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

South African Railways Class GO

Company type	Steam locomotive class
Industry	Railway transport
Founded	1954
Founder	L.C. Grubb (Chief Mechanical Engineer)
Headquarters	South Africa
Products	Articulated steam locomotives (Class GO Garratt)
Number of employees	25 locomotives built

Overview

The South African Railways Class GO 4-8-2+2-8-4 was an articulated steam locomotive introduced in 1954.

During that year, the South African Railways commissioned a fleet of 25 Class GO Garratt locomotives designed for light branch line duties. These engines featured a tank-and-tender configuration and utilized a 4-8-2+2-8-4 Double Mountain wheel arrangement. Notably, this class represented the final new steam locomotive model procured by the Railways.

Manufacturer

L.C. Grubb

The Class GO 4-8-2+2-8-4 Garratt locomotive, featuring both tank and tender, was engineered specifically for operation on lighter rail infrastructure. The design process took place in 1952 under the guidance of L.C. Grubb, who served as the Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1949 until 1954. Subsequently, an order for 25 units was placed with the German firm Henschel and Son. These locomotives were constructed immediately after the initial series of the Class GMA Garratts, which were also produced by the same manufacturer.

Manufactured in 1953, these locomotives entered service in 1954 and were assigned numbers ranging from 2572 to 2596. The Class GO marked the final steam locomotive type procured by the Railways prior to the widespread transition to electrification and diesel power. Notably, the Class 5E mainline electric locomotive was introduced a year following the Class GO, with the Class 31-000 diesel-electric model arriving in 1958.

Characteristics

In terms of design and overall appearance, the Class GO closely resembled the Class GMA, sharing many interchangeable components. It featured superheating, a mechanical stoker, Walschaerts valve gear, and piston valves. Both classes were built on a one-piece cast steel frame equipped with Franklin spring-loaded wedge horns, produced by Commonwealth Steel Castings Corporation in the United States. The primary modifications focused on weight reduction, including a smaller diameter boiler, a reduced firebox and firegrate area, and a coal bunker capacity decreased by half a ton.

The boiler employed a telescopic design with an internal diameter measuring 6 feet 2+3⁄4 inches (1,899 millimetres) at the first ring and expanding to 6 feet 4+1⁄8 inches (1,934 millimetres) near the firebox end. Due to this smaller boiler diameter, the Class GO was equipped with a chimney slightly longer than that of the Class GMA. Regarding the coal bunker, its capacity reduction led to a change in its front profile from an inverted "L" shape on the Class GMA to a "\" shape on the Class GO, alongside a lowered bunker height that sat below rather than level with the cab roof.

The engine units mirrored those of the Class GMA except for cylinders that were lined and sleeved to reduce their bore size from 20+1⁄2 to 18+1⁄2 inches (521 to 470 millimetres) to accommodate the smaller boiler dimensions. This adjustment resulted in diminished tractive effort, dropping from 60,700 to 49,430 pounds-force (270.0 to 219.9 kilonewtons) at 75% boiler pressure. Roller bearing axle boxes were installed on all wheels except crank-pins; cannon boxes were fitted on every axle except those on the inner Bissel trucks, which utilized outside bearings. The locomotive featured comprehensive mechanical lubrication, self-adjusting pivots, a U-shaped foundation ring welded at both inner and outer firebox bottom edges, and an all-welded firebox construction. Its engine units also incorporated Commonwealth cast steel frames.

Type X-17 water tender

Similar to Classes GM and GMA, the Class GO was configured as a tank-and-tender Garratt. Consistent with these classes, it carried water exclusively in its front tank while reserving coal storage for the rear bunker. To compensate for limited onboard water capacity, it was semi-permanently coupled to a specially designed Type X-17 water tender holding 6,815 imperial gallons (31,000 litres) of water. Both the Class GO and the initial batch of Class GMA locomotives utilized the second variant of this Type X-17 tender built in 1953. These tenders bore numbering corresponding to their locomotives and were painted black with red buffer beams.

