Denver & Salt Lake / Denver, Northwestern & Pacific Other Articulated Locomotives

Class 210 / L-77 (Locobase 5407)

Data from table in May 1916 RME.

Drury (1993) says that these locomotives were the beneficiaries of two updates to the Mallet design the railroad was already operating -- a leading truck to make it a better road engine and a mechanical stoker.

They apparently served their purpose well because all but one went to the Denver & Rio Grande Western in 1947, from which they retired a few years later (1949-1951) as 3370-3375.

Class 76 (Locobase 11471)

Data from "Locomotive Building," The Railway Age Gazette, Vol XLVIII, No 13 (1 April 1910), p. 923.

These Mallets didn't remain all-adhesion engines for long. In 1912, the railway, by now renamed Denver & Salt Lake, added a leading truck for better tracking. At the same time, they added a mechanical stoker. So modified, they served in a helper-engine role until 1947-1952.

Class 76 / L-77 (Locobase 6819)

Data from D&RGW 1956 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

Drury (1993) shows that these started out on the D & SL as 0-6-6-0 Mallets that acquired a leading truck in 1912 to improve their over-the-road qualities. The result was a very uncommon Mallet wheel arrangement in the US. At the same time they were fitted with mechanical stokers. A photo of 200 in 1947 (Drury, p. 162) underscores the short boiler over the engines, even if one mentally deducts the leading truck.

Still the design served its purpose for decades, retiring on the Denver & Rio Grande Western several years after that railroad bought the remaining locomotives in the class in 1947. See the as-built 2-6-6-0s also supplied to the D & SL in 1912 at Locobase 5407.

Specifications
Class	210 / L-77	76	76 / L-77
Locobase ID	5407	11471	6819
Railroad	Denver & Salt Lake	Denver, Northwestern & Pacific (D&SL)	Denver & Salt Lake
Whyte	2-6-6-0	0-6-6-0	2-6-6-0
Road Numbers	210-216 / 211-216	203-209 / 3363-3369	200-209
Gauge	Std	Std	Std
Builder	Alco-Schenectady	Alco-Schenectady	Alco-Schenectady
Year	1913	1910	1909
Valve Gear	Walschaert	Walschaert	Walschaert
	Locomotive Length and Weight
Driver Wheelbase	10'		10'
Engine Wheelbase	39.08'		39.17'
Ratio of driving wheelbase to overall engine wheebase	0.26		0.26
Overall Wheelbase (engine & tender)	72.75'		72.75'
Axle Loading (Maximum Weight per Axle)	55583 lbs		55683 lbs
Weight on Drivers	333800 lbs	327000 lbs	332000 lbs
Engine Weight	361000 lbs	327000 lbs	362000 lbs
Tender Light Weight	186000 lbs		176000 lbs
Total Engine and Tender Weight	547000 lbs	327000 lbs	538000 lbs
Tender Water Capacity	9000 gals	9000 gals	9000 gals
Tender Fuel Capacity (oil/coal)	12 tons	12 tons	12 tons
Minimum weight per yard of rail on which locomotive could run	92.72 lb rail	91 lb rail	92.22 lb rail
	Geometry Relating to Tractive Effort
Driver Diameter	55"	55"	55"
Boiler Pressure	225 psi	225 psi	225 psi
Cylinders (dia x stroke)	21" x 32"	21" x 32"	21" x 32"
Low Pressure Cylinders (dia x stroke)	33.5" x 32"	33.5" x 32"	33.5" x 32"
Tractive Effort	70456 lbs	70456 lbs	70456 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)	4.74	4.64	4.71
	Heating Ability
Firebox Area	229 sq. ft	236 sq. ft	229 sq. ft
Grate Area	72.20 sq. ft	72.20 sq. ft	72.20 sq. ft
Evaporative Heating Surface	4230	5271	4118
Superheating Surface	1046		1249
Combined Heating Surface	5276	5271	5367
Evaporative Heating Surface/Cylinder Volume	329.74	410.89	321.01
	Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation	16245	16245	16245
Same as above plus superheater percentage	19465.67	16245	20025.51
Same as above but substitute firebox area for grate area	61740.15	53100	63515.82
Power L1	9343.66	4076	10427.19
Power MT	370.27	164.88	415.45