The Lanz Bulldog was a tractor manufactured by Heinrich Lanz AG in Mannheim, Baden-Württemberg, Germany. Production started in 1921 and various versions of the Bulldog were produced up to 1960. John Deere purchased Lanz in 1956 and started using the name "John Deere-Lanz" for the Lanz product line. A few years after the Bulldog was discontinued the Lanz name fell into disuse. The Lanz Bulldog was one of the most popular German tractors, with over 220,000 of them produced in its long production life. The name "Bulldog" is widely used in Germany as a synonym for tractors even today, especially in Bavaria.
The Bulldog was a simple and easily maintained vehicle due primarily to its simple, single cylinder, horizontal, two-stroke, hot bulb engine. Initially the engine was a 6.3 litre, 12 horsepower unit, but as the Bulldog evolved the engine was increased to 10.3 litres and 55 horsepower. While hot bulb engines were crude, they were easy to maintain and could burn a wide variety of low grade fuels – even waste oils.
Bulldogs were also produced in Spain by Lanz Iberica S.A. at Getafe near Madrid. A total of 17,100 tractors were built from 1956 to 1963.
The Bulldog design was copied in other countries by several different manufacturers. While some of these copies were legitimately produced under license from Bulldog, most of them were built with each respective builders own frame and body design, being powered by unlicensed copies of the patented Bulldog hot-bulb engine. Some of these examples are:
"Le Percheron" was a licensed copy of the 25 HP hot-bulb Bulldog, built by Société Nationale de Construction Aeronautic du Centre (SNCAC) at Colombe in France from about 1939. It is believed that nearly 3,700 were built before production ceased in 1956.
The KL Bulldog was produced by Kelly & Lewis of Springvale, Victoria, Australia from 1948 to December 1952. Just over 860 were built, based on the 35 HP Model N Bulldog.
Ursus produced a copy of the 45 HP Bulldog at the ZM Ursus factory (Zakłady Mechanicze Ursus) in Poland in Ursus near Warsaw from 1947, called the C-45. It was replaced by the C-451 in 1957, and from 1960 the production was moved to Zakłady Mechaniczne in Gorzów Wielkopolski. About 55,000 Ursus C-45/C-451 were built from 1947 until 1965.