Denver & Rio Grande Western 4-8-2 "Mountain" Locomotives in the USA

Class 14-34 1/4 E - proposal (Locobase 6822)

Data from D&RGW 12 - 1937 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Chris Hohl for his 13 August 2020 email suggesting adding the word "proposal" to the designation of this engine and the same year as 6821 in the Year Built field.)

Locobase doesn't know for sure, but believes this, like Locobase 6821, is a proposal submitted to the D&RGW in the 1920s in response to an inquiry about a narrow-gauge Mountain engine. Chris Hohl determine this proposal was drafted in January 1925. Neither was built, probably because the railway was phasing out narrow-gauge operations.

Class 14-36 1/4 E - proposal (Locobase 6821)

Data from D&RGW 12 - 1937 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Locobase doesn't know for sure, but believes this is a proposal submitted to the D&RGW in the 1920s in response to an inquiry about a narrow-gauge Mountain engine; Locobase 6822 shows a smaller version. Neither was built, probably because the railway was phasing out narrow-gauge operations. This design compares well to other narrow-gauge Mountain designs in Locobase (most of which were sized to the Cape Gauge of 42"). It has a lot of boiler for the cylinder volume, a useful degree of superheat, and reasonably tall drivers

Class M-67 (Locobase 1344)

Data from 1937 D & RGW locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also"Most Powerful Passenger Locomotive in the World", Railway and Locomotive Engineering, Volume , No 12 (December 2022), pp. 323-325 ; Powerful Mountain Type Locomotives--Denver and Rio Grande Western Railway", Railway Journal, Volume , Volume 22 No 10 (October 1922), p.18; and "4-8-2 Type Locomotive for the Denver and Rio Grande Western Railroad", Engineering, Volume CXVI [116] (6 July 1923), pp. 26- (Thanks to Chris Hohl for his 24 November 2023 email correcting the driver diameter, supplying tender weight and original capacity. Works numbers were 63307-63316 in June 1922 and 64288-64696 in June 1923.

When built, the railroad press described the class as the largest passenger locomotives in the world.. They were the Rio Grande's first Mountains. Delivered three batches, all ran on unusually small 63" drivers to maintain an average higher speed over the railroad's challenging grades while hauling trains that normally required two Mountain types. .Tackling the severe curvature of even the main lines dictated the use of a floating front axle with spherical bushes that reduced the fixed driving wheelbase to 11 ft 2 in (3.40 m). 1501-1510 and 1521-1530 were identical; 1511-1520 had a booster engine mounted on the trailing truck and were designated M-78; these ran Grand Junction to Denver..

M-67s consumed 8,,000 gallons (30,280 litres) of water and 5 1/2 tons (5 metric tons) of coal per hour. A Duplex stoker significantly improved the fireman's lot. Firebox heating surface area amounted to 368 sq ft (34.19 sq m), of which five arch tubes contributed 35 sq ft (3.25 sq m) .. Later heating aids included thermic syphon adding 92 102 sq ft (8.55-9.48 sq m), but reducing arch tube area to 21 sq ft (1.95 sq m). Direct heating surface consequently grew to 456 sq ft (42.36 sq m), and total evaporative heating surface climbed to 4,698 sq ft (436.36 sq m) when fitted with the most syphons. A combustion chamber and, later, an Elesco feed water heater further enhanced the incoming water's willingness to steam.

R&LE pays particular attention to the trailing truck's Delta truck produced by Commonwealth Steel of St Louis. Their leading paragraph on this subject summarizes the economic and efficient truck design: "This truck combines in a single casting the radius bar members, journal box guides, end transom and equalizer pivot." Loaded at three points ("two at the rear and the third at the front end center pivot"), the truck used a separate equalizer made the truck "particularly easy riding." Considering its role in supporting the entire firebox and negotiating curves, such praise suggests a successful design.

The tender came in for its own extended analysis because of its great capacity and loaded weight, which Chris Hohl reports came to 267,600 lb (121,381 kg). While tankage didn't change, the tender's original 20 ton coal capacity later increased to the 25 tons shown in the specs.

Such large capacities and the locomotives' general level of quality, reported Engineering, meant these engines could haul expresses the full 302 miles running south and west of Denver to Minturn without a change. (Simple math suggests at least two, probably three water stops, however.). As Railway Journal pointed out, however, their specific remit was "service on the mountain divisions ...between Salida ...and Minturn." in which they crossed the Continental Divide at 10,240 ft (3,121 m) , the highest point on a transcontinental railroad.

Except for two scrapped in the latter half of 1949, the three batches served the D&RGW for three decades, before their retirements in 1950-1955.

Class M-75 (Locobase 204)

Dat afrom D&RGW 12 - 1937 FOLIO 10 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 76, p. 299; and DRGW net's archived ICC 2537 on the 14 October 1941 accident involving the 1501) at [], last accessed 18 July 2024. (Thanks to Bryan Clark for his 12 July 2024 email stating the reason for 1601's early scrapping.) Works numbers were 59240-59244 in May 1925 and 59293-59295, 59336-59337 in July.

These dual-service locomotives used three cylinders. Drury (1993) comments: "Their construction by Baldwin is something of a curiosity. They constitute five-sixths of Baldwin's three-cylinder production; and Brooks, which had built D&RGW's two-cylinder Mountains, was the chief advocate of three-cylinder power."

As delivered, the firebox had a combustion chamber offering 120 sq ft (11.15 sq m) of heating surface area, 25 sq ft (2.3 sq m) in arch tubes, and 85.5 sq ft (7.95 sq m) of Nicholson thermic syphons in the firebox only. (The two syphons and three arch tubes supported the brick arch.) Locobase notes the big-tube layout that included 2 1/4" tubes and more than five dozen 5 1/2" flues.

The first five engines had Worthington #4 feed water heaters; the last five were fitted with Elescos.. Each of the cylinders was supplied through a 12" (305 mm) piston valve.

The railway would later modify the firebox by deleting the arch tubes and increasing the thermic syphon area to 96 sq ft (8.9 sq m). At that point, the combustion chamber accounted for 100 sq ft (9.3 sq m) of direct heating surface, which now totalled 498 sq ft (46.25 sq m). Also, the boiler gained three heating tubes and somehow added 75 sq ft of superheater area even though the flue count and length remained the same. (Perhaps the elements themselves had slightly greater diameters or lengths within the flues.)

Using three cylinders on a locomotive burning low-calorie, semi-bituminous Rosebud coal seems an odd choice. Even though each of the three cylinder were smaller than that those of a comparable two-cylinder locomotive. Apparently the firebox and boiler proved big enough and the railway was apparently satisfied enough to maintain the design's three-cylinder layout until retirement in the late 1940s.

Class leader 1601 was dismantled in December 1941 Bryan Clark reported that the 1601 wrecked in an accident. The ICC 2537 report described the train: "First 38, symbol SPF-115, an east-bound second-class, freight train, consisted of engine 1601, 36 loaded and 4 empty cars and a caboose." This train departed from Helper, Utah on 13 October.

122 miles (196 km) later at 5:16 the next morning, the bridge's west abutment failed due to scouring by the Cisco Wash as the train crossed it at 45 mph (72.5 kph).1601 wound up on its side, killing the engineer was killed and injuring the fireman and front brakeman. Much of the train plunged into the Cisco Wash's channel. None of the crew were found to have contributed to the accident.

The next to go was 1604 in March 1948 and the last was 1607 in November 1949.