Polski-Fiat 621 "Tur" (1935)
Polish Light Lorry, 9400 produced +2800 621R buses and 800 specialized variants.
The Polski Fiat 621 was a Polish 2.5-tonne truck, most prolific lorry of the Polish Army in 1939, built under licence by PZInż but heavily modified to suit Polish weather and bad roads. The 621 L had modified superstructures and the 621 R was a 3-ton capable revised chassis ideal, both sold to the Army and civilian market. The production ran until the German invasion of September 1939. Those not destroyed in the fighting were either captured by the Germans and Soviets but many also fled south, to Romania and were incorporated into the Romananian army fighting on the eastern front.
Design
Development
The Polski Fiat 621 was a Polish 2.5-tonne truck, the workhorse of the Polish Army transportation in the interwar and until 1939, a dependable and basic lorry built under an agreement between Fiat and PZInż. The design basis was the Fiat 621, a derivative of the 1932
Fiat 618 which licence was already discussed by the Poles. The final model became the Polski Fiat PF 618 Grom, already mass produced granted in 1932 to Polish Państwowe Zakłady Inżynierii (PZInż) and extended in 1937 to produce the models Fiat 621, 508, 518 Ardita and 618.
Fiat 621
The FIAT 621 like the 618 was a rugged 4x2 lorry slightly larger than the 618, but produced in limited numbers in Italy under this factory name, before turning into a a model produced exclusively in Poland. The Fiat 621 made in 1929-31 had a payload of 1.7 tons. In 1930 it was replaced by the Fiat 621L with a longer wheelbase, increased payload to 2.25 tons and dual tyres a the rear to carry 2.5 tons. This model was made until 1935. Alongside, Fiat soon proposed the diesel variant Fiat 621 N manufactured from 1934 to 1939 and with a payload of 2.64 tons.
The Polish variant of 1935 was a result of the licensing agreement signed on September 21, 1931, between Fiat and PZInż. to produce a similar 2.5-ton truck derivative of the "Grom" in Poland. The model selected for production was the Fiat 621L and R, the bus variant called "Tur", built at the parent plant. The 621 enjoyed a good reputation among drivers and mechanics for several years due to its simple design and high durability. Unfortunately that durability was challenged in Polish conditions, so the PZInż. Research Office developed a modified version which became the "Polish Fiat 621".
Production started much later in 1935, wit initial assembly using Italian parts, but castings were made in 1935-38 and so by 1939 only 10% of parts remained imported. The remainder were manufactured locally. However by the time it entered production, the lorry was already outdated, and plans were underway to replace it with in-house designs, such as the PZInż 703.
Polish Modifications
The Polish version of the Fiat 621 was heavily modified to better suit Polish needs, cope with the harsh weather and dirt roads of Poland. The chassis was lenghtened, leading to two variants, the Polski Fiat 621L which received a longer chassis and cabin changes, and the Polski Fiat 621 R lenghtened futher to be used as a line of successful buses for the civilian market. Another led to a 2x6 3-tonne lorry for the army.
The Poslki-Fiat 621 had the following modifications:
- Strengthened chassis: frame, front and rear axles
- New leaf springs, joints and shock absorbers
- Wider wheelbase
- Redesigned mounting of cab doors
- A Larger fuel tank for both gasoline and diesel versions
- Cylinder block redesigned and produced of high-quality steel
- Weber carburettor replaced with a simpler and easier to maintain construction by Solex
Serial production went from 1935 at Państwowe Zakłady Inżynieryjne Works until 1939. In 1940, production was discontinued and the factory floot reconverted for PZInż 703 family. When World War II started with the invasion of Poland, all production ceased and the 621s still in the parking, not delivered yet were mostly captured. Thos in active service not destroyed, fled the country southwards to avoid capture.
Chassis and general design
For military use, the "Polfiat" 621 chassis was supplied at the FSOiP Special Body Shop outfitted with wood-and-steel driver's cab of distinctive angular shape with a wooden frame covered with sheet metal, and wooden cargo box. The Civilian versions had individually body-built in private body shops, but stuck to the PZInż. designs similar to the Fiat 618 "Grom".
The 621L had many body variants, sanitary, firefighting, garrison transport, airport version with an open 8-passenger body, command vehicle with radio station, field workshop, tractor fo a 4,500-liter tanker trailer with motor pump (800-2,200 l/min). The 621L developed as a portee was also used as a self-propelled 75 mm Model 14 anti-aircraft gun. The Army also used the super long chassis variant known as the 621 R bus, with some sub-variant declined as a 3-ton trucks.
They lad a longer and lowered frame with longitudinal members curved over the rear axle, a longer wheelbase, changed gear ratio in the inverted final drive, top speed increased from 50 to 64 km/h, and mountain brake, engaged when stopping on an incline. The model R also had lightened driveshafts and the chassis' curb weight was 50 kg heavier to 1,705 kg, with a greater turning radius. The army made good use of the 22-seater bus, but most were requisition in September 1939 to accelerate troop movements, being made for the civilian market originally.
