4-6-2 Steam Locomotives in Portugal

Class 301/1501/551 (Locobase 21324)

"Locomotivas de Vapor de Via Larga"p. 31 , posted Posted by Guarda Freio at 18:01, 23 September 2018, at [], last accessed 25 January 2026; and "Série 351 a 370 da CP" in Wikipedia at [], last accessed 8 February 2026.. Hemschel works numbers were 19880-19889 in 1924.

When the S e S adopted the Pacific wheel arrangement, they established the express passenger design that would haul the top services for decades. This decade of engines served the Caminhos de Ferro do Estado (CFE), but soon acquired the national railways 1500 series numbers in 1927. (The CP gave them new numbers in 1960 as diesels supplanted much of the steam roster and took lower numbers.)

The design used the duBousquet-de Glehn four-cylinder compound setup that differed from other such designs in using four sets of Walschaert valve gear The two inside cylinders drove on the first axle, the two outside drove the middle driving axle.

Like their slightly younger Pacific cousins (Locobase 21323), the 551s handled a variety of express passenger trains, although their axle loadings prevented them from crossing the Dona Maria Pia Bridge.

NB: If using the inside (fire side) diameter of 50 mm (1.97") in each tube, the tube heating surface measured 177.94 sq m (1,915 sq ft), which together with the firebox area, came to 191.90 sq m (2,066 sq ft) of evaporative heating surface area. Locobase uses the external diameters.

Class 601/501 (Locobase 21323)

"Locomotivas de Vapor de Via Larga"p. 31 , posted Posted by Guarda Freio at 18:01, 23 September 2018, at [], last accessed 25 January 2026; and "Série 351 a 370 da CP" in Wikipedia at [], last accessed 8 February 2026. Works numbers were 20435-20442 in 1924.

A year after the Sul e Suleste bought ten Pacifics (Locobase 21324), the CP ordered this octet of du Bousquet-DeGlehn four-cylinder compound 4-6-2 which divided the cylinders so that each pair turned a different axle. Although both classes used Belpaire fireboxes, the 501s redistributed the tubes and flues in the boiler, giving up 27 small tubes and adding six flues and supeheater elements

In 1939, the CP imported some light carriages built by the Budd Company of Philadelphia. Special trains tested the equipment with the engines reaching 140 kph (87 mph) on level track and averaging 107.8 kph (67 mph) over a three-hour+ and three-stop run. The shops fitted a streamlined casing on the 503 that complemented the Budd cars in making up the Flecha de Prata (Silver Arrow) as they appeared at the Portuguese World Exhibition

Although it satisfied the brief, the 600s (renumbered 501-508 in 1927) betrayed some limitations. A relatively high axle loading limited the total route mileage they could use. Tall drivers reduced hill-climbing, Wikipedia (as translated by Google) noted the class was "not capable of hauling long trains on the steep inclines between Caxarias, Albergaria and Vermoil," Double-heading cut average speed, but, says Wikipedia, the time lost was "normally recovered by more experienced crews." The streamlining on503 increased its fuel consumption. (A coal shortage during World War II led to the conversion to oil-burning in some of the class. The tender carried 11.16 cubic metres (2,950 US gallons) of oil.)

As the CP began operating diesel locomotives in passenger service in the late 1940s, the 500s continued to haul special trains and take trains through the Rossio Tunnel. Later conversion of much of Portugal's railway network to electric power established the redundancy of the high-stepping engines.

NB: If using the inside (fire side) diameter of 50 mm (1.97") in each tube, the tube heating surface measured 167.47 sq m (1,802 sq ft), which together with the firebox area, came to 183.17 sq m (1,972 sq ft) of evaporative heating surface area. Locobase uses the external diameters.