Brecon & Merthyr 0-6-0 Locomotives in Great_Britain

Class Details by Steve Llanso of Sweat House Media

Class Cymbeline (Locobase 20352)

Data from "West Somerset Mineral Railway", Locomotive Magazine, Volume XX [20] (15 July 1914, pp. 196-197. See also the informative, heavily illustrated website of the West Somerset Mineral Railway, last accessed 25 February 2018 at [] . See also coments of M Conybeare to "Captain Henry Whatley Tyler, "On the Working of Steep Gradients and Sharp Curves on Railways", in James Forrest (ed.), Minutes of Proceedings of the Institution of Civil Engineers, , pp. 334-335. Works numbers were 995-996 in 1866.

According to the WMSR website, this sextet was identical to the three ordered by the WMSR and described in Locobase 20351. The B&M order number in Sharp, Stewart's books was E492.

Cymbeline's August 1866 performance served to illustrate Conybeare's point that "exceptionally steep gradients" didn't necessary need special locomotive running gear. He noted that in the previous ten years he'd laid out the longest continuous gradient on the descent from the summit in the Brecon Beacons into the Usk valley. Using relatively heavy 70 lb/yard (35 kg/metre) rail, the 6.62 miles (10.7 km) sloped at an average 1 in 38.8 (2.58%).

In defiance of prevailing opinion that 1 in 40 was too steep to operate economically, the B&M put the Cymbeline to work on a 20-mile (32.2 km) stretch that included 8 1/2 miles (13.7 km) of 1 in 38 and 1 in 40. Trailing an average load of 85 tons, the engine ran 1,897 miles (3,054 km) burning 703 cwt (78,736 lb/37,714 kg) of coal for an average of 41.5 lb/mile (12.35 kg/km). Oil consumption amounted to 45 pints and tallow 44 lb (20 kg).

Conybeare attributed the good results to the joint attention of the builder and the railway to create locomotives that were "specially and carefully designed for the particular work they had to do." He said they were "as good as good a type of engine working steep gradients with economy any in England."

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID20352
RailroadBrecon & Merthyr
CountryGreat Britain
Number in Class6
Road Numbers
Number Built6
BuilderSharp, Stewart
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)12.67 / 3.86
Engine Wheelbase (ft / m)12.67 / 3.86
Ratio of driving wheelbase to overall engine wheelbase1
Overall Wheelbase (engine & tender) (ft / m)12.67 / 3.86
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)80,460 / 36,496
Engine Weight (lbs / kg)80,460 / 36,496
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)80,460 / 36,496
Tender Water Capacity (gals / ML)1140 / 4.32
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 0.55 / 1
Minimum weight of rail (calculated) (lb/yd / kg/m)45 / 22.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)55 / 1397
Boiler Pressure (psi / kPa)120 / 8.30
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x610
Tractive Effort (lbs / kg)12,863 / 5834.57
Factor of Adhesion (Weight on Drivers/Tractive Effort) 6.26
Heating Ability
Tubes (number - dia) (in / mm)148 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)14.29 / 4.36
Firebox Area (sq ft / m2)89.50 / 8.31
Grate Area (sq ft / m2)11.80 / 1.10
Evaporative Heating Surface (sq ft / m2)1185 / 110.09
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1185 / 110.09
Evaporative Heating Surface/Cylinder Volume187.95
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1416
Same as above plus superheater percentage1416
Same as above but substitute firebox area for grate area10,740
Power L12848
Power MT234.11

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