Doosan kit tackles gravel extraction above and below water

Kieswerke Silzen Peissen GmbH (KSP) has purchased three powerful new Doosan machines for the company’s Silzen-based operations carrying out gravel extraction both above and below water. The new machines comprise the Doosan DL420-5 wheeled loader, a custom-made long-reach 60 tonne DX530LC-5 excavator and the state-of-the-art DL420CVT-5 (continuously variable transmission) wheeled loader.

The two KSP plants in Silzen comprise about 70 ha of approved mining area, of which approximately 20 ha is being developed underwater and is called Plant 1. The materials obtained from the water in Plant 1 are cleaned in the company's washing systems and then sorted. Plant 1 mainly produces concrete aggregates, screes and special building materials for use on golf courses and riding arenas as well as special sands for playgrounds. The second plant in Silzen – Plant 2 – has been operating for about 15 years and is directly opposite Plant 1. Plant 2 produces materials for applications including road building. The permit for this work covers approximately 40 hectares.

The two wheeled loaders are used in the above-ground mining and for various loading operations, whilst the DX530LC-5 excavator is responsible for the extraction and earthworks carried out underwater at Plant 1.

Working in Nine Metres of Water

The underwater work was previously carried out using a nearly 40-year-old scraper, which had to be replaced at short notice. There were strict requirements that the new excavator had to meet: it had to be able to work in a water depth of up to 9 m and be delivered within two months.

Atlas Hamburg was able to offer a solution for this to the Silzen Peissen gravel works using the Doosan DX530LC-5 with a customized 18 m boom. In order to optimise the excavator for underwater work, Atlas Hamburg also made a number of other changes to the machine.

As a result, 900 mm wide tracks have been installed to keep the ground pressure as low as possible. The stability with the long boom was also increased by widening the undercarriage and by adding an additional three tonne counterweight. For machine control, Atlas Hamburg also installed a 2D control system from Zimmermann. This helps the operator to work efficiently and accurately, even without being able to see the attachments at the end of the boom. In addition, the excavator uses a submerged quick coupler, a 1.7 m³ Hardox dumping bucket for underwater construction and a 2800 mm pivoting trough for earthworks above water.

Norma Henkensiefken, owner of KSP, said: "After the high performance of the first Doosan DL420-5 they supplied, coupled with its reliability and speed, we also approached Atlas Hamburg to supply the excavator. Since the excavator arrived, the experience we have had with it and the wheel loaders has been extremely positive. The Doosan machines are very good value for money and extremely powerful."

Continuously Variable Transmission for Maximum Efficiency

The latest addition to the fleet at KSP is the Doosan DL420CVT-5 wheeled loader, the first model in the Doosan wheel loader range to be equipped with a Continuously Variable Transmission (CVT).  A CVT transmission is composed of a hydraulic motor combined with a hydraulic pump which provides a smooth and continuous speed variation.

The CVT design combines the benefits of a mechanical transmission and a hydrostatic transmission in the same machine. It allows the DL420CVT-5 to automatically transition from hydrostatic power at low speed to the mechanical system to operate at higher speeds.

By combining the two types of transmission, the new CVT technology ensures high loads can be carried at low engine speeds with high dynamics for an optimum wheel loader operating cycle.  The DL420CVT-5 therefore provides an increase in machine performance for operators working in digging, loading and lifting applications.

Jens Rausch, Operations Manager at KSP, added: "The DL420CVT-5 with continuously variable transmission is the optimum machine for our application in the extraction and loading operations. Compared to the DL420-5 with conventional gearboxes and also compared to other comparable machines in our fleet, the DL420CVT-5 delivers significantly more power with lower fuel consumption."