Trials and tests of new prototypes took place from 1936 to 1937 on testing grounds in Kummersdorf and Ulm. They resulted in the Daimler-Benz design being chosen for full-scale production and in early 1937, Waffenamt ordered Daimler-Benz to produce the first series (0-Series) of their design.
Krupp’s ZW prototype, designated as MKA, featured leafsprings and bogie wheel mountings type of a suspension. In turn, many features of this vehicle were used in the design of Panzerkampfwagen IV, which was designed by Krupp.
The PzKpfw III design was composed of four sections - hull, turret, and front superstructure with the opening for the turret and rear superstructure with the engine deck. Each section was of a welded construction and all four were bolted together. The hull was divided into two main compartments divided by a bulkhead. The front compartment housed the gearbox and steering mechanism, and the rear one both the fighting and engine compartment. Basic hull, turret, superstructure and crew layout remained unchanged throughout the production life of Panzerkampfwagen III series.
After modifications, the first Panzerkampfwagen III Ausf A (1-Serie) was produced in May of 1937 by Daimler-Benz, with total of 10 produced until the end of 1937 (chassis numbers 60101-60110). Some sources state that as many as 15 were manufactured. Only eight Ausf As were armed (and equipped units of 1st, 2nd and 3rd Panzer Division and took part in the Anschluss, the take-over of Sudetenland and the Polish Campaign) and other unarmed Ausf As were used for further testing.
In 1937, the Ausf B (2-Serie) was produced by Daimler-Benz with total of 15 produced (chassis numbers 60201-60215). A number of Ausf Bs saw service during the Polish Campaign. In October of 1940, five Ausf B tanks were modified and used as prototypes of Sturmgeschutz III series.
In June of 1937, the next variant Ausf C (3a-Serie) was produced by Daimler-Benz and its production ended in January of 1938, again with total of 15 produced (chassis numbers 60301-60315). A number of Ausf Cs saw service during the Polish Campaign.
In January of 1938, the next variant Ausf D (3b-Serie) was produced by Daimler-Benz and its production ended in 1939 with total of 55 produced (chassis numbers 60221-60225 and 60316-60340). Only 30 Ausf Ds produced in two groups of 15 were armed, and another 25 unarmed Ausf Ds were used for further testing. A number of Ausf Ds saw service during the Polish Campaign and in Norway.
The warly models of Panzer III (Ausf A, B, C and D) were pre-prototypes of the entire series produced exclusively by Daimler-Benz. All were unsuitable for large-scale production but each new model was considered an improved version of the previous one. Each model featured different type of suspension e.g. Ausf A - individual coil springs, Ausf B - two sets of leaf springs, Ausf C - three sets of leaf springs and Ausf D - angled leaf springs.
Ausf A, B, C and D were powered by 250hp petrol Maybach HL 108 TR engines with a 5 or 6 speed Zahnradfabrik gearbox. All early models were armed with 37mm KwK 35/36 L/46.5 gun and three 7.92mm MG 34 machine guns (two mounted co-axially beside the main armament in the turret and one in the hull). Their armor protection ranged from 5 to 15mm, offering protection only against anti-tank rifles and machine gun fire. The reason behind the inadequate armor protection was a result of Daimler-Benz keeping the vehicle in its designated weight range of 15 tons. Some of early models were up-armored and had their maximum armor protection increased to 30mm. Ausf A, B, C had simple drum shaped "dustbin" commander’s cupolas, while Ausf D had cast cupolas similar to that of the PzKpfw IV Ausf B.
A few of the early Panzer IIIs saw actual combat (with units of 1st, 2nd and 3rd Panzer Division) during the Polish Campaign, others were troop tested (1937-February 1940). In February of 1940, existing number of early Panzer IIIs was handed over to NSKK for training purposes. Afterwards, only a few Ausf D saw service with PzAbt zbV 40 (along with PzKpfw NbFz VI) during fighting in Norway in April/May of 1940, followed by service with PzAbt zbV 40 in Finland, 1941/42.
Raw Materials Used in Production of PzKpfw III:
In December of 1938, the Ausf E (4-serie) entered production, and 96 were produced by Daimler-Benz, Henschel and MAN when production ended in October of 1939 (chassis numbers 60401-60496). It was the first PzKpfw III that was produced in any significant number. The basic design remained unchanged from its predecessor, but it featured a new independent torsion bar suspension, designed by Ferdinand Porsche for the automotive industry in 1930s. It was composed of six roadwheels and three return rollers. The Ausf E was armed with a 37mm KwK 35/36 L/46.5 gun and three 7.92mm MG 34 machine guns (two in the turret and one in the hull). Its armor protection ranged from 12 to 30mm. During production, escape hatches were installed on both sides of the hull and a vision port was added on the superstructure side for the radio-operator. The driver’s visor was provided with an upper and lower sliding shutter, which could be closed together. Also two-piece side hatches were installed in the turret. Unlike its predecessors, the Ausf E was powered by new 300hp petrol Maybach HL120TR engine with a new Maybach Variorex 10 speed gearbox. It was also heavier than all previous models, which were in the 16 ton range but Ausf E weighted 19.5 tons. From August 1940 until 1942, all Ausf E tanks were rearmed with a 50mm KwK 38 L/42 gun mounted in an external mantlet also housing one MG. At the same time, armor protection was increased by the installation of 30mm armor plates to the hull, front and rear, as well as the superstructure front. During service, the number of Ausf E tanks was also reworked to Ausf F standard.
