Canadian Pacific Articulated Locomotives in Canada

Class R1a (Locobase 3569)

Data from "Mallet Pusher Locomotive: Canadian Pacific Railway," Engineering News, Volume 63, No 14 (1910), pp. 413-414. See also "Mallet Articulated Compound for the Canadian Pacific", Railway and Locomotive Engineering, Volume 23, No 6 (June 1910), pp. 242; and Lionel Wiener, Articulated Locomotives (1930). (Thanks to Chris Hohl , whose question about the odd numbers of these 0-6-6-0s led to an expansion of the two existing entries and drafting of a third.)

Designed by H H Vaughan for helper service over the passes of the Canadian Rockies, this locomotive was a very unusual Mallet for a variety of reasons. Together with four slightly less odd compounds (Locobase 15025) and one all-simple-expansion (Locobase 3570), the six were the only articulateds ever operated by a Canadian railroad.

All had the two cylinder sets centered under the boiler. As seen in profile, the front driver set led, then its pair of LP cylinder, then the HP cylinders and finally the driver set they drove. All four cylinders were fed by piston valves, those for the HP measuring 11" (279 mm) in diameter and the LP using 12" (305 mm) diameter valves. As Wiener (1930) points out, this reduced steam pipe length, a reasonable goal especially for compounds.

The 1950 (later 5750) had within the boiler shell an interesting array of heating devices. Just ahead of the firebox, the 289 2" (51 mm) boiler tubes measured only 9 feet (2.743 m) long. Ahead of the conventional nest of tubes was a vertical superheater whose 69 tubes of 1 3/4" (44.5 mm) diameter intercepted the flow of gas from the boiler to the feedwater heater forward. Externally, this showed as a box on the boiler over the front cylinder set. The feedwater heater's 281 2" (51 mm) diameter tubes were 8 feet (2.438 m) long.

The next four compounds were considerably less odd; see Locobase 15025.

Although these can't be seen as failures, the CP decided on rigid-wheelbase locomotives of greater power (culminating in the 2-10-4 Selkirks) and this five-engine class (and one more simple-expansion variant, which see at Locobase 3570) were converted to 2-10-0 Decapods in 1917; see Locobase 4529).

Class R1b (Locobase 15025)

Data from Roy V Wright, 1912 Locomotive Cyclopedia (New York: Simmons-Boardman, 1912), p. 186 (Figure 94). (Thanks to Chris Hohl , whose question about the odd numbers of these 0-6-6-0s led to an expansion of the two existing entry and drafting of a third.)

These were the five production all-adhesion helper engines based on the single experimental locomotive shown in Locobase 3569. The complicated boiler arrangement of the latter was replaced by a more conventional superheated design.

But the class still fell short of expectations and only three years later, all abandoned articulated operation in favor of a 2-10-0 layout; see Locobase 4529.

Class R1c (Locobase 3570)

Data from "Simple High Speed Articulated Locomotive", Railway Age Gazette, Volume 53, No 2 (12 July 1912), pp. 50-53; and "Notes on Simple Mallet Locomotives", Railway Engineer, Volume 34, No.2 (February 1913), pp. 40-41. See also Roy V Wright, 1912 Locomotive Cyclopedia (New York: Simmons-Boardman, 1912), p. 234 (Figure 154). (Thanks to Chris Hohl , whose question about the odd numbers of these 0-6-6-0s led to an expansion of the two existing entry and drafting of a third. Chris also suggested a clarification about the R-1c's place in articulated history.)

The single simple-expansion Angus followed the five compound articulateds described in Locobase 3569 and 15025. Chris Hohl points out that both the R1c and the Pennsylvania's HH1s were manufactured in October 1911. But because the HH1s was retained at Altoona for stationary runs on the rollers of its locomotive test plant, the R1c was the first North American articulated simple-expansion engine derived from the compound Mallet layout to enter service.

Like the others, it operated on the CP as a helper engine over the 2.2% grade in the Canadian Rockies. A curious feature of this locomotive was the centered position of its four cylinders. All four cylinders were cast to the same design with inboard valves and outboard cylinders. The front driver set preceded its cylinders, the rear driving set trailed its pair. The boiler's tube count included 167 2 1/4" tubes, 18 2" tubes, and 22 5 1/4" flues.

Even odder was the disparity in length between the 2 1/4" tubes and the 5 1/2" flues. The former measured 18 feet 2 inches (5.54 m) and the latter ran 20 feet 4 1/8" (6.2 m).

Obviously the goal of 50-mph (80 km/h) operation was never achieved with this all-adhesion articulated. Like its compound brothers (Locobase 3569 and Locobase 15025), this engine became a 2-10-0 Decapod in 1917 (Locobase 4529).