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 - Schmidt Type A (Locobase 4518)

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

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.

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.

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 G2 - Vaughan-Horsey (Locobase 6556)

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

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 Vaughan-Horsey superheater and retained the 21"-diameter pistons; some V & H upgrades also adopted the 22 1/2" piston diameter, and increased the superheater flue diameter to 5 1/4". 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 pp286-287 for his comments on initial problems with the design.)

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 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.

First in a series of big, powerful Pacifics. The figure for number of engines in the class covers all versions of the G3.

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 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."

This seems to be one of the locomotives to which James Partington, Estimating Engineer for Alco, compared his company's #50000 in a 5 November 1921 Railway Age article. It's certainly a very close match, although Partington's weights (181,500 lb on the drivers, 299,000 lb total engine weight) are much lower.

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.

Also had 28 2" tubes.

G-3d firebox had combustion chamber . A nickel-steel boiler allowed considerably higher boiler pressure 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.

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" 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. Firebox heating surface included 40 sq ft of arch tubes.

Compared to the earlier G1s and G2s, this small class of medium-drivered Pacifics had much larger boilers. Because the cylinder volume increased as well, the boiler proportions and performance were approximately the same as the earlier design. 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)