Panzer IV
The Panzerkampfwagen IV, commonly known as the Panzer IV, is a German medium tank developed in the late 1930s and used extensively during the Second World War. Its ordnance inventory designation was Sd.Kfz. 161.
The Panzer IV was the most numerous German tank and the second-most numerous German fully tracked armoured fighting vehicle of the Second World War; 8,553 Panzer IVs of all versions were built during World War II, only exceeded by the StuG III assault gun with 10,086 vehicles. Its chassis was also used as the base for many other fighting vehicles, including the Sturmgeschütz IV assault gun, the Jagdpanzer IV self-propelled anti-tank gun, the Wirbelwind and Ostwind self-propelled anti-aircraft guns, and the Brummbär self-propelled gun.
The Panzer IV saw service in all combat theatres involving Germany and was the only German tank to remain in continuous production throughout the war. The Panzer IV was originally designed for infantry support, while the similar Panzer III was to fight armoured fighting vehicles. However, as the Germans faced the formidable T-34, the Panzer IV had more development potential, with a larger turret ring to mount more powerful guns, so it swapped roles with the Panzer III whose production wound down in 1943. The Panzer IV received various upgrades and design modifications, intended to counter new threats, extending its service life. Generally, these involved increasing the armour protection or upgrading the weapons, although during the last months of the war, with Germany's pressing need for rapid replacement of losses, design changes also included simplifications to speed up the manufacturing process.
The Panzer IV was partially succeeded by the Panther medium tank, which was introduced to counter the Soviet T-34, although it continued to be a significant component of German armoured formations to the end of the war. It was the most widely exported tank in German service, with around 300 sold to Finland, Romania, Spain and Bulgaria. After the war, Syria procured Panzer IVs from France and Czechoslovakia, which saw combat in the 1967 Six-Day War.
Development history
Origins
The Panzer IV was the brainchild of the German general and innovative armoured warfare theorist Heinz Guderian. In concept, it was intended to be a support tank for use against enemy anti-tank guns and fortifications. Ideally, each tank battalion in a panzer division was to have three medium companies of Panzer IIIs and one heavy company of Panzer IVs. On 11 January 1934, the German army wrote the specifications for a "medium tractor", and issued them to a number of defense companies. To support the Panzer III, which would be armed with a anti-tank gun, the new vehicle would have a short-barreled, howitzer-like as its main gun, and was allotted a weight limit of. Development was carried out under the name Begleitwagen, or BW, to disguise its actual purpose, given that Germany was still theoretically bound by the Treaty of Versailles ban on tanks. MAN, Krupp, and Rheinmetall-Borsig each developed prototypes, with Krupp's being selected for further development.The chassis had originally been designed with a six-wheeled Schachtellaufwerk interleaved-road wheel suspension, but the German Army amended this to a torsion bar system. Permitting greater vertical deflection of the road wheels, this was intended to improve performance and crew comfort both on- and off-road. However, due to the urgent requirement for the new tank, neither proposal was adopted, and Krupp instead equipped it with a simple leaf spring double-bogie suspension, with eight rubber-rimmed road wheels per side.
The prototype had a crew of five; the hull contained the engine bay to the rear, with the driver and radio operator, who doubled as the hull machine gunner, seated at the front-left and front-right, respectively. In the turret, the tank commander sat beneath his roof hatch, while the gunner was situated to the left of the gun breech and the loader to the right. The torque shaft ran from the rear engine to the transmission box in the front hull between the driver and radio operator. To keep the shaft clear of the rotary base junction, which provided electrical power to the turret including the motor to turn it, the turret was offset to the left of the chassis centre line, and the engine was moved to the right. Due to the asymmetric layout, the right side of the tank contained the bulk of its stowage volume, which was taken up by ready-use ammunition lockers.
Accepted into service under the designation Versuchskraftfahrzeug 622, "experimental motor vehicle 622", production began in 1936 at Fried. Krupp Grusonwerk AG factory at Magdeburg.
Ausf. A to Ausf. F1
The first mass-produced version of the Panzer IV was the Ausführung A, in 1936. It was powered by a Maybach HL108 TR, producing, and used the SGR 75 transmission with five forward gears and one reverse, achieving a maximum road speed of. As main armament, the vehicle mounted the short-barreled, howitzer-like Kampfwagenkanone 37 7.5 cm KwK 37 tank gun, 24 calibres in length, which was a low-velocity weapon mainly designed to fire high-explosive shells. Against armoured targets, firing the Panzergranate at the KwK 37 could penetrate, inclined at 30 degrees, at ranges of up to. A MG 34 machine gun was mounted coaxially with the main weapon in the turret, while a second machine gun of the same type was mounted in the front plate of the hull. The main weapon and coaxial machine gun were sighted with a Turmzielfernrohr 5b optic while the hull machine gun was sighted with a Kugelzielfernrohr 2 optic. The Ausf. A was protected by of steel armour on the front plate of the chassis, and on the turret. This was only capable of stopping artillery fragments, small-arms fire, and light anti-tank projectiles. A total of 35 A versions were produced.In 1937, production moved to the Ausf. B. Improvements included the replacement of the original engine with the more powerful Maybach HL 120TR, and the transmission with the new SSG 75 transmission, with six forward gears and one reverse gear. Despite a weight increase to, this improved the tank's speed to. The glacis plate was augmented to a maximum thickness of, while a new driver's visor was installed on the straightened hull front plate, and the hull-mounted machine gun was replaced by a covered pistol port and visor flap. The superstructure width and ammunition stowage were reduced to save weight. A new commander's cupola was introduced, which was adopted from the Panzer III Ausf. C. A Nebelkerzenabwurfvorrichtung was mounted on the rear of the hull starting in July 1938 and was back fitted to earlier Ausf. A and Ausf. B chassis starting in August 1938. Forty-two Panzer IV Ausf. Bs were manufactured.
