The S2 was a class of 0-8-0 shunting locomotives designed by L.C. Grubb for service in harbours. For this task, it had to be much lighter than the classes S and S1. Originally, Grubb decided to use the Watson Standard no. 1 boiler as this was the lightest one. Krupp was the only company who found themselves able to build a locomotive powerful enough that kept within the weight limits. However, they had to use their own design of boiler since the no. 1 standard boiler was still too heavy. Now they weighed less than 48 tons and had flangeless drivers on the third axle due to the tight curves in the docks. They were coupled to six-axle tenders similar to Vanderbilt tenders which weighed more than 54 tons.

100 were built in 1952 and 1953. Around 20 were used for shunting in the inland, while all others worked in harbours. In the seventies one was painted blue for use as a shunter for the Blue Train. In 1981 four were loaned to Mozambique for service in the docks of Maputo. Withdrawals had already commenced in South Africa in 1979 and by 1982, all but one were gone. the last one worked as a shed pilot in the inland until 1985. Three have been preserved, two of which are being owned by the Transnet Heritage Foundation.