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Industry

New Transport Sets Delivered. They Will Move Polish Tanks [ANALYSIS]

Zestawy do tansportu, Mercedes Zetros, naczepa Dobrowolski, Wojsko Polskie
One of the heavy military technology transport kits of up to 67.5 tonnes delivered at the end of 2023. The set comprises a Mercedes Benz Zetros 3348 AS 6x6 truck tractor and a DOB70W low bed semi-trailer.
Photo. Dobrowolski Sp. z o.o.

As part of the agreement between the Armament Agency and the consortium of Dobrowolski Sp. z o. o. (leader), Autobox Innovations Sp. z o. o. Sp. j. and Top Gun A. Goryca, at the end of 2023, the first stage of delivery of sets for transporting heavy military technology, including main battle tanks weighing over 60 tonnes, was completed. The set (tank transporters) includes a Mercedes Benz Zetros 3348 AS 6x6 tractor unit and a Dobrowolski DOB70W low bed semi-trailer.

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Let us recall that the contract for the transport sets, as mentioned earlier, was signed by the Armament Inspectorate (currently the Armament Agency) in October 2021. Under the contract, 31 sets will be delivered under a guaranteed order, and another 78 were provided for under option law. The value of the guaranteed order is PLN 115.9 million gross, and the price of deliveries under the option right is PLN 271.6 million gross. Deliveries will be made in 2023-2026.

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The procedure was carried out in May 2020. Its subject was the delivery of sets for transporting tanks and heavy-tracked equipment with a load capacity of over 60 tons. The consortium’s offer was selected in July and August this year. Jelcz Sp. z o. o. submitted the second proposal, but it was more expensive (a total of over PLN 520 million for the primary order and the option). According to the documents provided by the ordering party, Jelcz’s offer provided only a 48-month warranty, while the mentioned consortium provided a 96-month warranty. The evaluation criteria for the submitted offers included - price (weight 75), warranty (weight 15), and functional properties (weight 10). Both were rated at 73.33 and 100 points, respectively and as a result, the second submitted offer was selected as the most advantageous.

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Currently, the Polish Army has seven sets. The following stages of the contract are to be implemented by the following schedule:

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  • Stage II by the end of October 2024 - eight sets;
  • Stage III by the end of October 2025 - eight sets;
  • Stage IV by the end of October 2026 - eight sets.

In addition, in the years mentioned above, the contract option right may be exercised in 26 copies (78 in total).

The transport sets delivered to the Polish Army are adapted to transport the heaviest tracked vehicles in the equipment of the Polish Army, such as Leopard 2PL tanks.
Photo. Dobrowolski Sp. z o.o.

Dobrowolski DOB70W semi-trailer

The sets are intended for long-distance transport and technical evacuation of tanks and heavy-tracked equipment during peace, crisis, and war. They have a load capacity of 67.5 tons and a total length of 21 meters. In turn, the vehicle combination’s permissible total weight (GVW) is 120 tons.

The described sets« most prominent „element” is the DOB70W low bed semi-trailer designed and manufactured by Dobrowolski Sp. z o. o. It is equipped with six 12-ton SAF axles, including three fixed and three self-steering (the first two and the last), with the possibility of locking. The possibility of locking the steering axles makes it easier to drive in muddy terrain while maintaining single-wheeledness. In turn, when driving on paved roads, the steered axles ensure high maneuverability of the set.

Wheels with a diameter of 19.5” are equipped with drum brakes and run-flat inserts, allowing you to continue driving after losing tire pressure. If a wheel needs to be replaced, each axle can be lifted separately, even with a loaded trailer. The electric and pneumatic systems are adapted to work with all tractors used by NATO armies, including the US Army.

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The loading deck has movable stops that facilitate the correct load distribution on the trailer (for even distribution of weight on the axles). In addition to the transport of tracked and wheeled vehicles, it also enables the transport of sea containers with dimensions - 2x10”, 2x15”, 20”, 30”, palletized loads, mesh and Mauser containers, as well as long loads using stanchions.

The loading capacity of the DOB70W is 67.5 tons, which, with its weight of 19.1 tons, makes it one of the lightest structures of this type on the market. The length of the semi-trailer is 14.8 m, including nearly 10 m of the loading deck.

The main load-bearing element is the central frame, a closed box structure that ensures stiffness and resistance to torsional forces. The openwork ramps can be extended and retracted, enabling the loading of various types of tracked and wheeled vehicles, including passenger vehicles and faulty vehicles. Equally important, this ramp design ensures excellent visibility for the driver in the rear-view mirrors. They do not accumulate dirt (mud, snow, stones) and improve aerodynamics when running „empty.”

The so-called „gooseneck” provides considerable space for connecting various tractors. It also has a movable box with a kingpin, which enables cooperation with military and civilian tractor units. Moreover, the kingpin is replaceable. One person can perform all these activities in a few minutes.

