While the Germans invaded the Soviet Union in 1941 they discovered the bad road conditions in this vast country. Even more when summer turned to Autum and the primitive roads changes into mud slides. Wheeled and half tracked vehicles became bogged down easily and the need for fully tracked vehicles arose.
Steyr, an Austrian company which produced weapons and vehicles for the Wehrmacht after the annexation by the Germans, suggested a conversion of their 1500A light truck. This development led to the Raupenschlepper Ost. The Raupenschlepper, Eng. Tracked Prime Mover, should help the army keep on moving equipment during the Rasputitsa, the Soviet mud season.
Steyr made three basic version of the Raupenschlepper. RSO 01 had a cast metal carbine, one piece including a metal roof. The other versions 02 and 03 had simplified cabins with soft-top canvas roofing’s. All three basic version had wooden cargo beds with drop sides. Around 4850 of the RSO/01 were produced. The simplified versions were built under license by Auto Union and others, together they constructed 12300 RSO prime moves during the war.
Next to the three basic types the German army experimented with all kinds of variants. An ambulance was made, armored types, types with guns (artillery, Anti-aircraft of anti-tank guns) were made. A snow blower and plough, a semi-trailer, there was even a floating version, a Schwimm RSO.
The first types used a Steyr V8 3.5 liters petrol engine which provided 85 PS and gave the vehicle a top speed of 17 km/h (14 km/h on the third type) with a range of about 300 kilometers. It was the same engine that was used in the Steyr 1500A vehicle. Later versions, the RSO/03, received the Deutz 4 cylinder diesel engine with 66 PS.
Crews loved the Raupenschlepper due to its reliability, its four inline metal wheels on each side kept the prime mover easy to maintain and it did not clog easily with mud or dirt like the overlapping wheels of the German halftracks did.
The RSO weighed 3700 to 3900 kg and could carry a load of 1500 kg and had a crew of 2.
After the war around 1500 units were built for use in agriculture and foresting.