Bulldozers, diggers, tractors: these heavy machines all apply the same basic hydraulic powers for their trays and claws. Around 85% of all hydraulic fluids leave their system through slow leaks, line breaks or system failures. Exhausted lubricants could be a severe fire risk, with a cumulative impact on plants, fish, and wildlife. When the fluids need to be disposed of at the end of their life, the cost, at €1 per kg, is around the same as the lubricant itself. As the costs associated with disposal rise, there is a growing demand for alternative options.
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Now, however, researchers have found a solution: an environmentally-friendly hydraulic system, using water instead of oil.
The project, named HYDRO-COAT - supported by a European Union (EU) grant of €1.1 million - tackles the technological challenges of switching hydraulic fluids, from the obvious issue of rust to others, like how to ensure a smooth, friction-free power transmission. The main breakthrough of the project has been applying nanotechnology to coat key parts of the hydraulic system, and showing that water can deliver the same performance and durability as traditional mineral oils.
"The hydraulic fluids are flammable, sometimes toxic and are not readily biodegradable," says project coordinator Pietro Luigi Cavallotti. Although biodegradable synthetic oils have been developed, they show lower performance, poor lubrication, higher costs, greater wear and seal compatibility problems, and long-term stability concerns. "However, HYDRO-COAT proved that you can substitute mineral oil with water in power hydraulics."
The work of the research team focused on applying innovative coating to the pump parts, distributors, cylinders and other hydraulic components. The team used two novel technologies. The first is a special Diamond Like Coating (DLC), which layers carbon on the pump, and is both extremely hard and has low internal stresses. The second is a Columnar Nanostructured Coating (CNC), which is a nano-structured metallic coating. Using tap water, it was tested on excavation equipment and went beyond any initial expectations. "All the components passed the functional tests," says Cavallotti. "The performance of the developed machine is flawless."
Cavallotti expects the technology to reach the consumer market in 2014. He says using water could cut costs associated to hydraulics by up to 30%. And the market potential is huge: Europe makes over half of the global high power hydraulic machines.