In the last model of the Pz. IV, the Ausf. J, the hand crank became almost paramount when the auxiliary engine/generator and power traverse were removed from the tank. To help compensate, the gunner was then supplied with a new manual gearing system to ease the work, but it still took a lot of muscle to rotate the turret with its long gun. Although the coax MG was normally aligned with the main gun and gunner's sights, it could also be elevated independently, and the vision flap on the right side of the mantlet that we saw in an earlier sketch continues to allow the weapon to be visually sighted by the loader. In later vehicles (beginning with the Ausf. F2) this whole system was deemed unnecessary and wouldn't have worked anyway with the revised L/43 gun mount, so the coax MG was fixed in its mount and the small vision flap to the right of the mantlet was finally eliminated.
The Army's Technical Regulations Leaflet 1944 No 256 speaks of the introduction of an "Eastern Front Track" (German: Ostkette) for the Pz Kw IV which increased the overall width to 320.6 cm. In March 1944 the final version of the Pz Kw IV appeared, the Model J. Army Technical Regulations Leaflet 1944 No 184 of 3rd March 1944 states that the electric turret-traversing gear was discarded in this "J" version, and an auxiliary fuel container of 200 litres capacity was built into the engine compartment. The total fuel load was now about 680 litres. At the same time the hand traversing mechanism had to be fitted with a second reduction gear to permit the turret to be turned when the vehicle was travelling on an incline. Some armoured aprons fitted to the sides of this version, consisted of a strong wire netting in place of the usual sheet steel. Rheinmetall-Borsig of Unterliiss were made responsible for the production of the 7.5 cm KwK 40 L/48 which armed the Model H. The vehicles were produced practically until the end of the war in 1945.
