The joints were austenitic steel welds and the plates were made of chromium-molybdenum steel. The hull was separated by 2 bulkheads into the driving, fighting, and engine compartment. The welded turret had seats for the commander, gunner, and loader. The cupola was towards the rear of the turret and had 5 ports.
The drive ran to the gearbox and sprocket in the front of the vehicle. The suspension was paired bogies that were size 470x75-660 and mounted on longitudinal twin quarter elliptic springs, with 4 return rollers. The sprocket wheel was in the front with the idler in the rear.
The engine exhausts were fitted on the right side of the engine compartment which sucked in the air and this was expelled out the left side after passing through the radiator. The fans were driven by belts and double V-belts from the crankshaft.
A Wilson-Krupp type clutch and brake provided the steering.
The electricity to traverse the turret was provided by a shunt motor. This was a type P/6 DKW 2 cylinder, 2 stroke engine which produced 15 hp at 2,800 rpm, and had a capacity of 585 cc.
Ausf A: BW/1. An auxiliary engine provided power to the turret. There were numerous vision slits and the commander had a drum cupola with 8 vision slits. The driver's plate superstructure was further forward. This allowed the driver to see to the right.
Ausf B: BW/2. Had a larger engine, a 6 speed
transmission, a modified cupola, and thicker armor. There was a conical
shaped hood installed over the right signal port in the roof of the
turret. The hatches over the driver and radio operator were now one piece.
The front of the superstructure was now a single straight piece with no
hull machine gun which was replaced by a visor and pistol port.
Ausf C: BW/3. Only 134 were produced out of an order of 300. In August 1939, 6 chassis were given to the Inspectorate for Engineers to use for bridge laying tanks. Changes were an altered motor mount, improved turret race, redesigned gun mantlet housing, and an armored sleeve to protect the coaxial MG. Starting at chassis no. 80341 the engine was modified to improve carburation. Starting in late 1940 additional armor was bolted on to the hull and superstructure.
Ausf D: BW/4, BW/5. First large scale production of
this type. Wider tracks, larger sprockets, and hull stowage bin. Increase
in side and rear armor from 15mm to 20mm. Late production vehicles had
armor plate bolted and welded to turret and hull front. The front
superstructure plate was stepped and the radio operator was moved back
further than the driver. Hull MG was installed. Some of the last produced
had 30 mm plates bolted and welded onto the hull superstructure front and
20 mm to the sides.
Ausf E: BW/6. Appeared late in 1939. New cupola, segmental shutters, new driver visor, new simpler sprocket, exhaust fan installed in turret roof, and the turret rear was made from one bent piece of armor. Based on the battle experience in Poland additional armor was added to the front and sides of the hull. On late production models access flaps were fitted with a single hinge instead of two.
Ausf F1: BW/7. Original order was for 500 to be
built by Krupp-Gruson. This was increased when Vomag received an order for
100 and Nibelungenwerke for 25. Before these were all completed the OKH
ordered that the rest of the order have
7.5 cm KwK 40
L/43 installed as soon as possible and a total of 25 were converted to
Ausf F2, SdKfz 161/1: BW/7. As Ausf F1 was rolling off production lines, the T-34 was encountered on the Russian front. Hitler ordered the PaK 40 antitank gun fitted into all new PzKw IVs. Ammunition storage was altered to allow for the larger rounds. The gunner's and commander's seat was altered to allow more room. There was an auxiliary hand crank for traverse for the loader. The initial production models had a single-baffle, spherical muzzle brake.
Ausf G: BW/7, BW/8. Initially 1,750 were ordered, and of those 10 chassis were used for Hummel prototypes and 53 chassis for Brummbär. Dropped vision ports from turret sides. New cupola with thicker armor and single hatch cover. In the summer of 1942 a new muzzle brake with a double baffle and a system to allow transfer of coolant to aid in cold weather starting was installed (Kühlwasser-Austauscher). In January 1943 the driver's scope was eliminated. In 1943 Schürzen we installed to the side of the hull and the turret. Late production Ausf Gs had new drive sprocket and radio antenna was moved to left hull rear. 75 mm gun had double baffle muzzle brake. Starting on June 20, 1942, extra armor was bolted or welded on to approximately 700. 1,275 received the 7.5 cm KwK 40 L/43. From late March 1943 the 7.5 cm KwK 40 L/48 was installed.
Ausf H: 30 of the 3,935 chassis built were used for the StuG IV and 130 for the Brummbär. New sprocket of welded and webbed construction, external air filters, all steel return rollers, side skirts and skate rail for AA MG. Has a new transmission. Late production vehicles had 85mm armor replacing the belted or welded armor of earlier vehicles. The vision slits for the gunner and radio operator were eliminated as they would have been useless with the skirt armor around the turret. The commanders hatch in the cupola was now a one piece cover.
Ausf J, SdKfz 161/2: 142 of the chassis were used for the Brummbär and 278 for the Panzer IV/70(A). Auxiliary engine removed and (turret could only be hand cranked) replaced by extra 44 gallon fuel tank. All vision ports deleted except gunners. Nähverteidigungswaffe was added as a smoke discharger and close defense. Steel road wheels, vertical exhaust mufflers, and hull sides extended beyond the front hull plate were changes made during production. Return rollers reduced to 3 on later models. Side skirt on many vehicles was heavy gauge steel mesh.
