WWII Tech Pubs Briefing
Sonderkraftfahrzeug (SdKfz) 251

Written by
Justin Riggir

Caption

[ Top of Page | Feedback ]

Overview

WWI ended with Germany firmly convinced that the tank had paid a large part in her downfall. The German Army was equally convinced that for tanks to be exploited to their fullest, they needed to be supported with infantry. On the few occasions that Allied tanks had advanced on an objective without infantry support, the defenders had been repulsed from their positions, however as soon as the tanks withdrew then it was a simple matter for the infantry to re-occupy the vacant ground.

The Versailles Treaty of 1919 imposed severe military restrictions on the German Army; however Germany was permitted to have a very small number of armored cars and armored lorries to deal with the smoldering civil unrest of 1919. By late 1920, the German Reichswehr had organized seven motor transport battalions, each of which was equipped with 15 armored personnel carriers, as permitted by the Allied Control Commission.

Germany noted the small amount of experimentation with armored forces during the inter-wars period, particularly the British Experimental Mechanized Force of the 1920s. This force was set up to study, on a small scale, the experiences of the last years of WWI, and resulted in the idea of coordinated tank, infantry, assault engineers and artillery attack under one command, the basic principle of the German Panzer-Division. 

Consequently when Germany began to re-arm and form the Panzer-Divisions during the 1930s there was a recognized need for armored personnel carriers to equip the infantry. In 1926 the Germany Army tested a number of trucks and half-tracks to determine future procurement and operational policy. A number of half-tracks were purchased, mainly as artillery tractors, and it was decided that this type of vehicle was ideal for cross-country use. This was to lead to a requirement for prototypes in six weight classes. These were built and tested, and in time led to the famous series of half-track gun tractors used extensively by the Germans in all theatres of WWII.

In 1937, it was decided to fit an armored body to the 3-tonne half-track, as this vehicle would be large enough to carry a full infantry section of ten men and their equipment. The Hanomag-built chassis had a faceted, well-sloped armored body designed by Büssing-NAG, with a strong resemblance to that used on the armored cars, and only minimal changes to the chassis were needed, such as the canting back of the steering wheel. After successful trials, the Mittlerer SchutzenPanzerwagen (medium infantry armored vehicle) with the ordnance designation SdKfz 251was rushed into production, with the first vehicles which were ready in the spring of 1939 equipping an infantry company in I Panzer-Division for troop trials.

The current (1938) production version of the 3-tonne tractor, the Hanomag H kl 6, was used and this basic design was ‘frozen’ until production ended in 1945, although many details were changed during this time. In comparison to other half-track which mostly used the simple track and spring bogie designed by the Frenchman Adolphe Kégresse, the German half-tracks were radically different and highly sophisticated for the period. The normal front wheels, which were steered conventionally, supported the front end and the long three-quarter length track units supported the weight of the vehicle. Drive was taken from the transmission via a Cletrac-type controlled differential with steering brakes on the shafts to the front sprocket wheels. This acted automatically as the front wheels were steered more than 15 degrees, thus braking the tracks as required to assist the vehicle turning.

The gearbox was a four-speed type with two-speed auxiliary boxes for off-road use, giving eight forward and two reverse gears. Initially the sprocket wheels had rollers on the wheel perimeter that engaged detachable rubber track pads fitted to the inside of the track which also cushioned the wheel paths. The tracks were fitted with sealed, lubricated needle roller bearings. This system gave long track life and excellent traction, however it was high quality and thus expensive to produce. Later production vehicles had conventional socket teeth and dry track pins to simplify production and reduce costs. The suspension was by sprung torsion bars, with the road wheels being interleaved and of the perforated disc type with solid rubber tires. This interleaved suspension gave excellent flotation, although it was vulnerable to becoming immobile with frozen mud or snow if parked overnight during winter.    

