MINExpo 2016: World's first hydrostatically powered crawler tractor in the 70-tonne category: the Liebherr PR 776

The new PR 776 is powered by a Liebherr 12-cylinder diesel engine developing up to 565kW (757HP). It has a maximum operating weight of 74 tonnes (81.6 tons) and is equipped with blade capacities of 18.5m³ / 24.2yd3 (semi-U blade) or 22m³ / 28.8yd3 (U blade).

Efficiency and performance: modern, infinitely variable drive concept

The modern drive concept of the new PR 776 offers extremely efficient and safe operation to customers. A new feature in this machine class is the infinitely variable hydrostatic travel drive, which is used for all crawler tractors produced by Liebherr.

The ECO function is standard in all Liebherr Generation 6 crawler tractors – including the new PR 776. It allows operators to choose between high performance and maximum efficiency. The ECO mode enables greater travel drive efficiency in light to medium operations and also provides greater fuel savings.

The proactive power control is another innovation of Generation 6 crawler tractors. Internal engine and external machine parameters are recorded, such as the current deflection of the joystick. If required, the engine power is automatically increased for a brief period based on the current requirement. As well as responding more rapidly, the machines offer a significant increase in performance potential and pulling power with a higher reverse speed.

The intelligent Liebherr engine management system combined with the hydrostatic driveline allows Liebherr to master and optimize all equipment systems and processes to maintain constant engine speed, increase overall machine efficiency and reduce fuel consumption of the PR 776. The Liebherr travel drive concept distinguishes itself from other drive concepts available on the market, with which the engine speed fluctuates sharply during operation. All of these measures lead to significantly lower fuel consumption than the industry standard with similar pushing performance.

Another key advantage of hydrostatically powered crawler tractors when working in restricted spaces is the excellent manoeuvrability with continuous power to both tracks.

With an optional GPS machine control system, the work progress and the surrounding area can be visualized. This, in turn, increases machine productivity and minimizes operator stress and strain. Pendulum-mounted guide wheels and track rollers ensure excellent chain traction and significantly reduce equipment vibration.

Operator comfort: Intuitive operation

The operator quickly finds his bearings in the new cab of the PR 776 platform which was developed especially for this machine class. A focal point for development was the simple and safe operation of the crawler tractor. The multifunction joystick houses all operating and steering movements at the palm of the operator’s hand with only one electronic input element. This intuitive operating concept was subject to rigorous testing at Liebherr and is an important innovation of the 70-tonne (77.2-ton) crawler tractor category, particularly in mining applications.

The modern and spacious workstation in the PR 776 ensures excellent environment for greater performance and relaxed working conditions. The cab is designed for the job. All instruments and operating controls are carefully organized for easy reach. All key functions and machine settings can be adjusted by the operator via touchscreen display. ECO function parameters, automatic engine speed reduction, travel drive response, steering as well as standard safety functions such as the rear view camera can be all be accessed through the intuitive touchscreen display.

Operators can conveniently adjust multiple machine settings including travel drive, blade and rear ripper to their needs. Ergonomically shaped joysticks ensure operator comfort. An automatic air-sprung seat detects and adjusts to the operator’s shape and deactivates the machine when exiting the cab without a safety lever having to be actuated.

Maximum safety with excellent view of equipment and surrounding area

The modern design of the new Liebherr PR 776 offers all-round visibility for safe and efficient day-to-day operation. Safety is enhanced by the excellent visibility of the worksite, the blade and rear ripper, which is assured by the larger panoramic windows and downward slopes of the PR 776. A new feature in this class is the Roll Over Protective Structure (ROPS) / Falling Object Protection Structure (FOPS) integrated directly in the cab structure as standard for Liebherr crawler tractors.

Forward visibility is completely unobstructed as the exhaust system and lifting rams have been positioned behind the A-pillars. Also, the side view of the working area is clear and unobstructed by the extended work platform. This allows access to the cab, service points and filler necks for auxiliary and operating fluids.

Another safety factor are the newly developed illuminated safety steps. Depending on the chosen equipment level, high performance LEDs are used for ideal illumination of the work area. The modular lighting concept is one feature of the new machine design and makes it possible for the lighting to be adapted optimally to the respective use.

Reliability: robust components manufactured in-house

Liebherr diesel engines have powered construction machinery all around the world for decades. Developed for tough conditions, they guarantee maximum operational safety, reliability and a long service life thanks to the robust design and state-of-the-art technology. With the tried-and-tested hydrostatic Liebherr travel drive, components with high wear such as multi-speed gearboxes, steering clutches or service brake, are not installed. Instead, the high-quality hydraulic pumps and engines work practically wear-free and are particularly reliable.

Liebherr also has different custom-developed configuration packages for extreme applications such as deserts where extreme climates and low temperatures are common.

Optimal service accessibility and long change intervals

Centrally located maintenance points, access flaps and engine compartment doors that open to a wide angle, a tilting cab as standard equipment and, as an option, a radiator fan that can be swung out for cleaning – all of these are features that speed up and simplify servicing work on the new Liebherr crawler tractor. The new PR 776 has exceptionally long change intervals for operating fluids such as hydraulic or engine oil. Depending on the nature of the work, and provided that regular checks are performed, the change interval for Liebherr-plus oils can be as long as 8,000 hours of operation.

The standard Liebherr fleet management system LiDAT provides an accurate and efficient overview of essential servicing work, warning messages, the machine’s position and actual consumption data and filling levels. Depending on the agreement with the customer, the data is updated several times a day and can be called up whenever needed via the Internet.