Heinrich Büssing had set up his company at Braunschweig in 1903, when he built his first truck: a 2-tonne payload machine powered by a 2-cylinder gasoline engine and featuring worm drive. That successful design was later built under licence by other companies in Germany, Austria. Hungary and England. Before the Great War Büssing had progressed to building heavy-duty trucks for loads of between 5 and 11 tonnes, powered by 6-cylinder engines. Work on the KZW 1800 started already before the war, as a result of a cooperation project between the firm of Büssing and the German High Command, with the aim of constructing a heavy tractor, that could be used to tow the heavy guns that had started to appear.
The result of this cooperation was the big KZW 1800 (KZW = Kraftzugwagen). Like the pre-war trucks of the same company, it too was powered by a 6-cylinder Otto 90 Horsepower engine. The tractor was produced during the years of 1916-17. It had a straight frame with a front winch. The big rear wheels had retractable wheel spuds. The gun crew had a special bench seat at the rear of the big cab. Some tractors had a small rear body for ammunition. Others, like the one above, were produced with wheels of equal size.
The need for motor transport had at last been acknowledged by the German Army: at the end of 1915 it was decided that all Fussartillerie, like the 21cm Mörser, and not just the super-heavy guns, should be pulled by motor vehicles. The guns were either pulled just in the standard manner, or using a special method, which menat that the gun was suspended in the air, between the tractor and a special trolley, a so called Lastenvertailergerät (Cargo Distributor Apparatus). On the photo below, a 21 cm Mörser can be seen transported in this manner.