Kleines Kettenkraftrad HK 101 Sd.Kfz.2 Kettenkrad

The history of the Foundation’s Kleines Kettenkraftrad Sd.Kfz.2 ‘Kettenkrad’ can be traced back to Austria in the 1970s, where for reasons unknown it was completely dismantled. The body tub (which carries the chassis number) was then sold in 1980 to a collector in Cologne, Germany, who kept it until 1986.

In 1986 the body tub was again sold to another collector, this time in the UK. This collector acquired most of the missing parts from a variety of sources and sold the still-dismantled vehicle in 1995 to another English collector. At this stage, it was in a very poor condition. Its bodywork, mechanical and electrical parts were then partially restored before being purchased by the Foundation in 1995.

This Sd.Kfz.2 was in bad shape as the front forks and steering gear had been ripped off in a previous accident and a good correct replacement had to be found. Study of the chassis number where the steering assembly meets the chassis tub proved this Kettenkrad to be a product of Stoewer Werke AG. of Stettin. This information steered us towards the earlier headlamp bearing steering assembly as opposed to the later simplified headlamp free example delivered with the Kettenkrad on purchase. A cosmetic restoration ensued where some cardinal sins were committed including the repair of bullet damage to the front wheel hub and the rear hand rails on one side which had sustained raking machine gun fire at some point in her history. The rear hand rail and panel were not accurately attended to and the result although superficially acceptable was far from correct. The fuel tanks appeared longer than examples from the lead assembler of these interesting Sd.Kfz.2 Kettenkrads, NSU Werke AG of Neckarsulm. This made for some difficulty in mounting replacement bins on the rear of the driver’s area. A more complete restoration is planned unless of course we are able to upgrade to an original vehicle with provenance
given that here is no known service history of this vehicle during the Second World War.

Design and Development

This design originated with the Luftwaffe as a requirement issued during late 1938 for a small but powerful artillery prime mover to equip the then newly formed German Paratroop (Fallschirmjäger ) units. The first such Paratroop units were the 7th Flieger Division and the Fallschirmjäger Sturm Abteilung . The Fj. Sturm Abt. were mainly glider borne infantry for use against coup-de-main targets, whereas the much larger 7th Flieger Division was a parachute infantry division that also contained typical divisional back-up units such as those listed below, all of which contained towable guns:

• Fallschirm Artillerie Abteilung 7
  using Skoda 7.5cm Gebrigskanone 15/28 guns weighing 716kg
• Fallschirm Flak MG Abteilung 7
  using 2cm Flak 30/38 anti-aircraft guns weighing 750kg
• Fallschirm Panzer-Jäger Abteilung 7
  using 3.7cm Pak 36 anti-tank guns weighing 440kg

Whilst all of these guns could be either air dropped using quintuplet parachute arrangements, or air transported using the Junkers JU 52, once deployed they had no mechanised towing vehicles and had to rely on horses, dogs, mules or the soldiers. Thus their immediate tactical usage was very restricted, and as a prime reason for using paratroopers is the quick movement onto an objective, something motorised for towing these guns was needed.

As quickly became apparent, however, anything with enough power to pull guns would itself be large and heavy. Thus the Germans had three major considerations directing their design work:

1. Sufficient power to pull a 750kg artillery piece across rough ground.

2. Small enough to fit through the side loading doors of the standard transport plane of the time, the Junkers JU 52. The overall size and weight of the new prime mover was expected to prohibit parachute dropping. As well as risking potential damage caused by the impact, 800kg was the maximum parachute load under a JU52.

3. The standard artillery tractor designs of 1938/1939 were a series of mechanically similar but dimensionally different half-track vehicles ranging from 1 to 18 tons towing capacity.

By successfully combining all the above needs, a tractor dimensioned 3000mm x 1000mm x 1200mm and weighing 1280 kg was arrived at. It was powerful enough to tow the gun weights but also small enough to fit the JU 52 side doors. The use of a single front wheel cleverly overcame the more typical and far more complex twin front wheel steering and even more importantly considerably reduced the overall rigid length and cubic volume of this prime mover. If required, the front wheel and mudguard could be very easily removed for transit, whilst not inhibiting the vehicles mobility to any great extent. The driver’s manual also recommends this action for crossing deep mud and rocky terrain.

