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PZInż. 140 (4TP)

Republic of Poland (1937-1939)
Light Reconnaissance Tank – 1 Prototype Built

The story behind the construction of the 4-tonne reconnaissance tank in Poland dates back to 1932. The Plan for the Expansion of Armored Weapons, Anti-Tank Weapons and Motorization developed at that time provided for the commencement of work on a modern vehicle of this type in Poland. The 4-tonne tank of the British Vickers company was to be used as a reference for it.

It is worth mentioning that the Cavalry Department was exerting strong pressure to start work on a modern reconnaissance tank. The aim was to equip cavalry units with such vehicles. At the same time, it was decided that 4-tonne tanks would be more effective than the available TK tankettes. The possibility of equipping new vehicles with a 47 mm caliber gun was particularly stressed. Finally, Vickers was asked to present its design. The show took place on 27 October 1932 at the Rembertów training ground.

Vickers Light Tank 4 ton model 1933
Vickers Light Tank 4 ton model 1933 before being shipped to Poland
Source: Leksykon pojazdów mechanicznych Wojska Polskiego 1918-1939, A. Jońca (Edipresse, 2018)

The financial situation in the country following the economic crisis put a stop to any tangible work in this area. It should be pointed out, however, that preliminary studies on a 4-tonne tank were initiated by the Military Engineering Research Institute’s (WBInż, Wojskowy Instytut Badań Inżynierii) Armored Weapons Design Office (Biuro Konstrukcyjne Broni Pancernych) as early as in the financial year 1934/35. However, their results are not known.

The issue returned in 1935, however, when the General Staff, being aware of the low combat value of the manufactured tankettes and armored cars, considered the possibility of buying British 4-ton Vickers tanks for large cavalry units. Eventually, however, they decided to commission the design of a vehicle with similar parameters domestically. This task was given to the PZInż (Państwowe Zakłady Inżynierii, the Polish National Engineering Works) Study Bureau (Biuro Studiów) in 1936.

Light Reconnaissance Tank – PZInż. 140 (4TP)

The main designer of the vehicle, which would receive the factory designation PZInż. 140, was engineer Edward Habich. During the development of this tank, he used many elements from his earlier design – the amphibious PZInż. 130 tank. The project and its documentation were completed on 16th December 1936 and work was immediately started on building the first prototype. The construction of this new vehicle utilized the best and most recently available solutions observed in similar foreign-built vehicles – the light Vickers tanks developed by the engineers Carden and Loyd, especially the Vickers-Carden-Loyd Light Amphibious Tank (prototypes of which had been demonstrated in Poland) and the Swedish Landsverk 100 (L-100 – for the assessment of which a special committee had been sent to Sweden).

Design

The 4TP chassis utilized an indigenously-designed suspension in the form of torsion bars connected to hydraulic shock-absorbers placed in a horizontal position. It consisted of a front-drive sprocket, a rear idler wheel and two sets of rubber-tired roadwheels on each side of the tank. The two return rollers on either side guided the tracks, consisting of 87 cast single-pin double-wedged links with a width of 260 mm and a pitch of 90 mm.

The crew was housed in a crew compartment on the left side of the hull, with the engine compartment to their right. The crew consisted of a driver and a commander. The driver’s position was in the front of the vehicle with the transmission to his right. In front of the driver, there was a single-piece hatch which constituted part of the front plate with an additional observation hatch in the center with a viewport. The driver also had access to a rotating periscope designed by Polish engineer Rudolf Gundlach. The one-man turret was placed above the crew compartment, shifted slightly to the left in relation to the centreline of the hull. It had a two-door access hatch in the rear and an additional hatch on the roof. The turret itself was operated manually and was supposed to be equipped with another periscope on the roof which could be used by the commander. Series-production tanks were also supposed to be equipped with radio stations.

The hull was built from steel plates which were bolted together – a feature borrowed from the Vickers 4-ton Light Tank which resulted in an increased vehicle weight (by approx. 80-90 kg). Despite popular opinion, the hull was not riveted. The front plates had a thickness ranging from 8-17 mm, the sides – 13 mm, the rear of the hull – between 10-13 mm, the floor – 4-8 mm and the top – 5 mm. The turret was made out of rolled sheet steel with a thickness of 13 mm around the sides and 5-6 mm on top.

