Bullish on dozer innovation

Liebherr’s new PR 766 crawler tractor meets the strictest emission norms without the use of a diesel particulate filter and offers a host of advanced features in the 50t category

When it comes to earthmovers, few other categories of equipment stand for power and brute force like a bulldozer does. And when it comes to equipment manufacturers, few other brands spell quality and innovation as Liebherr does.

So when the two – the bulldozer and Liebherr – come together, what customers get are products with some of the best reputations in the market for performance and reliability.

Liebherr’s dozer line-up already includes a wide sweep of models, from the small 15t PR 716 to the 70t behemoth PR 776. A comprehensive range of weight classes are covered by the Teutonic equipment giant, with models in the 40, 30 and 24t classes. What was missing from the Liebherr dozer stable, however, was an updated presence in the popular 50t class. And now, with the introduction of the new PR 766 dozer – or crawler tractor, as Liebherr says – that missing piece of the line-up jigsaw has finally fallen in place.

The new PR 766 crawler tractor offers the best conditions for continuing the success story of Liebherr crawlers, now in the 50t category. With operating weights of between 46.2t and 54.2t, the PR 766 is the successor model to the successful PR 764. The latest model in the crawler tractor generation, the PR 766 is driven by a powerful 422hp, 8-cylinder V-engine. With a blade capacity from 13.6 to 17 cubic metres and a travel speed of 11kph, it has all the basic attributes necessary to be a hard-punching machine in its weight class.

According to Leibherr, the PR 766 is characterised by a few innovations and improvements over its predecessor. The first of these is an engine management system with proactive power adjustment and an Eco mode to optimise machine performance and fuel consumption. A very significant step in the PR 766 is that it achieves Stage IV/Tier 4 emission standards by means of Selective Catalytic Reduction (SCR) only without the use of a diesel particulate filter (DPF). Another improvement is in the ergonomics department where the new developments in design enable the operator to work more efficiently, safely and comfortably. Reliability is also improved through the Liebherr drive technology.

The diesel unit in the PR 766 embodies the latest generation of Liebherr engine technology and therefore complies with the most advanced emission standards in the world. In this generation of engines, Liebherr combines emission reduction in compliance with the applicable standards with additional combustion savings in two technological steps. First, an optimised combustion process minimises the particles while they are still inside the engine. Liebherr has achieved this by developing its own Liebherr common rail injection system in conjunction with the engine control also developed by the company. In the second step, the exhaust gas after-treatment concept uses selective catalytic reduction. As a result, the new Liebherr diesel engines surpass Stage IV/Tier 4 emission standards without the use of a diesel particulate filter.

As a result of the hydrostatic drive in the PR 766, the speed of the diesel engine can be kept constant in practical use regardless of the required load. The unit therefore always runs at the optimum efficient speed. The fact that speed fluctuations are avoided, sets the Liebherr travel drive apart from all other large crawler tractor drive concepts currently available on the market, the company claims. Essential drivetrain components are developed in-house and optimally coordinated, which increases the efficiency of the system as a whole.

As with all of Liebherr’s Generation 6 crawler tractors, the PR 766 comes equipped with the ‘ECO function’. This gives the driver the opportunity to choose between high performance and maximum efficiency. In lightweight to moderately heavy applications, the ECO control system ensures increased efficiency and therefore additional fuel savings compared to conventional drive concepts.

The proactive power adjustment is another innovative feature of Generation 6. This involves both internal engine and external machine parameters being recorded, such as the deflection of the drive joystick, and the engine power is automatically increased for a short period based on the current demand. As well as enhanced response behaviour, this results in a noticeable improvement in performance capability and torque output.

The new PR 766 Litronic is equipped with an oscillating undercarriage as standard. This allows the track rollers to be flexibly adapted to the surface. As a result, the machine’s traction, but also its smooth running, is significantly increased, particularly when used on stony ground. Unevenness in the ground is ironed out through the elastic suspension and impact loads are reduced to a minimum. This not only increases comfort for the driver, but also improves the service life of the undercarriage and reduces the wear on the installed components and the steel structure.

