Using its extensive experience in manufacturing reliable and durable large excavators for the mining industry, Hitachi is now supplying a wide range of these models for dredging projects. The excavators are mounted on to pontoons, which are stabilised in the water by means of spuds.
Hitachi was the first manufacturer in the Japanese market to produce an excavator for use on a pontoon. It has supplied approximately 240 excavators for such applications, mainly in Japan for port construction or maintenance projects. Some have been involved in recovery operations following the devastating tsunami in March 2011.
Demand from Europe and China for excavators used on pontoons is also increasing, however. Hitachi has sold four EX1200s to a sector of the Chinese Government, for example. It believes that one of the reasons this industry is growing year on year is the expansion of the Panama Canal and the increase in vessel sizes around the world, so that all major ports are now in need of expansion.
A wide range of Hitachi models can be found on pontoons and the most popular are the EX1200-6, EX1900-6 and EX3600-6. The largest available is the EX8000-6 backhoe, which is a new model launched in 2013, providing customers with an 800-tonne option.
The large excavators share many similarities with the standard mining models, delivering high levels of productivity and durability, operator comfort and easy maintenance. Manufactured at the Development Centre of Mining and Heavy Equipment Division in the Rinko Works factory, they are designed to work in challenging environments, 24 hours a day. They also have the same advanced technological features, including an on-board computer (DUL), which monitors the performance of the engine and hydraulic system.
Some aspects of the design have been modified to allow for easy maintenance while the machine is working at sea. These excavators have a new fast-fill system at the front, for example, allowing easy access to refill fuel and lubricants. On the standard mining excavator, this system is located under the counterweight to provide easy access at ground level.
The excavators can also be customised to meet the needs of individual customers, with the help and expertise of official Hitachi dealers. For example, an EX1900-6 excavator was recently delivered to the Jan De Nul Group, with a custom-modified front attachment by Belgian dealer Luyckx.
This machine was required to work on dredging and marine construction projects in Dubai. The front attachment provided a maximum digging depth of 18m. It also had additional piping for a breaker attachment and was delivered with two arms, measuring 8m and 5.5m, which can both be used with the breaker.
Working in a marine environment has implications for the after-sales requirements of this machine, which differ to those of a mining excavator. The EX1900-6 is equipped with an anti-seawater specification, but working in the ocean can cause corrosion, which does not usually occur in a mine. Cylinders require extra care, additional painting is required and lubricants must be refilled at least every four to five hours to prevent the wearing of pins and bushes. This is because more earth and sand enter into the bucket pin due to the water pressure.
Working underwater also makes it difficult to see the material being dredged or excavated, which tends to place more stress on the excavator than if it was operating above sea level. On the swing circle, extra care is required to prevent the bolts from loosening, and daily inspections are vital.
One of the most challenging aspects of supplying this particular excavator was the fact that the pontoon had been built for use with a competitor’s machine. In order to make the EX1900-6 fit on to the pontoon and for sufficient swing clearance between spud holes, the Hitachi engineering department had to adjust the front attachment several times.
Due to the growing demand for excavators used in dredging operations, Hitachi is already looking to the future concerning the development of these machines. One of the main challenges will be to introduce an electric model with a low-range voltage, because of high oil prices and strict emission regulations.