Panzer IV is the common name of a medium sized tank that was developed in the late 1930s by Nazi Germany and used extensively in World War II. The official German designation was Panzerkampfwagen IV (abbreviated PzKpfw IV) and the tank also had the ordnance inventory designation Sonderkraftfahrzeug 161.
It was initially designed as an infantry-support medium tank to work in conjunction with the Panzer III tank which was intended to engage the enemy tanks. Later in the war its gun and armor upgraded and took over the tank-fighting role while Panzer IIIs were either put into infantry support duties or converted into other vehicles. The Panzer IV was the most common German tank of World War II, and was used as the base for many other fighting vehicles, such as tank destroyers and |self-propelled anti-aircraft guns.The Panzer IV was the workhorse of the German tank corps, being produced and used in all theatres of combat throughout the war. The design was continually upgraded to deal with the increasing threats from allied forces. The Panzer IV has the distinction of being the only German tank to remain in continuous production throughout all of World War II, with over 8,500 units produced from 1937 to 1945.
The concept for the Panzer IV was the brainchild of German Generaloberst Heinz Guderian, intended as a support tank to defeat the allied anti-tank guns and fortifications. Ideally, a panzer division would be composed of three medium companies — equipped with the Panzer III—and one heavy company—equipped with the Panzer IV.On 11 January 1934 the German Army decided the specifications for a "medium tractor" and issued them to a number of defense companies. To support the Panzer III tank, which was to be armed with a 37-millimeter (.46 in) tank gun, this "medium tractor" was to be armed with a 75-millimeter (2.95 in) main gun and had a weight limit of 24 tonnes (39.68 tons). Development was carried out under the name Bataillonsführerwagen (battalion commander's vehicle), or BW, to hide the actual purpose of the tank, given that Germany still adhered to the Treaty of Versailles.MAN, Krupp and Rheinmetall-Borsig developed their own prototypes, with Krupp's being chosen for further development.The vehicle had originally been designed with a six-wheeled interleaved suspension, but the German Army changed their requirements to a torsion bar suspension, allowing for a greater degree of vertical deflection of the roadwheels—greater vertical deflection of the roadwheels allows for an increase in the tank's and crew's tolerance in higher off-road speeds.Neither type of suspension was adopted, as due to the urgent requirement for the new tank, the Army allowed Krupp to equip it with a leaf spring double-bogie suspension. The prototype's hull placed the engine bay to the rear, with the driver and radio operator (also the hull gunner) placed to the front—on the left and right sides, respectively—with the transmission box between them. In the turret, the tank commander sat beneath his roof hatch, while the gunner was situated on the left side of the gun breech and the loader on the right. The vehicle's turret was offset 66.5 millimeters (2.62 in) to the left of the center line of the chassis, while the engine was moved 152.4 millimeters (6 in) to the right, allowing the torque shaft to clear the rotary base junction while connecting to the transmission box. The rotary base junction provided the electrical power necessary to turn the turret. Due to this setting, the right side of the tank offered much more stowage volume and was taken up by ready-use ammunition lockers for the loader.