Eric Bryan examines the only gun tractor small enough to fit inside the hold of a Junker Ju 52 aircraft.
Popularly named the ‘motorcycle halftrack’, Kettenkrad translates as ‘tracked motorcycle’. Also called the SdKfz 2 or Kleines Kettenkraftrad HK 101, the Kettenkrad was designed in 1939 as a gun tractor which could pull artillery through boggy, snowy, or muddy ground where other vehicles would flounder.
The Kettenkrad was tailored to fit into the cargo hold of Junkers Ju-52 tri-motor aircraft, which supplied the vehicle to airborne troops, though not via airdrop. It was manufactured by NSU in Germany, and later also by Stoewer in Poland.
Crew, accessories, and operation
Besides the driver, the Kettenkrad carried two soldiers on rear-facing seats at the back of the machine. It often pulled a 3.7mm anti-tank or 20mm anti-aircraft gun. There was also an NSU-made cargo trailer for the Kettenkrad, the Sonderanhänger 1 (Special Trailer No 1). The trailer’s unladen and gross weights were 242 and 1012 lbs.
The vehicle’s front wheel gave stability to high-speed driving. The wheel provided steering via the handlebars in gentle curves. For tighter turns, the Kettenkrad automatically engaged its tread breaks.
For severe off-road use, the vehicle’s manual recommended removal of the front wheel, turning the Kettenkrad into a pure tracked tractor. This configuration was effective in deep mud or loose rock where traction was at a premium and speeds were low.
As NSU was not equipped to design and manufacture an engine suitable for the Kettenkrad, the designers fitted it with the proven and reliable motor from the Opel Olympia car. Because Olympias were already in military use, field mechanics were familiar with servicing its power-plant.
Uses and service
Most Kettenkrads served on the Eastern Front, where they carried soldiers and towed guns and freight through oozing mud, and worked as communication cable-layers.
In the latter capacity, the Kettenkrads were sometimes fitted with spools and a special trailer for the playing out of the cable. There were two specialised variants: the SdKfz 2/1, for laying long-distance field-telephone cable; and the SdKfz 2/2, for laying heavy standard field-telephone cable.
Kettenkrads also saw service on the Western Front and in North Africa. In the desert, the machine could pull guns and trailers through deep, loose sand. In addition, the machines functioned on German airfields as aircraft tractors. In this capacity, they sometimes pulled the new Messerschmitt jet fighter, the Me-262, into takeoff position. This practice saved fuel from being burned while taxiing.
Wartime production of the Kettenkrad ceased in 1945, but NSU manufactured the vehicle until 1949 for agricultural purposes, where its narrowness made it ideal as a vineyard and forest tractor. Between 8,000 and 9,000 machines were made during the war, and another 550 post-war.
US forces encounter the Kettengrad
The US War Department published a report on the Kettenkrad in Tactical and Technical Trends in February 1943. Calling the machine a ‘German Motorcycle Tractor’, the report states US forces first encountered the vehicle during the invasion of Crete.
They noted it was used for towing light trailers or guns, was deployed in the Middle East and on the Eastern Front, and that it was appropriate for airborne troops. The report documented some Kettenkrad modifications for ‘Tropical Use’. These included increased cooling-fan speed, a Solex carburettor, push-button starter, and track-link extension plates for a larger footprint in sand or swamp.
Some Kettengrad specifications
Weight: 2726 lbs unladen, 3444 lbs for combat
Length: 9 ft 10 inches
Height: 3 ft 11 inches
Width: 3 ft 3 inches
Engine: 1478cc Opel four-cylinder, 36 bhp
Carburettor: Solex 32 FJ-II off-road or Opel System Carter
Front tyre: 3.50 x 19 inch, 25 psi
Tracks: forged steel, 40-link
Gearbox: three forward, one reverse; transfer box with off-road and on-road settings created six forward, two reverse gears.
Petrol tank capacity: two tanks, 4.62 imperial gallons each
Mileage: 18 mpg on-road, 13 mpg off-road
Top speed: 44 mph