The power unit was a newly constructed carburetor engine designed entirely by PZInż. The new power unit was the brainchild of two designers – engineers Jan Werner and Jerzy Dowkontt. They began work on the engine on 1st February 1936. The assembly of the prototype was begun in mid-April and ended on 15th August 1936. The very same day, the engine was mounted on an engine test stand and, after four hours of testing, it reached its planned power output of 95 hp. The first series of these engines, as well as its derivative – the PZInż. 425 – was started soon after. One of these was used on the amphibious PZInż. 130 and another was fitted on the PZInż. 140 asymmetrically relative to the main axis of the hull, on its right side. The engine torque was transferred by the main clutch and the transmission via the driveshaft to side clutches and the drive sprockets in the front of the hull.

Polish reconnaissance tank PZInż. 140 4TP
Polish reconnaissance tank PZInż. 140 (known to the military as the 4TP) after transfer to military representatives on 15th August 1937.
Source: Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)

Armament

The tank’s turret was structurally similar to the Bofors turret on the 7TP tank, the only difference being its smaller size. The armament was to consist of a 20 mm autocannon with a 7.92 mm coaxial machine gun (most likely the ckm wz. 30 – an indigenous unlicensed clone of the American Browning M1917 heavy machine gun) or even a 37 mm gun in place of the 20 mm gun. During the construction of the 4TP prototype, the Armored Command, under the order of the Ministry of Military Affairs, was considering arming the tank with a stronger gun, the 37 mm wz. 37 tank gun (the same as one the 7TP).

At the beginning, the use of the 7TP turret was proposed, but it proved impossible due to the turret ring diameter being too large. In July 1937, engineer Edward Habich designed and presented a new, slightly modified variant of the 4TP with the factory designation PZInż. 180 and a modernized turret, with a shape resembling a truncated prism. Compared with the original variant of the 4TP, this version was slightly heavier and larger, and armed with a 37 mm gun, used so far solely on light infantry support tanks.

Rejection and Further plans

The project was examined by BBT Br. Panc. at the beginning of August 1937, even before the prototype was completed. The vehicle’s fate was decided by the fact that the gun could only be operated by one crewmember – i.e. the tank commander. It turned out that the tank commander would be incapable of properly carrying out all of his duties (i.e. commanding the tank, observing, aiming, and loading). Building a larger, two-man turret was out of the question as too many modifications would have to be made to the vehicle. An additional drawback was that only some of the parts of the gun would fit in the proposed turret – the barrel with the breechblock and the hydraulic recoil mechanism; the other mechanisms would not fit in the turret and would have to be specially constructed.

Because of all these drawbacks, the proposal failed. Later on, arming the 4TP tank with a locally-built flamethrower designed by the Sappers Development Office (Biuro Badań Technicznych Saperów – BBT Sap.) and the Institute of Armament Technology (Instytut Techniczny Uzbrojenia – ITU) was considered, but this proposal was also never realized.

Ultimately, the finished prototype, the PZInż. 140/4TP, had a turret adapted to use a 20 mm autocannon and a machine gun. It was never armed because the Solothurn and Madsen guns available at the time were ill-suited to the task and there was no indigenously-designed weapon of this type in the Polish arsenal yet.

Polish reconnaissance tank PZInż. 140 (4TP)
Polish reconnaissance tank PZInż. 140 (4TP) during testing in the BBT Br. Panc. “Autumn 1937” (“Jesień 1937”) rally.
Source: Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)

Trials

On 15th August 1937, the PZInż. 140 tank was delivered to the military after factory trials. It was tested in the “Autumn 1937” (“Jesień 1937”) rally along with other prototypes. After its completion, it was sent back to PZInż. for repairs, removal of faults, and technical modifications to the design.

In May 1938, the PZInż. 140/4TP was put through more trials. The members of the committee of military experts decided that, despite several technical shortcomings, the tank was a modern design and, following several improvements, was fit for serial production.

Polish reconnaissance tank PZInż. 140 (4TP)
PZInż. 140 (4TP) during winter trials between 1937 and 1938.
Source: Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)

Further development

The main feature warranting redesign was the suspension. Despite the fact that it worked well and was flexible, the variant used in the prototype was too “soft” – which caused too much swaying motion on its transverse axis. As a consequence, the gun could not be properly aimed while driving, which was always a requirement of Polish tacticians and would be very important for reconnaissance duties. As well as this, individual parts of the prototype’s suspension were made of a not particularly strong material, which caused quite a lot of damage. It was planned that, in the future, materials of higher quality and durability would have to be used.

