Pak 40 auf Raupenschlepper Ost

Raupenschlepper Ost (German: “Caterpillar Tractor East”, more commonly abbreviated to RSO) was a fully tracked, lightweight vehicle used by the Wehrmacht in World War II. It 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.

By 1943 infantry anti-tank units at the front complained strongly that it was almost impossible to move their guns using trucks at daylight under enemy fire, leading to enormous losses of equipment during “emergency relocations” (at the time a euphemism for withdrawal), and their opinions reached the top ranks. OKW explored a previously considered proposal to fit the 7.5 cm PaK 40/1 anti-tank gun – by then the standard PaK used by the Wehrmacht – on top of an RSO chassis. After seeing the blueprints, Hitler ordered a limited production run for combat testing, before the prototypes were completed.

The project was carried out by Steyr. The suspension of the RSO remained unchanged, but the front driver’s compartment was replaced with a low, lightly armoured superstructure. The result was a lightweight, cheap to produce, and highly mobile infantry anti-tank weapon.