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

Class 458/L-95 (Locobase 16243)

Data from "Mallet Compound Locomotives for D & R G Ry", Railway Journal, Volume 19, No 4 (April 1913), p. 15. See also D&RGW 12 - 1937 Locomotive Diagrams supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange collection. (Thanks to Chris Hohl for his 9 April 2018 email noting the original road number series.. His 4 April 2023 email supplied information about an increase in boiler pressure and tender coal capacities and weights as noted below. ) Works numbers were 52038-52053 in December 1912.

These ten-axle Mallets were designed for helper service in the Salt Lake Division and were the first really big articulateds on the road. Indeed, they were described in the RJ report as "the most power ful locomotives that could be built" under the 50,000 lb axle-loading constraint According to RJ ( whose language appears to have been supplied by either the D&RG or Alco), the class represented "the very latest information as to proportion and [they] emply the best economy factors."

Some of the firebox heating surface area came from a long combustion chamber. In addition to prolonging the flame path for increased heat exchange through greater direct heating surface area,, the chamber's length allowed a large boiler to use 24 foot (7.32 m) tubes. When operated in simple expansion (all four cylinders receiving live steam), starting tractive effort rose to 112,000 lb (50,802 kg or 498.20 kN). HP cylinders used 14" (356 mm) piston valves to supply steam while the LP cylinders used slide valves.

According to the Rio Grande's specifications, the plan was for one of these Mallets to take the place of two Consolidations in helper service: "Not only will the number of locomotives per train be reduced," the 1913 report explained, "but a greater total tractive effort per train will be obtained, which can be used to meet increased tonnage or adverse conditions."

The report said that eastbound from Springfield, Utah (just south of Provo) to Thistle, "a distance of fifteen miles [24.2 km], the maximum resistance is due to a 1.0 per cent grade in combination with 7 1/2 degree curves. From Thistle to Tucker, a distance of 17 miles [27.4 km], the maximum resistance is a 2.3 per cent grade in combination with 8 degree curves. From Tucker to Summit, a distance of 7.9 miles [12.7 km], the maximum resistance is due to a 3.97 per cent grade in combination with 11 degree curves. This is the crucial part of the division."

All of the class was renumbered in the 3400 series in 1924. It may have been then that at least some of class replaced the low-pressure cylinders' slide valves with 14" (356 mm) piston valves; boiler pressure setting rose to 210 psi (14.5 bar). Most (eleven) were fitted with Elesco exhaust steam injectors; the other five used a Sellers design. All but 3402-3403 and 3409-3411, which had Simplex stokers, used Duplex stokers.

Later tenders incresed coal capacity to 16 tons or 20 tons with coal boards; The 16-ton tender weighed 173,200 lb (78,562 kg). Filled to the coal boards' tops, the tender weighed 181,200 lb (82,191 kg).

See Locobase 435 fir details on the 1941 boiler and firebox updates.

The class continued serving the railroad through World War II. (3412 almost made it; it was scrapped in October 1944.)

Class L-107 (Locobase 315)

Data from D&RGW 1 - 1952 Folio L locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.Works numbers were 64298-64307 in May 1923.

Mallet compound with 39-in LP cylinders. Later variant of the L-95 and basically a copy of the USRA heavy articulated (Locobase 330). Note the good boiler proportions in which the firebox heating surface included 49 sq ft (4.55 sq m) of arch tubes and 82 sq ft (7.6 sq m) of combustion chamber for a total of 435 sq ft (40.41 sq m). Before long, direct heating surface expanded in one of two ways. In one, 115 sq ft (10.7 sq m) of syphons replaced the arch tubes; that version is shown in the specification. In the other, firebox circulators added 76 sq ft (7.05 sq m) to the surface for a total of 462 sq ft (42.9 sq m).

They saw out steam, being retired in 1947-1951.

Class L-131 (Locobase 316)

Data from tables in 1930 Locomotive Cyclopedia and D&RGW 1 - 1952 Locomotive Diagram supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also Dave Straight and John Hill, "D&RGW 3600 Locomotives", 24 July 2015 post in their Colorado Steam blog at [], last accessed 11 December 2016. (Thanks to Chris Hohl for supplying the valve gear ID, to John Hill for his 8 December 2016 email question about tractive effort; and to Chris again for his October 2020 email reporting the engine-and-tender wheelbase.) Works numbers were 67320-67329 in August 1927.

Firebox heating surface includes the combustion chamber (170 sq ft/15.8 sq m) and thermic syphons in both the combustion chamber and in the firebox (137 sq ft/12.7 sq m). It's likely that, as delivered, the class had an additional 32 sq ft (2.97 sq m) in arch tubes, but Locobase hasn't yet confirmed this. By 1946, no arch tubes showed in the diagrams.

The boiler was fitted with Elesco feedwater heater, valve motion had limited cutoff of the 14" (356 mm) piston valves, and a Simplex stoker fed coal to the firebox. 3606 was the only engine fitted with circulators (143 sq ft/13.3 sq m),

John Hill correctly noted that the 131 in the D&RGW's designation for this class represents the tractive effort and wondered why Locobase showed 140,000+. The higher figure is a direct calculation of tractive effort from the variables, which include boiler pressure minus 15%. Locobase's editor queried the data entry program to see what lower boiler pressure would result in 131,000 lb and hit that figure with 225 psi.

