The Class 16 4-6-2 Pacific type passenger locomotive was designed by D.A. Hendrie, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1910 to 1922. It was built by the North British Locomotive Company in Glasgow, Scotland, who delivered twelve locomotives in 1914, numbered in the range from 790 to 801.
Characteristics
The design of the Class 16 closely followed that of Hendrie's Class 15 4-8-2 Mountain type which was introduced at the same time from the same builders and many parts were made interchangeable.
The cylinders were arranged outside the plate frames, with the piston valves above the cylinders and actuated by Walschaerts valve gear. The boilers were equipped with superheaters and had Belpaire fireboxes. The engines were delivered new with Type MP1 tenders with a 10 long tons (10.2 tonnes) coal capacity and a 4,250 imperial gallons (19,300 litres) water capacity.
Power comparison
When it was built in 1914, the Class 16 was considered to be a very large and powerful express locomotive, even when compared to British locomotives which were built to run on 4 feet 8 1⁄2 inches (1,435 millimetres) broad gauge. As built, with 60 inches (1,524 millimetres) diameter coupled wheels, the ratio of wheel diameter to rail gauge was the same as that of a broad gauge locomotive with 81 inches (2,057 millimetres) diameter coupled wheels. Their tractive effort of 29,890 pounds-force (133.0 kilonewtons) at 75% boiler pressure exceeded the 27,800 pounds-force (124 kilonewtons) at 85% boiler pressure of Churchward's The Great Bear Pacific on the Great Western Railway and equalled, also at 85% boiler pressure, that of Gresley's later Great Northern Pacifics. This made the Class 16 the most powerful express passenger locomotive design yet to have been built in Great Britain at the time.
