In 1899 the mechanic engineer Heinrich Kleyer (1853-1932) founded automobile production on the base of his small factory Adler, producing bicycles and typewriters. At first they produced cars, which had a good success, and already in some years the factory became one of the biggest enterprises in Frankfurt-on-Main. The car with the 4.5 hp power engine to ship 400 kg load, entered the Adler program since 1902. The next models of the load-carrying capability from 200 kg up to 2.5 tons were equipped with 2- and 4-cylinder engines of the cubic capacity 1.0-3.1 liters and 8-30 hp power. In 1908 the 3-ton truck with the 2-liter 20 hp power engine was added to them.
In 1925-28 the truck program consisted of numerous light-duty pickups and vans for 400-1000 kg load, and also included several models of 1.5-3.5 t cargo-carrying capability and with the 60 hp power engine. During the economic crisis the company Adler turned out to be in a difficult financial situation and had to phase out the heavier vehicles’ production. To support the production the company began to produce the trucks Bussing-N.A.G. since 1931. The own 1.5 ton pickups could not compete at the market and were produced till 1934 upon which the unprofitable production of the Adler trucks was canceled. Till 1939 the firm made vans and ambulance wagons on the car chassis, as well as pickups small batches with the cargo-carrying capability 500-1000 kg.
In the height of the Second World War the firm Adler hooked into production of the D7 (Sd. Kfz.10) and Hk16 (Sd.Kfz.11) half-track carriers, developed by the firms Demag and Hanomag respectively. Till the spring of 1945 they were produced in the quantity of 10,000 units. Simultaneously the firm assembled gasoline engines Maybach, transmission groups for the tanks Tiger and trailers. In the spring of 1945 the factory Adler was completely destroyed by the Allies air fleet.