Leichte Traktor – Grosstraktor I / II / III – Neubaufahrzeug PzKpfw V / VI

Early Projects and Prototypes Leichte Traktor – Grosstraktor I / II / III – Neubaufahrzeug PzKpfw V / VI

Daimler Benz's Grosstraktor I
Daimler Benz's Grosstraktor I

Daimler Benz’s Grosstraktor I as monument
at the barracks of Panzer Regiment 1 in Erfurt.

Between 1926 and 1932, Rheinmetall-Borsig, MAN, Krupp and Daimler Benz were ordered by Reichswehr to build prototypes of light (10-12 tons) and medium tanks (to 23 tons) under the cover name of "tractor" in order to hide their military potential from the Treaty of Versailles. Prototypes were tested from 1926 to 1933 at Kama (Panzertruppenschule Kama), near Kazan in USSR under high security, being "unofficial". Kama was the codename created by words Kazan and Malbrandt. Oberstleutenant Malbrandt was the one, who selected the location for artillery and tank testing. Kama was a joined Red Army and Reichswehr training and testing ground of military technology – similar facilities existed for the airforce and gas warfare.  The facilities were also used by the German companies involved in the weapon development.  This was part of German – Soviet treaty from Rapallo signed in 1922, which focused on development of military technology as well as Berlin Friendship Treaty of 1924. Their designs were based on lessons learned with the development of Leichte Kampfwagen I and II (1918-1919), which existed only as prototypes.

WD Schlepper
WD Schlepper

In 1927, Germans designed two self-propelled guns based on fully tracked Hamomag tractors as commercial Hanomag tractors were already in use with the army. First was 3.7cm WD Schlepper 25PS, which was a lightly armored 25hp Hanomag WD tractor with pedestal mounted 37mm PaK L/45 gun. The gun had limited traverse of 30 degrees only. The vehicle also carried single machine gun for defence.Second was 7.7cm WD Schlepper 50PS, which was 50hp Hanomag WD tractor with pedestal mounted 77mm K light gun. The gun had full 360 degrees traverse.Both self-propelled guns were accepted into service with the German Army (Reichswehr) in 1927. Small number of vehicles was produced and was used mainly for testing.

Top Left – 3.7cm WD Schlepper 25PS
Bottom Left – 7.7cm WD Schlepper 50PS

Since 1926 till 1929, at least 146 officers finished the training school at Kama. The most famous "cadet" was Von Kleist. The person responsible for the training in Germany was Gen. Lutz and in USSR, the NKVD Komissar Unshlicht. All the German "tractor" prototypes were tested at Kama Proving Grounds. The training program was quickly finished at the beginning of 1929.

A very interesting thing – the training was not under the control of the NKO (Ministry of Defence), but under the control of the NKVD ( Ministry of State Security).
The German pilots were at the same time on training in Lipetzk Military Air School and the officers of the Chemical defence in Astrachan Military School of the Chemical Warfare. At least 500 officers graduated succesfully from these two schools.  In 1933, all three facilities were closed due to political developments in both Germany and USSR.

In 1939, USSR purchased samples of the all German AFVs. They were put on trials and the comission came up with the verdict that they had poor reliability. The opposite "verdict" was made concerning Me-109, which was purchased at the same time. The pilots said that it was better than Soviet fighters.

Leichte Traktor (VK 31)
Leichte Traktor (VK 31)