Panzerkampfwagen IV als Tauchpanzer: 42 Ausf Ds converted for underwater operations in Operation Sealion. The engine air intakes and the exhaust were fitted with non-return valves in place of the mufflers. The cupola, mantlet, and MG mountings were covered by waterproof fabric. The driver's visor was altered by using a metal cover with a vision block that was water tight. A rubber tube that was inflated went around the turret ring.
Brückenleger IV: "Bridgelayer." 20 Ausf C & Ds were made into bridgelayers.
Infanterie Sturmsteg: "Infantry Assault Footbridge." 2 produced that had an infantry assault bridge mounted. Looked similar to a ladder on a fire truck having a telescopic catwalk.
Bergepanzer IV: 36 were converted from October to December 1944 the turret was removed and a wooden structure with a crane was added.
Panzerbefehlswagen mit 7.5 cm KwK L/48: From March to September 1944, 97 Ausf Hs were converted. The aerial for the FuG5 was mounted on top of the turret, and a star antenna was fitted to the right side of the tail plate on the hull for the FuG7 or FuG8 radio.
Munitionsschlepper für Karlgerät: A Ausf D was used in October 1939 as the chassis for an ammunition carrier that could carry 4 600 mm rounds for the Karl 600 mm motar. A crane was installed for lifting these rounds. 13 Ausf F1s were converted in 1941.
Wirbelwind: Had Quad 2 cm AA FlaK 38 guns mounted. About 90 made in 1944.
Möbelwagen: 3.7 cm Flak 43 L/60 mounted. The 4 sides could be let down horizontally. 240 made from 1944-45.
Ostwind: 3.7 cm Flak 43/1 L/60 mounted. Had 6 sides to the turret. 45 made from 1944-45.
Kugelblitz: Twin 3 cm MK 103/38 mounted in a low rounded open topped turret. Only 2 made in early 1945.
Brummbär: Mounted a 15 cm StuH43 L/12. 298 built.
Jagdpanzer IV: Mounted 7.5 cm Pak 39 L/48. 800 built in 1944.
Panzer IV/70(V): Mounted 7.5 cm Pak 42 L/70. 900 built by Vomag from Aug. 1944 to March 1945.
Panzer IV/70(A): Mounted 7.5 cm Pak 42 L/70. 300 built by Alkett from Aug. 1944 to March 1945.
Nashorn: 8.8 cm Pak 43/1 L/71 mounted on lengthened hull. 500 built 1943-45.
10.5 cm K18 auf Panzer Selbstfahrlafette IVa: Two prototypes were built for the purpose of destroying fortified bunkers. These were presented to Hitler on March 31, 1941. On May 26, 1941, Hitler decided that these would be developed as a heavy Panzerjäger so that it would be able to engage any heavy tanks from Britain or other countries. Production was to start in the spring 1942, but requirements changed and production didn't take place.
10.5 cm leFH18/1 (Sf) auf Geschützwagen IVb (SdKfz 165/1): Krupp-Gruson produced 8 prototypes for troop trials in November 1942. Had only 3 double bogies and 3 return rollers on each side. Had a Maybach HL 66 P engine installed. The turret could be moved 70° each way. It was to carry 5 crew members and 60 rounds of ammunition. The project was canceled in favor of full traversing turrets and the ability to dismount the main gun.
10.5 cm leFH18/1 L/28 auf Waffenträger GW IVb: Krupp built 3 prototypes in 1943. The turret fully rotated and a lifting gantry was carried on the vehicle.
211 saw action in Poland, 19 were lost. 278 were available for the invasion of France. 439 were available for the invasion of Russia.
During the invasion of Russia, many of the tanks had two wheeled trailers that had two 200 liter gas tanks. Some also had a supply of 20 liter gas cans on the turret roof. Many vehicles carried twice the normal ammunition supply inside their tanks. This helped them be relatively independent from the trailing supply columns early on in the invasion.
Ausf A: Saw action in Poland, Norway, and France. Removed from front line units in early 1941. Used for training.
Ausf B: Saw action in Poland, France, Balkans, and Russia. Phased out of service by 1943.
Ausf C: 14 were used by the 1st Panzer Division and 8 by the 1st Light Division in Poland. Increased armor on turret front.
Ausf D: Saw action in France, North Africa, Balkans, and Russia.
Ausf E: 40 Ausf Ds & Es were sent to North Africa with the 5th and 8th Panzer Regiments.
Ausf F1: Was used to refit the 2nd and 5th Panzer Divisions. Also used as replacements to units at front.
Ausf F2, SdKfz 161/1: Some sent to Western Dessert in 1942 and British call them "Mk IV Special." 75 mm KwK 40 had muzzle velocity of 2,428 ft/sec and could penetrate 89 mm @ 30°. Early models had single baffle, but later models had double baffle muzzle brake.
Ausf J, SdKfz 161/2: These were furnished to Bulgaria, Croatia, Finland, Hungary, Italy, Rumania, Spain, and Turkey.
Panzerkampfwagen IV als Tauchpanzer: Used by the 18th Panzer Regiment at River Bug in 1941. Also issued to the 6th Panzer Regiment of the 3rd Panzer Division.
Brückenleger IV: 4 were issued to each BL Zug (bridging platoon) in each Panzer Division. Used with the 1st, 2nd, 3rd, 5th, and 10th Panzer Divisions in 1940.
Panzerbe0bachtungswagen IV: Issued primarily to Hummel batteries.
10.5 cm K18 auf Panzer Selbstfahrlafette IVa: They were issued to the 521st Panzerjäger Detachment for the proposed attach on Gibraltar. There were then used in Russia with the 3rd Panzer Division.