Short answers, pulled from the story.
Sächsische Maschinenfabrik was founded in 1837 by August Götze and Richard Hartmann in Chemnitz as the firm Götze and Hartmann. Hartmann became the dominant figure and gave his name to the company in its 1898 renaming.
Sächsische Maschinenfabrik built 4,699 locomotives between 1848 and 1929. The majority were delivered to the Royal Saxon State Railways, but customers included railways across Europe and beyond.
The founding of the Deutsche Reichsbahn in 1920 spread locomotive construction orders across multiple manufacturers, sharply cutting the company's volume. Between 1920 and 1924 only 64 locomotives were built for the Deutsche Reichsbahn, and the political aftermath of the First World War closed many export markets. The worldwide economic crisis of the late 1920s was the final blow, leading to liquidation in 1930.
The Sächsische Maschinenfabrik vormals Richard Hartmann AG was liquidated in 1930. The surviving textile machinery operations continued under successor companies until production finally ceased in 1998.
In 1896 Gustav Hartmann, a son of founder Richard Hartmann, established a subsidiary of Sächsische Maschinenfabrik in Luhansk. That subsidiary exists today as the Lokomotivfabrik Luhansk.
Preserved locomotives built by Sächsische Maschinenfabrik are held at museums including the Dresden Transport Museum, the Saxon Railway Museum in Chemnitz, the Chemnitz Industrial Museum, the Ambarawa Railway Museum in Indonesia, the National Technical Museum in Prague, and the German Steam Locomotive Museum in Neuenmarkt, among others.