Efficient hydraulics for compact road pavers

Efficient hydraulics for compact road pavers
Marginal Column

March 2017


Networked mobile hydraulics and electronics from Rexroth increase the driving and operating comfort of compact road pavers.

With a length of five meters, but just 1.80 meters wide, the Citypaver SD1800 from Dynapac is ideally suited to tight construction site environments and movement in heavily built-up city centers. The Citypaver uses the HYDROTRAC GFT 8000 transmission units from Rexroth. This modular drive series combines two and three-stage planetary gearboxes with axial piston motors to create an individually adapted drive package for mobile working machines.

Efficient hydraulics cut diesel consumption

As with any new mobile working machine development, reduced exhaust emissions and lower diesel consumption were both part of the specification. The power of the 54 Kilowatt diesel engine is intelligently distributed to the paver functions, reducing power losses to a minimum. Both the hydrostatic drive concept and the thermostatically controlled fan and load dependent hydraulic pumps contribute to this. Instead of power consuming fixed pumps, compact A1VO axial piston variable pumps from Rexroth are fitted. This variable pump enables energy savings of ten to 15 percent to be achieved. A further increase in energy efficiency is achieved through load pressure independent flow sharing.

The hydrostatic travel drive and working hydraulics are networked with a state-of-the-art control unit via CAN bus. Dynapac group realizes machine control by using two RC28 mobile controllers in master/slave mode from the Rexroth BODAS modular range. Combining the two controllers provides greater freedom in terms of the driving and working functions while complying with functional safety requirements.

BODAS DI4: universally usable operating and display unit. Magnifier

BODAS DI4: universally usable operating and display unit.


Complex functions at the push of a button

For the first time in this class, the new Citypaver uses the entire functionality of the PaveManager 2.0 operating system from Dynapac, which users will be familiar with from larger SD pavers.

Thiberio Tanus, the product manager for the Compact and Citypavers, emphasizes: “It was an explicit objective of the new development to adapt the operation and comfort of the large machines for the smaller Citypavers as far as possible.” With PaveManager 2.0 the road pavers automate functions such as the recording of laying parameters, storage of laying progress, and automatic settings for the straight crossfall angle and slope.

Dynapac utilizes the freely configurable BODAS DI4 display from Rexroth for the visualization and operation. This opens up a wide range of options for custom visualization and function assignment, which Dynapac are utilizing to the full. In addition to two hard keys for set functions, twelve freely programmable function buttons are available. In addition, the driver can intuitively select functions without visual contact with the control panel using a turn/push button. The new SetAssist function enables the driver of the machine to save the position of the screw conveyor and slab at the push of a button before they move the paver from one section to the next. The innovative TruckAssist system supports correct and safe docking of trucks on the paver.

The display also simplifies commissioning and service. Without the need for an external diagnostic unit, authorized maintenance engineers or operators can use the display to access the BODAS controllers integrated into the machine in master mode, and to read active and saved faults. This accelerates diagnosis. The service engineer can load new parameters for the BODAS controllers or transfer new sequence programs using the integrated USB interface. Last but not least, the display ensures short standstill periods, for example, because the joystick can be calibrated using the display after replacement. Anup Jacob, group leader for the Compact and Citypaver at Dynapac, is overall very positive: “When it comes to programming and parameterizing the control units, Rexroth brought their extensive experience with travel drives on large machines to bear and supported us the whole way, from design to commissioning.”