South African Class 8 4 8 0

Evolution

The first 8th Class locomotives of the Cape Government Railways (CGR) were 2-8-0 Consolidation types, designed by H.M. Beatty, the Chief Locomotive Superintendent of the CGR from 1896 to 1910. They entered service in 1901 and were later to become the South African Railways (SAR) Class 8X.

While these first Schenectady and ALCO-built 2-8-0 locomotives were being subjected to exhaustive testing on all types of traffic and under varying conditions, some trouble was experienced with the leading two-wheeled pony truck. When designs were prepared at Salt River for a later order for more locomotives, the pony truck was replaced with a four-wheeled bogie and the coupled wheelbase was shortened from 14 feet 6 inches (4,420 millimetres) to 13 feet 6 inches (4,115 millimetres).

Manufacturer

The 23 locomotives of 1902 and 1903 were the first 8th Class locomotives of the CGR to be built with a 4-8-0 Mastodon type wheel arrangement. These locomotives were built by Neilson, Reid and Company in 1901 and 1902, and delivered in three batches in 1902 and 1903. In spite of the difference in wheel arrangement, these Mastodons and the earlier Consolidations of the CGR were all grouped together into the 8th Class.

They were conceived as mixed traffic locomotives, equally suitable for goods and passenger work. They had larger coupled wheels than the CGR 7th Class, bar frames, used saturated steam and had Stephenson valve gear. In service, it was found that the four-wheeled bogies and the 12 inches (305 millimetres) shorter fixed wheelbase made them steadier and easier riding than their 2-8-0 Consolidation predecessors.

Tenders

The first batch of three locomotives, numbered in the range from 801 to 803, went to the CGR's Western System in 1902. They were delivered with Type XD tenders which had a coal capacity of 5 long tons 10 hundredweight (5.6 tonnes) and a water capacity of 2,730 imperial gallons (12,400 litres).

Of the second batch of ten locomotives which arrived in 1902, eight were numbered in the range from 358 to 365 and allocated to the Midland System, while the other two became numbers 771 and 772, allocated to the Eastern System. These engines were delivered with Type XE1 tenders which had a coal capacity of 10 long tons (10.2 tonnes) and a water capacity of 2,855 imperial gallons (13,000 litres).

The last batch of ten locomotives, numbered in the range from 773 to 782, arrived in 1903 and all went to the Eastern System. These engines were delivered with Type XF tenders which also had a coal capacity of 10 long tons (10.2 tonnes), but a water capacity of 3,000 imperial gallons (13,600 litres).

Class 8 sub-classes

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (CGR, Natal Government Railways and Central South African Railways) were united under a single administration to control and administer the railways, ports and harbours of the Union. Although the South African Railways and Harbours came into existence in 1910, the actual classification and renumbering of all the rolling stock of the three constituent railways were only implemented with effect from 1 January 1912.

When these 23 locomotives were assimilated into the South African Railways (SAR) in 1912, they were renumbered in the range from 1069 to 1091, but they retained their Class 8 classification.

The rest of the 8th Class Consolidations and Mastodons of the CGR, together with the Class 8-L1 to 8-L3 4-8-0 Mastodon locomotives of the Central South African Railways, were grouped into nine more different sub-classes by the SAR. The other 4-8-0 locomotives became SAR Classes 8A to 8F and the 2-8-0 locomotives became Classes 8X to 8Z.

Modification

During A.G. Watson's term as Chief Mechanical Engineer of the SAR from 1929 to 1936, many of the Class 8 to Class 8F locomotives were equipped with superheated boilers, larger bore cylinders and either inside or outside admission piston valves. The outside admission locomotives had their cylinder bore increased from 18 ¹⁄₂ inches (470 millimetres) to 19 inches (483 millimetres) and retained their existing SAR Class 8 classifications, while the inside admission locomotives had their cylinder bore increased to 20 inches (508 millimetres) and were reclassified by having a "W" suffix added to their existing SAR classification letters.

Of the Class 8 locomotives, five were equipped with superheated boilers, 19 inches (483 millimetres) bore cylinders and outside admission piston valves, while retaining their Class 8 classification.

Four locomotives were equipped with superheated boilers, 20 inches (508 millimetres) bore cylinders and inside admission piston valves and reclassified to Class 8W.

Works numbers

The Class 8 and Class 8W works numbers, renumbering and superheating modifications are shown in the table.

Service

In SAR service, the Class 8 4-8-0 family of locomotives served on every system in the country and, in the 1920s, became the mainstay of motive power on many branch lines. Their final days were spent in shunting service. By 1972, they were all withdrawn from service.

Illustration

The main picture shows Class 8 no. 1088, ex CGR no. 779, at East London c. 1930, as built with slide valves, but with a rebuilt Type XF tender. The following pictures serve to illustrate the original slide valve configuration and the modified piston valve and superheating configuration.