When operating crawler tractors in low temperatures, Liebherr offers numerous special options ex-works, which have been developed in close collaboration with end users. Other extreme conditions are also dealt with without fuss by the machine and Kai Friedrich, the company’s managing director, earthmoving and mining division, says Liebherr products have key advantages in the current market, notably technical reliability and durability – especially in the challenging heat, humidity and dust levels of the Middle East, as proven by the five models popular here, starting from the 20t-class PR734 to the giant 70t-class PR776.

Speaking to CMME in an earlier interview, Friedrich had said: “Our machines have been proven to be very reliable. They are certified, and as a result they are accepted by large global companies, all of which have strict safety requirements.”

Intuitive operation

Speaking of safety turns the focus immediately to the operator and his environment. Liebherr says that the large cab in the PR 766 is identical to the driver’s platform in the 70t PR 776 crawler tractor launched last year. During the development of this new driver’s platform, the focus was placed on simple and safe machine operability. The driver will get to grips with the interior of the modern cab designed for maximum comfort immediately and intuitively. With Liebherr’s successful single-lever operation, the driver can control all driving and steering movements with just one joystick.

The spacious work area in the PR 766 provides the best conditions for effortless work. The special features in the cab include the centralised control elements and the touch-controlled colour display, as well as many storage areas and a climate-controlled storage compartment. The driver can use the central display to intuitively control important operating parameters, such as the ECO function, the travel drive’s response behaviour and the steering, and use comfort and safety functions, for example the rearview camera, which is fitted as a standard.

The driver can adjust the control elements for the travel drive, blade and rear-mounted ripper to the most suitable ergonomic position for them. The ergonomically optimised shaping of the joystick makes working as comfortable as possible. The desired travelling speed range can be preselected directly on the joystick. 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 the driver having to actuate a safety lever. The joystick for the rear-mounted ripper is a new feature; this can now be adjusted in two axes and serves as a handle for the driver during the ripping process.

The modern design of Liebherr’s new PR 766 offers the driver an excellent view in all directions, which makes work particularly efficient and increases safety in daily use. Edges which slope away on all sides and the all-round panoramic window ensure ideal panoramic visibility of the land, as well as the blade and rear-mounted ripper.

Liebherr’s modern design, overall quality and excellent usability, of which operator-friendliness is but one aspect, has made the brand increasingly popular in the Middle East, says Friedrich. “Liebherr has experienced positive developments and market figures indicate substantial growth in equipment sales. Dealers and subsidiaries are also seeing progress in sales and expansion. In fact, market figures since the 2009 recession show that in the Middle East, the number of Liebherr machines exported to the region has continuously increased,” he says.

A huge reason behind this is Liebherr’s technology, reliability and durability, Friedrich adds. And this is one aspect in which the new PR 766 is not found wanting. The machine’s hydrostatic Liebherr travel drive omits high-wear components, such as torque converters, multi-speed gearboxes, steering clutches and service brakes. Instead, high-quality and particularly reliable hydraulic pumps and hydraulic motors operate with virtually no wear.

Centralised maintenance points, wide-opening access flaps and engine compartment doors, as well as a tilting operator’s cab as standard, enable easy maintenance access. This is enhanced by engine compartment lighting as standard, which makes sure that daily checks can be performed quickly and efficiently, even in poor lighting conditions. The intervals for changing the hydraulic oil on the new PR 766 can be extended to up to 8,000 operating hours if the hydraulic oil is monitored accordingly.

The LiDAT fleet management system, which is supplied as a standard, provides comprehensive machine data with this state-of-the-art communication technology. This additionally improves efficiency in practical, by enabling optimised operational planning and reliable remote monitoring. The data is updated several times a day and can be conveniently called up at any time using a web browser. An automatic alarm can be set up for particularly important information, for example if the machine leaves a predefined zone or if a critical operating situation arises.

The PR 766 is currently available initially in the North American market, says Liebherr. However, with the 50t dozer an important piece of kit in the Middle East, CMME feels it only remains to be seen when, rather than if, a version of the machine suitably modified for lower emission standards is seen on region’s job-sites.

SPECIFICATIONS: Leibherr PR 766 Crawler Tractor

Operating weight: 46.2-54.2t

Blade capacity: 13.6-17 cubic metres

Engine: 8-cylinder V

Power: 422hp

Travel speed: 11km/h


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