| Weight | 130t – 145t |
| Driving Wheels | 4ft 6ins |
| Boiler Pressure | 200psi Superheated |
| Cylinders | Outside – 21in x 26in |
| Tractive Effort | 31,850lbf |
| Valve Gear | Poppet |
In 1935, the South African Railways (SAR) placed fifty steam locomotives built by the North British Locomotive Company in Glasgow in service. These became the class 19C and were the first locomotive class in South African to use rotary cam poppet valve gear and also the first to be built new with a Watson Standard boiler.
In 1934 the SAR identified a need for locomotives to operate on the branch lines and requested tenders for the supply of fifty class 19B locomotives with Walschaerts valve gear. North British tendered for a rotary cam poppet valve gear as an alternative to Walschaerts valve gear. Even though this would increase the cost per locomotive by £200 it was decided to accept this tender in view of the good reports received concerning poppet valve gear. This variation on the design led to these locomotives being designated class 19C when they were delivered in 1935.
The locomotives were shipped as kits and erected at the Salt River workshops. Many remained stationed at Cape Town while being subjected to exhaustive testing.
The axle load of the tenders supplied with the locomotives exceeded the permissible limits on the branch lines on which the locomotives were intended to operate. Upon delivery the tenders were exchanged for tenders with a lighter axle load. This policy was followed with all the classes 19B, 19C and 19D, except the last batch of class 19D which was delivered with type MX torpedo tenders.
The class 19C locomotives were the first to be built new with Watson Standard boilers which followed the standardisation of locomotive boilers and engine parts introduced by A G Watson. This following his appointment as the Chief Mechanical Engineer of the SAR in 1929. At the time, 88 different types of locomotive were in service, for which some fifty types of replacement boiler were still being ordered.
Some of the locomotives were built with steel fireboxes for use in those areas where good or treated water was readily available, while others were still equipped with copper or composite fireboxes for use in areas with poor water quality. Copper or composite fireboxes are considerably more expensive to manufacture and repair than steel ones. It was only by the late 1960s, when severe corrosion was no longer a big problem as a result of the availability of water treatment facilities throughout the country, that copper and composite fireboxes were no longer considered necessary.
On the class 19C, the proportion of reciprocating parts balanced was reduced to 20% (normally 50% – 75%), which resulted in a big decrease of vertical hammer blow on any wheel at 50 miles per hour. 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.
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. A number of innovations, self cleaning smokebox and spark-extinguishing equipment, were tried to reduce the problem but were not successful.
The locomotives were designed for mainline as well as branch line service. They initially worked in the Witwatersrand area, the Eastern Cape and Western Cape. In the Western Cape they were the mainstay of the service for more than forty years. The Calvinia and Sakrivier branches in the Northern Cape were worked by the locomotives from at least 1950 or earlier. Around 1970 a few were stationed at Bloemfontein from where they worked the line to Aliwal North.
The Poppet valves made the Class 19C a very free-running locomotive, although it required special maintenance techniques. As a result, the whole class was allocated to the Western Cape during the Second World War and based at the Paardeneiland shed in Cape Town. From here, they worked on branch lines such as those from Cape Town to Saldanha, along the long branch line via Klawer to Bitterfontein, and across Sir Lowry’s Pass to Caledon, Bredasdorp and Protem in the Overberg.
Locomotives working between Malmesbury and Bitterfontein were usually equipped with type MX torpedo tenders. Bitterfontein in the thirstland was a rare terminus in that it had no locomotive water at all. Engines had to work out from the last water stop at Lutzville and back, a round trip of 100 miles which including climbing from almost sea level to an elevation of more than 1,100 feet at Bitterfontein while performing shunting along the way. When locomotives without the MX tender undertook this duty they had take along an additional water tender.
The class 19C locomotives were withdrawn from service in 1978 but none were sold for industrial use because of the special maintenance required for the poppet valves and secondly because Cape Town was a long distance away from any potential industrial operators, which would increase the cost of relocation after purchase.
Preservation
North British Locomotive Company Works No 24172 2439
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