Rheinmetall-Borsig Leichte Traktor – Versuchskonstruktion (VK) 31

Development of light tanks was initiated in May of 1928 and in October of 1928, Krupp and Rheinmetall-Borsig were ordered to design light tanks. The vehicle was to be based on the chassis that could be also used as a base for a self-propelled mount for 37mm gun, armored supply carrier and tractor.  Krupp in co-operation with Rheinmetall-Borsig began work on three prototypes. Krupp produced 4 men prototype powered by 6 cylinder 100hp Daimler-Benz M36 truck engine.  Rheinmetall’s 4 men prototype was powered also powered by Daimler-Benz M36 truck engine.Both designs had very similar specifications and were very similar in their design with the main difference being the suspension. Krupp used coil springs, while Rheinmetall used leaf springs suspension. Both vehicles known as Leichte Traktor (VK 31) were armed with 37mm KwK L/45 and light machine gun mounted in a turret (designed and produced by Swedish AB Landsverk and Bofors) mounted in the rear. Prototypes were ready in April and May of 1930 and two Krupp and two Rheinmetall vehicles were then tested in Kama in June of 1930. Rheinmetall-Borsig also produced third (mild steel) prototype, which was a 3 men self-propelled mount for 37mm Pak L/45 gun. This early Panzerjager was basically the same as the tank version with main difference being smaller turret and modified superstructure. Leichte Traktor vehicles proved to be successful during tests and were used for training purposes at Kama, but were seen as experimental vehicles unsuited for combat. From 1931 to 1932, Rheinmetall worked on improving and modifying their prototypes (e.g. new track type and suspension). In 1931, 289 were ordered, but in 1932, this project was cancelled in favour of other developments (such as Kleintraktor / La.S) and both Krupp and Rheinmetall produced only 3 prototypes. In 1933, co-operation with the Soviet Union ended and all four vehicles returned to Germany, where they were used for training at Panzer Gunnery School at Alt-Gaarz at Wustrow. Eventually, one of Rheinmetall’s prototypes with modified suspension ended up as a monument at Putlos.

Daimler Benz's Grosstraktor I
Daimler Benz's Grosstraktor I

Daimler Benz’s Grosstraktor I at Unterluss ready to be shipped to Kazan, Russia.

In 1925, Rheinmetall-Borsig, Daimler Benz and Krupp were ordered to design medium (heavy) tanks – codenamed Armeewagen 20 (Army Car 20). The following specifications were to be fulfilled: length of 6m, width of 2.4m, 75mm gun mounted in a rotating turret and weigth of 15tons. Each company was to produce two mild steel (6-14mm) prototypes disguised as commercial vehicles. Krupp designed their own turret, while Rheinmetall designed a turret to be mounted on their own design and that of Daimler-Benz. Work started in 1925 and tests were planned for 1929/30. Daimler Benz’s Grosstraktor I was designed by Dr.Porsche and was armed with single 75mm KwK L/24 gun and three to four 7.92mm schwere MGs. It had amphibious capabilities and was powered by Daimler M182206, 6-cylinder gasoline engine with total power of 255(260)hp. It had a leaf springs sophisticated suspension and hull design. Only two mild steel prototypes were built in 1929 (nr.41) and 1930 (nr.42) and were secretly tested. It appears that one of the prototypes was rearmed with a longer version of 75mm gun. Both vehicles had problems with their transmissions and their testing was limited.

Grosstraktor II
Grosstraktor II

Rheinmetall-Borsig’s Grosstraktor II

Rheinmetall-Borsig’s Grosstraktor II was armed with single 75mm KwK L/24 gun and three to four 7.92mm schwere MGs. Its overall design was simpler from that of Grosstraktor I, it included side access doors and also had amphibious capabilities. Only two prototypes were produced, first in 1928 (nr.45) and the second one in 1929 (nr.46), while both were then modified in 1930, 1932 and 1933. Rheinmetall’s design was powered by 6-cylinder BMW Va engine with total power of 250hp. Krupp’s Grosstraktor III was also similar to other designs but differed with many detail differences. Also only two prototypes were produced, first in 1928 (nr.43) and the second one in 1929 (nr.44), while both were then modified in 1931. Both vehicles had coil springs suspension and their weight (16-16.4tons) and speed (40-44km/h) depended on the prototype.In general, all were similar in design to British Medium Tank Mark III (which was also produced in limited number and used for testing) and Medium Tank Mark C (some 36 were produced before World War I ended along with with 14 completed afterwards).

Grosstraktor III
Grosstraktor III

Krupp’s Grosstraktor III as monument
at the barracks of Panzer Regiment 5 in Wunsdorf, 1937.

None of those prototypes entered production due to numerous problems and defects encountered during tests.  Their nature was more of experimental vehicles that would provide the army, designers and manufacturers with experience to be used in the future development, deployment and production of new generation of tanks. 

