With its Generation 6 crawler excavators Liebherr achieves new levels of performance, economy, operator convenience and reliability. The new series of machines, which were on display at the 2009 Intermat, set new standards for crawler excavators in the 21 to 28 tonne category.
There are three of these new-generation crawler excavator models: the R 906 with a service weight of 21.7 - 23.3 tonnes, the R 916 Litronic (23.7 - 26.4 tonnes) and the R 926 Litronic (25.7 - 27.1 tonnes), the figures depending in each case on the machine’s equipment specification. Each of the three new models is powered by a Liebherr four-cylinder construction-machinery diesel engine. Outputs are 105 kW (143 hp) for the R 906 Litronic, 115 kW (157 hp) for the R 916 Litronic and 130 kW (177 hp) for the R 926 Litronic. These Liebherr engines comply with internationally valid exhaust emission limits (stage IIIA/tier 3). Engine management with CAN bus system integration keeps engine speeds more constant and thus optimises fuel consumption and makes more efficient use of the available power.
In response to differing market requirements and customers’ wishes, each of the three new crawler excavator models is available in either a ‘Classic’ or an ‘Advanced’ version. The ‘Classic’ Generation 6 versions are intended for typical earthmoving tasks; the ‘Advanced’ versions are equipped with an even higher level of innovative Liebherr technologies and are thus high-performance ‘full option’ products, suitable for all kinds of tasks. In addition to earthmoving, their very high performance offers customers valuable benefits in mining, embankment construction, industrial applications or on demolition sites.
The large number of hydraulic consumers on modern hydraulic excavators, often with three or more in use at the same time or partially synchronised, calls for the installation of technically mature, high-quality systems. All Generation 6 crawler excavators are therefore equipped with the “Positive Control” hydraulic system, which is a new development, and the corresponding control-system logic.
Two independent hydraulic circuits make it possible to energise components in the most efficient manner. In particular when movements have to be superimposed, the necessary volumetric flow can be made available quickly enough, with optimal use of the available energy. Maximum individual movement speeds are obtained by adding the pump circuits together.
The Liebherr “Positive Control” hydraulic system thus enhances performance when excavator movements have to be superimposed, for instance when grading and during travel either straight ahead or in a curve. The Advanced version’s higher operating pressure also increases tractive effort as well as tearout and breakout power.
