Lanz Bulldog: The Tractor Started with Fire and a Steering Wheel

The Tractor Started with Fire and a Steering Wheel: The Lanz Bulldog Phenomenon

It's hard to imagine today an engine with a displacement of over 10 liters with a single cylinder. It's even harder to believe that such an engine could run on almost any liquid fuel – from crude oil to used oil. And to start it after a standstill, the tractor driver first had to heat the engine with an open flame, and then use the steering wheel instead of a starter.

This was the German Lanz Bulldog – one of the most unusual tractors in the history of world engineering. This machine became a symbol of German agriculture and brought fame to the Heinrich Lanz AG company for decades.

One Cylinder with a Volume of More Than 10 Liters

Serial production of the Lanz Bulldog began in Mannheim in 1921. The main feature of the tractor was its engine – a horizontal single-cylinder two-stroke unit of colossal size.

Even today, its characteristics look impressive. The displacement was 10.3 liters, the cylinder diameter reached 225 mm, and the piston stroke was 260 mm. The dimensions of the single cylinder are quite comparable to an ordinary household bucket.

However, the huge volume did not mean high power. Depending on the version, the engine developed approximately 45–55 horsepower. Its main strength was not speed performance, but traction at minimum RPM.

The operating range was within 540–750 rpm. At the same time, the engine could function almost on the verge of stopping, emitting rare dull thuds, more reminiscent of artillery shots than the operation of a familiar engine.

The advantages of this scheme were:

But the engine's starting process was especially unusual.

Blowtorch Instead of an Ignition Key

Early Lanz Bulldogs lacked the familiar elements of modern technology:

The tractor was equipped with a hot-bulb engine. In the front part of the cylinder head, there was a special incandescent chamber – the so-called hot bulb. Unlike other engine elements, it was not water-cooled.

Before starting a cold engine, the tractor driver would take a blowtorch and heat the bulb with an open flame for 10–15 minutes. After the metal glowed cherry-red, the starting process could begin.

Fuel, entering the incandescent chamber, evaporated and ignited due to temperature and compression of the mixture.

However, there was still one problem: how to turn the crankshaft of an engine with a displacement of more than ten liters?

Engineers solved it in a very original way. The steering wheel, along with its shaft, was removed from the driver's seat and installed into a special socket on the end of the crankshaft. Using the steering wheel as a huge handle, the tractor driver manually cranked the engine. After starting, the shaft was removed, and the steering wheel was returned to its place.

After that, the engine could run for a very long time without stopping. But the machine had another feature that seems completely incredible today.

How the Tractor Drove Backwards Without a Reverse Gear

Early versions of the Lanz Bulldog had no reverse gear at all. Nevertheless, the need to move backward did not disappear.

A solution was found thanks to the peculiarities of the low-speed two-stroke engine.

To engage "reverse," the driver almost completely cut off the fuel supply. The huge flywheel gradually lost speed. At a certain point, its energy was no longer enough to pass the top dead center and overcome compression.

Then an unusual process occurred:

As a result, the engine started in reverse.

After that, the tractor driver engaged the usual first gear and added gas. The machine began to move backward without any separate reverse gear.

This method required serious experience, good hearing, and a precise sense of timing. Nevertheless, it was successfully used in practice for many years.

Why the Legendary Tractor Became History

By the mid-1950s, the advantages of the design gradually ceased to outweigh its disadvantages.

Agricultural machinery was rapidly developing. The market saw the emergence of:

Against this background, the heavy single-cylinder tractor, which required heating with a blowtorch before starting, looked increasingly archaic.

The turning point came in 1956 when the controlling stake in Heinrich Lanz AG was acquired by the American corporation John Deere.

Initially, the legendary tractors received the new owner's signature green and yellow paint scheme. Then the American company gradually began to shift production to its own technical standards.

Hot-bulb engines no longer met the demands of the time. Already in 1960, new John Deere-Lanz tractors appeared, equipped with modern multi-cylinder engines.

Soon, the production of single-cylinder Bulldogs was finally discontinued. A few years later, the Lanz name itself disappeared: after 1967, it was no longer used in the company's name.

A Machine That Became a Legend

Today, the Lanz Bulldog has become a cult collector's item. Well-preserved examples are valued at hundreds of thousands of euros at auctions.

This tractor remains a monument to an era when technology was created primarily for reliability and the ability to work in any conditions. The huge single-cylinder engine, starting with fire and a steering wheel, and the ability to change direction by reversing the engine itself made the Lanz Bulldog one of the most unusual and recognizable agricultural machines in history.

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