South African Class 14C 4-8-2, 1st batch

During the 1930s, many serving locomotives were reboilered with a standard boiler type designed by A.G. Watson, CME of the SAR at the time, as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.[3][4][5]

All twenty locomotives were eventually reboilered with Watson Standard no. 2 boilers and reclassified to Class 14CR. Only slight alterations were necessary to the engine frames. In the process, the boiler pitch was raised from 7 feet 7 inches (2,311 millimetres) to 8 feet 1 ¹⁄₂ inches (2,476 millimetres), which raised the chimney height from 12 feet 9 ³⁄₈ inches (3,896 millimetres) to 13 feet ³⁄₄ inch (3,981 millimetres) and exceeded the loading gauge height of 13 feet (3,962 millimetres) above the railhead. The only other engine on which reboilering resulted in the exceeding of the height restriction was the Class 15BR.[2]

The reboilered engines were also equipped with Watson cabs with their distinctive slanted fronts, compared to the conventional vertical fronts of their original cabs. Early conversions were equipped with copper and later conversions with steel fireboxes. Three of them, numbers 1762 to 1764, would not undergo further modifications and would retain the Class 14CR designation.[2][3][4]

Their original Belpaire boilers were fitted with Ramsbottom safety valves, while the Watson Standard boiler was fitted with Pop safety valves. An obvious difference between an original and a Watson Standard reboilered locomotive is usually a rectangular regulator cover, just to the rear of the chimney on the reboilered locomotive. In the case of the Class 14C, two even more obvious differences were the Watson cab and the absence of the Belpaire firebox hump between the cab and boiler on the reboilered locomotives.[3][4]

Around 1930, the question of maximum axle loads for locomotives was thoroughly investigated by the Mechanical and Civil Engineering Departments of the SAR. It was found that, among some other locomotives, the Class 14C had a rather severe vertical hammer blow effect on the track when running at speed due to an undue proportion of the reciprocating parts being balanced. Modifications were accordingly made to the Class 14C to allow some of them to run on 60 pounds per yard (30 kilograms per metre) track.[2]

The locomotives had weights attached between the frames to increase adhesion. Over time, most of the Class 14C family of locomotives were "rebalanced" by having these weights increased or reduced to redistribute, increase or reduce the axle loading and adhesive weight by altering the loads on the individual coupled wheels, leading bogies and trailing pony trucks. Coupled wheel axle loading adjustment was achieved by attaching steel boxes, filled with an appropriate amount of lead, over each axle between the frames. Their boiler pressure setting was reduced from 190 to 180 pounds per square inch (1,310 to 1,241 kilopascals).[3][4][6]

The lighter version of the rebalanced locomotives was reclassified to Class 14CB, with the "B" indicating branch line service. Those which had also been reboilered with Watson Standard no. 2 boilers were reclassified to Class 14CRB.[3][4][6]

Several of the locomotives had their cylinders bushed to reduce the bore from the as-built 22 to 21 ³⁄₄ inches (559 to 552 millimetres). At the same time the boiler pressure setting of the Classes 14C and 14CR locomotives was adjusted upwards from 190 to 195 pounds per square inch (1,310 to 1,344 kilopascals) to keep their tractive effort more or less unaffected by the reduction in piston diameter. The boiler pressure setting of the branchline Classes 14CB and 14CRB was adjusted upwards from 180 to 183 pounds per square inch (1,241 to 1,262 kilopascals).[2][3][4]

The Class 14C was placed in service on the Cape Eastern system, working the Umtata branch into Transkei and on the mainline to Cookhouse. Some went to the Cape Western system, where they banked up the Hex River Pass from De Doorns and later worked with Class 19C locomotives across Sir Lowry's Pass to Caledon and Bredasdorp in the Overberg. A few were also used on the Cape Midland system, in Natal and the Eastern Transvaal.[5]

In their later years, many of these locomotives remained on the Cape Western system, most being shedded at Paardeneiland in Cape Town and at Beaufort West, and one at De Aar, where they were mostly used as shunting engines and on short local pick-ups. A large number were also used on the Cape Eastern system, shedded at East London and used as shunting engines, on local pick-ups and also in suburban service. A few also served their last years in the Eastern Transvaal, shedded at Pietersburg and Witbank.[6]

Between 1918 and 1921, the Rhodesia Railways (RR) purchased a slightly lighter version of the original Class 14C from MLW. These were designated the RR Class 11. A further batch was built in 1948 and designated RR Class 11A. Some of the RR Class 11s and all the RR Class 11As were eventually sold to Caminhos de Ferro de Moçambique (CFM) and were utilised on the line between Mozambique and Swaziland.[6]