consumption of the poppet valve Class 19C with the piston valve Class 19D. The Class 19D performed slightly better. However, the valve travel of the Class 19D is compared to a valve travel of about in all previous engines fitted with piston or slide valves. It was concluded that, had the valve travel of the Class 19D been retained at , the test would have shown an advantage for the poppet valves. Balancing The balancing of these locomotives represented another advance on former practices. Until then, locomotives had been balanced to an extent of 50% to 75% of their reciprocating parts, and fully as regards their revolving parts. On the Class 19C, the proportion of reciprocating parts balanced was reduced to 20%, which resulted in a big decrease of vertical hammer blow to not more than on any wheel at . 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. Modifications 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. In the late 1960s Johannes Barnard, the assistant locomotive superintendent at Cape Town, invented a self-cleaning smokebox and a way to blow char out of the smokebox when the engine was standing in non-sensitive places such as at water stops. While on the run, excess char was diverted into a box mounted below the smokebox door. 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. Another of Barnard's experiments was with spark-extinguishing equipment installed on a Class 19C and a Class GEA Garratt. The spark extinguishers were mounted on the chimneys and consisted of two long tubes to extend the exhaust horizontally. The tubes had spray pipes around their vertical outlets at the end to drench any sparks that may have survived the journey along the tubes. In the case of Class 19C no. 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 experiments were not successful. Service The Class 19C was designed for mainline as well as branch line service. They initially worked in the Witwatersrand area,