The Ganz (Ganz vállalatok, "Ganz companies") electric works in Budapest is probably best known for the manufacture of tramcars, but was also a pioneer in the application of three-phase alternating current to electric railways. Notable engineers employed by Ganz in the field were Kálmán Kandó and Ottó Bláthy. The company is named after Ábrahám Ganz.
In 1976 Ganz-Mávag supplied ten 3-car diesel trainset to the Hellenic Railways Organization (OSE), designated as Class AA-91 and four metric gauge 4-car trainsets, designated as Class A-6451. In 1981-82 Ganz-Mávag supplied to OSE 11 B-B diesel-hydraulic DHM7-9 locomotives, designated as class A-251. Finally, in 1983, OSE bought eleven 3-car metric gauge trainsets, designated as Class A-6461. All these locomotives and trainsets have been withdrawn with the exception of one standard and one metric gauge trainset.