The Adler factory produced bicycles, typewriters, motorcycles and calculators as well as automobiles. Before World War I, the company used two- and four-cylinder De Dion engines in cars ranging from 1032cc to 9081cc; starting in 1902 (the year Edmund Rumpler became technical director),  they also used their own engines. These cars, driven by Erwin Kleyer and Otto Kleyer (sons of company founder Heinrich Kleyer) and Alfred Theves, have won numerous sporting events. In the 1920s, Karl Irion competed with many Adlers; Popular models of the period included the 2298cc, 1550cc and 4700cc four-cylinder and the 2580cc six-cylinder. Some of the Standard models, built between 1927 and 1934, featured bodies designed by Gropius. The Adler Standard 6, which went into series production in 1927, had a 2540cc or 2916cc six-cylinder engine, while the Adler Standard 8, which appeared a year later, used a 3887cc eight-cylinder engine. The Standard 6, first seen in public at the Berlin Motor Show in October 1926, was the first continental European automobile to use Lockheed hydraulic brakes (the Triumph 13/35 offered them in the UK in 1924 and Duesenberg offered them in United States in 1920), when it was equipped with an ATE-Lockheed system. From 1927 to 1929 Clärenore Stinnes was the first to circumnavigate the world by car, aboard an Adler Standard 6.  In December 1930, Adler assigned the German engineer Josef Ganz, who was also editor-in-chief of Motor-Kritik magazine , as a consulting engineer. In early 1931, Ganz built a lightweight Volkswagen prototype in Adler with a tubular chassis, mid-engine and independent wheel suspension with oscillating axles at the rear. After completion in May 1931, Ganz dubbed his new prototype Maikäfer (May Beetle). After a takeover in Adler, further development of the Maikäfer was halted as the company’s new technical director Hans Gustav Röhr focused on front-wheel drive cars. In the 1930s, the company introduced Trumpf and Trumpf-Junior front-wheel drive models, ranging from 995cc flathead sv engines to four-cylinder 1645cc. These have achieved many successes in the races, including in the Le Mans race. The 1943cc Favorit, the 2916cc six-cylinder Diplomat (with 65 hp (48 kW) at 3800 rpm, and the 1910cc four-cylinder and 2494cc six-cylinder models (with Ambi-Budd and Karmann bodywork) ) were all rear-driven; these were built until World War II. The last new car introduced by Adler was the 1937 2.5-liter; it had a six-cylinder engine producing 58 hp (43 kW). Thanks to a Aerodynamic bodywork designed by Paul Jaray, this car could run at 125 km / h (78 mph).  After World War II, the decision was made not to resume car manufacturing. Motorcycle production resumed in 1949 and continued for eight years, leading to the production of the MB 250S. As part of the war repairs to the Allies, the Adler motorcycle designs were ceded to Britain; however it is an urban legend that the Adler designs formed the basis of Ariel ‘ s  Frec cia and count models. Adler increasingly focused on the production of office equipment. The company partnered with Triumph to form Triumpf-Adler, and was taken over by Grundig in 1957, then later by Olivetti.  In 1993 Olivetti sold Adlerwerke AG, still listed on the stock exchange, with the entire historic site of the Frankfurt plant to real estate investor Roland Ernst and to the construction company Philipp Holzmann.