub-classes (likely a few in each) offered combinations such as 21 1/4"-diameter pistons and 225-psi boiler, 20"-diameter pistons and a 250-psi boiler, and in some cases, retention of the original 21"-diameter piston and 200-psi boiler. By the diagram book's 1947 publication date, all G2s then in service had been converted to the Schmidt superheater variant. A few had been fitted with Elesco feed water heaters.

For the Vaughan-Horsey variant, see Locobase 6556.

Similar in most respects to the G1s of the same span (1906-1914), this much larger class had 70" drivers. They were supplied by Alco-Schenectady, Canadian Pacific shops, and Montreal Loco Works and stayed in service until 1940-1961.

Class G3a/G3b/G3c (Locobase 2738)

Data from 1947 Canadian Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. See also F P Roesch, "Questions and Answers- 4911- Size of 23-- Class Pacific Type on Canadian Pacific Railway", Brotherhood of Locomotive Firemen and Enginemen's Magazine, Volume 71, No. 2 (15 July 1921), pp. 17-18; and William H. Winterrowd,"A Locomotive Designed for Rigorous Operating Conditions", Railway Review, Vol 68, No. 25 (18 June 1921), pp. 925-936.

First in a series of big, powerful Pacifics. The figure for number of engines in the class covers all versions of the G3. Winterrowd spells out all of the considerations behind this design in his Railway Review article.

A National Park Service Steamtown special history study on its G3c gives details on how these came to be produced:"William H. Winterrowd had become chief mechanical officer of the Canadian Pacific Railway (CPR) in April 1918 as the World War was winding down." The study describes the other types of locomotives Winterrowd developed, then notes:

"For passenger service, CPR needed heavier locomotives because "heavyweight" six-wheel truck all-steel cars had rapidly replaced the older, lighter wooden passenger cars on main line runs. Building on Vaughan's successful G-l and G-2 Pacifics manufactured well before the World War, Winterrowd's team produced plans for four G-3-a 4-6-2s with 75-inch drive wheels for service over relatively flat terrain and five G-4-a Pacifics with smaller 70-inch drivers [Locobase 4522] for main line service in hilly terrain. Numbered 2300 through 2303, one of the G-3-a locomotives appeared in July 1919 and the other three in August."

The firebox had a short combustion chamber and five arch tubes contributing to direct heating surface area. Fourteen-inch (356 mm) piston valves enjoyed 7" (179 mm) travel

After evaluating the relative performance of the two classes, Winterrowd concluded that the 75" driver was the appropriate size for the heavyweight expresses he wanted to pull. So a year later, CP's shops turned out five G-3b in August-September 1920 and another in January 1921. A year and a half later, the class went into series production with class G3c 2310-2318 appearing in June 1923 and 2320-2325 in July.

These all had Type A superheaters and Elesco feed water heaters. They would later trail larger tenders weighing 295,000 lb (133,810 kg) loaded with 14,400 US gallons (54,504 litres) of water and 21 long tons (23.2 short tons) of coal.

The G3d with nickel-steel boiler appears in Locobase 133, while later G3s with Type E superheaters are described in Locobases 5049 and 134."

Class G3d (Locobase 133)

Data from tables in 1930 Locomotive Cyclopedia and from 1947 Canadian Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.Works numbers were 66764-66787 in August-October 1926.

Also had 28 2" tubes. G-3d firebox had combustion chamber and five arch tubes . A nickel-steel boiler allowed considerably higher boiler pressure (which led to a reduction in cylinder volume) and a reduction in the number of fire tubes. On balance, there was less total heating surface, but more of it was superheated.

3e, f, g, & h were later series with much more superheat surface; see Locobases 5049 and 134."

Class G3e/G3f (Locobase 5049)

Data from 1947 Canadian Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

These were the first of the "superpower" G3s with smaller cylinder diameter, higher BP, and a Type E superheater that resulted in a much higher percentage of dry steam. The firebox had 33 sq ft of thermic syphons.

G3e 2351-2365 works #1944-1958 October-November 1938

G3f 2366-2377 1970-1981 April-June 1940

Data taken from specifications published by CLC in 1945 and reproduced in http://www.trainweb.org/oldtimetrains/altloco.html (consulted in May 2002). The table depicts the G3e, as indicated by a reference to a 1938 order; G3fs were identical except for slightly higher weights.. A later sub-class is described on Locobase 134.