Fate and Conclusion

The armored development plan for the years 1937-1942, adopted by the Armament and Equipment Committee (Komitet do spraw Uzbrojenia i Sprzętu – KSUS) stipulated the replacement of the TK and TKS tankettes with a 4-tonne reconnaissance tank. The programme expected the production of around 480 vehicles of this type to equip 18 tank reconnaissance companies as part of infantry divisions as well as four so-called Motorised Units (Oddział Motorowy – OM) part of a motorized brigade.

The final trials of the 4TP tank before the start of the war took place in May 1939. After their completion, the tank had driven over 4,300 km without any major malfunctions.

The fate of the tanks was discussed for a long period of time. In the end, the General Staff decided that the time needed to set up production for the tank would cause significant “aging” of the design, especially given the apparent low usefulness of light tank designs following the analysis of the use of tanks in the Spanish Civil War. Ultimately, the tank was never ordered into production.

Polish reconnaissance tank PZInż. 140 (4TP)
Side, top, front and rear view blueprints of the PZInż. 140 (4TP). Source: Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)


The single built prototype of the PZInż. 140 (4TP).


Hypothetical ‘in-service’ PZInż. 140 (4TP) with 20 mm nkm wz. FK-A autocannon and ckm wz. 30 coaxial machine gun.

Both illustrations were produced by the author, Bernard Baker, and funded by our Patreon campaign

Specifications

Dimensions (L-W) 3.84 x 2.08 x 1.75 m (12.60 x 6.82 x 5.74 ft)
Total weight, battle-ready 4.33 tons (8,660 lb)
Crew 2 (commander/gunner, driver)
Propulsion PZInż. 425, 6-cyl, 95 hp, 22 hp/ton
Suspension Torsion bar, leaf sprung bogies
Speed (road) 55 km/h (34 mph)
Range (road/off road)/consumption 450-240 km (280-150 mi)/60 l/100 km
Armament 20 mm autocannon (proposed Nkm wz.38 FK), 7.92 mm machine gun (proposed Ckm wz. 30)
Ammunition 200 rounds for 20 mm autocannon and 2500 rounds for machine gun
Armor 4 to 17 mm (0.16-0.67 in)
Total production 1 (prototype)

Sources

Czołg rozpoznawczy PZInż. 140, Piotr Zarzycki (Wielki Leksykon Uzbrojenia Wrzesień 1939, Tom 141 Prototypy broni pancernej, 2018)
Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)
Leksykon pojazdów mechanicznych Wojska Polskiego 1918-1939, A. Jońca (Edipresse, 2018)
Nowe rozdanie, czyli TKS wersji 2.0, Jędrzej Korbal (Technika Wojskowa Historia nr. spec. 6/17, 2017)
http://derela.pl/tkdpl.htm
Pojazdy Wojska Polskiego 1939, A. Jońca, R. Szubański i J. Tarczyński (Warszawa: Wydawnictwo Komunikacji i Łączności, 1990)


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WW2 Polish Prototypes

PZInż. 130

Republic of Poland (1937-1939)
Light Amphibious Tank – 1 Prototype Built

At the end of the 1920s, the well-known tank designers from the Vickers company – engineers John Valentine Carden and Captain Vivian Loyd – built a new, specialized variant of a small reconnaissance tank, an amphibious vehicle known as the Vickers-Carden-Loyd Amphibian Tank.

The vehicle did not, however, pique the interest of the British War Office enough to place orders. By the end of 1931, Vickers received permission to export the tank and buyers were found almost immediately. The U.S.S.R. bought 8 tanks (on the basis of which they designed the T-37A and the T-38), Thailand (then known as Siam) bought 2, China bought 29, and the Netherlands ordered 2 for service in the Dutch East Indies. Interest in the tank was also shown by other countries, such as Japan, Finland, and Poland.

