Cape Government 4-6-0 Locomotives in South_Africa

Class Details by Steve Llanso of Sweat House Media

Class 4th Class 4-6-0TT 1880 (Locobase 20236)

Data from [], last accessed 6 August 2017. Works numbers were 2361-2366 in 1879 for the Midland lines, 2385-2390 in 1880 for the Eastern lines, and 2431-2436 in 1881 for the Midland lines

These "tank-and-tender" locomotives were the first Cape Government to be designed locally, in this case by Michael Stephens of the Western System. Twelve went to the Midland System while six, which had 38" (965 mm) drivers were delivered to the Eastern System where grades could be quite severe.

Many South African locomotives trailed an auxiliary water tender behind standard tenders. The latter were attached to the locomotive through typical semi-permanent drawbar couplers. But this "tank and tender" setup allowed the locomotive to operate without a tender when shunting (switching) and attach a larger tender for road work. For shunting work, the crew brought coal fuel on board the engine in bags; there was no coal bunker. As shunter, the engine took water from side tanks containing 720 US gallons.

Hooking up the separate tender used a link-and-pin coupling instead of the drawbar coupler. It may have been simpler, but Locobase wonders if the connection's looseness reduced acceptable speeds. On the other hand, Wikipedia points out that these were the first to use compensated springing on all coupled wheels.

(See Locobase 20237 for the much more numerous 4th class engines from 1882-1883 that dispensed with the easily uncoupled tender.)

John D Tilney, the Cape Eastern System's Locomotive Superintendent installed extended smokeboxes with very effective spark-arresters that reduced engine-induced wildfires. Midland adopted the setup for several of its own. He also patented a form of grate shaker that, while reducing available grate area slightly to 10.9 sq ft (1.01 sq m), may have improved coal economy. His patent drawing shows both a sloping grate and brick arch.

Much of this class experienced relatively short careers. At least one was shown as hired out to work the Mafeking-Bulawayo extension into Rhodesia in 1896.

The first Midland batch of 1879 were off the rolls by 1899. Eastern's half-dozen were gone by 1904. Only the middle four of the last six (by now renumbered 0451-0454) survived to be placed in 4th class by the South African Railways in 1912.

Class 4th Class 4-6-0TT 1882 (Locobase 20237)

Data from [], last accessed 6 August 2017. Stephenson's works numbers were 2451-2459 for the Western System, 2461-2470, 2476-2480 for the Midlands System, and 2472-2475 for the Eastern System in 1882; and 2460 and 2471 in 1883 for the Midlands System. (Road numbers were W47-W55, M58-M67, E35-E38, M73-M75, M84-M85, respectively.) Neilson & Company of Glasgow works numbers were 2828-2848 in 1882 for the Western System (W56-W76); 2951-2954 and 2978-2983 in 1883 to the Eastern System (E39-E42, E45-E46, E43-E44, E47-E48, respectively); and 2984-2987 for the Midlands System (M76-M79).

Locobase 20236 shows the first eighteen "tank-and-tender" locomotives delivered to the Eastern and Midland Systems in 1879-1881. The next batch was significantly more numerous and differed in using the typical semi-permanent drawbar couplers to connect tender to tank. Firebox area decreased slightly, but the small tubes measured 4" (102 mm) longer than those of the earlier locomotives.

Beginning in the early 1890s, all of the class received extended smokeboxes because the modification smoothed and enhanced the draught.

Stephenson's 33 locomotives repeated the Stephenson link motion valve gear set up. Neilson & Company of Glasgow delivered 35 locomotives in 1883 with Joy valve gear.; these were rebuilt with Stephenson gear in 1896 because the Joy gear proved less satisfactory. The "Converted Joys" were easily distinguished from the rest because they lost their side tanks at the same time. Six of these were sold to the Oranje-Vrijstaat Gouwerment-Spoorwegen (OVGS) in 1897 and redesignated G.

Three of the Stephensons (470-470 from Midlands, 477 from Western) were sent to the Kowie Railway, a short line connecting Port Alfred on the coast with Grahamtown inland. They were renumbered 1, 3, and 2, respectively. Three Stephenson and two Neilsons were shown having been rented out to the builders of the Mafeking-Bulawayo extension into Rhodesia in 1896.

Seventeen of the CGR engines survived to be designated as Obsolete 4th class by the South African Railways in 1912. Some worked as switchers as late as 1832.

Class 4th Class 4-6-0TT 1884 (Locobase 20238)

Data from[], last accessed 6 August 2017. Works numbers were 3068-3071 in 1883.

Locobase 20236-2039 shows the 86 "tank-and-tender" locomotives delivered to the CGR's three systems in 1879-1883. The quartet shown here and four Eight-wheeler bogie engines were designed by the Eastern System's John D Tilney to see if he could get useful work out of the low-grade coal then being mined in the Stormberg coalfields, where the Molteno and Cyphergat collieries were operating.