The semi-trailer is equipped with boxes, i.e., storage compartments located on the work deck and the side, facilitating daily work and providing a safe place to transport additional equipment (e.g., equipment for securing the load).

The DOB70W semi-trailer from Dobrowolski was designed based on the recipient’s requirements (army), confirmed during tests conducted at the Military Institute of Armor and Automotive Technology in Sulejówek. The manufacturer created a light structure capable of transporting the heaviest military technology used by the Polish Army. In addition, combined with the Mercedes-Benz Zetros 6x6 tractor unit, the entire set is characterized by high mobility in various roads, terrain, and climatic conditions.

Zetros with Dobrowolski semi-trailers had their public premiere during last year's International Defence Industry Exhibition (MSPO) in Kielce.
Photo. Mateusz Multarzyński/Defence24.pl

Zetros 3348 AS 6x6 tractor unit

Zetros 3348 AS 6x6 tractor units delivered by EWT Automotive Polska Sp. z o. o., an authorized dealer of Mercedes-Benz vehicles. The tractors selected for the described sets are equipped with 6-cylinder, in-line OM460 engine with a capacity of 12.8 liters, generating a power of 350 kW/476 HP and a maximum torque of 2,300 Nm. The engines meet the Euro 3 exhaust emission standard and are designed to run on F34 (JP-8) aviation fuel. The drive unit is paired with a 6-speed Allison 4500 SP automatic transmission equipped with a retarder, power take-off, and a VG2800 reduction box (with an oil cooler). The intake system uses a preliminary centrifugal (cyclone) filter mounted on the chimney (so-called snorkel). The vehicle is also capable of wading to a depth of 800 mm. The drive system has been optimized for sets with a GVM from 44 to 120 tons. The vehicle’s maximum speed is electronically limited to 90 km/h. It is also equipped with cruise control.

Although the tractor’s GVW is 30 tons (kreb weight is 18.2 tons), it uses axles for the 35-ton variant with a load capacity of 9 tons on the front axle and 16 tons on the rear axles (tandem). All of them are suspended on leaf springs and equipped with differential locks. The wheelbase is 4,800 mm (between the first and second) and 1,450 mm (between the tandem axles). All of them are equipped with 14.00 R20 wheels with run-flat inserts and off-road tires. The drum braking system is also equipped with an ABS that the driver can disable. It is adapted to work with the dual-circuit trailer system. The parking brake additionally acts on the front axle.

In addition to the standard fuel tank with a capacity of 500 liters mounted on the right side, Zetros also received an additional (reserve) 200-liter tank on the left side.

The M-type (medium) driver’s cabin used on the tractor is equipped with two beds (upper and lower) and three seats for the crew (the driver’s seat is suspended). A round roof hatch with a side-sliding cover was installed on the roof. The additional equipment included, among others, a filter and ventilation system, air conditioning, independent water heating (including the engine), a refrigerator with a capacity of 21 liters, two 24V/15A sockets, and radiotelephones (one mobile and two portable) for communication between the driver and the crew. The primary exterior mirrors are electrically adjustable and heated.

The vehicle’s electrical system uses four 12V 100 Ah batteries, a 28V/150 A alternator, and a single-pole main switch. The tractor’s equipment includes an external power supply cable for starting the engine.

Behind the Zetros cabin, a special structure was installed housing a set of winches supporting tracked equipment loading onto a low bed trailer. Two working winches, installed on the right and left sides of the structure, are a product of the renowned company Sepson AB with a pulling force on the first coil of 240 kN. The working length of the rope is 60 m, and its diameter is 24 mm. The winding/unwinding speed is from 3 to 4.5 m/min. The third winch, from Husar Winch, has a pulling force of 90.4 kN. The length of its rope is also 60 m, and its diameter is 12 mm. It is also used for self-evacuation of the vehicle. Hence, its rope can be led both forward and backward using a roller system.

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All winches mounted on the tractor are controlled by radio (range 100 m). The supplier of this system is Tele Radio Polska.

The vehicle is adapted for rail, sea, and air transport following the requirements of STANAG 4062 Ed 6. Zetros also meets the requirements for electromagnetic compatibility under the Defense Standard.

The described sets, together with 23 Jak tank transporters delivered in 2022 (made up of Jelcz 882.62 tractor units with an armored cabin and ST775-20W multi-axle low bed semi-trailers), constitute a significant strengthening of the Polish Army’s capabilities in the transfer of heavy military technology. Considering the expansion plans of the Polish Armed Forces, it is expected that purchases of this type of logistic equipment will continue, as they constitute an essential element of support for armored, mechanized, and artillery units. Interestingly 2018, Lithuanians ordered eight similar sets for EUR 5.6 million. In their case, Zetros 3643 tractor units and EMPL semi-trailers were chosen.

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