Vickers-Loyd Amphibian Tank. Source: Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)

At the same time, Vickers also offered small two-man reconnaissance tanks and tractors for sale, all based around the same chassis. News of the new British designs soon reached the Polish Armored Command. Despite serial production of the TK tankettes and a finalized design for the TKS, the weapons development plan had foreseen the design of a small new light tank with its armament in a rotating turret and a more powerful machine gun, such as one with a caliber of 13 mm or even a 20 mm cannon. The tank was to potentially replace the TK/TKS tankettes in the near future.

For this reason, talks with a Vickers representative on the demonstration of the vehicles were started as early as 1932 in Warsaw. In September 1932, the British company shipped three vehicles to Poland – the amphibious tank, the 4 tonne reconnaissance tank and an artillery tractor, all based on the same chassis. They were demonstrated to representatives from various competent institutions and military authorities. The presentation of the amphibious tank’s capabilities took place in Modlin on 8th October 1932, on the banks of the Vistula near the Military Yacht Club. On 25th October of the same year, all three vehicles were demonstrated in Rembertów, near Warsaw, in which the amphibious tank’s ability to overcome ground obstacles and water hazards was greatly admired by the Polish committee.

As a result of these demonstrations, the head of the Department of Engineering Supply (Departament Zaopatrzenia Inżynierii), Colonel Tadeusz Kossakowski, presented a proposal to the Polish General Staff for the purchase of five 4-tonne tanks and one amphibious tank. These were to be a test bed for further research and models on which to base domestic designs.

The General Staff, however, only agreed to the purchase of three vehicles, but even these were never bought due to a lack of funds. Due to this, it was decided that similar vehicles were to be designed without acquiring foreign templates. The Armored Weapons Development Office (Biuro Badań Technicznych Broni Pancernych – BBT Br. Panc.) laid down the tactical and technical requirements for an amphibious tank and a 4-tonne tank design which was entrusted to PZInż (Państwowe Zakłady Inżynierii, the Polish National Engineering Works). Both vehicles were to be standardised and the components were to be highly interchangeable.

Light Amphibious Tank – PZInż. 130

Armored Command expected the amphibious tank to be used in operations in Eastern Poland, especially in the Polesie region, abundant with swamps, rivers and lakes, where normal tanks would have had difficulties due to the character of the terrain.

Design

The main designer of the PZInż. 130 (as well as the 4-tonne reconnaissance tank – the PZInż. 140) was the head of the Tanks Department of PZInż, Engineer Edward Habich.

Most of the components of the tank were unified with those of the PZInż. 140, including the engine, drive train, suspension and track mechanism (with the road wheels and tracks being of a lighter construction to reduce the overall weight). The turret was taken from the second variant of the TKW tankette and was to house a machine gun, with the possibility of also mounting a 20 mm auto-cannon in the future. The small weight to hull volume ratio, along with the hermetically sealed and the watertight construction allowed for the floatation of the tank. To ensure greater stability while floating, the track covers were built as floatation devices filled with cork. The vehicle was propelled in the water by a screw housed in a special retractable hydrodynamic cover, connected to the control levers and side clutches, and acting as a rudder. The power was transmitted from the engine through the transfer case independently of the momentum transmitted to the tracks, which allowed for the simultaneous movement of both the tracks and the propeller. This made it easier for the tank to drive into and out of the water as well as overcome obstacles in shallower waters.

The PZInż. 130 just before submission for trials – differences between this vehicle and the Vickers-Loyd Amphibian Tank include the modern suspension and Gundlach periscope. Source: Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)

Initial Trials

The design and technical documentation for the tank were completed in Autumn 1936. Work on the construction of the prototype started at the beginning of 1937 and finished in the summer of the same year. After a short series of factory tests, the tank was transferred to the military representatives on 15th August 1937 and demonstrated to officers from various institutions on 2nd October. During the demonstration in Beniaminów, the tank was driven by its designer despite the fact that this had been forbidden by the organisers fearing some unforeseen accident. Fortunately, neither the vehicle nor its designer were hurt during the trial.

From 5th October, the PZInż. 130, along with other prototype vehicles, took part in a test rally under the codename “Autumn 1937” (“Jesień 1937”). The route started in Warsaw and led through Brześć (present-day Brest), Wołkowysk (Vawkavysk), Pinsk, Łuck (Lutsk), Buczacz (Buchach), Stryj (Stryi), Żurawica, Lublin and ended up back in Warsaw with a total distance of about 1,861 km with around half of the route being driven off-road. Additional tests for the PZInż. 130 were carried out on Lake Lubiąż (Lyubyazh) and on the Pina River near Pinsk.

