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

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

300px No. 2592 standing out of service at De Aar loco depot, 14 November 1979

Type and origin Power type Steam Designer South African Railways Builder Henschel and Son Serial number Henschel 28705-28729 Model Class GO Build date 1953 Total produced 25

Specifications Configuration 4-8-2+2-8-4 "Double Mountain" Garratt Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia 30 in (762 mm) Driver diameter 54 in (1,372 mm) Trailing dia 30 in (762 mm) Minimum curve 275 ft (84 m) Wheelbase Total: 86 ft 4 in (26,314 mm) Engines: 6 ft 10 in (2,083 mm) bogie 14 ft 5 in (4,394 mm) coupled 30 ft 4 in (9,246 mm) total Length 93 ft 10 in (28,600 mm) Height 13 ft (3,962 mm) Frame Cast frame, 45 ft (13,716 mm) between pivot centres Axle load 13.4 long tons (13.6 t) on 7th & 8th drivers Adhesive weight 106.8 long tons (108.5 t) Loco weight 326,600 lb (148.1 t) empty 172.1 long tons (174.9 t) w/o Fuel type Coal Fuel capacity 11 long tons (11.2 t) Water cap 1,660 imp gal (7,500 L) front 6,750 imp gal (30,700 L) in Type X-20 auxiliary tank wagon Boiler 6 ft 2.75 in (1,899 mm) inside diameter at 1st ring 6 ft 4.125 in (1,934 mm) inside diameter at firebox 13 ft 6.5 in (4,128 mm) inside length 6 ft 9.5 in (2,070 mm) pitch Boiler pressure Firegrate area 56.6 sq ft (5.258 m2) Heating surface 2,625 sq ft (243.870 m2)  • Tubes 241 tubes 2 in (51 mm) diameter 36 tubes 5.5 in (140 mm) diameter 2,399 sq ft (222.874 m2)  • Flues 26 sq ft (2.415 m2)  • Firebox 200 sq ft (18.581 m2) Superheater:  • Heating area 546 sq ft (50.725 m2) Cylinders Four Cylinder size 18.5 in (470 mm) bore 26 in (660 mm) stroke Valve gear Walschaerts

Performance figures Tractive effort 49,430 lbf (220 kN) at 75% pressure

Career Operators South African Railways Class Class GO Number in class 25 Numbers 2572-2596 Delivered 1954 First run 1954 Withdrawn 1977

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

In 1954 the South African Railways placed twenty-five Class GO light branchline Garratt articulated steam locomotives with a 4-8-2+2-8-4 Double Mountain type wheel arrangement in service. It was the last new steam locomotive type to be acquired by the Railways.

Manufacturer

The Class GO 4-8-2+2-8-4 Garratt locomotive was designed to operate on lighter rails. The designs were prepared in 1952 under the supervision of L.C. Grubb, the Chief Mechanical Engineer (CME) of the SAR from 1949 to 1954, and an order for twenty-five of these locomotives was placed with Henschel and Son in Germany, immediately following on the order for the first batch of the Class GMA Garratt that was built by the same manufacturer. They were built in 1953 and were delivered and placed in service in 1954, numbered in the range from 2572 to 2596.

The Class GO turned out to be the last new steam locomotive type to be acquired by the Railways before full scale electrification and dieselisation commenced. The Class 5E mainline electric locomotive entered service a year after the Class GO, and the Class 31-000 diesel-electric locomotive in 1958.

Characteristics

In design and general appearance the Class GO was very similar to the Class GMA, with an identical one piece "Commonwealth" cast steel frame and roller bearing axle boxes on all wheels, but not on the crankpins. It had cannon boxes on all axles except those of the inner pony trucks, which had outside bearings. Many parts were, in fact, interchangeable. The chief differences were aimed at reducing weight, such as a smaller boiler with a reduced diameter, a smaller firebox and grate area and a half ton smaller capacity coal bunker.