The use of this single wheel has frequently confused observers, with even the Germans calling it a Kettenkrad, the word “Krad ” being a German abbreviation of 'Kraftrad' (motorcycle). However it is nothing of the sort. It is a full half-track vehicle with a single front wheel. It is only superficially like a “Krad ” at the front end, no other part is. The use of the front wheel was to aid climbing and ditch/trench crossing.

Thus the Kettenkrad came into existence as a specialised tool for use by specialised Luftwaffe troops (Fallschirmjäger ). At this time -1939/40- no other use was envisaged or planned for this vehicle.

There were, however, other specialist troops in other branches of the Wehrmacht who would have benefited greatly from this new vehicle. For example, the German Mountain Troops (Gebirgsjäger ), who also had similar problems with gun movement in difficult circumstances. The lack of co-operation stemmed from the fact that the Fallschirmjäger were all Luftwaffe troops whilst the Gebirgsjäger were all Heer (Army) troops. Initially this was enough to put them worlds apart. It should be emphasised here that the Kettenkrad was a Luftwaffe initiative. They commissioned the design for own use via their own Luftwaffe design and procurement offices, much like they would an aeroplane specification and requirement. By the time of the German airborne invasion of Crete in May 1941, the situation had improved and both services were working together under Wehrmacht control. However only the Fallschirmjäger had the Kettenkrad at this time. Crete was its first use in combat, where it was delivered by both air and sea transport.

Production

The prime contractor chosen for the design and final assembly, tracks and gearbox was NSU-Werke A.G. of Neckarsulm.
Other contracted main assembly suppliers were:

• Engine, Adam Opel A.G. of Russelheim am Main
• Carburators, initially Opel A.G., but soon replaced by Deutsche Vergaser-Gesellschaft of Berlin (Solex)
• Electrical, Robert Bosch G.m.b.H. Stuttgart, Nova-Technik G.m.b.H. Munich and Osram G.m.b.H. Stuttgart
• Air filter, Alfred Knecht K.G. of Stuggart
• Handle bar controls, Fischer A.G. of Frankfurt am Main
• Brakes, Deutsche Perrot-Bremse G.m.b.H. of Mannheim-Friedrichsfeld

Between eleven and thirteen distinctly different prototype Kettenkrad appear to have existed. To a great extent all look like the final Kettenkrad, but some were just wooden mock-ups. Some were a mixture of wood and metal components, but most were running vehicles. Their differences were mainly to do with the front wheel and road wheel designs. Wire spokes, cast spokes or plain flat discs were all trialled, as well as one more or one less axle than finally used. Different diameter wheels and various body shapes were tried. This body design effort was largely concentrated at the rear end, which changed shape many times.

First Production Vehicle Technical Specification

The final Kettenkrad design produced a vehicle with steering via a handlebar through a single front wheel. But as with all the German half-track family after a few degrees of turn, a “Cletrac” braked differential, slowed down and braked the track drive in the direction being selected.

The front mudguard carried a number plate and Notek blackout lamp, with the headlamp immediately above. Side lights were also fitted to the front mudguard extensions.

The Opel Olympia, 1.5 litre, 36 HP, 4 cylinder water cooled petrol engine was contained in a one piece box shaped body tub along with 3 forward 1 reverse gears with a high and low ratio gearbox, final drives and transmission, suspension torsion bars and radiator. As the engine and radiator had no direct airflow over them a shaft driven cooling fan and air duct was installed at the rear end of the body tub to ensure that cooling air was forced over the radiator.

The body tub was a two part welded item with the main joint being in a horizontal plane immediately below the side mudguard. The gearbox case could be either a steel or aluminium casting.

The instrumentation consists of a centrally located water temperature gauge flanked on the left with a 4000 rpm rev counter and on the right with 80 km/hr speedometer. A co-axial socket was fitted centrally below the instrument panel, and an oil pressure warning light was also fitted adjacent to the Notek lamp switch. Very soon a binnacle mounted oil pressure meter was located just below the dashboard in lieu of the oil warning light. Approximately 550 Kettenkrad were fitted with this, after which it was removed.

