World's first hydrostatically powered crawler tractor in the 70 tonnes category premieres in China: Liebherr PR 776

The PR 776 is powered by a Liebherr 12-cylinder diesel engine developing 565 kW (768 HP / 759 HP). The PR 776 has a maximum operating weight of 74 t and is equipped with blade capacities of 18 m³ / 23.5 yd3 (semi-U blade) or 22 m³ / 28.8 yd3 (U blade).

Efficiency and performance: Modern, infinitely variable drive concept

The modern drive concept of the 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 from Liebherr.

Another advantage of the modern drive concept is the optimization of pressure flow. Hydraulic servo pressure is based on-demand according to the task. If, for example, the full feed of pressure supply is not required when operating, this is automatically returned.

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

The proactive power control is another innovation of the 6th generation 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, pulling power and a higher reverse speed.

Liebherr custom-engineers integral equipment solutions. The intelligent Liebherr engine management system combined with the Liebherr Power Efficiency System and 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. Differentiating Liebherr’s travel drive concept 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 crawlers when working in restricted spaces is the excellent manoeuvrability with continuous power to both tracks.

With an optional GPS navigation system, the work progress and the surrounding area can be visualized, increasing machine productivity and minimizing 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 PR 776 platform 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 for the 70 t crawler tractor’s 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 purposely designed. All instruments and operating controls are carefully organized for easy reach. All key functions and machine settings can be adjusted by the operator via the 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’s comfort. An automatic air-sprung seat detects and adjusts to the operator 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 on the PR 776.

Another feature in this class is the ROPS / FOPS protection 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.

The developed illuminated safety ladders are another safety factor. For optimal illumination of the working area, 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 to the respective use.

Reliability: Robust components manufactured in-house

Liebherr Diesel Engines have powered construction machinery 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 has also custom-developed different configuration packages in-house 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 are all features that speed up and simplify servicing work on the Liebherr PR 776 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, 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.