As it was mentioned above, Porsche received an order directly from Hitler, due to good relations between Hitler and Porsche. Porsche's company had no experience in making tanks. This order ensured that fresh ideas would be applied to the creation of a tank and that Hitler's desire for a tank with a diesel engine would be fulfilled.
Professor Doctor Porsche directed the creation of an 800 hp air cooled diesel engine that reached 15 hp/ton. The diesel powered a generator, which supplied electricity for an electric motor, which in turn powered the tracks. The motor's speed was controlled by a foot pedal with the help of relays. Steeling was performed with a handle that would alter the rotation speed of motors.
These types of motors needed 2 tons of copper each, which was a difficult element for Germany to obtain in 1942.
The undersigned had a chance to establish mechanical deficiencies of the Porsche Tiger compared to the Henschel Tiger. The delay caused by relays working caused hesitation in the driver, as the vehicle did not react to a change in controls right away. It took some time before all relays activated, and only then did the speed change. The design work on an electric motor was done by Siemens-Schoenert in Berlin. The undersigned cannot recall the name of the chief engineer.
The air cooled engine did not regenerate spent energy, and even though this vehicle had a 200 hp advantage over the Henschel Tiger, it did not have the expected agility on road or off road.
The cooling system could also consume a lot of power, the cooling fan drawing 40 hp. It also generated unprecedented amounts of noise, which could be heard from kilometers away, and any enemy would notice its approach from a large distance. The undersigned does not know how much effort Professor Porsche dedicated to correction of these flaws, but work on a hydraulic transmission has already begun at the time the electric engine was being built. The Woight company at Heidenheim an der Brenz developed a hydraulic system using the Fottinger method. This system was composed of two transmission mechanisms, one of which had 6 settings mapped to engine rotation speeds, and the other was a direction mechanism, which could switch between two turning radii. There was no switching between the transmission mechanism and the turning mechanism, as due to the design of the hydraulics, the turning radius was controlled with a hydraulic pump. This mechanism was not completely finished when the undersigned left.
Professor Porsche used his old idea of a rod spring that he developed ten years ago at the Schtoeber company. The spring was parallel to the direction of motion, and was deformed by the road wheels. Due to its design, it could be very short, and could be affixed simply, with little materials. However, it had one deficiency. The mechanism that deformed the spring was made from expensive materials, since it had to meet requirements in a very compact size. Most problems during trials were caused by this component, as it needed chrome-nickel steel, which was no longer produced in Germany at the time."