Digging blind is an art that only few really master. Someone who does is Jens Boock. He dips the stick of this new machine, a Cat 340F LRE excavator, into the murky water, and that down to 9 m, to retrieve sand and gravel (Fig. 1). Wet extraction was the reason for Kieswerke Nord, a gravel works based in Bad Segeberg, Northern Germany, to deploy a new excavator with a long reach and an 18-m-long boom. The working conditions with which machine operators like Jens Boock have to contend present special challenges owing to the very cohesive deposit – both with regard to extraction and processing – to enable the production of 150 different products for road construction.
The driver of the new Cat 340F LRE has to ‘feel the way’ carefully to fill the 1.6-m³ bucket. “With time you do get a feeling for it,” he says. He can draw on relevant experience and routine. As soon as he takes the full bucket out of the water, the excess water has to be able to drain off – for this purpose, special holes have been drilled into the bottom of the bucket – the sand and gravel mix has to drain off before he can swing the bucket by 90° and stockpile the excavated material in the right place. Sand and gravel have been extracted by Kieswerke Nord at the site since 2012 – the deposits were previously worked in a dry extraction operation with a wheel loader, but Kieswerke Nord switched to wet extraction to further develop the deposit to a 7-hectare area. For this reason, the gravel works is introducing the excavator with the long-front boom – it has to maintain a sufficient distance to the shore, but not sacrifice any stability. 850-mm-wide shoes plus increased counterweight guarantee the required stability (Fig. 2).
This construction machine was geared to increase productivity in excavation and lower running costs. More than enough power is supplied by the Cat Acert engine C 9.3 on the basis of the EU emission stage IV for the hydraulics to move 2000 t of material per day with both speed and precision. “On account of the long boom, we are dealing with a special machine, so the operator has to take special consideration of the physical laws of the leverage effect,” explains company owner Torsten Ahlert. He opted for the Cat 340F LRE because of its cost efficiency – the machine offers more potential applications – even after wet extraction – than the alternatives, that is cable excavator or suction dredger, which were also theoretically possible. In addition, it is easy to operate in comparison with these machines. Another factor against a suction dredger: the deposit would have been much too small for the entire machine equipment together with the downstream retention basin.
The first visual contact with the new working machine came at the bauma trade fair, when Torsten Ahlert awarded the contract on paper. “Technical specifications were crucial as we couldn’t take a standard model. The machine has to fulfil our specifications with regard to volume. In favour of Caterpillar is the overall concept that is based on the service and financing package,” explains Torsten Ahlert. His wife Claudia adds: “Why should you change your main supplier if you are satisfied with him. Zeppelin, that isn’t an anonymous hotline, there are real people behind the company.” One is Dirk Carstensen, who as sales executive looks after the company. The cooperation between the raw materials operation and construction machine dealer has grown over the years (Fig. 3).
Introducing machines against the will of the employees is out of the question for the business owner. For this reason, he always takes the opportunity to try out machines in advance. Not only the opinion of Jens Boock is then wanted, but also that of Rudi Magmussen, who operates the Cat 966K XE, or that of Ingo Wagner, who steers the Cat 320EL. “If the employees then wave the technology through, it is more easily accepted later in operation,” says the head of the company. With the employees, he discusses the equipment, especially details like steering or the seat, but also the suspension.