The Ausf. C replaced the B in 1938. This saw the turret armour increased to, which brought the tank's weight to. After assembling 40 Ausf. Cs, starting with chassis number 80341, the engine was replaced with the improved HL 120TRM. The last of the 140 Ausf. Cs was produced in August 1939.
Production changed to the Ausf. D; this variant, of which 248 vehicles were produced, reintroduced the hull machine gun and changed the turret's internal gun mantlet to a thick external mantlet. Again, protection was upgraded, this time by increasing side armour to. As the German invasion of Poland in September 1939 came to an end, it was decided to scale up production of the Panzer IV, which was adopted for general use on 27 September 1939 as the Sonderkraftfahrzeug 161.
In response to the difficulty of penetrating the thick armour of British infantry tanks during the Battle of France, the Germans had tested a gun — based on the 5 cm Pak 38 anti-tank gun – on a Panzer IV Ausf. D. However, with the rapid German victory in France, the original order of 80 tanks was cancelled before they entered production.
In October 1940, the Ausf. E was introduced. This had of armour on the bow plate, while a appliqué steel plate was added to the glacis as an interim measure. A new driver's visor, adopted from the Sturmgeschütz III was installed on the hull front plate. A new commander's cupola, adopted from the Panzer III Ausf. G, was relocated forward on the turret eliminating the bulge underneath the cupola. Older model Panzer IV tanks were retrofitted with these features when returned to the manufacturer for servicing. 206 Ausf. Es were produced between October 1940 and April 1941.
In April 1941, production of the Panzer IV Ausf. F started. It featured single-plate armour on the turret and hull, as opposed to the appliqué armour added to the Ausf. E, and a further increase in side armour to. The main engine exhaust muffler was shortened and a compact auxiliary generator muffler was mounted to its left. The weight of the vehicle was now, which required a corresponding modification of track width from to reduce ground pressure. The wider tracks also facilitated the fitting of track shoe "ice sprags", and the rear idler wheel and front sprocket were modified. The designation Ausf. F was changed in the meantime to Ausf. F1, after the distinct new model, the Ausf. F2, appeared. A total of 471 Ausf. F tanks were produced from April 1941 to March 1942.
Ausf. F2 to Ausf. J
On 26 May 1941, mere weeks before Operation Barbarossa, during a conference with Hitler, it was decided to improve the Panzer IV's main armament. Krupp was awarded the contract to integrate again the Pak 38 L/60 gun into the turret. The first prototype was to be delivered by 15 November 1941. Within months, the shock of encountering the Soviet T-34 medium and KV-1 heavy tanks necessitated a new, much more powerful tank gun. In November 1941, the decision to up-gun the Panzer IV to the gun was dropped, and instead Krupp was contracted in a joint development to modify Rheinmetall's pending anti-tank gun design, later known as 7.5 cm Pak 40 L/46.Because the recoil length was too great for the tank's turret, the recoil mechanism and chamber were shortened. This resulted in the KwK 40 L/43. When the new KwK 40 was loaded with the Pzgr. 39 armour-piercing shell, the new gun fired the AP shell at some, a substantial 74% increase over the howitzer-like KwK 37 L/24 gun's muzzle velocity. Initially, the KwK 40 gun was mounted with a single-chamber, ball-shaped muzzle brake, which provided just under 50% of the recoil system's braking ability. Firing the Panzergranate 39, the KwK 40 L/43 could penetrate of steel armour at a range of.
The longer 7.5 cm guns made the vehicle nose-heavy to such an extent that the forward suspension springs were under constant compression. This resulted in the tank tending to sway even when no steering was being applied, an effect compounded by the introduction of the Ausführung H in March 1943.
The Ausf. F tanks that received the new, longer, KwK 40 L/43 gun were temporarily named Ausf. F2. The tank increased in weight to. Differences between the Ausf. F1 and the Ausf. F2 were mainly associated with the change in armament, including an altered gun mantlet, internal travel lock for the main weapon, new gun cradle, new Turmzielfernrohr 5f optic for the L/43 weapon, modified ammunition stowage, and discontinuing of the Nebelkerzenabwurfvorrichtung in favor of turret mounted Nebelwurfgerät. Three months after beginning production, the Panzer IV Ausf. F2 was renamed Ausf. G.
