The type 70 was a 0-8-0T tank locomotive designed by MÁVAG for work on 760 mm narrow gauge lines. Most notably, this included field and logging railways. For tight curves, it had Klien-Lindner hollow axles which could be radially adjusted. A total of 284 locomotives were built by MÁVAG and two Romanian companies over a span of more than 80 years. With the types 51, 85 and 94, MÁVAG also offered heavier and lighter variants which were built in smaller numbers.
The first locomotives were ordered by an operator from Transylvania and soon also MÁV ordered 31 where they became class 490. The first batches were built between 1906 and 1914. After World War I, many came to Romania, Czechoslovakia, Poland, Italy and Yugoslavia. Further batches were produced between 1942 and 1950, of which 28 more locomotives went to MÁV. The later locomotives had Walschaerts instead of Stephenson valve gear and a water capacity of four instead of two cubic meters, what led to an increased axle load of 6 instead of 5.5 tonnes. In total, 152 had been built in Hungary.
After World War II, Romania still had demand for more locomotives for its logging railways. So Reșița built 120 more between 1951 and 1958, which had and axle load of 6.2 tonnes and a boiler with less tube surface, but a larger grate. While the original MÁVAG locomotives could reach up to 230 hp when firing coal, the Romanian locomotives which were mostly fired with wood could not reach an output of more than 200 hp.
Nevertheless, Romanian logging railways were not able to replace their steam locomotives with diesel locomotives or to move their traffic onto the road due to problems with the procurement of diesel. On the other hand, wood could be obtained for free from the sawmills. So the tractor works at Reghin produced twelve more locomotives of this old design between 1982 and 1987. The last ones were in regular service until 2001. Today more than 30 are still existing, with around half of them still in running order.
