Wikipedia
The Leichttraktor (Vs.Kfz.31) was a German experimental tank.
After the First World War, Germany was restricted in military development by the Treaty of Versailles but a secret program under the name cover "Traktor" was developing armoured military vehicles and artillery. Its engine was in the front, and the turret was rear-mounted. Both Rheinmetall and Krupp produced prototypes, and in 1928, Rheinmetall was awarded the order of 289 tanks; however, the order was cancelled. Krupp models had coil spring suspensions, while Rheinmetall had leaf spring suspensions.
The Germans tested the tank in the Soviet Union under the Treaty of Rapallo – agreed between the USSR and Germany in 1922 under high secrecy and security. The testing facility used from 1926 to 1933 was Panzertruppenschule Kama, located near Kazan in the Soviet Union.
The location was a joint testing ground and tank training ground for the Red Army and Reichswehr. It was codenamed "Kama" from the words Kazan and Malbrandt because the testing grounds were near Kazan and Oberstleutenant Malbrandt was assigned to select the location for testing.
Leichter Traktor ("Light tractor") was a cover name for all three light tank designs produced there. In the early years of World War II it was used as a training tank.