Equipment container for installation of all the electrical and hydraulic componentsView of the compact hydraulic system in the equipment container


In August of last year, ARDELT was awarded an order for the modernisation of a balancer crane. The crane, which was manufactured by ARDELT, is operated by Scholz Recycling in Espenhain.

The Scholz Group is a business which operates throughout Germany and the whole of Europe and has specialised in the recycling of all types of metal. The crane, which was delivered in 1993, serves to feed a metal shredder at the company's works in Espenhain.

The crane has a lifting capacity of 6 tonnes at an outreach of 32 metres. In order to meet the most varied requirements for goods handling the crane is equipped with a hydraulic crawler track drive. The power supply to the crane is either by means of a diesel generator set mounted on the crane or via a permanent feeder cable.

Since its commissioning, the crane has fulfilled all the customer’s expectations and has been extensively used in a range of handling operations. Naturally, the technology that was available when the crane was built no longer corresponds to the current state of the art. An inspection of the crane’s steel structure and slew bearing carried out by ARDELT showed that, despite the 27,000 accrued operating hours, the whole structure remains in very good condition, which means that a complete refurbishment is a perfectly feasible option.

In comparison to other mobile cranes, a balancer crane offers decisive advantages. Because its lifting capacity is not restricted at a large working radius, it can be used to replace several smaller cranes. Direct and very fast goods handling becomes possible through the direct linking of the load attachment device. With this design, the crane’s counterweight equalises the mass of the main boom and the front boom with grab (balance principle). It requires only the energy necessary to move the handled goods. In this way, a balancer crane achieves a very good ratio between the handling capacity and the amount of energy used. Together with the crane’s high operating speeds, this means the balancer crane represents an optimum crane for goods handling.

Working together on an intensive cooperation project, ARDELT and Scholz Recycling were able to determine the required scope of the modernisation work.

With this, a particularly difficult challenge was the requirement that the assembly time for the crane’s modernisation should be kept as short as possible.

However, as a manufacturer of complex cranes in the form of articulated-jib luffing cranes and hydraulic balancer cranes, ARDELT was able to provide through its experienced engineers the competence and knowledge necessary for this project. On this basis a technical strategy could be prepared for the successful modernisation of the balancer crane.

With this, the modular construction principle used by ARDELT proved to be a decisive advantage. All the hydraulic and electrical components needing modernisation are installed in an equipment container. Therefore, assembly work on the crane is limited to the necessary minimum. The equipment container was fully assembled in-house at ARDELT and then put into operation. By conducting extensive tests during the commissioning of the container before the start of on-site assembly, it was possible to reduce the time required at the site to a minimum. The container is equipped with all the necessary connections, so that after completion and testing it can be connected to the existing crane system without problem.

This concept brings decisive advantages in comparison to traditional methods and, in most cases, it can be implemented universally.

The following individual components of the crane were renewed or modernised:

- Equipment container for installation of the hydraulic system and the electrical switch cabinets

- Air-conditioned electrical room in the equipment container

- Pump group to supply the hydraulic cylinders for the crane’s main boom, forearm, grab and slewing gear. The hydraulic pumps are controlled according to the oil demand as required during operation. This contributes to energy optimisation of the whole system.

- Main valve block with integrated proportional valves for controlling the hydraulic actuators. With this, control of the proportional valves is implemented via a hydraulics PLC. This allows optimum fine adjustment of the crane’s movements.

- Oil tank with a capacity of 1,600 litres. The tank is equipped with a heater to maintain the hydraulic oil at operating temperature in low temperature conditions and during long standstill periods. During operation, the hydraulic oil is kept within the prescribed temperature range by means of an oil cooler mounted on the roof of the equipment container. The oil tank is additionally equipped with various filter elements for the separation of water and foreign particles.

- Programmable logic controller (PLC) for recording all the relevant data on the crane. The control system is designed to allow load-independent and time-independent control of the crane’s movements. In this way, the optimum method of operation is automatically chosen for each load. An interface is provided between the control system and the hydraulic valves through the use of programmable switching amplifiers that are optimally tuned for the operation of electric proportional valves.

- Display of all operating data of the crane by means of touch-screens. In addition to the important data necessary for operation of the crane, direct display of all occurring faults is also provided. For each displayed fault, comprehensive help information is also available to assist the service personnel. This reduces the downtime in the event that a fault should occur. Through the installation of a Teleservice device the ARDELT service technicians can directly access the control system, in order to provide the operator’s service personnel with the optimum and fastest possible support.  

- Crane driver’s cabin fully air-conditioned. The installed control stand for operation of the crane is ergonomically designed to allow the crane driver optimum control when operating the crane. Large areas of the cabin are glazed in order to ensure excellent all-round visibility.

Reconstruction of the balancer crane began in February of this year. In the first construction phase, the old hydraulic system, the old cabin and the electrical equipment were removed. This was followed by a basic cleaning of the crane in preparation for installation of the new system parts.

Next, the crane’s supporting structure was suitably modified to accept the new equipment container and the new cab. The structural steel components necessary for this were prefabricated in the ARDELT works. Despite adverse weather conditions, it was possible to maintain the time schedule for the assembly work. After modification of the supporting structure, the equipment container and the cabin could be installed. The equipment container was delivered to the construction site with all the necessary electric cables pre-installed. In this way, it was possible to gain further time-savings during the modernisation of the crane.

When the assembly of all the components, including the electrical assembly, renewal of the crane’s hose connections and refilling of the hydraulic system was complete, commissioning of the crane could now begin.

Thanks to all the completed preliminary work and equipment presettings, commissioning of the crane proceeded according to plan, and without problems.

On completion of all the work, acceptance of the crane was carried out by a crane expert.

Due to the extensive preparatory measures and the chosen technological solutions it was possible to hand over the crane to the customer at the end of March, after only 7 weeks of assembly work.

After successful conclusion of the modernisation, the customer once more had at his disposal a well-proven crane, suitably modified to meet his requirements.

Modernisation of the balancer crane proved to be the correct choice. Compared to the alternative solutions, it offered significant financial and technical advantages.

Through the reconstruction, it was possible refurbish the crane for a new life and with use of the latest modern technology the results show decisive benefits with regard to reliability and efficiency.





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