In 1933, after completed tests and end of co-operation with the Soviet Union, four functional vehicles returned to Germany. Krupp and Rheinmetall-Borsig prototypes were used for training purposes in continuation with the work started at Kama. Eventually, they were handed over to the 1st Panzer Division and took part in maneuvers in August of 1935. Both Daimler-Benz Grosstraktors ended up as monuments at 1st Panzer Regiment headquarters at Erfurt and 5th Panzer Regiment headquarters at Wundsdorf. After 1935, remaining four prototypes were used for training purposes at Panzer Gunnery School at Putlos. In 1937, one of Krupp and Rheinmetall Grosstraktors ended up as a monument at 5th Panzer Regiment headquarters at Wunsdorf. The remaining two were either scrapped or used for target practice.Grosstraktors were extensively tested and lessons learned from them provided the German designers with valuable experience, which was then used in the direct development of Neubaufahrzeug and eventually of other designs.

Another of early German armored fighting vehicles was Räder-Raupen Kampfwagen M 28 (GFK). The vehicle was designed by Merker in 1928 and was a light tank with a switchable running gear. The vehicle was developed for Swedish Landsverk (partially owned by the Germans) and six prototypes were produced. Single one was tested at Kama in 1930, but the vehicle proved to be problematic. Germans were not interested in continuation of the development and in 1929, further development took place in Sweden by Landsverk. Based on Räder-Raupen Kampfwagen M 28 (GFK) in 1931, Landsverk produced few L-30 (Strv fm/31) and in 1933, L-80 prototype. 

PzKpfw NbFz V
PzKpfw NbFz V

PzKpfw NbFz V (Rheinmetall)

Development of new medium tank started in October of 1932 and in 1933, Army High Command (Reichswehr) granted a contract for a development of a "heavy tractor" (Grosstraktor). Both Rheinmetall-Borsig and Krupp were ordered to develop heavy tank and both provided their designs. At first vehicles were designated as PzKpfw VII (PzKpfw IV neu Art), but in October of 1933, they were designated as Neubaufahrzeug ("Newly Built Vehicle"). Rheinmetall’s Model A and Krupp’s Model B were very similar in their overall design and mainly differed in the armament and arrangement of the weapons mounted in the turret. Rheinmetall’s (PzKpfw NbFz V) design had 37mm Tankkanone L/45 installed over a 75mm KwK L/24 and Krupp’s (PzKpfw NbFz VI) design had 37mm Tankkanone L/45 installed beside 75mm KwK L/24. Both designs had two slightly modified Panzer I‘s turrets armed with machine guns (one mounted in the front and other in the rear). Those two tank designs were to complete the family of standardized German tanks.

Role/Type: Model:
Light Training Tank PzKpfw I
Light Reconnaissance Tank PzKpfw II
Medium Tank PzKpfw III
Support Tank PzKpfw IV
Heavy Tank PzKpfw NbFz V
Heavy Tank PzKpfw NbFz VI

PzKpfw NbFz V and VI’s designs were very similar to the contemporary British Vickers "Independent" tank, Soviet T-35, French Char-2C and proved to be too complex to produce and did not perform as expected. Only two (designated Nr.1 and Nr.2) mild steel prototypes were built by Rheinmetall in 1934 and three more armored prototypes (designated Nr.3, Nr.4 and Nr.5) in 1935/36. NbFz Nr.1 was the only one mounted with Rheinmetall’s turret armed with 37mm Tankkanone L/45 installed over a 75mm KwK L/24 gun and turret mounted frame antenna. Other four vehicles were mounted with Krupp’s turret armed with 37mm Tankkanone L/45 installed beside 75mm KwK L/24, while 105mm KwK L/28 gun was planned. In August of 1935, Nr.1 and Nr.2 took part in the exercises of a Panzer Division, while the other three were extensively tested on the proving grounds at Putloss in 1935 and 1936. In 1937, it was decided to convert NbFz tanks to Nebel Panzer armed with 105mm gun able to fire smoke ammunition, but there is no further evidence of any work being done. At that time the German Army wanted to gain experience with multi-turreted tanks, but soon this project was cancelled in favour of the Panzerkampfwagen IV development which would eventually become the main battle tank of the Panzertruppe until the end of World War II. Overall multi-turreted tanks were inferior to German designs and tactics, which relied on high mobility rate instead of firepower.  In general, multi-turreted tanks proved to be unsuccessful when used in combat and were gone from the battlefield by 1942.  In Spring of 1939, Krupp’s PzKpfw NbFz VI was shown at the International Automobile Exposition in Berlin.

PzKpfw NbFz V (Rheinmetall) on the production line.
PzKpfw NbFz V (Rheinmetall) on the production line.