The chassis was of the conventional girder type frame with welded cross-members. There were armored belly plates under the chassis and the hull was of two sections bolted together, the front section consisting of the engine and driving compartments, and the rear one containing the passenger and fighting compartment. Both electric welding and riveting was used in the construction of the hull, as some firms in SdKfz 251 construction group had facilities for riveting but not welding. The engine was a Maybach HL42TUKRM 6-cylinder, 100-hp water-cooled unit of 4 liters capacity. The basic variant had a crew of two, a driver and a vehicle commander; Most variants had a simple interior fitted with padded bench seats along each side; were open topped and had large double doors at the rear. The basic infantry squad complete with their machine-gun was carried by one vehicle, with four vehicles carrying a complete platoon.

There were four basic production models that were mechanically similar with external detail differences, each being a further simplification of its predecessor reducing production time and costs. The first production type in 1939, the Ausführung A, had three prominent vision ports in each side of the hull superstructure. The radio aerial was fitted to the right front fender and a simple swivel bracket without a shield was fitted to the front and rear of the fighting compartment. This was soon succeeded by the Ausführung B, the major type in service during 1940, which included improvements suggested by service experience. The side vision ports in the passenger compartment were omitted, tools and equipment were re-arranged and the forward MG34 mount fitted with a shield. Stowage lockers were fitted on each side between the superstructure and mudguards.

The Ausführung B continued in production until the end of 1940, although the Ausführung C entered production in mid-1940. A single plate which left the radiator exposed at the bottom of the vehicle replaced the angled two-piece front plate of the earlier models, and armored cooling intakes were fitted prominently on the sides of the engine compartment. The radio aerial was re-positioned to the superstructure in both the Ausführung B and C. In 1942, in order to speed up production and cut costs, many of the German AFVs were simplified as much as possible. In the Ausführung D, which was of all-welded construction and remained in production from late 1943 until the war’s end, faceted areas for example, the vehicle’s back and engine compartment sides were replaced by single large plates. The engine cooling intakes were incorporated under the engine compartment’s side amour and the stowage lockers, which were originally detachable, were built in as part of the superstructure. The vision ports were replaced by simple vision slits.  

There were some 23 official variants, and also unofficial variants, as well as numerous prototypes carrying such pieces as 8.8cm PaK guns, Flakvierling quad 2cm mounts, and a variety of old tank turrets and odd weapons. Some of these variants were of the fire support type, for example, various anti-tank guns, flame-throwers, the 8cm mortar, several mounting either the 2cm anti-aircraft cannon or a drilling of three 1.5cm or 2 cm ex-aircraft cannon, a variant with six frames for launching either 28cm or 32cm Wurfrahmen rockets, and a variant mounting the ex-PzKpfw IV 7.5cm KwK37 L/24 gun. There were also variants fitted with extra radios for specialist communication roles such as maintaining regimental and divisional links, a telephone exchange and cable-laying variant, various specialist artillery variants such as armored observation, survey, sound ranging and flash spotting. There was also an armored ambulance, a variant for assault pioneers fitted with brackets for assault bridges, and one mounting an infrared searchlight used by the night attack units formed in 1944.

With the success of the SdKfz 251 a similar vehicle, the SdKfz 250, was developed using the smaller Demag 1-tonne half-track. Although this was not as versatile as the larger SdKfz 251 as it was only large enough to carry six men, it was found ideal for such roles as towing guns or ammunition trailers and complemented the larger vehicle in service. It was ideal as a platoon or company commander’s vehicle and where the SdKfz 251 was really too large for a role, for example carrying the 8cm mortar, the SdKfz 250 was able to release the SdKfz 251 for other more urgent roles. For although over 15,000 SdKfz 251s were manufactured during WWII there were never enough to go around. In theory all of a Panzer-Division’s infantry were to be equipped with SdKfz 251s, however, usually only one battalion, or at best two, per Panzer-Division were so equipped.

Post WWII the Skoda-built model of the SdKfz 251 was used as the basis for the OT-810 that was used as the standard troop carrier of the Czechoslovakian Army until well into the 1970s. This was similar to the Ausführung D version of the original design, however with the troop compartment now fully enclosed.

[ Top of Page | Feedback ]

Variants

[ Top of Page | Feedback ]

Production Numbers

[ Top of Page | Feedback ]

Specifications

[ Top of Page | Feedback ]