The PZInż. 130 before a water test with visible hydrodynamic cover and screw. Source: Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)

Further Trials and Eventual Fate

The overall evaluation of the tank by the military committee was positive – the power to weight ratio was favorable, the acceleration was good, and the tank could easily drive over rough and marshy terrain. The defects that were found were deemed normal for a newly-designed vehicle and, after the rally, the tank was returned to PZInż to introduce improvements and iron out mistakes.

The next test rally took place in May 1938 and led through the Knyszyn Forest to Vilnius Nieśwież (Nyasvizh) and Biała Podlaska with a combined distance of over 800 km which the PZInż. 130 also managed to complete with positive results. This proved the same in all subsequent tests, all of which the tank managed to complete without any significant failures. The last trial of the tank took place in May 1939 and the prototype drove a combined distance of over 3,500 km (other estimates place it as high as 5,000 km).

Unfortunately, at the same time, the General Staff decided there was no need for such a vehicle, and the prototype was returned to the Ursus test workshop. The reasons given were the lack of production capabilities for such a specialised vehicle, its comparatively thin armor and use of factory time which could be spent on building heavier and better armored tanks. At the outbreak of the Second World War, the vehicle most likely remained in the PZInż factory in Warsaw and in Spring 1940 was transported by rail to Germany, where it was put on display as a war trophy at the Leipzig Trade Fair.

Side, top, front and rear view blueprints of the PZInż. 130. Source: Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)

Conclusion

The tank was marked by a great reliability of movement and an ability to cover large distances at a high average speed. The mechanisms were straightforward and the handling and maintenance procedures were very simple. The vehicle was well stabilized, as a result of which driving the tank did not tire out the crew. However, despite its obvious advantages the tank did not enter mass production due to the fact that it would have delayed the construction of much more urgently needed tanks, such as the 7TP, as well as the design of vehicles with substantially more firepower.

PZInż.130 captured by the Germans, in the winter of 1939/40. Source: Polish amphibious tank prototype PZInż.130, derela.pl


Illustration of the single prototype built in 1937.


Illustration of a Hypothetical in-service variant with the 20 mm wz. 38 FK-A autocannon.


Illustration of a Hypothetical in-service variant with the ckm wz. 30 machine gun

These illustrations were produced by the Author, Bernard Baker, and funded by our Patreon camapaign.

Specifications

Dimensions 4.22 x 2.08 x 1.88 m (13.85 x 6.82 x 6.17 ft)
Total weight, battle ready 3.92 tons (7,840 lb)
Crew 2 (commander/gunner, driver)
Propulsion PZInż. 425, 6-cyl, 95 hp, 24.2 hp/ton
Suspension Torsion bar, leaf sprung bogies
Speed (road) 60 km/h (37 mph) – on land
7-8 km/h (4-5 mph) – in water
Range 360-220 km (225-135 mi)/58-66 l/100 km
Armament 20 mm autocannon (proposed Nkm wz.38 FK) (200 rounds) or 7.92 mm machine gun (proposed Ckm wz. 30) (2500 rounds)
Armor 4 to 8 mm (0.16-0.31 in)

Sources

Czołg pływający PZInż. 130, Piotr Zarzycki (Wielki Leksykon Uzbrojenia Wrzesień 1939, Tom 141 Prototypy broni pancernej, 2018
Czołgi rozpoznawcze PZInż.-130 i PZInż.-140, Janusz Magnuski (Nowa Technika Wojskowa nr. 11/93, 1993)
Nowe rozdanie, czyli TKS wersji 2.0, Jędrzej Korbal (Technika Wojskowa Historia nr. spec. 6/17, 2017)
derela.pl/tkdpl.htm
Pojazdy Wojska Polskiego 1939, A. Jońca, R. Szubański i J. Tarczyński (Warszawa: Wydawnictwo Komunikacji i Łączności, 1990)

Video


Tracked Hussars Shirt

Charge with this awesome Polish Hussars shirt. A portion of the proceeds from this purchase will support Tank Encyclopedia, a military history research project. Buy this T-Shirt on Gunji Graphics!