PR 746 and PR 756: Liebherr expands new Generation 6 Crawler Tractors upwards

The new Liebherr crawler tractor PR 746 Litronic offers an operating weight of 28,900 kg to 30,800 kg and its Liebherr diesel engine returns 185 kW / 252 HP. The largest of the new Generation 6 crawler tractors, the PR 756, has an operating weight of 38,300 kg to 41,150 kg and an engine output of 250 kW / 340 HP.

The main components of the new crawler tractors come from Liebherr’s own production facility. Among these are the diesel engine and the common rail injection system as well as the hydraulic and electronic components. These are adapted optimally to the requirements of the machine programme. Here, Liebherr can draw from over 50 years of experience in the development of crawler tractors.

In April 2014, sales began of the PR 736 Litronic, previously presented as a pre-series machine at the Bauma 2013 trade fair, and thereby the first crawler tractor of the new Generation 6. Many customers have been impressed since then by the qualities of the new machine.

The new crawler tractors PR 746 and PR 756 are powered by 6-cylinder Liebherr diesel engines that comply with the stage IV / tier 4f emissions standards. In order for the requisite emissions and consumption targets to be fulfilled, Liebherr has optimised the entire combustion process and has already reduced the particulates within the engine to a minimum. For ideal adaptation of the various parameters, support is provided, among other things, by the development of an in-house common rail injection system including an in-house electronic engine management system.

To simplify the system and to optimise exhaust gas after treatment for challenging operations, selective catalytic reduction, SCR technology and thereby a diluted urea solution, e.g. AdBlue®, are employed. The efficient combustion in turn facilitates lower fuel consumption and provides economical benefits to the customer.

Highest performance and economy

The Generation 6 Liebherr crawler tractors feature a newly-developed, electronically-controlled drive management system with integrated ECO function. This enables the driver to choose between high performance and maximum economy. Here, compared with the previous generation, the ECO control system ensures more efficient operation of the travel drive for light to medium-heavy operations.

Another new feature of the Generation 6 is the proactive power control. In this instance, internal engine parameters as well as external machine parameters are detected, such as the current degree of drive joystick deflection, resulting in engine performance being elevated automatically for a short period to match the current demand. As well as responding more rapidly, the machines offer a tangible increase in performance potential and pulling power.

This hydrostatic drive keeps the engine speed at a constant level. All of the drive components and the intelligent Liebherr engine management are harmonised optimally to each other. The Liebherr travel drive is distinguished by a high level of efficiency and low fuel consumption.

To simplify the use of automatic machine control systems, Liebherr supplies ex-factory preparation kits for leading manufacturers’ systems; these kits are also available for Generation 6 crawler tractor models. This makes it significantly easier to install 2D and 3D control systems and affords the operator the highest level of flexibility in choosing the system.

The combined inch brake pedal installed as standard on both machines makes it easier to switch from conventionally driven machines to the new Liebherr Generation 6 crawler tractors because the braking function of the hydrostatic travel drive can also be activated with the foot pedal as well as the joystick. An optimal enhancement to this is the 3-stage drive joystick (forward, stop and reverse positions), which is available as an option.

Modern design and convenient new cabin

The modern design of the new Generation 6 crawler tractors, with falling edges on all sides and uninterrupted panoramic glass pane, offers the driver an optimal all-round view of the terrain as well as the blade and rear ripper. The view over the engine cover is not hindered by the exhaust system and rams as these have been positioned behind the A-pillar. A good all-round view promotes particularly efficient work and increases safety in daily use.

The driver cab has been newly designed from scratch: The new drive controls can be moved longitudinally to the most ergonomic position for the driver and, with the new T-shape, allow more ergonomic handling and thereby more comfort. The desired travelling speed range can be preselected directly on the joystick. In this way, control of the tractor can be apportioned precisely, especially at low speed. Driver detection takes place automatically by means of the integrated seat contact switch without a safety lever having to be actuated.

All tractors of the new Generation 6 are equipped with the touch-sensitive system display for Liebherr earthmoving machines. In this way, important operating parameters such as the ECO function and convenience functions such as the air conditioning system can be operated intuitively with a clear overview.

For optimal illumination of the working area, modern lights such as high performance LEDs are used depending on the chosen equipment level. The modular lighting concept is an element of the new machine design and makes it possible for the lighting to be adapted optimally for the respective use.

Simple maintenance and low operating costs

Centralised servicing points, wide-opening access flaps and engine compartment doors, a driver cab that tilts as standard and fans that fold out for cleaning (optional on engine side) facilitate perfect service access and simplify the maintenance process. The replacement intervals for the hydraulic fluid on new models can be up to 8,000 operating hours, depending on deployment and with regular quality checks.

The running gear of both crawler tractors has been completely re-developed. The considerably larger diameter of the split sprocket wheel with more teeth in engagement extends the service life of the bushes and sprockets. For the new PR 756 Litronic, there is a pendulum chassis available as an option. This makes it possible to adapt the track rollers flexibly to the ground. In particularly rocky terrain, the pulling force to be transmitted and the machine’s smooth running properties are thereby significantly increased. Unevenness in the ground is ironed out through the elastic suspension and impact loads are reduced to a minimum. This increases not only the service life of the chassis but also protects the whole machine against damage.

Using state-of-the-art communication technology, the Liebherr fleet management system, LiDAT, installed as standard, provides detailed information about the machine’s operation and allows it to be managed efficiently, optimises planning and allows remote monitoring. Depending on the subscription, the details are updated several times a day and can be called up whenever needed in a web browser. An automatic alarm function can also be set-up if a machine leaves a predetermined zone, for example, or if a critical operating situation arises.