Madrid-Saragossa & Alicante No. 1801 to 1810

In the thirties, the MZA searched for a fast locomotive that could haul the heaviest express trains. It was developed by MTM as a successor of the series 1701 that had to use the latest advancements in steam locomotive technology. The new type was to be completely streamlined and used a boiler pressure of 20 bars to maximize power without enlarging the boiler. Other features were Lentz valve gear, an ACFI feed water heater, automatic lubrication and a Kylchap exhaust. Production was postponed during the Civil War and numbers 1801 to 1810 were completed in 1939. Only the first one was completely streamlined with covered cylinders, partially covered drivers and a tender whose bogies were also covered.

The rest of the batch received only partial streamlining. On test runs, 1801 delivered 3,000 hp at 110 km/h. In World War II, obtaining the high-quality lubricating oils for steam temperatures of 400°C was difficult, and so the boiler pressure was reduced to 18 bars to decrease the superheating temperature. Also the streamlining of the first locomotive was partially dismantled, as the speed of express trains had fallen. With the founding of RENFE, the ten locomotives became 241.2101 to 241.2110. The first withdrawals took place in 1971 and the last class members were probably gone in 1974.