First prototype of the Bungartz U1, fitted with 9.5 hp Ilo petrol engine. Fuel consumption 2 to 2.5 liter per hour. The machine had 4 forward and 2 reverse speeds, optional was a 2 forward and 1 reverse transmission. Shown here with a potatoe digger.

This is a somewhat newer prototype of the Bungartz U1, note the difference in the shape of the cover plating.

Bungartz U1 production model with Ilo E400A petrol engine, 10.5 hp at 3000 rpm from 400 cm3. Note the different, bent, steering column.

Bungartz U1 with Ilo E400A petrol engine. 10.5 hp at 3000 rpm from 400 cm3. The older model had a bent steering column. The one on the picture is from around 1950, assumingly running somewhere in Africa.

Bungartz U1FTr with Ilo E400FTr paraffin engine. Lubricated by an oil pump on front of the engine, allowing to use unmixed fuel (either petrol or paraffin). 9.5 hp at 3000 rpm. Another difference is that these engines are crank started, whereas the petrol models have a belt pulley.

Bungartz U1V with Bungartz 450 engine, running in Greece. 12 hp on petrol, 11 hp on paraffin. The machine is fitted with a double tank to enable switching between the two fuels. The engine is of four stroke design, but without oil in the crankcase. Lubrication is performed by an oil pump, pressing oil to all bearings. After having done its job, the oil is sucked into the carburettor and burned in the engine.

Probably a prototype for the Bungartz U1D, with 14 hp Stihl diesel engine. The engine cover is different from the later production models.

Bungartz U1D with Stihl 131 engine. This is a 14 hp two stroke diesel engine, having two funny properties: one needs to close a choke valve before starting, and the engine has one valve (most uncommon for a two stroke). The burned gases leave the combustion room via an outlet valve. When starting, this valve can be lifted to take away compression. At every revolution of the starting crank, the engine turns five times; this makes a rest between two start attempts very welcome!

Bungartz U1E with AEG electric motor. In WWII fuel was very scarce in Germany, so Bungartz proceeded where Siemens had stopped experimenting with electric power for tractors. Immediately after the war had ended, petrol engines were used again. I have never seen any electrical powered garden tractors at all.