Indonesia has also used steam locomotives since 1876. The last batch of E10 rack tank locomotives were purchased in 1967 (Kautzor, 2010) from Nippon Sharyo. The last locomotives – the D 52 class, manufactured by the German firm Krupp in 1954 – operated until 1994, when they were replaced by diesel locomotives. Indonesia also purchased the last batch of mallet locomotives from Nippon Sharyo, to be used on the Aceh Railway. In Sumatra Barat (West Sumatra) and Ambarawa some rack railways (with a maximum gradient of 6% in mountainous areas) are now operated for tourism only. There are two rail museums in Indonesia, Taman Mini and Ambarawa (Ambarawa Railway Museum).