Locobase later (July 2018) returned to John Hill's question and worked the orginal formula, but lowered the BP coefficient to .80. The result was 131,850 lb, which agrees almost exactly with the tractive effort shown in the diagram (131,800 lb). Given the large grate and low-calorie coal, Locobase suspects that the railroad applied the lower coefficient to its formula. Also note an inconsistency: the Rio Grande Western's class ID for this decade of articulateds was the tractive effort in thousands, rounded DOWN. The earlier class's designator was the same tractive effort, rounded UP.

Ten engines that were simple-expansion improvements on the earlier Mallet compounds. Rated at 3,300 tons on the east side of the Continental Divide (maximum grade 1.42%) and 1,400 tons on the west slope (max grade 3%). Straight and Hill comment on the class's profligate consumption of fuel: " I remember being told that for every four scoops of coal into the firebox, one went straight up the smokestack."

A further quote underscores the volcanic pall this locomotive could cast: " Dave's friend, retired D&RGW employee Gerry Decker, relates in a letter to Dave about his father Dean who was a D&RGW conductor. Gerry says,

'...Dean was on the first one [of the 3600s] west with tonnage. He said the road foreman got off after a few tunnels and rode the caboose to Bond. He told Dean at Bond that he wouldn't have ridden through another tunnel if they gave him what it cost new at the factory! He referred to it as `a miserable S.O.B!'...Dean always remarked how bad they smoked. The company issued the crews some old WW1 gas masks and he said they were useless! The best they could do was keep a box of packing waste and a bucket of water in the cab. They would grab a wad of waste, dip it in the water, and cover their faces in it while going thru the tunnel. Dean also carried a small mirror with him to help pick cinders out of his eyes. He said he could get a cinder in his eye by just looking at a picture of a 3600. ... Dean said that there was a practice in helper service for other engines to be ahead of a 3600 because they put out too much smoke and heat that would about kill the crews on the smaller engine. He said they tried that at first but that didn't last too long.'"

All of the class served the Rio Grande until diesels took over in the mid-1950s and all were scrapped between October 1955 and October 1956.

A later class of 10 (3610-3619) from Alco was designated L-132; see Locobase 16242.

Class L-132 (Locobase 16242)

Data from D&RGW 1 - 1952 Locomotive Diagram supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Chris Hohl for supplying the valve gear ID and to John Hill for his 8 December 2016 email question about tractive effort.) Works numbers were 68328-68337 in June 1930.

When the D&RGW bought ten more of these massive articulateds (see Locobase 316 for the earlier batch), the new engines reflected two substantial changes: Alco's Brooks works had been shut down and Schenectady introduced the superpower-type tube and flue layout that eliminated most of the small tubes in favor of many more, smaller diameter superheater flues.

Firebox heating surface includes the combustion chamber (170 sq ft/15.8 sq m). By 1946, most of the class had the two firebox thermic syphons in the firebox (137 sq ft/12.7 sq m). Three--3612, 3615, and 3617--had three thermic syphons offering 153 sq ft (14.21 sq m). See Locobase 316 for comments on these smoky locomotives.

John Hill correctly noted that the 131 in the D&RGW's designation for this class represents the tractive effort and wondered why Locobase showed 140,000+. The higher figure is a direct calculation of tractive effort from the variables, which include boiler pressure minus 15%. Locobase's editor queried the data entry program to see what lower boiler pressure would result in 131,000 lb and hit that figure with 225 psi.

Locobase later (July 2018) returned to John Hill's question and worked the orginal formula, but lowered the BP coefficient to .80. The result was 131,850 lb, which agrees almost exactly with the tractive effort shown in the diagram (131,800 lb). Given the large grate and low-calorie coal, Locobase suspects that the railroad applied the lower coefficient to its formula. Also note an inconsistency: the Rio Grande Western's class ID for this decade of articulateds was the tractive effort in thousands, rounded UP. The earlier class's designator was the same tractive effort, rounded DOWN.

Class L-95 - updated (Locobase 435)

Data from 1937 D & RGW locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were 52038-52053 in December 1912. (Thanks to Chris Hohl for his 4 April email correcting the total wheelbase, adding tender capacities without coal boards, and fixing a mistake in loaded tender weight

These Mallets preceded the 2-10-2s described in a Railway Age Gazette article of 3 August 1917. Used in Minturn-Malta (Tennessee Pass), Colorado helper service. Rio Grande's calculation of compound tractive effort yielded 96,000 lb (43,545 kg or 427 kN).

The specifications refer to the later boiler (new in 1941) whose firebox heating surface included 114 sq ft (10.59 sq m) in the combustion chamber and 88 sq ft (8.18 sq m) in thermic syphons in both the firebox and the combustion chamber. Other changes included the deletion of 49 small tubes (19.2 % of the original total) from the boiler to make room for twelve more large flues for superheater elements (a 33% increase), adhesion weight increase of slightly more than 10 short tons.

Chris Hohl noted that when loaded with 16 tons of coal, the tenders weighed 223,400 lb (101,333 kg). Adding coal boards increased coal capacity to 20 tons and tender weight to 231,400 lb as shown in the Locobase specs.

Four of the class went to the scrapper in the 1940s beginning with 3412 in October 1944 and ending with 3402 in August 1948. By the early 1950s, only four L-95s remained in service. Three still had their syphons, but 3405 had traded in its syphons for 76 sq ft (7.06 sq m) of security circulators (it also still had slide valves supplying steam to the LP cylinders.).

The remaining twelve met the ferro-knacker in the early 1950s with 3414 going in Febraury 1950 and the class leader finishing off the class in May 1952.