Mineral Point & Northern 4-6-0 "Ten-Wheeler" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 50 (Locobase 14118)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volume 43, p.205. See also , Nadler, Paul S. "The history of the Mineral Point and Northern Railway Company (parts I and II)" Wisconsin Magazine Of History. Volume: 38 /Issue: 2 (1954-1955) Baldwin works numbers were 38848-38849 in November 1912.

The MP&N was a southwest Wisconsin road laid to exploit the "black jack" zinc ore north of the city of Mineral Point. After much discussion and delay, the MP&N began construction in 1904 from four miles south of Mineral Point at Highland Junction northwest along the Pecatonica River to Linden (12.8 miles away) and over a hill to Highland, 12 miles further up the track. The first trains entered Linden in August 1904 and Highland on 5 December 1904.

Although a success in many ways, the line constantly ran at a deficit, a condition exacerbated, says Paul Nadler, by two fatal accidents that occurred in 1909 and 1911. Still, the Mineral Point Zinc Company saw value in the road and put up the $50,000 needed to buy the 50 and 51. The Baldwin specs note that grades amounted to 1 and 2%. The "rough track" had 60 lb/yard (30 kg/metre) rail and 10-degree curves (radii of 574 feet/175 metres).

World War I increased traffic volume because of the high demand for zinc, but prices declined beginning in 1917. Passenger service ended in 1919 as part of a long decline that Nadler details in Part II of his history. The "cataclysmic" blow came on 1 January 1928 when New Jersey Zinc closed all of its mines, thus eliminating a major source of zinc ore. Mineral Point Zinc tonnage over the MP&N dropped by almost two-thirds from 101,980 tons in 1927 to 36,061 tons in 1928 and revenue by 37%.

One of the two 4-6-0s was idled in 1929 because the railroad couldn't afford the $500 in repairs. The right of way deteriorated as deferred maintenance became foregone maintenance.

Despite local protests, the inevitable resort to abandonment became official in March 1930. Both engines were sold to the Rutland, Toluca & Northern in Granville, Illinois. In a sad coda to the MP&N's story, the two Ten-wheelers were smashed into each other in a staged crash at Magnolia, Ill on the RT&N on 30 June 1935. The spectacle, which was intended to raise money to finance that road's reorganization, proved a flop when the two engines failed to meet on a trestle and instead collided in a "cornfield meet" some distance from the bridge.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID14118
RailroadMineral Point & Northern
Number in Class2
Road Numbers50-51
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.66
Engine Wheelbase (ft / m)22.83 / 6.96
Ratio of driving wheelbase to overall engine wheelbase 0.53
Overall Wheelbase (engine & tender) (ft / m)50.96 / 15.53
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)104,000 / 47,174
Engine Weight (lbs / kg)139,000 / 63,049
Tender Loaded Weight (lbs / kg)100,000 / 45,359
Total Engine and Tender Weight (lbs / kg)239,000 / 108,408
Tender Water Capacity (gals / ML)5000 / 18.94
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)8 / 7
Minimum weight of rail (calculated) (lb/yd / kg/m)58 / 29
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)57 / 1448
Boiler Pressure (psi / kPa)180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)19" x 26" / 483x660
Tractive Effort (lbs / kg)25,194 / 11427.82
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.13
Heating Ability
Tubes (number - dia) (in / mm)290 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)13.50 / 4.11
Firebox Area (sq ft / m2)143 / 13.29
Grate Area (sq ft / m2)29.20 / 2.71
Evaporative Heating Surface (sq ft / m2)2180 / 202.53
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2180 / 202.53
Evaporative Heating Surface/Cylinder Volume255.57
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5256
Same as above plus superheater percentage5256
Same as above but substitute firebox area for grate area25,740
Power L15804
Power MT369.10

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