South African Class GMA 4-8-2+2-8-4

South African Class GMA & GMAM 4-8-2+2-8-4

Class GMAM no. 4079 Lindie Lou, Capital Park, 30 September 2006

Type and origin ♠ Configured as Class GMA ♥ Configured as Class GMAM Power type Steam Designer South African Railways (L.C. Grubb) Builder Henschel and Son Beyer, Peacock and Company North British Locomotive Company Serial number Henschel 28680-28704, 29600-29629 BP 7550-7552, 7677-7681, 7750-7776, 7826-7855 NBL 27691-27702, 27769-27778, 27783-27792 Model Class GMA Build date 1953-1958 Total produced 120

Specifications Configuration 4-8-2+2-8-4 (Double Mountain) Driver 3rd & 6th coupled axles Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 30 in (762 mm) Coupled dia. 54 in (1,372 mm) Trailing dia. 30 in (762 mm) Tender wheels 34 in (864 mm) Minimum curve 275 ft (84 m) Wheelbase 86 ft 4 in (26,314 mm)  • Engine 30 ft 4 in (9,246 mm) each  • Leading 6 ft 10 in (2,083 mm) each  • Coupled 14 ft 5 in (4,394 mm) each  • Tender 35 ft 9 in (10,897 mm)  • Tender bogie 5 ft 9 in (1,753 mm) Pivot centres 45 ft (13,716 mm) Wheel spacing (Asymmetrical) 1-2: 4 ft 10 in (1,473 mm) each 2-3: 4 ft 9 in (1,448 mm) each 3-4: 4 ft 10 in (1,473 mm) each Length: ​  • Over couplers 93 ft 10 in (28,600 mm) engine 43 ft 10 4⁄5 in (13,381 mm) tender 137 ft 8 4⁄5 in (41,981 mm) total Height 13 ft (3,962 mm) Frame type Cast Axle load ♠ 15 LT 7 cwt (15,600 kg) ♥ 15 LT 14 cwt (15,950 kg)  • Leading ♠ 20 LT 16 cwt (21,130 kg) front 20 LT 16 cwt (21,130 kg) rear ♥ 21 LT 16 cwt (22,150 kg) front 21 LT 9 cwt (21,790 kg) rear  • 1st coupled ♠ 14 LT 14 cwt (14,940 kg) ♥ 14 LT 18 cwt (15,140 kg)  • 2nd coupled ♠ 15 LT 5 cwt (15,490 kg) ♥ 15 LT 8 cwt (15,650 kg)  • 3rd coupled ♠ 15 LT 2 cwt (15,340 kg) ♥ 15 LT 6 cwt (15,550 kg)  • 4th coupled ♠ 14 LT 13 cwt (14,890 kg) ♥ 14 LT 17 cwt (15,090 kg)  • 5th coupled ♠ 14 LT 16 cwt (15,040 kg) ♥ 15 LT 4 cwt (15,440 kg)  • 6th coupled ♠ 15 LT 5 cwt (15,490 kg) ♥ 15 LT 12 cwt (15,850 kg)  • 7th coupled ♠ 15 LT 7 cwt (15,600 kg) ♥ 15 LT 14 cwt (15,950 kg)  • 8th coupled ♠ 14 LT 17 cwt (15,090 kg) ♥ 15 LT 4 cwt (15,440 kg)  • Trailing ♠ 12 LT 14 cwt (12,900 kg) front 12 LT 17 cwt (13,060 kg) rear ♥ 12 LT 17 cwt (13,060 kg) front 13 LT 3 cwt (13,360 kg) rear  • Tender bogie 25 LT 4 cwt 2 qtr (25,630 kg)  • Tender axle 12 LT 12 cwt 1 qtr (12,810 kg) Adhesive weight ♠ 119 LT 19 cwt (121,900 kg) ♥ 122 LT 3 cwt (124,100 kg) Loco weight ♠ 187 LT 1 cwt (190,100 kg) ♥ 191 LT 8 cwt (194,500 kg) Tender weight 50 LT 9 cwt 1 qtr (51,270 kg) Total weight ♠ 237 LT 10 cwt 1 qtr (241,300 kg) ♥ 241 LT 17 cwt 1 qtr (245,700 kg) Tender type X-17 (2-axle bogies) X-20 (2-axle bogies) X-17, X-20 permitted Fuel type Coal Fuel capacity ♠ 11 LT 12 cwt (11.8 t) ♥ 14 LT (14.2 t) Water cap ♠ 1,650 imp gal (7,500 l) ♥ 2,100 imp gal (9,500 l) Tender cap 6,790 imp gal (30,900 l) Firebox type Round-top  • Firegrate area 63.2 sq ft (5.87 m2) Boiler: ​  • Pitch 8 ft 6 in (2,591 mm)  • Diameter 6 ft 11 1⁄2 in (2,121 mm)  • Tube plates 13 ft 6 1⁄2 in (4,128 mm)  • Small tubes 282: 2 in (51 mm)  • Large tubes 50: 5 1⁄2 in (140 mm) Boiler pressure 200 psi (1,379 kPa) Safety valve Pop Heating surface 3,211.2 sq ft (298.33 m2)  • Tubes 2,974 sq ft (276.3 m2)  • Arch tubes 25.2 sq ft (2.34 m2)  • Firebox 212 sq ft (19.7 m2) Superheater: ​  • Heating area 747 sq ft (69.4 m2) Cylinders Four Cylinder size 20 1⁄2 in (521 mm) bore 26 in (660 mm) stroke Valve gear Walschaerts Valve type Piston Couplers AAR knuckle

