This is something I wrote a while back for another site I frequent. I think I posted it here a while ago.
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Some really big thumpers
The first farm had four old tractors. Two Lanzs like this.

This is the second one. It made me smile. See that rear tyre with the zig-zag lugs? That was made by Goodyear. When it was introduced to the market in the mid 60s they brought two worn ones to us to relug (sort of retread but only the lugs get replaced in a patented system that Mastertreads had the franchise for & I was the foreman in that factory). So we re-lugged them for Goodyear so they could have photos to show when the launched the tyre on the market. So this tractor was working in the 60s.

This one had no name on it but I have found that it is a fairly old Lanz Bulldog. Made in Germany with a single cylinder motor. When I was at school the dairy used a single cylinder Hanomag tractor to pull the milk trailer around Rondebosch & I remember it well. I was amused to find an Australian website of recordings of these lovely huge ‘Thumpers’. Well a 10 litre single is something special. Think about it. That is part of the exhaust pipe just above the front axle & it comes out again above the light.
http://www.dynapay.com.au/tony/lanz/LanzSounds/LanzSounds.htm
Another view of the same Lanz. Look at that a yellow number plate – when did those come in? 80s? Goodness these were long lasting tractors.
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. Deere & Company 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 Bulldog was an inexpensive, simple and easy to maintain vehicle. This was chiefly due to its simple power source: a two-stroke hot bulb engine single cylinder horizontal engine. Initially the engine was a 6.3 litre, 12 horsepower unit, but as the Bulldog evolved this was increased to 10.9 litres and 54 horsepower. While hot bulb engines were crude , they were easy to maintain and could burn a wide variety of low grade oils –even waste oils.
The Bulldog was one of the most popular German tractors, with over 250,000 of them produced in its long production life.
A similar machine was built in Argentina, by the State Industry Company IAME, under the name Pampa. Its production ceased in 1963 after 2760 units were produced for the local market.
The Bulldog is similar to the Field Marshall produced in England and other European semi-diesel tractors produced in a similar time frame.
From Wikipedia:
http://en.wikipedia.org/wiki/Lanz_BulldogHere is a link to a diagrammatic explanation of how the Lanz 2-stroke worked.
http://pagesperso-orange.fr/kostalan-life/2%20Stroke%20Diesel.htmlI have looked for a good page describing the lovely Lanz tractors but can find very little. Here is a link to an illustrated page describing the history of the Argentinean copy – the Pampa. They chose to copy the Lanz because they were indestructible and ran on any burnable fluid like old engine oil or margarine.
http://www.pampa-traktor.de/pampainfoen.html
How about this photo of a Lanz Bulldog I found on the web researching for posting?
Lennon is sitting on this road model.

Here is a quote I found on some site
Those tractors are very famous to collectors, the Lanz Bulldogs are the "Bugattis" of the tractors.

This old Deutz was in front of that last Lanz.