Tech specs
The 621L Body was made in Wood and steel truck, with a wooden cargo bed covered with a canvas cover, mounted on a frame made of C-sections.
It was powered by a Fiat 122B (PZlnż. 367) carbureted, 6-cylinder, in-line, four-stroke, side-valve, liquid-cooled, front-mounted, rear-wheel drive displacing 78 × 103 mm / 2952 cm³ with a compression ratio: 5.1:1. It was coupled with a dry clutch, multi-disc for a gearbox which had 4-speed forward and reverse. The suspension coprised a front rigid axle, with semi-elliptical leaf springs, hydraulic arm shock absorbers. The rear had a single rigid axle with semi-elliptical leaf springs, rubber Fenders.
There were mechanical drum brakes on all 4 wheels, as well as a handbrake, mechanical brake on the drive shaft. The tires were Polish Stomil 9.00 x 20" tire (twin wheels on the rear axle). Its wheelbase was 3650 mm and the chassis, naked, weighted 1655 kg, for a full weight unladen of 2350 kg.
Polski Fiat 621L specifications |
| Lenght | 5780 mm |
| Width | 2070 mm |
| Height | 2620 mm |
| Weight | 2350 kg |
| Crew | 1+9 |
| Propulsion | Fiat 122B 6-cyl. 3L petrol: 45hp or 33,9 kW/2600 rpm |
| Suspension | Leaf springs fwd and rear |
| Speed (road) | 50-55 km/h |
| Range | 24-25 l/100 km |
| Armament | None |
| Production | 9400 (13,000 all chassis) |
Production
Initially, assembly of the licensed vehicles was to be carried out in the workshops of the Fiat representative appointed for this purpose, the "Polski FIAT" joint-stock company, under the supervision of the State Engineering Works in Warsaw. It should be noted that although the purchase was primarily driven by military needs, as PZInz was closely linked to the Ministry of Military Affairs, civilian needs were also taken into account. It is worth noting that as early as 1934, work began on the C4P artillery tractor based on the PF 621 L.
In all, between 1935 and 1939, 13,000 Polski-Fiat 621 were manufactured by PZInż. (buses from FSOiP PZInż.) in the 621 L and R chassis, 9,400 621 L trucks, 2,800 were 621 R buses and heavy trucks. The remaining were 800 special military models in small series like the tanker, workshop, mobile field kitchen, and command vehicle, not including the half-track version further developed as the
C4P tractor.
Production in the first half of 1935, used exclusively Italian components mated on a Polish frame and chassis. However, in the second half of 1935, domestically produced components started to be incorporated with the aforementioned changes until there were only 13.7% of parts still imported in a very short period in 1936, ad at the eve of the war, only 10%, the carburetors (From Solex to Weber) and rolling bearings still imported. The cost also fell accordingly, in 1934 16,520 złoty, down to 10,000 złoty in 1935 and 8,150 złoty in 1938 mostly due to high production volumes and 20% tax discount for domestic production. In addition many components such as the engines, clutches, and gearboxes among others were shared with the TKF and TKS tankettes and C2P tractors. Changes in production included modernizing the driver's cab and installing a metal body in place of the wooden one.
The Polski-Fiat 621 in action
The Polski-Fiat 621 was the bedrock of Polish Army transporation in 1939. It was deployed in most motorized units of the Polish Army to carry ad resupply infantry. Most were destroyed in Lufwaffe attacks the first days, and in the weeks of the Invasion, as well as by Soviet forces. When the situation was lost, many Poles fled the country to Romania. The Romanian army in June 1941 joined the "axis crusade" in the Soviet Union and most were lost at this occasion. The others captured both by the Soviets and Germans also saw servoce until spare parts dried out.
Note that the 621 was used also under its Polish origin, from 1940 by the Wehrmacht, notably on the eastern front, and was aslmost indistinguishable from the Italian Fiat 621s captured after September 1943. Given its modifications, the Polski-Fiat of course performed much better. The German army used The Fiat 621 in different variants. The Fiat 621 was used by the German regular police, either a Fiat 621 L or a Fiat 621 N. Among the most intersting Polish derivatives were the Wz.38 field workshop, for motorized columns of 40 mm Bofors anti-aircraft gun batteries, tractor unit for towing tankettes and tanks (The 621L was sturdy enough to carry a TKS Tankette, despite it was slightly above its maximum rated payload), and the self propelled 75 mm wz.14 gun portee truck of mobile AA batteries.
Narcyz Witczak-Witaczyński - Motorcycle school group in the barracks in Garwolin.
The Museum of Technology in Warsaw has a unique 3-ton R-type truck and a firefighting version of the L-type in its collection. The firefighting version (based on the L-type) is housed at the Firefighting Museum in Mysłowice, and several Polish Fiat trucks – particularly the L-type firefighting versions – are also in private hands. On June 9, 2013, the Wroniec Historical Association "Historica" publicly presented a replica of the Polish Fiat 621 L "Tur" for the first time, built from scratch, during the 56th Infantry Regiment Day celebration.