Durchbruchswagen II

The first mention of the need to develop a new tank weighing 30 tons fell in the report of General Lies for the Heeres Waffenamt of 30.10.1935. The new tank was to have at least 20 mm armor and was to be armed with a 75 mm cannon with a muzzle velocity of at least 650 m/s. The specification period followed. After more than a year, Baurat Kniepkamp (an automotive expert from WaPrüf 6) turned to Henschel to develop a new tank under the code name Begleitwagen B.W. (reinforced). Designation B.W. they also carried tank versions Pz.Kpfw. IV, therefore 12.3.1937 proceeded to rename I.W. (Infanteriewagen), which was shortly changed again on April 28, 1937 to D.W. (Breakthrough car). In 1939, this designation was changed to VK 30.01 alte Konstruktion.
On the planning production list of the company Henschel from 1.10.1939 there was an intention to produce one prototype D.W. I with the Cletrac system control mechanism and the second D.W. II with multi-stage control mechanism. Both prototypes were completed and tested by Henschel in the second half of 1938.

The D.W. prototype platform II was made of mild (unarmoured) steel. In addition to the drive and tensioning wheels, the chassis consisted of five double castors around the circumference with a rubber rim suspended by torsion bars and three support rollers. The strips were 300 mm apart. The belts had lubricated needle roller bearings. An interesting feature was the drive wheel, which was not round with gearing, but had the shape of a 9-angle into which the guide teeth of the belts fit (a similar principle as the Soviet tank T-34)
Vehicle D.W. II was very similar to its predecessor D.W. I.

The details of the construction are reported by Dr. Adersa from 2/1945:

The control mechanism was due to insufficient performance ZW38 from the company Daimler Benz (from the tank Pz.Kpfw. III Ausf.E modified and equipped with magnetic clutches, three-speed reverse gear differential, modified transmission, brakes and torsion bars.
The gearbox, parking brakes, torsion bars and belts were also changed (spacing 260 mm, D.W. 1 had a spacing of 300 mm).

At the request of WaPrüf 6 for a new tower for B.W. (verstärkt) of 2.11.1936, the company Krupp responded with a conceptual proposal on 22.2.1937. After revising the requirements, he informed on March 12, 1937 Dr. Olbrich (WaPrüf 6/IId company Krupp on icing decisions:

1. Project designation B.W. (verstärkt) was changed to I.W. (Information days).
2. The conceptual design of the company Krupp sketched on the drawing AKF 30304 from 22.2.1937 will be used for further development. The inner circulating diameter of the tower was to be 1500 mm.
3. Cannon 7.5 cm Kw.K. L/24 from the tank Pz.Kpfw. IV will be used in the new tower. No design changes to the weapon will be allowed except when changing the thickness of the armor protection.
4. The armor of the tower was set at 50 mm on the front of the tower, 20 mm on the shield of the cannon and 15 mm on the ceiling of the tower.
5. The radio equipment will be located in the back of the tower behind the cannon.
6. The weight gain does not affect the previous design of the tower bearing and has been fully accepted. No electric drive of the tower was planned.
7. There was a discussion in Essen on the design of windows. If possible, protruding screw heads from the tower should be eliminated.
8. The production of the steel tower was to be preceded by the production of a wooden model.
9. The completion of the project should be accelerated.

June 24, 1938 WaPrüf 6/IId in the company Krupp ordered a prototype tower made of unarmoured steel. On May 26, 1939, the tower was completed and subsequently, by order of Major Crohn, on June 8, 1939, transferred to the company Grusonwerk in Magdeburg, where comparative tests with a complete tank tower were to be carried out. url=/topic/view/15043/Pz-Kpfw-IV] Pz.Kpfw. IV[/url].

Thomas L. Jentz, Hilary L. Doyle - Germany´s Tiger tanks D.W. to Tiger I Design, production & modifications, year of publication 2000, Shiffer Military History, ISBN 0-7643-1038-0
Spielberger, Walther J. (1987) - The Panzerkampfwagen Tiger and its abortion. Stuttgart: Motorbuch-Verlag. ISBN 3-87943-456-5.[/Sources]