South African type MX tender  The South African type MX tender was a steam locomotive tender. Type MX tenders entered service in 1949, as tenders to the last batch of Class 19D Mountain type steam locomotives which entered service on the South African Railways in that year. Type MX tenders were built in 1948 by North British Locomotive Company. The South African Railways (SAR) placed its final batch of fifty Class 19D locomotives in service in 1949, built by North British. The new Type MX tender for these engines was designed by Dr. M.M. Loubser, Chief Mechanical Engineer of the SAR from 1939 to 1949. The Type MX tender had a coal capacity of , a water capacity of and a maximum axle loading of . It was a tank wagon type tender with a cylindrical water tank, similar in appearance to the North American Vanderbilt type tenders, and was the first of its kind on the SAR. It rode on three-axle Buckeye bogies to reduce the axle load and became commonly known as a "Torpedo" tender. Only the last batch of fifty Class 19D locomotives were delivered new with Type MX tenders, which were numbered in the range from 3321 to 3370 for their engines. An oval number plate, bearing the engine number and tender type, was attached to the rear end of the tenders. Since many tender types are interchangeable between different locomotive classes and types, a tender classification system was adopted by the SAR. The first letter of the tender type indicates the classes of engines to which it could be coupled. The "M_" tenders could be used with the locomotive classes as shown, although in some cases engine drawbars and intermediate emergency chains had to be replaced or adjusted to suit the target locomotive. The second letter indicates the tender's water capacity. The "_X" tenders had a capacity of .