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

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

No. 2592 staged at De Aar, 14 November 1979

Type and origin Power type Steam Designer South African Railways (L.C. Grubb) 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) 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 Pivot centres 45 ft (13,716 mm) Wheel spacing (Asymmetrical) 1-2: 4 ft 10 in (1,473 mm) 2-3: 4 ft 9 in (1,448 mm) 3-4: 4 ft 10 in (1,473 mm) Length: ​  • Over couplers 93 ft 10 in (28,600 mm) Height 13 ft (3,962 mm) Frame type Cast Axle load 13 LT 8 cwt (13,620 kg)  • Leading 20 LT 12 cwt (20,930 kg) front 20 LT 18 cwt (21,240 kg) rear  • 1st coupled 13 LT 7 cwt (13,560 kg)  • 2nd coupled 13 LT 7 cwt (13,560 kg)  • 3rd coupled 13 LT 6 cwt (13,510 kg)  • 4th coupled 13 LT 6 cwt (13,510 kg)  • 5th coupled 13 LT 7 cwt (13,560 kg)  • 6th coupled 13 LT 7 cwt (13,560 kg)  • 7th coupled 13 LT 8 cwt (13,620 kg)  • 8th coupled 13 LT 8 cwt (13,620 kg)  • Trailing 11 LT 18 cwt (12,090 kg) front 11 LT 18 cwt (12,090 kg) rear  • Tender bogie 24 LT 17 cwt 3 qtr (25,290 kg)  • Tender axle 12 LT 8 cwt 3 qtr (12,640 kg) Adhesive weight 106 LT 16 cwt (108,500 kg) Loco weight 172 LT 2 cwt (174,900 kg) Tender weight 49 LT 15 cwt 3 qtr (50,590 kg) Total weight 221 LT 17 cwt 3 qtr (225,400 kg) Tender type X-17 (2-axle bogies) X-17, X-20 permitted Fuel type Coal Fuel capacity 11 LT (11.2 t) Water cap 1,660 imp gal (7,550 l) front Tender cap 6,815 imp gal (31,000 l) Firebox type Round-top  • Firegrate area 56.6 sq ft (5.26 m2) Boiler: ​  • Pitch 8 ft 9 1⁄2 in (2,680 mm)  • Diameter 6 ft 4 1⁄8 in (1,934 mm)  • Tube plates 13 ft 6 1⁄2 in (4,128 mm)  • Small tubes 241: 2 in (51 mm)  • Large tubes 36: 5 1⁄2 in (140 mm) Boiler pressure 200 psi (1,379 kPa) Safety valve Pop Heating surface 2,625 sq ft (243.9 m2)  • Tubes 2,399 sq ft (222.9 m2)  • Arch tubes 26 sq ft (2.4 m2)  • Firebox 200 sq ft (19 m2) Superheater: ​  • Heating area 546 sq ft (50.7 m2) Cylinders Four Cylinder size 18 1⁄2 in (470 mm) bore 26 in (660 mm) stroke Valve gear Walschaerts Valve type Piston Couplers AAR knuckle

Performance figures Tractive effort 49,430 lbf (219.9 kN) @ 75%

Career Operators South African Railways Class Class GO Number in class 25 Numbers 2572-2596 Delivered 1954 First run 1954 Withdrawn 1977 Scrapped 1984

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

In 1954, the South African Railways placed 25 Class GO light branchline tank-and-tender 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.

The Class GO 4-8-2+2-8-4 tank-and-tender 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 25 of these locomotives was placed with Henschel and Son in Germany. Their construction immediately followed that of the first batch of the Class GMA Garratt, which 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.

In design and general appearance, the Class GO was very similar to the Class GMA and many parts were interchangeable. It was also superheated, with a mechanical stoker, Walschaerts valve gear and piston valves, and was built on an identical one-piece Commonwealth cast steel frame. The chief differences were aimed at reducing weight, such as a smaller boiler with a reduced diameter, a smaller firebox and firegrate area and a half ton smaller capacity coal bunker.

The boiler was of telescopic construction, with an inside diameter of 6 feet 2 ³⁄₄ inches (1,899 millimetres) at the first ring and 6 feet 4 ¹⁄₈ inches (1,934 millimetres) at the firebox end. As a result of the smaller diameter boiler, the Class GO had a slightly longer chimney than the Class GMA. On the coal bunker, the reduced capacity 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.