Siemens 2 PS Bodenfräse (Boden = soil), the first walk behind model of Siemens, built from 1920. The four stroke benzol engine was made after the "Grunder" system, weighed 55 kg, had 500 cm3 piston deplacement and 3 - 3½ hp. The Siemens Blockwerk manufactured 700 of these engines from 1920 till 1922. The Bodenfräse had 2 forward gears of 0.93 and 1.87 km/h and a total weight of 170 kg.

The 2 PS Bodenfräse was probably built in license of Grunder, Switserland.
In England, Geo. Monro Ltd. advertised a similar tiller as the Rototiller Type 4. Propably made by or in license from SIMAR, Switserland.

Siemens Gartenfräse K1, with a 4 hp 4-stroke engine. This engine has the cooling fan behind the cylinder, which carries horizontal cooling ribs.
Picture courtesy of Wolfram Holldack.

The Siemens 4 PS Gartenfräse K3 (Garten = garden) followed the 2 PS model in 1924. The Siemens Blockwerk made it's four stroke petrol engine with 90 mm cylinder bore, 110 mm piston stroke, 500 cm3 and a weight of 84 kg. The crankcase consisted of two aluminium castings, the cylinder was air cooled and provided with vertical cooling ribs. The flywheel contained the cooling ventilator, blowing the air up along the cylinder's cooling ribs. The intake and exhaust valves were fitted in hanging position in the cylinder head. During 1924 and 1925, 200 of these Gartenfräse tillers were made.

The Siemens Plantagenfräse S (Plantage = plantation) had an 8 hp water cooled two stroke engine, and was made between 1923 and 1927. Working width 90 cm, 20 spring tines with 470 mm diameter, rotating at 200 rpm. Two forward speeds of 1.08 and 2.16 km/h. The tractor weighed 360 kg.
A Siemens brochure states that the tiller was shipped from Geneva, Switserland, so they were made by SIMAR as the SIMAR No. 10, and only distributed in Germany by Siemens.

SIMAR Leichtfräse C2 (Leicht = lightweight), imported into Germany by Siemens-Schuckert because they lacked this size of machine theirselves. The small 2-stroke engine developed 2½ hp, weighed 108 kg and drove 1.1 or 1.3 km/h (dependent of the size of wheels). Working width was 35 cm, almost a hectare could be cultivated daily. The C2 sold for 980 Reichsmark in 1928.

Plantagenfräse Siemens S no. 1546 from 1925, owned by Polish machinery collector Maciej Orzałkiewicz. Water cooled 8 hp two stroke engine no. 547.
Pictures: Marek Ronovský, 2018.

Plantagenfräse Siemens S from 1925 with engine no. 783, at a tractor collector in Elsendorp. The exhaust muffler is missing. In my collection since 2021.

Plantagenfräse Siemens S Nr. 1898 from 1927, in my collection.

Siemens Gartenfräse K1 no. 1096, with a 4 hp 4-stroke engine. This engine has the cooling fan behind the cylinder, which carries horizontal cooling ribs. This K1 is on display at the Deutsches Landwirtschaftliches Museum in Hohenheim.

This "Siemens 4 PS Gartenfräse" was sold on eBay in August 2008. The engine was in running order! Unknown where the machine is now.
It has the old steering rod height adjustment.

This "Siemens 4 PS Gartenfräse", model K3, made 1924 or 1925, is on display in the Gartenbaumuseum Cyriaksburg in Erfurt, Germany.
Newer steering rod height adjustment, similar to the K4.

Motor einer Siemens 4 PS-Gartenfräse, Nr. 50176, in privater Sammlung.
Bilder: Thomas Adam, 12 Aug. 2012.

Motor und Getriebe einer Siemens 4 PS-Gartenfräse, Type 92462, Motornr. 10359.
In meiner Sammlung.