South African Class 17 4-8-0TT

South African Class 17 4-8-0TT
SAR Class 17 no. 1432, circa 1930
Type and origin Power type Steam Designer Natal Government Railways (William Milne) Builder Dübs and Company South African Railways Serial number See table Model SAR Class 17 Build date 1926-1929 Total produced 21
Specifications Configuration: ​  • Whyte 4-8-0TT (Mastodon)  • UIC 2’Dn2t Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 25+3⁄4 in (654 mm) Coupled dia. 39 in (991 mm) Tender wheels 34 in (864 mm) Wheelbase 44 ft 11+1⁄2 in (13,703 mm) ​  • Engine 19 ft 9 in (6,020 mm)  • Leading 5 ft (1,524 mm)  • Coupled 11 ft (3,353 mm)  • Tender 16 ft 1 in (4,902 mm)  • Tender bogie 4 ft 7 in (1,397 mm) Length: ​  • Over couplers 52 ft 2+1⁄2 in (15,913 mm) Height 12 ft 2+1⁄2 in (3,721 mm) Frame type Plate Axle load 8 LT 10 cwt (8,636 kg) ​  • Leading 9 LT 6 cwt (9,449 kg)  • 1st coupled 8 LT 2 cwt (8,230 kg)  • 2nd coupled 8 LT 10 cwt (8,636 kg)  • 3rd coupled 8 LT 3 cwt (8,281 kg)  • 4th coupled 8 LT 3 cwt (8,281 kg)  • Tender bogie Bogie 1: 16 LT 15 cwt (17,020 kg) Bogie 2: 17 LT 18 cwt (18,190 kg) Adhesive weight 32 LT 18 cwt (33,430 kg) Loco weight 42 LT 4 cwt (42,880 kg) Tender weight 34 LT 13 cwt (35,210 kg) Total weight 76 LT 17 cwt (78,080 kg) Tender type 2-axle bogies or 3-axle Fuel type Coal Fuel capacity 5 LT 10 cwt (5.6 t) Water cap. 1,358 imp gal (6,170 L) engine Tender cap. 2,600 imp gal (11,800 L) tender Firebox: ​  • Type Belpaire  • Grate area 24 sq ft (2.2 m2) Boiler: ​  • Pitch 7 ft (2,134 mm)  • Diameter 3 ft 10+3⁄4 in (1,187 mm)  • Tube plates 10 ft 10+1⁄8 in (3,305 mm)  • Small tubes 187: 1+3⁄4 in (44 mm) Boiler pressure 160 psi (1,103 kPa) Safety valve Ramsbottom Heating surface: ​  • Firebox 62 sq ft (5.8 m2)  • Tubes 930 sq ft (86 m2)  • Total surface 992 sq ft (92.2 m2) Cylinders Two Cylinder size 17 in (432 mm) bore 21 in (533 mm) stroke Valve gear Stephenson Valve type Slide Couplers Johnston link-and-pin AAR knuckle (1930s)
Performance figures Tractive effort 18,670 lbf (83.0 kN) @ 75%
Career Operators South African Railways Class Class 17 Number in class 21 Numbers 1415–1435 Delivered 1926-1929 First run 1926 Withdrawn 1961
The leading coupled axle had flangeless wheels

The South African Railways Class 17 4-8-0TT of 1926 was a steam locomotive from the pre-Union era in the Natal Colony.

Between 1926 and 1929, to address a shortage of suitable shunting locomotives, the South African Railways rebuilt twenty-one Class A 4-8-2 Mountain type tank steam locomotives to Class 17 4-8-0 Mastodon type tank-and-tender locomotives.^[1][2][3][4]

The Natal Government Railways (NGR) Class D 4-8-2T Mountain type tank locomotive was designed by William Milne, the locomotive superintendent of the NGR from 1877 to 1896, and built by Dübs and Company. One hundred of these locomotives were delivered in ten batches by Dübs between 1888 and 1899 and in 1915 another two were built from spare parts by the South African Railways (SAR) in their Durban shops.^[1][5]

Beginning in 1905, these NGR Class D locomotives, originally known on the NGR as the "Dübs A", were gradually reboilered and fitted with Belpaire fireboxes with wider firegrates. The unmodified locomotives were then designated NGR Class D1 while the modified locomotives with Belpaire fireboxes were designated Class D2.^[1][5][6]

In SAR service, the NGR Class D1 and D2 were both designated Class A in 1912 while the modified locomotives were referred to as Class A Belpaire.^[1][5]

When a shortage of suitable shunting locomotives developed in the 1920s as a result of increasing traffic throughout the country and particularly on the Witwaters­rand, the SAR modified twenty-one of the Class A Belpaire 4-8-2 Mountain type tank loco­mo­tives.^[1][4][7]

The modifications were done between 1926 and 1929 and consisted of the removal of their trailing bissel bogies and coal bunkers, the shortening of their main frames and the addition of tenders to increase their coal and water capacity, thereby converting them to 4-8-0 Mastodon type tank-and-tender locomotives.^[1][4][7]

Tenders from various scrapped locomotive types were used. The tender depicted in the main picture is a three-axle tender while the official SAR locomotive diagram depicts a tender with four axles on two bogies.^[1][2][3]

These rebuilt 4-8-2TT locomotives were reclassified to Class 17 and renumbered in the range from 1415 to 1435. They were employed as shunting engines around Durban, Pietermaritzburg and Port Elizabeth and gave more than thirty years service in this format. In October 1957 Pietermaritzburg’s last two Class 17s were transferred from Masons Mill to Greyville near Durban. The locomotives were all withdrawn from service by 1961, more than seventy years after the first Class A locomotive was built.^[3][4][7][8]

In November 1953 two of these locomotives, numbers 1423 and 1431, were purchased by the Zambezi Saw Mills Company for use on their Livingstone-Mulobezi logging railway in Northern Rhodesia. These two engines were scrapped between 1961 and 1963.

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