One of the most identifiable of the German half-tracked pieces of World War 2 became the SdKfz 2 kleines Kettenkraftrad Typ HK 101 (popularly recognized as the "Kettenkrad"). The vehicle was a small, three-man design incorporating the frontal portion of a motorcycle fro steering with a customized rear passenger section built upon a tracked wheeled arrangement. The Kettenkrad was, therefore, a small unarmored half-track vehicle, a complement to the larger, full-sized breeds utilized by the German Army, and its uses ultimately proved many for the German military.
The concept of the Kettenkrad vehicle was born through a patent obtained by engineer Heinrich Ernst Kniepkamp in June of 1939. It took the resources of the German motorcycle concern NSU Werke AG of Neckarsulm to make the concept a reality to which the vehicle caught the interest of the growing German military. The military saw the value of the compact system for both its army and airborne divisions. It could be used as a prime mover of artillery systems or heavy cargo loads, as an all-terrain messenger vehicle or as an all-terrain utility vehicle. In any role, the Kettenkrad held several distinct beneficial qualities over that of a traditional motorcycle, full-sized half-track or pack animal.
The compact dimensions of the Kettenkrad allowed the system to be relatively easily transported by powered aircraft (Junkers Ju 52), glider or truck and it could maneuver the debris-strewn remnants of French and Soviet cities and villages with some ease thanks to its inherent agility. Road speeds were excellent, roughly 43 miles per hour on ideal surfaces, which allowed it to keep pace (or outpace) mechanized formations. The tracked nature of the design allowed the little vehicle to navigate uneven terrain such as rocky mountains and slopes of 60% grade while even fording low-lying water sources. The tracks also ensured that the vehicle could be turned within a tight radius as required.
The Kettenkrad was crewed by a single operator seated in a tub-style surround aft of the motorcycle handlebars used in steering the frontal rubber-tired road wheel. To his front was the instrument panel which laid horizontally and featured applicable system gauges. To either side of the seat were the twin fuel tanks which doubled as arm rests. His lower back was supported by the jutting upper structure of the Kettenkrad design. Aft of the driver was a two-seat passenger area to which the occupants faced the rear. Hand rails (early versions built from metal tubing, later ones with solid rails) ensured some safety though the entire design was left open to the elements. A towing facility was fitted to the rear of the vehicle to accept a variety of wheeled battlefield equipment. A special two-wheeled cargo carriage (the SdAnh 1 "Sonderanhanger") was designed alongside the Kettenkrad system itself and was to be used in conjunction when possible. The vehicle lacked any onboard communications suite and self-defense weaponry was to be provided by the crew.
The Kettenkrad was powered by an automobile grade engine installation - the Opel Olympia liquid-cooled four-cylinder 1.478 liter engine of 36 horsepower output at 3,400rpm. The engine was mated to a three-speed transmission system. Top road speed was 43.4 miles per hour with an operational range of 161 miles. Dimensions of the vehicle included a running length of 3 meters, a width of 1 meter and a height of 1.2 meters while overall weight was 1.56 tons. Suspension was via a torsion bar system which served the four road wheels to a track side, the drive sprocket being fitted at the front of the arrangement.
The basic Kettenkrad prime mover was developed into two other distinct production forms, both designed to lay down communication lines for the advancing German Army. The SdKfz 2/1 kleines Kettenkraftrad fur Feldfernkabel was fitted with a thin framework of pipes over the midsection of the Kettenkrad hull (aft of the driver)for supporting a communications line reel while the similar SdKfz 2/2 kleines Kettenkraftrad fur schwere Feldfernkabel was completed with a different heavier framework to mount a large communications line spool. Both versions allowed for communications lines to be laid at speed.
German military interest in the small vehicle was strong enough to order an initial batch of 500 vehicles in 1940. Deliveries of the design began in 1941 and, by June, German soldiers were enjoying the benefits of their new ride as they were in operational service along the Eastern Front in the war with the Soviet Union. In service, the type was categorized as a "prime mover" intended to haul portable battlefield artillery pieces and a portion of their crew - which it did, with some ease. Hauling capabilities actually proved greater than initially anticipated spurring greater production in 1942 of 1,208 further examples. This total was then bested in 1943 by the 2,450 units produced. By this time more additional manufacturing resources had been added (automobile maker Stoewer Werke of Stettin) to keep up with demand and, in 1944, another 4,490 examples were delivered, signifying the peak of Kettenkrad production in the whole of the war. It was only due to the lack of additional resources, which were either tied to other programs or non-existing at this point in the war for Germany - that production of Kettenkrad systems suffered through the final months of the war. With the fall of Berlin in May of 1945 to the Soviets and the end of the war in Europe, Kettenkrad production ceased for the interim.
The Germans certainly valued their nimble little Kettenkrads and used them in all manner of battlefield roles beyond the originally intended ones. It could haul many types of small and large caliber towed artillery (75mm pieces noted) and various trailer designs beyond the two-wheeled carriage developed specifically for the Kettenkrad. It could help free stuck vehicles and traverse areas that were too confined for tanks and half-tracks or too soft for infantry and wheeled vehicles. It proved the perfect blend of tank and motorcycle to the point that German Luftwaffe airborne troopers found great value in the system as well - it fitting nicely into awaiting Junkers Ju 52 transports. The Kettenkrad held a certain curiosity to Allied troops who, it appears, never fully appreciated the value of the Kettenkrad as many accounts place the vehicle at the center of many-a-joyride for American soldiers. Beyond their operational service along the East Front, the Kettenkrad saw service on the West Front and in the North African Campaign.
After the fallout of war in Europe, the Kettenkrad entered production once more though as a civilian-minded piece, sold to farmers who appreciated the hauling aspects of the little machine. Some 550 examples were believed produced during this period.
In all, 8,345 Kettenkrad examples were produced until 1949. Today, they may be found as museum pieces or in private hands - their engines still operational.