Brecon & Merthyr 0-6-2 Locomotives in Great_Britain


Class Details by Steve Llanso of Sweat House Media

Class 1405 (Locobase 10121)

Data from "Six-wheels Radial Saddle Tank, Brecon & Merthyr Ry.," The Locomotive & Railway Carriage & Wagon Review, Vol IV (August 1899), p. 121. See also "Brecon and Merthyr Railway," The Locomotive, Volume VIII (9 May 1903), pp. 322-325. and John Speller's Web Pages - Great Western Railway Narrow Gauge-Brecon & Merthyr Railway, last accessed 21 February 2015 at [] . Works numbers 1405-1406.

South Wales railways often preferred the radial tank because of its flexibility around curves and its abilty to pull heavy trains. The railway ran from Brecon, home to several iron foundries, down to Merthyr, then on toward Newport or on a branch to Caerphilly out to Pontypridd. Altogether, including running rights to Newport, the railway covered 68 1/4 miles (110 km) . It was a busy coal road, but also operated a "vigorous passenger service", says John Speller.

They were taken over by the Great Western under the Grouping plan of 1922. At that point their numbers were 1674 and 1677.


Class 36 (Locobase 15967)

Data from "Railway Notes-Brecon and Merthyr Railway", The Locomotive, Volume 16, Number 211 (15 March 1910). Works numbers were 3379-3382 in 1910 and 3577-3580 in 1914.

The saddle-tanks described in Locobase 10121 had served this South Wales railway for more than ten years when the B&MR's locomotive superintendent James Dunbar drew up the specs for the new quartet. They too would be radial tanks, but would carry their water in side tanks. Every part of the power equation was scaled up with the guiding requirement of hauling 10 1/2 ten-ton loaded wagons up a 1 in 40 grade (2.5%). One measure of the line's traffic demands and sturdiness was a relatively high axle loading of 18 tons 15 cwt..

They also were fitted with an automatic vacuum brake suitable for handling heavy passenger traffic demand in the summer. Alas for all the trouble taken to produce a suitable locomotive, the class was found to be "too small in the wheels and too sluggish to be quite satisfactory for passenger train work." So additional locomotives of greater size and power arrive in 1915; see Locobase 20536.

NB: The tube length is estimated from the given tube heating surface area and a calculation of tube surface area using various length estimates.


Class 45 (Locobase 20536)

Data from "Six-Coupled Radial Tank Locomotive: Brecon and Merthyr Railway", The Locomotive, Volume XXIII [23] (16 April 1917), pp. 65 and update on 15 September 1917, p. 193. Works numbers were 3645-3647 in 1915.

Locobase 15967 laid out the service for which the B&M radial tanks were intended and noted that the 1910 class were deemed to have wheels too small and performance too sluggish to serve the railway's passenger service.

Although the new specification was aimed at interchangeability among the radial tanks, the new engines had a 1/2" (12.7 mm) reduction in cylinder diameter (possibly through inserting a sleeve), taller drivers, less heating surface and grater area, and substantially less engine weight.

At the time of writing in April 1917, the LM was able to report that the 45s had "been found to be quite satisfactory , both on heavy mineral as well as on passenger train service. An adhesion weight percentage of 87% was applied primarily to the mineral trains over gradients as steep as 1 in 38 (2.6%). Passenger traffic was limited to "perhaps one short trip only with a colliery workmen's train or passenger train."

Principal Dimensions by Steve Llanso of Middle Run Media

Class14053645
Locobase ID10121 15967 20536
RailroadBrecon & MerthyrBrecon & MerthyrBrecon & Merthyr
CountryGreat BritainGreat BritainGreat Britain
Whyte0-6-2ST0-6-2T0-6-2T
Number in Class283
Road Numbers2, 436-4345-47
GaugeStdStdStd
Number Built283
BuilderVulcan FoundryRobert Stephenson & CoRobert Stephenson & Co
Year189419091915
Valve GearStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)12.17 / 3.7115.25 / 4.6515.25 / 4.65
Engine Wheelbase (ft / m)19.33 / 5.8921.75 / 6.6321.75 / 6.63
Ratio of driving wheelbase to overall engine wheelbase 0.63 0.70 0.70
Overall Wheelbase (engine & tender) (ft / m)19.33 / 5.8921.75 / 6.6321.75 / 6.63
Axle Loading (Maximum Weight per Axle) (lbs / kg)42,000 / 19,05139,424 / 17,882
Weight on Drivers (lbs / kg)121,632 / 55,171117,824 / 53,444
Engine Weight (lbs / kg)149,968 / 68,024136,640 / 61,979
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)149,968 / 68,024136,640 / 61,979
Tender Water Capacity (gals / ML)1320 / 52088 / 7.911560 / 5.91
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 3.30 / 3 3.10 / 3
Minimum weight of rail (calculated) (lb/yd / kg/m)68 / 3465 / 32.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)55.50 / 141054 / 137260 / 1524
Boiler Pressure (psi / kPa)150 / 10.30175 / 12.10175 / 12.10
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x61018.5" x 26" / 470x66018" x 26" / 457x660
Tractive Effort (lbs / kg)15,934 / 7227.5524,512 / 11118.4720,885 / 9473.29
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.96 5.64
Heating Ability
Tubes (number - dia) (in / mm)148 - 2" / 51244 - 1.75" / 44
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)1411.58 / 3.53
Firebox Area (sq ft / m2)90 / 8.36123.50 / 11.47100 / 9.29
Grate Area (sq ft / m2)14.40 / 1.3421.50 / 218 / 1.67
Evaporative Heating Surface (sq ft / m2)1170 / 108.741420 / 131.921327 / 123.28
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1170 / 108.741420 / 131.921327 / 123.28
Evaporative Heating Surface/Cylinder Volume185.57175.55173.29
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation216037633150
Same as above plus superheater percentage216037633150
Same as above but substitute firebox area for grate area13,50021,61317,500
Power L1356539674175
Power MT215.71234.36

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