After the Mallet tank locomotives later known as Ed 2x2/2, the SCB had twelve more tender locomotives built, which were initially designated as the D4T. They had the same cylinder size as their predecessors, but a larger boiler thanks to the elimination of supplies onboard the locomotive. They were used on the Hauenstein line between Basel and Olten and were later designated D 2x2/2 by the SBB.

The maximum towing capacity on a ramp of one percent was 550 tonnes and on the Hauenstein, between 180 and 260 tons could now be towed on its 2.63 percent. The water supply was now almost twice as large as that of its predecessors and the coal supply of four tonnes was twice as large as that of the first series of the Ed 2x2/2.

As early as 1904, conventional locomotives of the type C 4/5, which also had a four-cylinder compound engine, were used on the Hauenstein. The D 2x2/2 were now used on other lines and retired between 1923 and 1926.