In 1935, the South African Railways placed fifty Class 19C steam locomotives with a 4-8-2 Mountain type wheel arrangement in service.

[1][2][3][4] When the need for more branch line locomotives became apparent in 1934, tenders were invited by the South African Railways (SAR) for another fifty Class 19B locomotives with Walschaerts valve gear, but redesigned by Chief Mechanical Engineer A.G. Watson with his Watson Standard no.

[1][2][3][5] Even though this would increase the cost per locomotive by £200, Watson decided to accept this tender in view of the good reports he had received concerning poppet valve gear.

[1][2][3] All fifty Class 19C loco­motives were erected at the Salt River shops and numbered in the range from 2435 to 2484, and many remained stationed at Cape Town while being subjected to exhaustive testing.

As built, the Class 19C was delivered with Type MT tenders with a 12 long tons (12.2 tonnes) coal and a 6,000 imperial gallons (27,300 litres) water capacity, even though the axle load of 16 long tons 11 hundredweight (16,820 kilograms) of these tenders exceeded the permissible limits on the branch lines for which the Class 19C was intended.

The Type MP1 had a lighter axle load of 13 long tons 15 hundredweight (13,970 kilograms) and was therefore more suitable for branch line work.

2, but with the boiler barrel lengthened by 2 feet 4 inches (711 millimetres), and was suitable for the Classes 15, 15A and 15B locomotives.

During drifting, the reversing gear is placed in the neutral position where the exhaust valves are held fully open.

This was overcome by serrating the collars of the spindle bushes to allow the steam to escape and prevent entry into the cam boxes.

A.G. Watson is standing sixth from left in the group in front of the locomotive, with hat in hand.

Similar balancing methods on subsequent new locomotives enabled the SAR to adopt axle loads exceeding those permitted on many other railways of the world for comparable weight of rail.

[1][2] In the Western Cape, wheatland fires caused by locomotives were a huge problem for farmers as well as for the SAR who had to pay out the claims.

The consensus among railwaymen at the time was that these modifications were not entirely effective, but they remained in use for at least ten years nonetheless.

The spark extinguishers were mounted on the chimneys and consisted of two long tubes to extend the exhaust horizontally.

2456 the tubes fed the exhaust rearward to the outlets just ahead of the cab, which led to the engine being nicknamed Takbok (reindeer).

The Calvinia and Sakrivier branches in the Northern Cape were worked by Class 19C locomotives at least from 1950, probably earlier.

[3][8][11] The Poppet valves made the Class 19C a very free-running locomotive, although it required special maintenance techniques.

Engines had to work out from the last water stop at Lutzville and back, a round trip of 100 miles (161 kilometres) which including climbing from almost sea level to an elevation of more than 1,100 feet (335 metres) at Bitterfontein while performing shunting along the way.