To the left and right of the driver’s single saddle, were two 21 litre fuel tanks. In the middle and again on either side of the engine were two locker boxes. One contained the 6 volt battery, and a number of spare track links and other items were stored within them.

The rear of the Kettenkrad consisted of a double seat facing towards the rear with a very extensive 70 piece spares and tool kit stored beneath it. The passengers were equipped with grab handles on the side rails. Between the passengers was an air box. It carried the number plate, Notek lamp and multi-pin electrical connector. Below this was the tow hook

The tracks and road wheels were similar in design concept to many other German semi-tracks. Most of them employed interleaved road wheels with trailing arm and torsion bar suspension. Each individual wheel had solid rubber tyres. The 80 individual track links were hollow castings, with each acting as its own lubrication reservoir fed by a grease nipple, for the needle roller track link bearings. Each link mounted a BUNA rubber pad.

The tractor was capable of 70 km/hr on roads with a range of 260 km and a cross-country range of 175 km on full fuel tanks.

Sd. Ah. 1 Trailer

In late 1941 a specifically designed trailer was put into production. Manufactured by NSU this trailer was connected to the Kettenkrad by both a rigid towbar and an electrical cable. The cable enabled the trailer lights to work in conjunction with those on the Kettenkrad. The trailer body was also of an open box construction making it able to float. Its rims and two pneumatic 3,50-19 tyres were identical to those used for the Kettenkrad's own front wheel.

Manufacturing Period and Quantities Produced

NSU began Kettenkrad production early in 1941. Prototypes and some pre-production vehicles were built in 1940. On Crete in May 1941, about 55 are believed to have been used. This number does match the approximate artillery, anti-tank and flak gun total of the 7th Flieger Division at the time.

NSU had produced a minimum of 8870 by 1945 when the factory was occupied by US Army, although the true final production figure is currently unknown. In late 1943 a second company, Stoewer-Werke AG of Stettin, was given a contract and production started in December 1943 through to 1945. The Stoewer archive records 1302 Kettenkrad built in total.

For the Stoewer production all parts were imported from the existing NSU suppliers. There were no Stoewer made parts or unique Stoewer variations to this vehicle during the production period. They did incorporate all the changes as implemented by NSU. Also in 1943 a third company was appointed, Simca Industries of Paris, France. They were chosen to produce 2500 complete Kettenkrad in 1944 but only got as far as producing tracks, wheels, torsion bars, trailing arms and lower body tubs before the Allied liberation in mid-1944. Before this all their parts production was sent to NSU and Stoewer for inclusion in their new build Kettenkrads.

The total of Kettenkrad production during WWII is therefore likely more than 10,172.

Construction Modifications

The following construction modifications were applied to both NSU and Stoewer built Kettenkrads between 1941 and 1945. Apart from these noticeable modifications there would have been a myriad of smaller changes, often to do with cost reductions and/or conservation of scarce materials.

• 1941: the idler wheel changed from a large diameter 8 spoke wheel to a smaller diameter 6 spoke wheel.
• 1941: the 8 spoke inner track double wheels changed to 6 spokes.
• 1941: the oil pressure light becomes a binnacle mounted dial meter at chassis no 11 0016.
• 1941: the carburettor changes from an Opel to a Solex design at chassis no 11 0501.
• 1941: the airfilter design changes from 1st pattern to 2nd pattern at chassis no 11 0501.
• 1941: the dynamo design is changed from 1st pattern to 2nd pattern at chassis no 11 0501.
• 1941: the rear air intake design changes from 1st pattern to 2nd pattern at chassis no 11 0543
• 1942: the oil pressure meter is removed at chassis no 11 0551.
• 1942: the front fork design is changed from 1st pattern to 2nd pattern at chassis no 11 1021
• 1942: the silencer design is changed at chassis no 11 1027.
• 1942: the dashboard changed from a flat panel to a shallow slope at chassis no 11 1301
• 1942: the rear air intake design changes from 2nd pattern to 3rd pattern at chassis no 11 1515.
• 1942: the rear number plate changed from angled corners to oblong at chassis no 11 1515.
• 1942: the starter motor is changed from a foot operated mechanical start to an electric start.
• 1942: the outer single wheel hole sizes became smaller and the pressed spokes became less well defined.
• 1942: the exhaust pipe cover is changed at chassis no 11 1568.
• 1943: the 50 mm water temperature gauge became 60 mm diameter at chassis no 11 1796.
• 1943: the winterisation kit is fitted to all newly made vehicles and retrospectively as a field fitted accessory if required.
• 1943: the rear side rails are filled-in with steel panelling
• 1944: headlamp removed.
• 1944: the front fork dampener is changed from a spring to hydraulic
• 1944: side mudguards removed.
• 1944: the front body hook positions changed from high to low
• 1944: the front side lights removed.
• 1944: the front wheel mudguard changed design and the support stays changed from round to flat in section.

