wheel arrangement did not prove to be very successful and with the exception of the Type JV tender, a similar experimental tender which had been built in the Salt River shops in 1936 during the design phase of the Class 21 as a prototype test-model of the Type FT tender, it was not used again on the SAR. Comparison, in working order, with the Type MR tender showed that the Type FT tender weighed more than the Type MR while it carried the same amount of coal and only more water, the difference representing a weight of . Another characteristic unique to the Type FT tender and its Type JV prototype was their left sides, where both had a space built-in to stow the fire-irons and rakes. The stowage space was open at the top, where the upper sides of both tender types were tied to the top of the coal bunker by four metal straps. The Bissel or pony axle design is commonly used on steam locomotives with a single leading or trailing axle and was later also used on the Class 4E electric and Classes 32-000 and 32-200 diesel-electric locomotives. Service The locomotive began its career on trials at Braamfontein in 1937, working the Rhodesian Mail trains between Randfontein and Mafeking. The Class GM entered service a year later and when it was found that the Garratt outperformed the on this line, no. 2551 was transferred to Pretoria where it spent the rest of its working life on the line between Pretoria and the Eastern Transvaal. Here it took loads exceeding those given to the Class 15CA. At the time, it seemed that ten-coupled engines could not be used as general utility types suitable for the rather severe curvature which existed on SAR lines, particularly those with rail of and where the curvature was generally more severe than elsewhere. A ten-coupled locomotive could only have 25% more tractive effort than an eight-coupled engine of similar axle load and with really heavy loads, the Garratt type had definite advantages and was much less severe on the track. During the Second World War, the locomotive was often used to haul long and heavy military trains, troop trains and sometimes Italian prisoners-of-war to the military unit and prisoner-of-war camp at Sonderwater near Cullinan. In the process it was made the official mascot of the oldest military unit in Pretoria, the Pretoria