This was the only one ever made. It was captured by the USA & taken back to Aberdeen Proving Ground for testing.
It was tested briefly but due to a breakdown & lack of spare parts all testing was halted & it was put on display.
Hydrostatic drive is very simple. In a traditional panzer IV you would have a transmission that would deliver power to the two front drive units.
In this prototype the transmission has been eliminated & replaced with a heavy duty high pressure hydraulic pump that is placed behind the engine.
The two rear idler wheels have been replaced with two hydrostatic drive units. The sprockets in the front are now the idler wheels.
So here is how it all works. The main engine powers the pump that feeds the two drive pumps. The driver has a half moon shaped steering wheel (like in the Tiger) instead of the two tiller levers that a traditional Panzer IV had. This would control a series of valves that would increase or decrease power to the drive units. So if you wanted to turn left you turned the wheel to the left & that would increase pressure to the right drive unit & lower pressure to the left unit. Its that simple. Its the same principal for forward a reverse motion. The accelerator pedal would increase or decrease pressure to the drive units as the engine rpm changed…so simple.
This was way ahead of its time & would have made a very interesting production model.