During its production run from March 1942 to June 1943, the Panzer IV Ausf. G went through further modifications, including another armour upgrade, which consisted of a face-hardened appliqué steel plate welded to the glacis—in total, so that frontal armour was now thick. This decision to increase frontal armour was favorably received according to troop reports on 8 November 1942, despite technical problems with the driving system due to added weight. At this point, it was decided that 50% of Panzer IV production would be fitted with thick additional armour plates. On 5 January 1943, Hitler decided that all Panzer IVs should have frontal armour. To simplify production, the vision ports on either side of the turret and the loader's forward vision port in the turret front were removed, while a rack for two spare road wheels was installed on the track guard on the left side of the hull. Complementing this, brackets for seven spare track links were added to the glacis plate.
For operation in high temperatures, the engine's ventilation was improved by creating slits over the engine deck to the rear of the chassis, and cold weather performance was boosted by adding a device to heat the engine's coolant, as well as a starter fluid injector. A new light replaced the original headlight and the signal port on the turret was removed. On 19 March 1943, the first Panzer IV with Schürzen skirts on its sides and turret was exhibited. The double hatch for the commander's cupola was replaced by a single round hatch from very late model Ausf. G. and the cupola was up-armoured from to. In April 1943, the KwK 40 L/43 was replaced by the longer KwK 40 L/48 gun, with a redesigned multi-baffle muzzle brake with improved recoil efficiency. The longer L/48 resulted in the introduction of the Turmzielfernrohr 5f/1 optic.
File:PzIV.Saumur.000a5s6s.jpg|thumb|right|A Panzer IV Ausf. J at the Musée des Blindés in Saumur, France, with its distinctive Zimmerit anti-magnetic mine coating, turret skirts, and wire-mesh side-skirts
The next version, the Ausf. H, began production in June 1943 and received the designation Sd. Kfz. 161/2. The integrity of the glacis armour was improved by manufacturing it as a single plate. A reinforced final drive with higher gear ratios was introduced. To prevent adhesion of magnetic anti-tank mines, which the Germans feared would be used in large numbers by the Allies, Zimmerit paste was added to all the vertical surfaces of the tank's armour. The turret roof was reinforced from to and segments. The vehicle's side and turret were further protected by the addition of hull skirts and turret skirts. This resulted in the elimination of the vision ports located on the hull side, as the skirts obstructed their view. During the Ausf. H's production run, its rubber-tired return rollers were replaced with cast steel, a lighter cast front sprocket and rear idler wheel gradually replaced the previous components, the hull was fitted with triangular supports for the easily damaged side skirts, the Nebelwurfgerät was discontinued, and a mount in the turret roof, designed for the Nahverteidigungswaffe, was plugged by a circular armoured plate due to initial production shortages of this weapon.
These modifications meant that the tank's weight increased to. In spite of a new six-speed SSG 77 transmission adopted from the Panzer III, top speed dropped to as low as on cross country terrain. An experimental version of the Ausf H was fitted with a hydrostatic transmission but was not put into production.
Despite addressing the mobility problems introduced by the previous model, the final production version of the Panzer IV—the Ausf. J—was considered a retrograde step from the Ausf. H. Born of necessity, to replace heavy losses, it was greatly simplified to speed production. The electric generator that powered the tank's turret traverse was removed, so the turret had to be rotated manually. The turret traversing mechanism was modified and fitted with a second gear which made hand-operation easier when the vehicle was on sloping terrain. On reasonably level ground, hand operation at 4 seconds to traverse to 12.5° and 29.5 seconds to traverse to 120° was achieved. The resulting space was later used for the installation of an auxiliary fuel tank; road range was thereby increased to, The remaining pistol and vision ports on the turret side hatches were removed, and the engine's radiator housing was simplified by changing the slanted sides to straight sides. Three sockets with screw threads for mounting a 2-ton jib boom crane were welded on the turret roof while the hull roof was thickened from to. In addition, the cylindrical muffler was replaced by two flame-suppressing mufflers. In June 1944 Wa Prüf 6 had decided that because bomb damage at Panzerfirma Krupp in Essen had seriously jeopardized tank production, all plates which should have been face-hardened for the Panzer IV were instead made with rolled homogeneous armour plate. By late 1944, Zimmerit was no longer being applied to German armoured vehicles, and the Panzer IV's side-skirts had been replaced by wire mesh, while the gunner's forward vision port in the turret front was eliminated and the number of return rollers was reduced from four to three to further speed-up production.
In a bid to augment the Panzer IV's firepower, an attempt was made to mate a Schmalturm turret – carrying the longer L/70 tank gun from the developing Panther Ausf. F tank design, and partly developed by Rheinmetall from early 1944 onwards – to a Panzer IV hull. This failed and confirmed that the chassis had reached the limit of its adaptability in both weight and available volume.