On the coal bunker this basically involved altering the inverted "L" front end profile of the Class GMA bunker to a "\" profile on the Class GO bunker, as well as lowering the bunker height from more or less in line with the cab roof on the Class GMA to somewhat below the cab roofline on the Class GO. The engine units were identical, except that the cylinders had been lined and sleeved to reduce the bore from 20.5 to 18.5 inches (521 to 470 millimetres) to suit the smaller boiler. This resulted in a correspondingly reduced tractive effort, from 60,700 to 49,430 pounds-force (270 to 220 kilonewtons) at 75% boiler pressure.

In order not to overstress the rails, driving wheel balancing was arranged to limit the hammer blow effect to a maximum of one ton per wheel at 45 miles per hour (72 kilometres per hour). The end result was a locomotive with a maximum axle load of 13.4 long tons (14 tonnes) that could operate on 45 pounds per yard (22 kilograms per metre) rails. It was superheated, with a mechanical stoker and Walschaerts valve gear, and could negotiate curves of 275 feet (84 metres) radius with a gauge widening of not more than 0.75 inches (19 millimetres) and a superelevation of 4.5 inches (114 millimetres).

File:30 025 060 X-20 (Side A).JPG

Type X-20 water tender

The most obvious visible differences between the Class GMA and Class GO were their coal bunker front ends, with the inverted "L" profile of the Class GMA and the "\" profile of the Class GO. On both locomotives their engines for their mechanical stokers were situated in the cutout on the front or cabside ends of their coal bunkers, but on the right or driver’s side on the Class GMA and on the left or fireman’s side on the Class GO.

The Class GO also had a slightly longer chimney as a result of the smaller diameter boiler. As was done with the Class GM and Class GMA, the Class GO carried water only in its front tank while the rear bunker carried only coal. The meagre water supply was therefore also augmented by semi-permanently coupling a purpose-built Type X-20 auxiliary tank wagon with a capacity of 6,750 imperial gallons (30,700 litres) to the locomotive.

Service

Upon delivery, they were briefly put to work on the line from Krugersdorp to Zeerust, after which they were relocated to the line from Belfast to Steelpoort in the Eastern Transvaal, stationed at Lydenburg. This is one of the toughest lines on the SAR with a ruling gradient of 1 in 33, that climbs in 95 miles (153 kilometres) from a nadir at 2,427 feet (740 metres) to the summit at Nederhorst at 6,875 feet (2,096 metres), the highest point on the SAR.

File:Class GO 2595 (4-8-2+2-8-4).JPG

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When the Steelpoort line was dieselised in 1972, they went to work on the branchline from Umtata to Amabele in Transkei and on the Greytown branchline out of Pietermaritzburg in Natal. They were unpopular in Transkei, however, being too small to replace two Class 14CRB locomotives, while their coupled wheelbase per engine unit was longer than that of the Class 14CRB and therefore took less kindly to the sharp curves at the Kei River crossing.

As a result, the Transkei locomotives were soon also relocated to Natal, where most of them ended up on the Natal North Coast line, stationed at Stanger, Empangeni and Gingindlovu. From Empangeni they also worked the line to Golela on the Swaziland border, and they also served briefly on the Eshowe and Nkwalini branchlines. They were soon withdrawn from the Eshowe branch, however, as a result of their tendency to start fires while climbing the 1 in 30 gradients through sugar cane fields.

Like the Class GMA, the Class GO was a successful locomotive that gave good service. However, after they were displaced by diesel-electric locomotives, the whole Class was relocated to De Aar in 1977, where the locomotives spent seven years standing idle before they were abruptly all written off in 1984, after only twenty-two years of actual revenue service. None were sold into industrial service.

Illustration

The main picture shows number 2592 after being withdrawn from service, staged at the De Aar loco depot, on 14 November 1979. The only preserved Class GO locomotive is no. 2575, which is on display at the Outeniqua Transport Museum in George.

• GO 2575.jpg

  No. 2575 on an excursion trip, George, 30 May 2005

• Class GO 2575 (4-8-2+2-8-4).JPG

  No. 2575 at the Outeniqua Transport Museum, 15 April 2013

• Class GO no. 2583.jpg

  No. 2583 at Germiston Shed, 16 September 1973