Class G3g/G3h/G3j (Locobase 134)

Data 1947 Canadian Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. See Locobases 2738, 4522, and 5049 for earlier variants of the G3/G4 design.

Last G3 variant and the design that was produced in the greatest numbers. A shorter, obviously less crowded boiler had 14 fewer small tubes and 27 flues that were 1/2" (12.7 mm) larger in diameter.

G3g 2378- 2417 CLC works #1982-2021 January 1942 - February 1943

G3h 2418-2462 CLC 2126-2170 August 1944 - April 1945

G3j 2463-3427 MLW 76116-76125 June 1948

This design pulled not only passenger, but also freight trains.

Class G4a/G4b (Locobase 4522)

Data from 1947 Canadian Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive collection. William H. Winterrowd,"A Locomotive Designed for Rigorous Operating Conditions", Railway Review, Vol 68, No. 25 (18 June 1921), pp. 925-936. (Thanks to Chris Hohl for the valve gear ID, a query about tender capacities, and a question about dimensions that revealed some very odd numbers.)

These were the only G4s because WH Winterrowd, Chief Mechanical Engineer, compared their utility to the identical G3 class shown in Locobase 2738 and found that the latter's 75" were more to his liking. So production of this 70" variant stopped at 18.

Firebox heating surface included 40 sq ft (3.7 sq m) of arch tubes and a short combustion chamber. Fourteen-inch (356 mm) piston valves served the cylinders.

The class could trail one of two tenders, either the 12,000 Imperial gallon/21 ton coal version or, for those G4s operating as oil burners, 8,000 ImpGal (36,336 litres) of water and 3,000 ImpGal (13,626 litres) of oil. According to Chris Hohl, the coal burners were 2708, 2710-2715 and the oil burners were road numbers 2700-2707, 2709, 2716-2717. 2711 was tested with smoke deflectors in 1941.

This satisfactory design carried on until 1954-1965."

Class G5 (Locobase 135)

Built for branch-line service as replacements for many older CPR engines. First 2 built by CPR at the Angus works; others by Montreal Locomotive Works and Canadian Locomotive Works. Plans called for as many as 600 to be procured, but only 102 were bought before dieselization curtailed the program.

"They proved as fast and as efficient as they were handsome," says OS Nock (RWC VI, pl 33), " and 'saw steam out' on many secondary lines of the CPR."

A February 1954 article in Trains magazine by FH Howard, reproduced on http://www.trainweb.org/oldtimetrains/destinedtodie.html (consulted in May 2002), agreed and provided many details on the class. Howard noted that the 1944 design had "scores of improvements", most notably a front-end throttle, roller bearings on the leading engine truck, and a Signal Foam Meter. Housing the throttle in the front allowed use of a dry pipe with slots along the underside, an arrangement "used", according to Howard, "for some years on this railroad instead of a steam dome".

Under the firebox was "probably the simplest trailing truck ever devised: not a truck at all, but an axle carried in the rigid frame with overwide pedestals set at a backward angle so when the axle moved laterally on curves, the journals were displaced longitudinally, giving truck action"

After successful trials in the East (1201) and West (1200), Montreal Locomotive Works delivered 30 G-5bs with mechanical stokers and Elesco exhaust steam injectors. 1946 saw 20 more from MLW and 20 from CLC and 1948 closed out the class with 30 from Canadian Loco.

(See Locobase 2413 for the very similar New South Wales C38. The two classes were designed separately for two very different railways, yet they have a striking resemblance)


