New modification for five-axle carrier trucks

• Top-notch construction vehicles with high payload reserves

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• Paul Nutzfahrzeuge GmbH modifies four-axle Mercedes-Benz Arocs tipper to install the mobile truck-mounted concrete pump K60H

• Electro-hydraulically steered trailing axle with lift mechanism and air suspension

• Increased payload of 42 t and gross vehicle weight of up to 55 t

• Successful cooperation with Cifa S.p.a.

Vilshofen on the Danube. As of now Paul Nutzfahrzeuge provides special carrier chassis for the new self-propelled Carbotech truck-mounted concrete pump K60H of the concrete machine manufacturer Cifa S.p.A. from Senago (Milan). To ensure the required load capacity and payload for the heavyweight and large-volume construction equipment the Bavarian specialist for chassis modifications carries out this conversion based upon the standard four-axle tipper chassis of the Mercedes-Benz Arocs 4151 K 8x4/4 type. Through the installation of a steered, lifting and air suspended trailing axle they are converted into a high payload chassis with five axles by Paul Nutzfahrzeuge.

The conversion of the Arocs standard chassis is done in close cooperation with the Italian manufacturer of the Carbotech K60H concrete pump. After conversion into a five-axle truck the Arocs chassis bear the type designation Mercedes-Benz Arocs 5551 K 10x4. Cifa presented the debut vehicle at the Intermat 2015 in Paris. It was met with great interest there: Paul Nutzfahrzeuge has already received a number of orders for the conversion of further five-axle Arocs chassis configurations for the new concrete pump model of the Italian manufacturer as well as for various concrete pumps of other international manufacturers.

Increasing the payload by 12 tons

The trailing axle supplied by the Bergische Achsen KG (BPW) has been fitted with an electro-hydraulic steering system, an air suspension, a lift mechanism and single tires by Paul Nutzfahrzeuge.

The chassis modified by Paul Nutzfahrzeuge has an empty weight of approximately 13 t. The technically permissible axle load distribution is made on the two steered front axles with an axle load of 9 t each. In addition, there are two rigid rear axles providing an axle load of 13 t each, as well as the trailing axle installed by Paul Nutzfahrzeuge with a load capacity of up to 12 t. This allows an increase of payload to 42 t. This optimizes the distribution of weight on the individual axles when transporting the heavy concrete pump which has a weight of approximately 37 t.

At the same time the gross vehicle weight is increased to a maximum of 55 t. This allows the transport in road traffic even in countries where there are relevant regulations. Furthermore, there is a reserve of five tons for extra payload. This allows for the transport of additional equipment accessories, hoses, water, diesel fuel and/or construction material without violating the regulations of the highway code or the technical limitations of the vehicle.

The new five-axle carrier trucks comply with the Euro-6 emission standard. Even after conversion the high engine output of the Arocs basic chassis of 375 kW/510 hp is fully maintained and ensures rapid mobility. The power transmission of the engine occurs onto the third and fourth axle of the five-axle chassis.

Material-preserving transport by means of air suspension

The air suspension of the trailing axle not only increases the payload but also contributes to an extremely material-preserving transport of the heavy construction equipment. Apart from the load relief of the other axles it is at the same time a relevant precondition for the implementation of a starting assistance to improve traction. Paul Nutzfahrzeuge has equipped the vehicle with this device, too.

High maneuverability through steerability of the trailing axle

The trailing axle is steered electro-hydraulically as a function of the steering angle of the front axle and the travel speed. The hydraulic tank reservoir for the steering system is mounted on the chassis frame. It is located behind the driver’s cab on the co-driver’s side.

The electro-hydraulic steering system increases the maneuverability of the vehicle combination on narrow construction site areas so that the turning circle of the five-axle truck with its radius of 25 m does not exceed the radius of the Arocs standard chassis on which the five-axle truck is based. A pumping process in extreme heights can thus be carried out even in cramped conditions. The necessary lift mechanism of the rear axle is automatically activated as soon as the signal to extend the support legs (outriggers) is generated.

Superstructure mounted on a compact carrier base

The new concrete pump K60H is fixed and firmly mounted on the frame of the five-axle chassis. The frame height has been reduced to 1,060 mm to adhere to the pre-defined overall height of the vehicle of less than four meters. This allows the use of the short CompactSpace M cab from the series production of Mercedes-Benz, without causing additional costs for elaborate changes. To adhere to the pre-defined height of the vehicle, 385/65 R 22.5 tires are fitted at the front axle and 445/65 R 22.5 tires are used at the single tire trailing axle. All other axles are equipped with 315/80 R 22.5 tires.

To adhere to the overall length of the chassis (10.75 m) and the total length of the vehicle (13.4 m), the standard wheelbase of 5,450 mm (measured from the first to the third axle) can be maintained; a wheelbase extension is not required. However, numerous additional conversions are essential to create the necessary free spaces for the installation of the four swing-out outriggers of the concrete pump. As a first step, the frame overhang at the rear end is shortened by 350 mm to 2,450 mm and the end cross-member is removed. The second front axle is repositioned by 300 mm to the rear in combination with the adaptation of the spring and axle connection. The electronically controlled compressed air unit (EAPU Electronic Air Pressure Unit), the air dryer, the battery tray including the two attached compressed air reservoirs, the catalytic converter as well as the two tanks for fuel and AdBlue are also repositioned by 300 mm to the rear.

K60H concrete pump for high performance

Paul Nutzfahrzeuge and Cifa S.p.A. have been cooperating successfully for many years to merge carrier chassis and concrete pumps to highly efficient units with maximum customer benefit. The new concrete pump of the Carbotech series of Cifa enables extended boom lengths in consideration of government regulations concerning weight limitations. It is distinguished by a boom with an overall length of 60 m which is divided up into six sections and features an RRZ folding system. The boom sections 1, 2 and 3 are made of high-tensile steel while the three segments at the top are made of lightweight and at the same time robust and durable Carbotech carbon fiber composite material. The diameter of the double-walled long-life pipeline amounts to 125 mm. The high performance of the HP1808ECX high tech pump assembly with closed circuit and a maximum pressure of 83 bar allows for an output of up to 180 m³ concrete per hour. The concrete pump is equipped with a martronic machine management system with LCD display, an integrated stability control, a concrete output volume control, a load-sensing proportional control for the placing boom and a fully hydraulic outrigger control.

Benefits regarding conversion time and cost efficiency

By using standard chassis from Mercedes-Benz the conversion time at Paul Nutzfahrzeuge GmbH is only six to eight weeks and results in considerable benefits with regard to cost efficiency in comparison with hundred percent special-purpose vehicle solutions. When selecting basic chassis for multi-axle carrier trucks Paul Nutzfahrzeuge is not restricted to Mercedes-Benz chassis, however, but will also modify appropriate chassis of other truck manufacturers as well.