Performance figures Tractive effort 60,700 lbf (270 kN) @ 75%

Career Operators South African Railways Class Class GMA & GMAM Number in class 120 Numbers 4051-4170 Delivered 1954-1958 First run 1954 Withdrawn 1988

External video

South African Steam - Garratts at Randfontein Estates Gold Mine 1994-1995. (30.16 minutes)

The South African Railways Class GMA 4-8-2+2-8-4 of 1954 was an articulated steam locomotive.

Between 1954 and 1958, the South African Railways placed 120 Class GMA Garratt articulated steam locomotives with a 4-8-2+2-8-4 Double Mountain type wheel arrangement in service. All the locomotives could be configured as either a Class GMA branchline or a Class GMAM mainline engine. This was the most numerous Garratt class in the world.

The light rail branchline Class GMA and mainline Class GMAM Garratt locomotive, a single Class which could be configured for either branchline or mainline working, was a development of the large Class GM branchline locomotive which was introduced on the South African Railways (SAR) in 1938. Like the Class GM, the Class GMA was a tank-and-tender Garratt which ran with a semi-permanently coupled auxiliary water tender to augment its meagre water capacity.

The locomotive was designed in 1952 under the supervision of L.C. Grubb, Chief Mechanical Engineer (CME) of the SAR from 1949 to 1954. An order for the first 25 of these locomotives was placed with Henschel and Son in Germany. They were built in 1953 and were delivered and placed in service in 1954, numbered in the range from 4051 to 4075. These first 25 locomotives were equipped with Type X-17 water tenders, built by the SAR in its Pietermaritzburg shops in 1953.

A second batch of 35 locomotives was delivered by Beyer, Peacock and Company (BP) in 1956. Of these, 23 were built by BP and numbered in the range from 4076 to 4098, while the other twelve, numbered in the range from 4099 to 4110, had been subcontracted by BP to the North British Locomotive Company (NBL). These twelve engines therefore bore works plates showing BP as well as NBL as builders.

This was followed by a third and final batch of sixty locomotives in 1958. Of these, thirty were delivered by BP, of which only ten, numbered in the range from 4121 to 4130, had actually been built by BP. The other twenty, numbered in the ranges from 4111 to 4120 and 4131 to 4140, had once again been subcontracted by BP to NBL. These twenty therefore also bore works plates showing BP as well as NBL as builders. The other thirty locomotives of the third batch, numbered in the range from 4141 to 4170, were again built by Henschel in Germany.