Lanz (Ackerluft, HR 7)
1 model in this series
Lanz (Ackerluft, HR 7) – the D 8506: a single-cylinder hot-bulb engine producing 22 kW, approved for several fuels, and a 3,650 kg weight as a classic Lanz Bulldog
Lanz, in full Heinrich Lanz AG, was based in Mannheim and became part of John Deere in 1956. The company name is inseparable from the Lanz Bulldog, distinguished by a horizontal single-cylinder two-stroke engine with a hot bulb in place of an injector. The D 8506 of the HR 7 series belongs to this Bulldog family.
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The D 8506 is cooled by thermosyphon action, meaning without a water pump, purely through the natural circulation of heated coolant, and runs on diesel oil, heavy oil, diesel fuel, kerosene or vegetable oil. At 540 rpm it produces 22 kW, or 30 hp. The machine weighs 3,650 kg, reaches 17.7 km/h, and measures 3,400 mm in length, 1,792 mm in width and 2,185 mm in height.
The hot bulb replaces the spark plug and injector with a glowing pre-combustion chamber that triggers ignition without an external spark, which allows the engine to run on very different, even lower-grade, fuels. The low speed of 540 rpm combined with a large flywheel smooths out the firing pulses of the single cylinder and, running slowly, delivers a high, even torque for heavy draught work such as ploughing.
When buying a used Bulldog of this type, the condition of the hot bulb and its preheating device matters most, since spare parts for this now-rare component are barely available new any more. The thermosyphon cooling requires an unobstructed coolant circuit free of deposits, and the flywheel and clutch should be checked for cracks after decades of use.
Sources: SpecCodex-Register: Kennwerte des Modells D 8506
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