In September 1939, another new variant, the Ausf F (5-serie) entered production. Until July 1940, 435 were produced by Daimler-Benz, Henschel, MAN, Alkett and FAMO (chassis numbers 61001-61650). It was a refined version of the Ausf E and it did not feature any significant modifications or changes other than an improved Maybach HL120TRM engine and modified upper hull nose (with air intakes). The first 335 Ausf F tanks were armed with a 37mm KwK 35/36 L/46.5 gun and three 7.92mm MG 34 machine guns (two in the turret and one in the hull). The last 100 tanks were factory armed with a 50mm KwK 38 L/42 gun mounted in an external mantlet housing one MG. Ausf F vehicles were fitted with a hull rear mounted rack of five smoke generators remotely released from the turret. Some vehicles were also mounted with a stowage box at the rear of the turret. From August 1940 until 1942, all 37mm Ausf F, just as Ausf E tanks, were rearmed with 50mm KwK 38 L/42 guns. They also had their armor protection improved at the same time as Ausf E tanks. Only 40 Ausf F tanks with 50mm KwK 38 L/42 guns were rushed into service before the end of the French Campaign and saw little or no combat. There is still controversy surrounding this as it is reported that the first PzKpfw III armed with 50mm guns entered production in July of 1940. The first production of Sturmgeschutz III assault guns / tank destroyers were based on the Panzerkampfwagen III Ausf F chassis and components. In 1942/43, a number of Ausf F tanks were rearmed with a 50mm KwK 39 L/60 gun. Rearmed and up-armored Ausf F tanks remained in service as late as June of 1944 (e.g. 116th Panzer Division in Normandy).
An interesting fact is that the study report of the captured PzKpfw III Ausf F made by the British in 1942, was then sent to United States Army Ordnance Department where it was decided to utilize a copy of German torsion bar suspension system in future American tanks (e.g. M18 Gun Motor Carriage, M24 Chaffee, M26 Pershing etc.).
In 1940/41, attempts were made to standardize the production of Panzer III and Panzer IV. A few prototypes based on the Panzer III Ausf G/H with new large overlapping roadwheels and FAMO suspension were produced - PzKpfw III Ausf G/H mit Schachtellaufwerk. Since 1940, prototypes were used for testing and training purposes. Further development was halted and in 1943/44, prototypes were fitted with dozers and were used to clean up the streets of bombed cities. This suspension was later adopted in Tiger and Panther.
From April 1940 to February 1941, 600 new Ausf G (6-serie) tanks were produced by Daimler-Benz, Henschel, MAN, Alkett, Wegmann, MNH and FAMO (chassis numbers 65001-65950). The Ausf G was a slight improvement over previous Ausf E and Ausf F tanks. Some 50 Ausf G tanks were armed with 37mm KwK 35/36 L/46.5 guns mounted in an internal mantlet, while the rest were armed with a 50mm KwK 38 L/42 gun mounted in an external mantlet. Both 37mm and 50mm tanks had additional two MG 34 machine guns, one in the turret and another in the hull. Armor protection ranged from 12mm to 30mm, although the majority of the protection ranged from 21mm to 30mm. Also a new pivoting visor for the driver (Fahrersehklappe 30) was installed. The turret was modified and mounted on the roof with a fan exhaust and one signal port was eliminated. Mid-production vehicles were mounted with the new type of commander’s cupola as used in the PzKpfw IV Ausf E, F and G, which became standard on all later models of PzKpfw III. Late production vehicles had wider 400mm tracks instead of standard 360mm tracks. The Ausf G was the first to be mounted with the "Rommelkiste" (Rommelbox) - turret mounted storage bin (Gepack Kasten), which then became the standard on all PzKpfw IIIs. From August 1940 until 1942, all 37mm Ausf G tanks just as Ausf E and F tanks were rearmed with the 50mm KwK 38 L/42 gun. Vehicles sent to North Africa were equipped with additional air filters and a different cooling fan reduction ratio. They were designated Ausf G(Tp), Tp being short for Tropisch / Trop / Tropen - tropical. A small number of Ausf G tanks remained in service as late as September 1944.