NbFz Nr.1 (Rheinmetall) in the Krupp factory in 1942.

Three (with Krupp turret) of the five saw service with Panzer Abteilung zur besonderer Vervendung 40 in Norway in 1940. All three formed platoon size unit known as Panzerzug Horstmann / Zug Putloss, commanded by Lieutenant Hans Horstmann. They arrived in Oslo on April 19th of 1940 and gave the Allies appearance of Germany having heavy tanks. Two served with PzAbt zbV 40, while the third served with 196th Infantry Division. This particular vehicle was immobilized, but not destroyed by the British soldiers (see "The History of a Rare Panzer" below), while one of two from PzAbt zbV 40, drove into the swampy area at Andalsnes and got stuck and was eventually blown up by the German engineers (that explains "The History of a Rare Panzer" below). On May 16th, the lost Nbfz was replaced by one of the mild steel prototypes and PzAbt zbV 40 had once again three NbFz tanks. It is known that PzAbt zbV 40 was stationed at Akershus Fortress (Oslo) in Norway in 1941 and then in Finland in 1942, but it seems that NbFz tanks never left Norway and were eventually captured by the Allies in 1945 and then scrapped.

PzKpfw NbFz VI in Norway.
PzKpfw NbFz VI in Norway.

PzKpfw NbFz VI (Krupp) in Norway, 1940.
Picture provided by Bjørn Jervås.

German source states that NbFz tanks were part of von Kleist’s 1st Panzer Gruppe on the Eastern Frontand that one of them was destroyed near Dubno on June 28th or 29th of 1941. Another source states that other two were destroyed near Romanian border in June of 1941. It is also reported that both returned to Germany in November of 1941. The only photographic evidence is that from Krupp factory from mid 1942, where one of Nbfz (Nr.1) tanks is being repaired with Sturmgeschutz III(40) assault guns on production line in the background. Probably one of two mild steel prototypes built in 1934 remained in Germany for tests and was eventually scrapped in 1941. The development of Leichte Traktor, Grosstraktors and Neubaufahrzeugs provided German designers and manufacturers with valuable experience in designing and producing the next generation of more powerful panzers that were soon to come.

PzKpfw NbFz VI
PzKpfw NbFz VI

PzKpfw NbFz VI (Krupp)
Specifications for Krupp Design – PzKpfw NbFz VI

Weight: 23000kg
Crew: 6 men
Engine: BMW Va / 12-cylinder / 290hp
Maybach HL 108 TR / 12-cylinder / 300hp
Speed: Road: 25-30km/h
Range: Road: 120km
Fuel Capacity: 457 liters
Lenght: 6.65m
Width: 2.90m
Height: 2.90m
Armament: 1 x 75mm KwK L/23.5 (L/24)
1 x 37mm KwK L/46.5 (L/45) (turret)
2 x 7.92mm MG13/34 (2 small turrets)
Ammo: 75mm – approx. 80 rounds
37mm – 50 rounds
7.92mm – 6000 rounds
Armor: 13-20mm

The History of a Rare Panzer.
Provided by Simon Orchard.

PzKpfw NbFz VIs in Oslo, April 19th of 1940.
This propaganda picture was taken in order to show Allies
that the German Panzertruppe was equipped with heavy tanks.

On the 25th April 1940, Gruppe Pellangahr (made up of elements of the 196 Infantry Division and some of PzAbt zbV 40 – special employment unit) ran into a British blocking position held by the 1st Battalion of Kings Own Yorkshire Light Infantry at the village of Kvam. The British had no heavy weapons only two 3" mortarsand five 25mm French Hotchkiss anti-tank guns. The lead element of the German advance included 3 panzers at least one of which was a NbFz VI (I believe there may have been two of them but I’m not sure). The British held theirfire until the enemy was at the range of 150 yards and then opened fire. The Panzers then attempted to maneuver into position, it was at this time that the NbFz VI was put out of action by one of the anti-tank guns (I believe also that a second panzer was immobilized). The Germans stopped to bring up their guns and call up the Luftwaffe, the British managed tohold on until the evening of the 26th before withdrawing. The remains of the NbFz VI (a section of the running gear) can still be seen in the small museum at Kvam and until the late 1980′s the 25mm anti-tank gun was still to be seen in good condition, left in spot where it was left by its previous owners in April of 1940.

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