Equipment Variations

Only two major production variations existed. These were:
The Sd.Kfz.2/1 to carry two large field telephone cable reels mounted on a tubular framework fixed immediately over the engine bay. The Kettenkrad trailer could also be towed and contained two more identical cable drums (Sd. Ah. 1/1).

The Sd.Kfz.2/2 carried one small field telephone cable reel mounted similarly to the 2/1, plus more in the trailer (Sd. Ah. 1/2).

Optional Field Modifications

Some additional factory applied and field modifications were:

The winterisation kit, applied to all vehicles at the factory after early 1943. It consisted of an extension to the radiator water piping and a petrol heater to heat up this water before starting the engine. Two small petrol heaters were added to be placed alongside the battery to keep it warm. A canvas insulation cover was fitted over the battery locker box. Modifications were also applied to the fuel system, so that fuel or alcohol could be introduced directly into the carburettor before attempting to turn the engine over. Optional air ducting was also available. When fitted it was used to move warm air from the hot side of the cooling unit at the rear, forward to the drivers compartment.

• Snow chains could also be issued at 40 chains per vehicle and were to be applied to every other track link. Additionally the drive sprockets 48 rubber segments in contact with the track would need to be replaced by hollow cast steel segments to resist the extra abrasion and allow for the additional bulk of these chains.
• Extension plates could also be added to the track links to reduce ground pressure for either mud or snow conditions.
• An additional steel fabricated storage box could be mounted directly above the engine compartment. This pressed steel box appears to have been manufactured in two different heights.

WWII Usage

Throughout WWII the Kettenkrad was used by the Luftwaffe Fallschirmjäger . However this vehicle was quickly seen by other sections of the Wehrmacht as an extremely capable and useful vehicle. It could be used not only as a prime mover but for general communications, food and ammunition supply in conditions that few other vehicles could manage. With the Wehrmacht’s eventual involvement in conditions as varied as Russian snow and mud and the North African desert sands, this vehicle proved to be invaluable for all types of units.

Even after Crete in 1941, when German Fallschirmjäger airborne operations were severely curtailed and hence their specific equipment requirements dwindled, production of the Kettenkrad continued to increase, with Stoewer also being brought into the production as well as similar plans made for Simca.

Post-War Manufacture

After the war production of the Kettenkrad continued. In 1946 NSU were contracted to re-open the Kettenkrad production line by the German Land and Forestry Organisation. They needed small vehicles with good cross country performance to work in the German forests. The vehicle was known as a Waldschlepper or forest tractor. Production continued into 1947 with approximately 550 NSU Waldschlepper built. The only externally noticeable difference from the 1945 WWII Kettenkrad was the replacement of the front mudguard mounted Notek lamp with a regular headlamp also mounted to the front mudguard. Most of these Waldschlepper were manufactured in a dark green colour and many had “WALDSCHLEPPER” stencilled on the fuel tank sides.

In addition NSU, a second post-war manufacturer was Babiole, an off-shoot of Simca in France. Several hundred of their Vignoble Tracteur (Vineyard tractor) were manufactured, but, except for a few prototypes, were not based on the existing WWII Kettenkrad.

During WWII Simca had manufactured wheels, suspension, tracks, axles, and the lower body tub. A Babiole tractor has all these Kettenkrad parts in its construction, but everything else is radically different.