His design attempted to reconcile conflicting facts: 1) Stormberg coal was a lot nearer and thus cheaper than the Welsh coal usually burned in CGR locomotives, but 2) its non-combustible component came to 29% of each pound dug out of the ground. The volatile parts would burn, but the grates would soon choke with ash and clinker. Tests showed that using Stormberg coal required 63.35 lb/mile (17.85 kg/km) while only 31.67 lb/mile (8.92 kg/km) of the Merthyr (i.e., Welsh-originated) coal was needed.

Several US railroads with similar low-calorie coal in abundance experimented with wide Wootten fireboxes or other designs to accomplish the same goal--some of the crews called these "dirt-burners", which seems fitting. Confined to a narrow firebox for several reasons, Tilney lengthened the firebox to enlarge the grate. Note too that he reduced steam pressure slightly. The long firebox created an uneven spacing between the first and second coupled axles (3 ft 4 in/1,016 mm) and second and third (4 ft 8 in/1,422 mm)

Although the locomotives performed well enough, stoking a long and narrow firebox proved challenging. When the Natal coalfields began yielding higher-calorie coal, burning dirt quickly fell out of use.

Beginning in the early 1890s, all of the class received extended smokeboxes because the modification smoothed and enhanced the draught. They also had their Joy valve gear removed and replaced with Stephenson link motion.

Only 644 remained in service in 1912 when the South African Railways added it as an obsolete 4th class engine. It was retired in 1918.

Principal Dimensions by Steve Llanso of Sweat House Media

Class4th Class 4-6-0TT 18804th Class 4-6-0TT 18824th Class 4-6-0TT 1884
Locobase ID20236 20237 20238
RailroadCape GovernmentCape GovernmentCape Government
CountrySouth AfricaSouth AfricaSouth Africa
Number in Class18684
Road NumbersM34-M39, E27-E32, M50-M55E35-E38, M58-M67, M73-M79, W47-W76E49-E52/641-644
Number Built18684
BuilderRobert Stephenson & CoseveralNeilson & Co
Valve GearStephensonStephenson or JoyJoy
Locomotive Length and Weight
Driver Wheelbase (ft / m)8 / 2.448 / 2.448 / 2.44
Engine Wheelbase (ft / m)17 / 5.1816.83 / 5.1318.25 / 5.56
Ratio of driving wheelbase to overall engine wheelbase 0.47 0.48 0.44
Overall Wheelbase (engine & tender) (ft / m)35.24 / 10.7435.03 / 10.6839.17 / 11.94
Axle Loading (Maximum Weight per Axle) (lbs / kg)19,488 / 884017,472 / 792517,472 / 7925
Weight on Drivers (lbs / kg)53,536 / 24,28447,264 / 21,439
Engine Weight (lbs / kg)73,248 / 33,22566,976 / 30,38078,512 / 35,612
Tender Loaded Weight (lbs / kg)51,744 / 23,47142,560 / 19,30545,052 / 20,435
Total Engine and Tender Weight (lbs / kg)124,992 / 56,696109,536 / 49,685123,564 / 56,047
Tender Water Capacity (gals / ML)2730 / 10.342760 / 10.452760 / 10.45
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 6.60 / 6 3.30 / 3 3.30 / 3
Minimum weight of rail (calculated) (lb/yd / kg/m)30 / 1526 / 13
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)42 / 106742 / 106738.50 / 978
Boiler Pressure (psi / kPa)140 / 9.70140 / 9.70130 / 9
High Pressure Cylinders (dia x stroke) (in / mm)15" x 20" / 381x50815" x 20" / 381x50815" x 20" / 381x508
Tractive Effort (lbs / kg)12,750 / 5783.3112,750 / 5783.3112,916 / 5858.61
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.20 3.71
Heating Ability
Tubes (number - dia) (in / mm)145 - 1.75" / 44145 - 1.75" / 44143 - 1.75" / 44
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)10.08 / 3.0710.37 / 3.1610.37 / 3.16
Firebox Area (sq ft / m2)65 / 6.0461.90 / 5.7583.23 / 7.73
Grate Area (sq ft / m2)11.70 / 1.0911.70 / 1.0918.25 / 1.70
Evaporative Heating Surface (sq ft / m2)753 / 69.96752 / 69.86763 / 70.89
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)753 / 69.96752 / 69.86763 / 70.89
Evaporative Heating Surface/Cylinder Volume184.08183.84186.52
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation163816382373
Same as above plus superheater percentage163816382373
Same as above but substitute firebox area for grate area9100866610,820
Power L1258325432405
Power MT319.10355.85

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