To reduce stress on rails, wheel balancing was arranged so that hammer blow did not exceed one ton per wheel at speeds up to 45 miles per hour (72 kilometres per hour). This engineering resulted in a maximum axle load of 13 long tons 8 hundredweight (13,620 kilograms), enabling operation on rails rated at 45 pounds per yard (22 kilograms per metre). The locomotive could negotiate curves with a radius as tight as 275 feet (84 metres), requiring gauge widening no greater than 3⁄4 inch (19 millimetres) and superelevation up to 4+1⁄2 inches (114 millimetres).

Visually distinguishing features between Classes GMA and GO included their coal bunker front profiles—the inverted "L" shape characteristic of the GMA contrasted with the "\" shape found on the GO—and the longer chimney present on the GO. On both types, mechanical stoker engines were positioned within cutouts at their coal bunkers' front or cabside ends; however, these were located on the right (driver's) side for Class GMA and on the left (stoker's) side for Class GO.

Service

Following their initial delivery, these locomotives underwent a brief trial period on the route between Krugersdorp and Zeerust. Subsequently, they were transferred to operate on the Eastern Transvaal line running from Belfast to Steelpoort, with their base at the Lydenburg shed. This particular route is among the most challenging on the SAR network, featuring a maximum gradient of 1 in 33 (3%). Over a distance of approximately 95 miles (153 kilometres), the line ascends from a low point at 2,427 feet (740 metres) elevation to reach its peak at Nederhorst, which stands at 6,875 feet (2,096 metres), the highest altitude encountered on the SAR system.

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

When diesel traction replaced steam on the Steelpoort line in 1972, these locomotives were reassigned to operate on the branch line connecting Umtata with Amabele in Transkei, as well as on the Greytown branch extending from Pietermaritzburg in Natal. However, their deployment in Transkei was met with dissatisfaction since they were insufficiently powerful to substitute for two Class 14CRB engines. Additionally, each engine unit's coupled wheelbase was longer compared to that of the Class 14CRB locomotives, making them less adept at negotiating the sharp curves near the Kei River crossing.

Consequently, the locomotives assigned to Transkei were soon moved again to Natal. There, the majority found service on the North Coast line with sheds located at Stanger, Empangeni, and Gingindlovu. From Empangeni, they also operated trains towards Golela on the border with Swaziland, and briefly served on the branch lines to Eshowe and Nkwalini. Their tenure on the Eshowe branch was short-lived due to their propensity to ignite fires while ascending gradients of 1 in 30 (3⅓%) through sugar cane fields.

Similar to the Class GMA locomotives, the Class GO proved to be reliable and effective throughout its service life. Nevertheless, following their replacement by diesel-electric units, all Class GO engines were transferred to De Aar in 1977. There they remained unused for seven years before being abruptly withdrawn from service and scrapped in 1984 after just 22 years of active revenue operation. None of these locomotives were sold for industrial use.

Preservation

Only a single example of the Class GO has been preserved. As of 2018

Number	Works nmr	THF / Private	Leaselend / Owner	Current Location	Outside SOUTH AFRICA	?
2575	Hensc 28705	THF	Transnet Heritage Foundation	Outeniqua Transport Museum

Illustration

The primary image features locomotive no. 2592 positioned at the De Aar locomotive depot in 1979. The sole surviving Class GO engine is no. 2575, which is exhibited at the Outeniqua Transport Museum located in George.

• Locomotive no. 2583 at Germiston Shed, 16 September 1973
  Locomotive no. 2583 at Germiston Shed, 16 September 1973
• Locomotive no. 2575 during an excursion in George, 30 May 2005
  Locomotive no. 2575 during an excursion in George, 30 May 2005
• Locomotive no. 2575 displayed at the Outeniqua Transport Museum, 26 August 2012
  Locomotive no. 2575 displayed at the Outeniqua Transport Museum, 26 August 2012