SUV PZInż. 303

Illustrative side view of a PZInz SUV. 303.

All-terrain vehicles were one of the main modes of transport in modern motorized and armored units. As these formations grew larger and larger, the need to equip them with all-wheel drive technology became more and more acute. After a turbulent era of Fiat design improvements, it's time to develop your own car.

Tested in Poland, the Tempo G 1200 had a design that fully deserved the title of extravagant. This small two-axle car was powered by two independently operating engines (each 19 hp) that drove the front and rear axles. The maximum speed of a passenger car with a mass of less than 1100 kg was 70 km / h, and the carrying capacity was 300 kg or 4 people. Although it had not been of interest to the expanding Wehrmacht since the 1935 uprising in Germany, two years later a pair of these machines appeared on the Vistula for testing. The Armored Weapons Technical Research Bureau (BBTechBrPanc.) After completing the July inspections and tests, it was decided that the vehicle had very good off-road performance, high mobility and a low price - about 8000 zł. The low weight was due to a non-standard way of manufacturing the case, which was based on stamped sheet metal elements, and not an angle frame.

The operation of the power unit in various conditions was defined as stable, and the silhouette of the car was defined as easily hidden. However, after passing 3500 km of tests, the condition of the car was clearly poor. The most important reason for issuing a negative final opinion was too fine work and the rapid wear of some overly complex elements. The Polish commission also stated that due to the lack of a similar design in the country, it is difficult to reliably attribute it to a test vehicle. Ultimately, the key variables that justified the rejection of the discussed German SUV were the symbolic carrying capacity, unsuitability for Polish road conditions and the rejection of the G 1200 design by the German army. However, it should be remembered that by this time various variants of the PF 508/518 were already entering adulthood , and the army was looking for a newer successor.

Mercedes G-5

In September 1937 at BBTechBrPank. Another German SUV Mercedes-Benz W-152 with a 48 hp carburetor engine was tested. It was a classic all-terrain vehicle 4 × 4 with a dead weight of 1250 kg (chassis with equipment 900 kg, permissible load on the body 1300 kg). During the tests, 800-kilogram ballast was used on the favorite military sandy tracks of Kampinos near Warsaw. The speed on the dirt road was 80 km/h, and the average pace on the field was about 45 km/h. Depending on the terrain, slopes up to 20° were covered. A 5-speed gearbox has proven itself among the Poles, ensuring the correct operation of the car on the road and off-road. According to experts from the Vistula, the car could be used as a car / truck with a payload of about 600 kg and as a fully off-road tractor for trailers weighing up to 300 kg. Further tests of the already improved version of the Mercedes G-5 were planned for October 1937.

In fact, this was the second part of the study of the capabilities of the Mercedes-Benz W 152. The G-5 version was a development of the car originally tested in Poland, and because of the great interest it aroused, was very willingly selected for further comparative tests. Laboratory work took place from May 6 to May 10, 1938 at the BBTechBrPanc enterprise. In fact, long-distance road trips with a length of 1455 km were organized a month later, from June 12 to 26. As a result, the rally track, leading along an already repeatedly tested route, was extended to 1635 km, of which 40% of all sections are dirt roads. It has rarely happened that a project prepared for only one car attracted the attention of such a large group of participants. In addition to permanent representatives of BBTechBrPanc. in the faces of Colonel Patrick O'Brien de Lacey and Major. Engineers Eduard Karkoz appeared in the commission: Horvath, Okolow, Werner from Państwowe Zakłady Inżynierii (PZInż.) or Wisniewski and Michalski, representing the military technical bureau.

The own weight of the car prepared for testing was 1670 kg with almost the same load on both axles. Gross vehicle weight, i.e. with payload, was set at 2120 kg. The German SUV also towed a single-axle trailer weighing 500 kg. During the tests, the average speed of the car during sectional speed measurements on the sandy roads of Kapinos was less than 39 km/h. on a bumpy road. The maximum slope that the Mercedes G-5 overcame during the march was 9 degrees in a typical sand cover. Subsequent ascents were continued, probably in the same places where the French Latil M2TL6 tractor had previously been tested. The German car climbed a hill with peat slopes with a steepness of 16,3 degrees without wheel slip. The tires that the test vehicle was equipped with (6×18) were smaller than those used later in PZInż. 303, and their parameters were more like the versions tested on PF 508/518. Permeability was estimated at less than 60 cm after partial disassembly of the exhaust pipe. The ability to overcome ditches was highly appreciated, mainly due to the well-thought-out design of the space under the floor of the car, which did not have protruding parts and sensitive mechanisms.

The attempt to cross a freshly plowed and wet field must have come as a surprise to the commission, as it reached a speed of 27 km/h, which was impossible for the PF 508/518 on the same terrain. Due to the use of the all-moving bridge mechanism in the G-5, which was later adopted by the Poles, the turning radius was about 4 m. What is very important, the Mercedes drove the entire route, from Warsaw, through Lublin, Lviv, Sandomierz, Radom and back to the capital it ran almost flawlessly. If we compare this fact with the extensive reports of any of the PZInż model equipment rallies. we will notice a clear difference in the quality of the prototypes and the state of their preparation for testing. The maximum off-road speed is 82 km / h, the average on good roads is 64 km / h, with a fuel consumption of 18 liters per 100 km. The indicators on dirt roads were also interesting - an average of 37 km / h. with a fuel consumption of 48,5 liters per 100 km.

The conclusions from the summer experiments in 1938 were as follows: During measurement tests on the experimental track and during long-distance tests, the Mercedes-Benz G-5 off-road passenger car worked flawlessly. The rehearsal route was generally difficult. Passed in 2 stages, about 650 km per day, which is a positive result for this type of car. The car could cover long distances per day when changing drivers. The car has an independent wheel suspension, but still, on bumps in the road, it shakes and throws at a speed of about 60 km / h. It tires the driver and drivers. It should be noted that the car has well-distributed loads on the front and rear axles, which are approximately 50% each. This phenomenon contributes significantly to the correct use of a two-axis drive. The low consumption of mats should be emphasized. propellers, which is about 20 l / 100 km of various roads. The chassis design is good, but the body is too primitive and does not provide a minimum of comfort for drivers. The seats and backs are hard and uncomfortable for the rider. The short fenders don't stop the mud, so the inside of the body is completely covered in mud. Bud. A tarp does not protect passengers from bad weather. The structure of the skeleton of the kennel is primitive and not resistant to shock. During long-range testing, frequent repairs were required. In general, the car has good handling on dirt roads and off-road. In this regard, the car showed the best performance of all previously tested vehicles of related types. Summarizing the above, the commission concludes that the Mercedes-Benz G-5 off-road vehicle, due to its design, low fuel consumption, ability to move on dirt roads and off-road, is suitable as a special type for military use, preliminary elimination of the above ailments on the body .