Tracked truck Raupenschlepper Ost or RSO in the short form. Literal Translation “Caterpillar Tractor East”. This small cargo truck was designed to function in the East where mud and snow made the roads impossible to use. RAL 7028 DG I, 6011 and 8012.
The RSO/01 with heavy wagon in 1942.
The Raupenschlepper Ost (RSO) in service from 1944, was the result of a competition to provide a crude but efficient prime mover for use by the infantry Divisions in Russia. It was a small fully tracked lorry showing Russian influence in its design, and could pull loads up to the 10.2cm gun-howitzer. Some chassis were used as SP gun mounts.
The development of the Raupenschlepper Ost RSO
The Tank commission. shocked by the results of the first winter in Russia developed under the Chairmanship of Dr. h. c. F. Porsche a list of requirements for the development of a fully tracked tractor. The company Steyr-Daimler-Puch AG submitted a first concept in the summer of 1942 which complied to a large extent with the requirements of the Panzerkommnission. These specification requirements were for:
- rapid and economic to produce
- low speed corresponding for lnfantriedivisionen
- no use of scarce raw materials (e. g. rubbers etc)
- excellent cross-country ability
- high load-and tow capacity in relation to vehicle’s weight
- reliability under all climatic conditions
After some changes. which were required by Hitler (i. e. ground clearance), production of the vehicle. now approved by the Army’s Armaments Office (Heereswaffenamt HWA). started in November 1942. The vehicle’s title was Raupensschlepper Ost RSO/ 01. The RSO adopted many of components from the Steyr 1500A (engine, clutch, gear, differential etc). Production reached 1500 units in 1942. A second series followed at the Steyr plant shortly after, with minor changes and now titled RSO/02. After the first positive troop experiences, the orders of the HWA were increased considerably so that further companies like Graef & Stift in Vienna, Auto Union AG Werk Wanderer in Siegmar-Schoenau and Kloeckner-Humboldt-Deutz AG, Werk Magirus in Ulm were entrusted with additional orders for production. With around 27.000 units produced by the end of the War and this was one of the most populous vehicles used by the Wehrmacht.
The first RSO (RSO/01) had a rounded cab of pressed steel. The RSO/02 had a flat-sided metal cab with a canvas roof, and the RSO/03 had a simple slab-sided metal cab with a canvas roof. Both of the later types of cabs were easier to manufacture and repair than was the early cab. The RSO/03 is sometimes called the Magirus RSO, because it was manufactured at the KHD Magirus plant. These were all forward-control vehicles, and all of the standard cargo models had wooden dropside beds.
Initially fitted with a Steyr 3.5-litre V8 petrol engine producing 85hp, the RSO/03 models had a 66hp 5.3-litre Deutz air-cooled 4-cylinder diesel engine that was better performing than the Steyr motor. The RSO gearbox had four forward and one reverse gear. Later models had a tractor-type final drive that replaced the automotive-type differential of earlier issues. Steering was controlled by levers which operated four hydraulic brakes at the sprockets and idler wheels. Top speed was about 19mph, though a 9-10mph road-cruising speed was usual. A spring-loaded pintle was at the back, and two towing hooks were attached to the front. A standard crew comprised a driver and navigator. ‘The RSO had four pressed steel disc road wheels per side, which were mounted in pairs, and a simple elliptic spring suspension system, together which handled Russian mud and snow capably. Its low ground pressure also helped the RSO to thrive in such situations. This was all a great improvement over the performance of German half-tracks such as the SdKfz 7, the complicated suspension and wheel arrangement of which was prone to becoming bogged down or frozen. Though having a high ground clearance, another advantage for operating in wintry Eastern Front conditions, the RSO’s low centre of gravity helped it to negotiate steep angles and grades. Its main disadvantages were its noisy engine, slowness, and lack of armour protection for the crew.
Other incarnations of the RSO included antiaircraft platform, field kitchen, troop transport, snow plough, mobile workshop, ambulance, and fuel tanker. There was an articulated version, the trailer being mounted on another tracked RSO chassis, which could carry 50 soldiers. There were also prototypes of an amphibious variant.
