Liebherr has expanded its Generation 6 dozer line to include two new models in the 30 to 40 ton class, the PR 746 and PR 756 Litronic. If you were at the 2013 Bauma, the big construction trade fair in Germany, you saw some of Generation 6 improvements with the introduction of the PR 736. If not, well here you go:
The most significant change to the new models is a redesigned operator station, and most impressive in that regard is the view to the blade. Liebherr put both the exhaust stack and the blade cylinders inline with the A pillars supporting the cab, so none of these elements crowd out your sight lines to the blade. With the cab glass dropping all the way to the floorboards you have a clear and unobstructed view of the top and bottom edges of the blade on both sides. The sheet metal slopes also aggressively downward so your view to the sides and the rear is excellent as well.
In the cab, the Generation 6 dozers put adjustable horizontal arm rests where your forearms sit naturally in the operator seats so your grasp of the joysticks is relaxed and natural. A display monitor allows you to set many of the machine’s parameters on a touch screen. Another nice touch–the storage compartment in the cab is cooled. Your lunch doesn’t go bad before you have a chance to eat it.
These dozers enjoy all the benefits of hydrostatic drive transmissions: infinite speed control, stepless gear changes, hill holding ability, dynamic braking and counter-rotation. An inch-brake pedal is standard and gives you creep control for tasks that require slow-speed finesse. And there is a power boost function for those times you really need to bust a move.
Hystats also electronically manage the power to the ground so your engine stays at a constant rpm, saving on fuel and improving engine life. You can also choose between a high-performance setting for maximum power and torque, or an ECO mode to save fuel in less demanding applications.
Daily service points are located on one side of the machine. The engine bay has a light in it, so you can don’t need a flashlight to do service work after the sun goes down. The cab tilts up hydraulically and the cooling fans swing out adding additional convenience and efficiency in the service cycle.
For the undercarriage, a larger drive sprocket with more teeth provides more wear surface and thus lasts longer. You can also order the PR 756 with an optional bogie system, what the company calls a pendulum chassis. In this design the bottom rollers of the undercarriage are paired up two-by two and each pair connects back to the frame on a single shaft so when you roll over a rock or other small obstacle the paired rollers oscillate over the obstruction rather lifting the whole machine up. The end result is a smoother ride and your grousers stay more firmly planted on the ground.
Liebherr’s fleet management telematics system, LiDAT, is installed as standard. And the dozers are configured to make it easy to install 2D and 3D GPS machine control systems.
The PR 746 weighs 63,714 to 67,902 pounds and uses a 252 horsepower engine. The PR 756 weighs 83,775 to 90,390 pounds and is driven by a 340 horsepower engine. The company uses its own 6-cylinder diesel engines in these machines. They are Tier 4 Final compliant and use SCR/urea injection as the primary emissions control technology.
This article was written by Tom Jackson, Executive Editor of Equipment World.