Specifications by Steve Llanso
ClassG1G2 - Vaughan-Horsey - 1st modG2d - Vaughan-HorseyG2f - Vaughan-HorseyG2p-u Type A - 30 unitG3a/G3b/G3cG3dG3e/G3fG3g/G3h/G3jG4a/G4bG5
Locobase ID4519 6556 15156 10809 4518 2738 133 5049 134 4522 135
RailroadCanadian PacificCanadian PacificCanadian PacificCanadian PacificCanadian PacificCanadian PacificCanadian PacificCanadian PacificCanadian PacificCanadian PacificCanadian Pacific
Whyte4-6-24-6-24-6-24-6-24-6-24-6-24-6-24-6-24-6-24-6-24-6-2
Road Numbers2200-22382500-26652500-26652500-26652300-23252326-23502351-23772378-24722700-27171200-1301
GaugeStdStdStdStdStdStdStdStdStdStdStd
BuilderseveralseveralseveralseveralseveralAngus WorksMontreal LWCanadian Locomotive CoseveralCanadian PacificSeveral
Year19061906190919211921191919261938194219191944
Valve GearWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase13'13'13'13'13'13.17'13.17'13.17'13.17'13.17'13'
Engine Wheelbase33.58'33.58'33.58'33.58'33.58'34.50'35'35'35'34.74'33.71'
Ratio of driving wheelbase to overall engine wheebase 0.39 0.39 0.39 0.39 0.39 0.38 0.38 0.38 0.38 0.38 0.39
Overall Wheelbase (engine & tender)59.27'59.96'64.54'64.54'64.54'67.83'73.81'75.62'67.09'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers139000 lbs139300 lbs155000 lbs155000 lbs155000 lbs181500 lbs183900 lbs198000 lbs199600 lbs193000 lbs151000 lbs
Engine Weight212000 lbs214300 lbs237000 lbs237000 lbs237000 lbs299000 lbs306500 lbs321000 lbs323000 lbs318000 lbs229500 lbs
Tender Light Weight122700 lbs122700 lbs142000 lbs169000 lbs169000 lbs178000 lbs238000 lbs222000 lbs196760 lbs295000 lbs191000 lbs
Total Engine and Tender Weight334700 lbs337000 lbs379000 lbs406000 lbs406000 lbs477000 lbs544500 lbs543000 lbs519760 lbs613000 lbs420500 lbs
Tender Water Capacity5000 gals5000 gals5000 gals7000 gals8400 gals9600 gals9500 gals12000 gals12000 gals14388 gals9600 gals
Tender Fuel Capacity (oil/coal)10 tons10 tons12 tons12 tons12 tons12 tons12 tons18 tons18 tons21 tons14 tons
Minimum weight of rail (calculated) on which locomotive could run77 lb/yard77 lb/yard86 lb/yard86 lb/yard86 lb/yard101 lb/yard102 lb/yard110 lb/yard111 lb/yard107 lb/yard84 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter75"70"70"70"70"75"75"75"75"70"70"
Boiler Pressure200 psi200 psi200 psi200 psi200 psi200 psi250 psi275 psi275 psi205 psi250 psi
Cylinders (dia x stroke)21" x 28"21" x 28"21" x 28"22.25" x 28"22.5" x 28"25" x 30"23" x 30"22" x 30"22" x 30"24.5" x 30"20" x 28"
Tractive Effort27989 lbs29988 lbs29988 lbs33664 lbs34425 lbs42500 lbs44965 lbs45254 lbs45254 lbs44826 lbs34000 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.97 4.65 5.17 4.60 4.50 4.27 4.09 4.38 4.41 4.31 4.44
Heating Ability
Firebox Area180 sq. ft191 sq. ft199 sq. ft199 sq. ft199 sq. ft297.60 sq. ft291 sq. ft291 sq. ft291 sq. ft298 sq. ft199 sq. ft
Grate Area45.60 sq. ft48 sq. ft45.60 sq. ft45.60 sq. ft45.60 sq. ft65 sq. ft65 sq. ft65 sq. ft65 sq. ft65 sq. ft45.60 sq. ft
Evaporative Heating Surface2957 sq. ft3122 sq. ft2914 sq. ft2926 sq. ft2610 sq. ft3530 sq. ft3272 sq. ft3497 sq. ft3176 sq. ft3530 sq. ft2576 sq. ft
Superheating Surface528 sq. ft530 sq. ft433 sq. ft433 sq. ft675 sq. ft803 sq. ft864 sq. ft1473 sq. ft1475 sq. ft803 sq. ft744 sq. ft
Combined Heating Surface3485 sq. ft3652 sq. ft3347 sq. ft3359 sq. ft3285 sq. ft4333 sq. ft4136 sq. ft4970 sq. ft4651 sq. ft4333 sq. ft3320 sq. ft
Evaporative Heating Surface/Cylinder Volume263.44278.14259.61232.21202.55207.11226.81264.94240.62215.65253.02
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation91209600912091209120130001625017875178751332511400
Same as above plus superheater percentage1048811040103061030611035154701966323238235951585713908
Same as above but substitute firebox area for grate area414004393044974449744815870829880281040331056337269760695
Power L11917418391162271447717529179612708447423466341789429413
Power MT912.33873.19692.41617.73747.96654.50974.061584.091545.24613.201288.30

Photos

Reference

Credits

Introduction and roster provided by Richard Duley. Class details and specifications provided by Steve Llanso of Sweat House Media.