This railroad was built in the early 1900s to serve eastern Merced county in northern California from near Sacramento to the western entrance of the Yosemite National Park. Laid with 70 lb/yard (35 kg/metre) rail, the line had maximum grades of 2.4% and curves no sharper than 18 degrees (210 foot/64 metre radii)
This Mogul was a typical saturated-steam engine (Baldwin class 8 32-D) with balanced slide valve and wagon-top boiler. The YVRR paid $17,340.18. The builder's photo shows a very tall, thin stack; a later one shows a shorter one with a screen. With oil-firing there was much less chance of sparks starting wayside fires.)
Engine #28, delivered almost 4 years later, was a duplicate although its weight guarantees had climbed to 120,000 lb (54,431 kg) on the drivers and 143,000 lb (64,864 kg) overall. It was wrecked in 1920 but rebuilt and survived to be scrapped with 27 after the railroad closed in 1945.
Later Baldwins numbered 29 and 25 were similar in size, but had Walschaert gear and piston valves.
When the YVRR went back to Baldwin to buy another Mogul nine years after its first purchase (described in Locobase 5970), some things stayed the same. The locomotive had the same wheel base and the boiler diameter remained the same. But much was different: now the locomotive was superheated and had 10" (254 mm) piston valves serving long-stroke cylinders. The grate was smaller as was the oil-burning firebox overall and the total heating surface. Axle loading went up as did tender weight. And the price jumped more than $10,000 to $27,541.77.
To allow for track play on curves, the front and rear flanged driver sets were spaced 53 1/4" (1,352 mm) apart, while the middle set of plain-tire drivers, which were one inch wider at 6 1/2" (165 mm), had a gauge of 52 3/4" (1,339 mm).
#25 was bought in 1925 as a sister to 29 (go figure the numbering scheme!). After 20 years with the YVRR, both 25 and 29 were leased to the Southern Pacific during World War II. After the war and the YVRR's abandonment, 25 was scrapped but 29 was sold to a railroad in Northern Mexico.
Here, [external link] (3 April 2004) picks up the 29's trail. At first used to construct the Sonora-Baja railroad, the engine soon transferred to Yucatan as SCyT's 7311-3. A long career in the Yucutan included adoption by the FC Unidos de Yucutan in 1960 and renumbering as 353 three years later. After going out of service in 1970 the locomotive idled in oblivion until it was rebuilt at the Merida shops by Jorge Gonzalez and friends.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Railroad||Yosemite Valley||Yosemite Valley|
|Number in Class||2||2|
|Road Numbers||27-28||29, 25|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||14.17 / 4.32||14.17 / 4.32|
|Engine Wheelbase (ft / m)||22.75 / 6.93||22.75 / 6.93|
|Ratio of driving wheelbase to overall engine wheebase||0.62||0.62|
|Overall Wheelbase (engine & tender) (ft / m)||51.16 / 15.59||51.17 / 15.60|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)|
|Weight on Drivers (lbs / kg)||113,750 / 51,596||120,270 / 54,554|
|Engine Weight (lbs / kg)||134,600 / 61,054||140,760 / 63,848|
|Tender Loaded Weight (lbs / kg)||90,400 / 41,005||100,240 / 45,468|
|Total Engine and Tender Weight (lbs / kg)||225,000 / 102,059||241,000 / 109,316|
|Tender Water Capacity (gals / ML)||4500 / 17.05||4500 / 17.05|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||2240 / 8.50||2240 / 8.50|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||63 / 31.50||67 / 33.50|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||57 / 1448||57 / 1448|
|Boiler Pressure (psi / kPa)||190 / 13.10||190 / 13.10|
|High Pressure Cylinders (dia x stroke) (in / mm)||19" x 28" / 483x711||19" x 28" / 483x711|
|Tractive Effort (lbs / kg)||28,639 / 12990.45||28,639 / 12990.45|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||3.97||4.20|
|Firebox Area (sq ft / m2)||160 / 14.87||148 / 13.75|
|Grate Area (sq ft / m2)||31.10 / 2.89||26.80 / 2.49|
|Evaporative Heating Surface (sq ft / m2)||2091 / 194.33||1571 / 146|
|Superheating Surface (sq ft / m2)||342 / 31.78|
|Combined Heating Surface (sq ft / m2)||2091 / 194.33||1913 / 177.78|
|Evaporative Heating Surface/Cylinder Volume||227.57||170.98|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||5909||5092|
|Same as above plus superheater percentage||5909||6009|
|Same as above but substitute firebox area for grate area||30,400||33,182|