Raupenschlepper Ost

Raupenschlepper Ost (RSO)
RSO towing 105 mm howitzer
Type	Prime mover
Place of origin	Nazi Germany
Specifications
Weight	2.5-3 t
Length	4.425 m
Width	1.99 m
Height	2.53 m
Crew	2 (including Driver assistant)
Armor	None
Main armament	None
Engine	Steyr V8 3.5l / 8-cylinder Petrol/ 85 hp (RSO/01) 5.5l / 4cyl Deutz diesel / 66 hp (RSO/03) 66/85 hp
Suspension	Fully Tracked
Operational range	300 km
Speed	30 km/h (18 mph)

Steyr V8 3.5l / 8-cylinder Petrol/ 85 hp (RSO/01)

Raupenschlepper Ost, literally "Caterpillar Tractor East", is more commonly abbreviated to RSO. This fully tracked, lightweight vehicle was conceived in response to the poor performance of wheeled and half-tracked vehicles in the mud and snow during the Wehrmacht's first autumn and winter on the Soviet Front.

The RSO was a contemporary with somewhat similar Allied full-tracked small artillery tractors in use in other armies (such as the Soviet STZ-5 "Stalingradec", and the U.S. Army's M4 Tractor), mostly originated from the pre-war light to medium series of Vickers artillery tractors.

Two variants of this vehicle were built: the basic cargo carrier, and a self-propelled antitank vehicle armed with a PaK 40 gun. Both shared the same chassis.

After the Wehrmacht's first fall and winter (1941–1942) on the Russian front, they found that the extremely primitive roadways in Russia and seasonal mud required a fully tracked supply vehicle to maintain mobility. Steyr responded by proposing a small, fully tracked vehicle based upon its 1.5-tonne truck (Steyr 1500A light truck) already in use in the army. The vehicle was introduced in 1942 as the Raupenschlepper Ost (RSO).

Initially designed as a prime mover and artillery supply vehicle, it eventually served in a wide variety of roles. Immediately after the vehicle reached the Eastern front, the combat units started using it for general transport duties. It gave outstanding service due to its reliability, its ease of maintenance, and its capability to take over a variety of roles - in every kind of terrain - that other vehicles lacked. The four road wheels per side, all in a single line as part of a "slack-track" system with no return rollers, comprised a much simpler suspension system, much more able to handle the rasputitsa mud season and Russian winter conditions, without mud or snow freezing between the wheels of the complex overlapping/interleaved Schachtellaufwerk suspension systems that German half-track vehicles like the SdKfz 7 possessed. Soon the orders for the RSO surpassed Steyr's production ability, and more manufacturers joined the vehicle's production in order to meet the ever increased demands.