Five additional Class L-105 "Challengers" arrived from Baldwin in 1942. These were similar to the Class L-105s bought in 1938 and were assigned road numbers 3710 through 3714.
In need of more locomotives to handle war-time traffic, the D&RGW ordered six more "Challengers". The War Production Board allowed six ALCO-built 4-6-6-4s to be delivered in 1943. The D&RGW did not like them, and leased them instead of buying them. These locomotives were designated Class L-97 and had four 21 x 32 cylinders, 69" drivers, a boiler pressure of 280 psi, a tractive effort of 97,350 lbs and weighed 627,000 pounds. In 1947, diesels were replacing many of the D&RGW's steam locomotives and the six Class L-97 "Challengers" were transferred to the Clinchfield Railroad.
There are no surviving D&RGW "Challengers".
|Class||Qty.||Road Number||Year Built||Builder||Notes|
|L-105||10||3700-3709||1938||Baldwin||Numbers 3700-3709 scrapped between 1951 and 1956|
|L-105||5||3710-3714||1942||Baldwin||Numbers 3710-3714 scrapped between 1951 and 1956|
|L-97||6||3800-3805||1943||ALCO||Numbers 3800-3805 sold to the Clinchfield in 1947. Became Clinchfield Class E-1 and assigned road numbers 670-675. Clinchfield numbers 670-675 scrapped in 1953.|
This second group of five engines had smaller heating surfaces and consequently different ratios from the 10 shown in Locobase 339. The engines were not exactly starved for quality heat, however, the firebox had 200 sq ft (18.58 sq m) of heating surface in three thermic syphons and arch tubes as well as 206 sq ft (19.14 sq m) in the combustion chamber.
A third group of six (3800-3805) L-97s were leased from the UP during World War II. They were returned to the UP, which then sold them to the Clinchfield in 1947. See the UP Challenger entry at Locobase 341..
Firebox had 200 sq ft of heating surface in three thermic syphons and arch tubes. These were built for dual-service operation over the Continental Divide. The BL article said that the L-105 would confront grades of up to 3%, curves as tight as 16 deg (although the design could handle 22 degrees). A very detailed account of the components and materials can only be sampled. Metallurgical research resulted in a silicon manganese steel boiler. The 15-ft long grate ended at a firebrick wall behind which was a cinder hopper, which, Locobase guesses, provided an alternative landing point for cylinders that might otherwise clog the tubes or flues. Nine of the ten engines used Elesco feed water heaters; the tenth settled for the Worthington SA. 14" (356 mm) piston valves supplied each of the cylinders.
Of course, the bed was case as a single piece. A General Steel Castings front truck's wheels turned in roller bearings and enjoyed a swing of 6" (152 mm) to either side. Under the firebox, a Delta-type truck with 8" (203 mm) swing also used roller bearings.
An eastbound L-105 running the 64 miles (103 kph) from Salt Lake City to Thistle hauled 2,750 tons at 38 mph (61 kph), then over the Solider Summit on a consistent 2% adverse grade and using a helper at 18 mph (29 kph), then back up to 37.5 mph (60 kph) from Helper to Grand Junction.
Five more were supplied in 1942 with different tube and flue counts; see Locobase 1345.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Railroad||Denver & Rio Grande Western (D&RGW)||Denver & Rio Grande Western (D&RGW)|
|Number in Class||5||10|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||12.17 / 3.71||12.17 / 3.71|
|Engine Wheelbase (ft / m)||61.50 / 18.75||61.50 / 18.75|
|Ratio of driving wheelbase to overall engine wheebase||0.20||0.20|
|Overall Wheelbase (engine & tender) (ft / m)|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||74,721 / 33,893||73,669|
|Weight on Drivers (lbs / kg)||435,472 / 197,527||437,939 / 198,674|
|Engine Weight (lbs / kg)||641,700 / 291,071||641,900 / 301,639|
|Tender Loaded Weight (lbs / kg)||393,630 / 178,548||394,000|
|Total Engine and Tender Weight (lbs / kg)||1,035,330 / 469,619||1,035,900|
|Tender Water Capacity (gals / ML)||20,000 / 75.76||20,000 / 75.76|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||26 / 23.60||26 / 23.60|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||121 / 60.50||122 / 61|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||70 / 1778||70 / 1778|
|Boiler Pressure (psi / kPa)||255 / 17.60||255 / 17.60|
|High Pressure Cylinders (dia x stroke) (in / mm)||23" x 32" / 584x813 (4)||23" x 32" / 584x813 (4)|
|Tractive Effort (lbs / kg)||104,833 / 47551.51||104,833 / 47551.51|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.15||4.18|
|Firebox Area (sq ft / m2)||806 / 74.91||806 / 74.91|
|Grate Area (sq ft / m2)||136.50 / 12.69||136.50 / 12.69|
|Evaporative Heating Surface (sq ft / m2)||5730 / 532.53||6341 / 589.31|
|Superheating Surface (sq ft / m2)||2525 / 234.67||2628 / 244.24|
|Combined Heating Surface (sq ft / m2)||8255 / 767.20||8969 / 833.55|
|Evaporative Heating Surface/Cylinder Volume||186.18||206.04|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||34,808||34,808|
|Same as above plus superheater percentage||45,598||44,902|
|Same as above but substitute firebox area for grate area||269,244||265,134|