This is a Lanz HL12 Bulldog, a 1920s German tractor powered by a single cylinder ‘hot bulb’ engine that was so ubiquitous, in some parts of Germany tractors are still known as ‘bulldogs’.
‘Hot bulb’ engines featured very few moving parts, no carburettor, no cooling system, and – much like the flux-capacitor in Doc Brown’s time machine – could run on almost anything.
This one has been recreated wonderfully by Nikolaus Löwe, who has replicated not only the engine but the Lanz’s full suite of 1920s mechanicals, and there’s more to see at his ‘Lanz HL12 Bulldog’ album via the link above.