Rexroth paves the way for development of innovative new machine
12 December 2011
A modern solution pushes the new Dynapac paving machine into the fast lane.
Each and every year, thousands of kilometers of streets and roads are built around the world. Paving machines play a vital roll, processing up to 1,100 tons of asphalt each hour. That’s a huge assignment and the reason why Dynapac GmbH put an emphasis on performance and user friendliness when engineering its new generation of pavers.
“We have adopted a modular construction principle, one we will be using for other models, too,” reveals General Manager Thorsten Bode. The first six versions are now ready for market – two models with electro-mechanical control and four with PLC..
New concept for the hydraulics
“Our partners to deliver the three central systems – internal combustion engine, hydraulic, and tamping beam – were selected early on. Close cooperation quickly ensued,” explained Carsten Bernhardt, Manager for Design and Development. The decision to select Rexroth as a partner was based on almost twenty years of successful collaboration.
Thomas Müller of Sector Management for Road Building Machinery was appointed as the Rexroth project director. He was responsible for coordinating all the trades, products and manufacturing sites. “This made it possible for us to contribute expertise in many industries, accumulated over decades,” he explains. “In this way I could, as needed, get experts from our company involved in the project.” They always found the best solution for every question – quickly and without additional communications effort for the customer. The ultimate result was a hydraulic concept that is convincing not only because of its high performance, but also because of its ease of maintenance. Wherever possible, all the hydraulic components are grouped together in the machine to achieve good accessibility.
Rexroth’s central electronic system permits measures to considerably reduce energy consumption and noise emissions.
The electronics need fear no comparison. Dynapac devised a modular control concept for the new road finishers. In the smaller units it commands the electro-hydraulic propulsion drive, while in the four larger versions the controls mimic the entire machine. A large share of the development work, consuming several man-years of work, was devoted to adapting the control functions to meet specific needs. According to Eberhard Lürding, project manager responsible for the work, this effort paid off for one particular reason: “We avoided using separate electronic units that would be operated with different interfaces and tools in each case.” That is why Rexroth developed a central electronic system into which third-party systems – such as regulators for tamping beam heating and functions – are integrated. Only one more process computer is needed – for leveling – and it also exchanges information with that central electronic unit made by Rexroth.
Persuasive new features
The central electronic concept let the developers realize a number of functions which simplify everyday work for the road building crew. The driver can select the “Variospeed” mode, in which the speed of the diesel engine is automatically matched to current power demand. The same operating principle is used for the hydraulically driven fan, which always regulates itself to the appropriate duty point. This not only makes the paving machine more economical; it is also easier on the ears, both for the road crew and those living near the construction site. The “Safe Impact” function also facilitates paving material refills during operation: “When a truck that fills the supply hopper bumps the paver during docking, that impact will cause unevenness in the road surface,” explains Carsten Bernhard. “We offer an optional, hydraulically damped advancing roller that absorbs this shock and makes for a flat and level wearing course.” In the operator’s cab, user-friendless is also a priority. In its PLC-controlled machines Dynapac implemented an intuitive operating menu for the driver, based on the BODAS DI3 color display. Already considered in the control concept are the wheeled pavers also in development by Dynapac.
The vehicles’ operating functions will be identical, while the driving functions will be much different. Thus the machines are equipped for the first time with a retarder function and the new series HLB high-level braking system made by Rexroth. This results in easily metered braking with minimum wear. Also included in the system is effective overspeed protection for the internal combustion engine.
Fewer parts, more service
The common parts policy aimed for by Dynapac has also been complied with in the new roadway finishers. “We were able to reduce the number of discrete components by thirty percent,” says Purchasing and Logistics Manager Thomas Matten. “That simplifies logistics and assembly and, at the same time, enhances parts availability for service work all around the world.” Management is thoroughly satisfied with this new type of cooperation – as are the customers. All the roadway construction companies that tested machines from the pre-production series were unanimously enthusiastic. Surprisingly, there was praise from an entirely unexpected quarter, as Product Manager Volker Behrens reports: “We even received compliments from the competition.”
Further information on Bosch Rexroth can be found at www.boschrexroth.co.uk. For further details contact Sean Kilgallen on (0)1480 223297 or by emailing email@example.com .