Leichte Traktor - Grosstraktor I / II / III - Neubaufahrzeug PzKpfw V / VI

Early Projects and Prototypes
Leichte Traktor - Grosstraktor I / II / III - Neubaufahrzeug PzKpfw V / VI

Daimler Benz's Grosstraktor I as monument
at the barracks of Panzer Regiment 1 in Erfurt.

Between 1926 and 1932, Rheinmetall-Borsig, MAN, Krupp and Daimler Benz were ordered by Reichswehr to build prototypes of light (10-12 tons) and medium tanks (to 23 tons) under the cover name of "tractor" in order to hide their military potential from the Treaty of Versailles. Prototypes were tested from 1926 to 1933 at Kama (Panzertruppenschule Kama), near Kazan in USSR under high security. Kama was the codename created by words Kazan and Malbrandt. Oberstleutenant Malbrandt was the one, who selected the location for artillery and tank testing. Kama was joined Red Army and Reichswehr training and testing ground of military technology. This was part of German - Soviet treaty from Rapallo signed in 1922, which focused on development of military technology as well as Berlin Friendship Treaty of 1924. Their designs were based on lessons learned with the development of Leichte Kampfwagen I and II (1918-1919), which existed only as prototypes.

In 1927, Germans designed two self-propelled guns based on fully tracked Hamomag tractors as commercial Hanomag tractors were already in use with the army. First was 3.7cm WD Schlepper 25PS, which was a lightly armored 25hp Hanomag WD tractor with pedestal mounted 37mm PaK L/45 gun. The gun had limited traverse of 30 degrees only. The vehicle also carried single machine gun for defence. Second was 7.7cm WD Schlepper 50PS, which was 50hp Hanomag WD tractor with pedestal mounted 77mm K light gun. The gun had full 360 degrees traverse. Both self-propelled guns were accepted into service with the German Army (Reichswehr) in 1927. Small number of vehicles was produced and was used mainly for testing.

Top Left - 3.7cm WD Schlepper 25PS
Bottom Left - 7.7cm WD Schlepper 50PS

Since 1926 till 1929, at least 146 officers finished the training school at Kama. The most famous "cadet" was Von Kleist. The person responsible for the training in Germany was Gen. Lutz and in USSR, the NKVD Komissar Unshlicht. All the German "tractor" prototypes were on trial at Kama Proving Grounds. The training program was quickly finished at the beginning of 1929.
A very interesting thing - the training was not under the control of the NKO (Ministry of Defence), but under the control of the NKVD ( Ministry of State Security).
The German pilots were at the same time on training in Lipetzk Military Air School and the officers of the Chemical defence in Astrachan Military School of the Chemical Warfare. At least 500 officers graduated succesfully from these two schools.
In 1939, USSR purchased samples of the all German AFVs. They were put on trials and the comission came up with the verdict that they had poor reliability. The opposite "verdict" was made concerning Me-109, which was purchased at the same time. The pilots said that it was better than Soviet fighters.

Rheinmetall-Borsig Leichte Traktor - Versuchskonstruktion (VK) 31