After only a few months of Eastern Front duties the vehicle proved to be very suitable for the troops and various branches of the armed services soon required this vehicle for different purposes. In addition a smaller version for the Gebirsgtruppe (Mountain troops) (designated as mountain tractor – Gebirgsschlepper), an amphibious version or ones which pulled sledges or semi-trailers for troop transportation were tested.
In November 1942, OKH, Gen. St. d . H/Organizations Abteilung (hereafter cited as OKH/Org. Abt.) urged the use of the new Raupenschlepper Ost (RSO – fully tracked carrier: East) as a towing vehicle for light and medium anti-tank guns or artillery pieces. But the RSO was not an effective prime mover, being too light and also unstable when cornering.
Reports soon carne hack from the Front which showed that the RSO had very rough, off road handling characteristics which disturbed the calibration of the towed guns sights. Therefore, a version as a weapon carrier was examined too. It was tested with such guns as the 7.5 cm Geb. H36, 10.5 cm Geb. H40 and 15 cm SIG33, 10.5 cm 1FH. 18/40 and 7.5 cm Pak 40, all with their trails on platform. All guns could be unloaded from the platform by means of a foldable crane, normally carried along the tailboard, and made ready for action at great speed. Firing from the platform was not possible. All these experiments did not develop into a production vehicle. A version with an armoured cab, (only soft steel plates) which resulted from a proposal of the HWA, achieved the attention of Hitler and the OKH and led to a small production of approx. less than 100 vehicles.
7.5cm Pak 40/4 Auf Gepanzerter Selbstfahrlafette Raupenschlepper Ost RSO
This was the tracked tractor developed at the same time as the Radschlepper Ost for service in snow and mud conditions of the Eastern Front during the war.
It was developed by Steyr during 1942 and used the transmission of the standard 1 1/2 – tonne Truck. The suspension was entirely tracked, though of crude design, which gave rise to excessive vibration in service. The suspension wheels were of steel, without rubber tyres, and springing was by quarter-elliptic leaf springs. Ground clearance was 55cm (21 1/2-in), which allowed the vehicle to keep moving in the worst conditions.
Steering was by simply breaking each track, without the use of any form of controlled differential, so that fine control of steering was almost impossible. Nevertheless, with a payload of 1 ½ tones and a towed rating of two tonnes, it was produced in between October 1943 and May 1944 and proved extremely useful in its designed role. They were built by Steyr, Auto-Union, Graf & Stift and KHD/Magirus. 83 RSOs were built with 60 mounting the 75mm PaK 40. The RSO began production in October of 1943 and it seems production ended at the end of May 1944.
The RSO with 7.5cm PaK40/4 vehicles were put on field trials with Army Group South. A production plan was formulated for 1944; March-60, April-100, May-150, June-200 and from July-400 per month.
There were also at least three other tank destroyers which were planned to be built on modified RSOs. PzJag K43/1, PzJag K43/2 and the PzJag K43/3 all mounting 88s.Of the 60 RSO/4 with PAK 40 14 each were given to Army Panzer Jager Abteilungen 743 and 744, 14 were issued to 18. Panzergrenadier Division and 7 were given to 1st Ski-Jager Brigade. They were not considered satisfactory on account of their low speed and noisy engine.
RSO/01 Steyr: 2600
RSO/01 Gräf & Stift: 4500 (approx)
RSO/01 Wanderer – AutoUnion: 5610
RSO/01 Klöckner-Deutz-Magirus: 12520
After the war, Magirus built some 1500 “Waldschlepper RS 1500” as half-tracks based on surplus RSO parts. They used the Deutz Diesel engine of the RSO/03.
The RSO/01 were equipped with a Steyr V8 of 3.5 liters. The RSO/03 built by Klöckner-Deutz-Magirus in 1944-45 had a 5.3 liter 4-cylinder Deutz diesel. Only about 600 were built.