Crawler Tractors
PR 724 – PR 764
Product information
Grade control systems
Grade control systems for crawler tractors
To be successful despite the constantly increasing cost and time pressures, construction machinery must meet the highest
demands regarding working speed and accuracy. Increasingly, automatic grade control systems are utilized to improve the
productivity of operator and machine.
They utilize existing planning data to automatically guide the machine attachments when removing or spreading material.
With the aid of the most up-to-date technology, complex surfaces and exact grades can be produced quickly and precisely.
Advantages of automatic
grade control systems:
The use of stakes and string lines, as well as personnel •
costs for these tasks are dramatically reduced
No loss of time due to constant measurement checks •
or extensive rework, resulting in better machine
utilization
Fewer passes mean less wear and lower fuel •
consumption
More accurate grading improves material economy •
due to controlled material usage
Signifi cant cost savings for the owner and •
ultimately higher profi ts
Liebherr crawler tractors are eminently suitable for application of automatic grade controls, thanks to their innovative
drive system. The hydrostatic drive provides uninterrupted power without the need to shift gears. Due to the long tracks
and the perfect match of front attachment, working hydraulics, and base machine, exceptional grading properties are
ensured.
Depending on the type of application, various technologies are utilized. To simplify the installation, Liebherr offers a
number of installation kits. They ensure that the retrofi t installation of the grade control system on the crawler can be
completed without requiring access into the interior of the machine.
Grade control systems
2
Laser control
Applications
Creation of horizontal or sloped grades with high accuracy •
Suitable for small to medium sized construction sites •
Application for construction of sports fi elds, storage or dump sites, road construction, •
housing and residential areas, etc.
Components
Symbol images only
In terrain On the dozer blade In the cab
Rotary laser 1 or 2 laser receivers Option:
Cross slope sensor
Control unit
How it works
The rotary laser rotates at high speed and in doing so generates a reference plane out of laser light. This plane can be
horizontal or sloped, but it is always planar (two dimensional).
The laser receivers are installed on masts on the blade of the crawler tractor. They catch the emitted laser beam and
determine the current elevation of the dozer blade in relation to the reference height. For applications with lower accuracy requirements, a single laser receiver is suffi cient to determine the elevation of the blade (single laser). Normally,
two masts or one mast and a slope sensor are installed, this “dual operation” allows both the blade elevation as well
as tilt to be determined).
The control unit processes the signals from the laser receivers and the slope sensor and constantly regulates the
elevation and tilt of the blade automatically via the working hydraulics.
When working in automatic mode, the operator only needs to steer the tractor, while the grade control automatically
regulates the movements of the blade, creating a grade parallel to the laser surface.
Useful information
Visual contact between the rotary laser and the crawler is required•
Simple and comparatively inexpensive system, however no 3D contours can be created•
Several machines can work in the same grading level with a single rotation laser•
Height accuracy < 1 cm•
Grade control systems
3
GPS control
Applications
Establishment of large grades and complex, three-dimensional surfaces •
Suitable for medium sized to very large construction sites •
Application in road and rail construction, construction of golf courses, industrial facilities, earth moving, landfi lls, •
etc.
Components
Symbol images only
In terrain On the dozer blade In the cab
Base station 1 or 2 GPS antennas Option:
Cross slope sensor
Control unit
How it works
The mast-mounted GPS antennas on the blade receive signals from several GPS satellites and thereby establish the
position of the blade. The base station is needed to achieve the required accuracy. Its position is measured exactly
prior to commencement of work; it continuously sends adjustment signals to the machine via radio.
Also with the GPS, operation with one or two masts is possible. In two-mast operation, the elevation and the tilt of the
blade as well as its orientation is determined - minimizing grade deviations caused by angling the 6-way blade.
The survey data of the desired terrain profi le is available at the jobsite in standardized formats. They are transferred to
the memory card of the control unit and shown to the operator graphically on the display.
The operator can select between various views and therefore knows exactly where the machine is at this point in his
working range.
The control unit processes the signals from the GPS receivers, slope sensors and base station and compares them with
the stored specifi cation values. The elevation and tilt of the blade is automatically regulated via the working hydraulics
- creating a profi le that corresponds to the specifi ed terrain data.
Useful information
Visual contact between machine and the GPS satellites must be present. Not suitable for work underground, in •
narrow valleys or in forests
No visual contact between machine and base station is required•
A base station can control any number of machines on the jobsite (radio connection)•
Height accuracy < 3 cm•
Grade control systems
4
Grade control with total station
Applications
Establishment of large grades and complex, three dimensional surfaces with high accuracy •
Suitable for medium sized to large construction sites•
Can be used in road construction, construction of golf courses, terrain preparation for large residential or •
commercial sites, airport runways, etc.
Components
Symbol images only
In terrain On the dozer blade In the cab
Total station
Receiver Cross slope sensor Control unit
How it works
The total station captures and follows the receiver, which is installed on a mast on the dozer blade. The distance to
the receiver as well as the horizontal and vertical angles to it are constantly determined. The total station is calibrated
before starting the work to determine its exact location. The calibration allows the elevation and tilt of the blade to be
constantly monitored - providing exceptional grading accuracy.
Since these systems work with one mast only, a cross slope sensor is always required to determine the tilt angle of
the blade.
As with the GPS, the terrain data is stored on a memory card in the control unit. It processes the signals from the total
station, the receiver and the slope sensor, compares them with the stored design values and guides the blade constantly on the desired terrain profi le.
Useful information
There must be visual contact between the machine and the total station. If it is interrupted momentarily, an •
automatic adjustment is made by the station, or the operator actuates a new target search after the obstacle is
removed
One total station is required for each construction machine •
Can be used for creation of 3D surfaces with high accuracy or where no GPS reception is possible •
Height accuracy < 1 cm•
Grade control systems
5
Pre-installation kits for Liebherr crawlers
Which control system on which tractor?
Generally laser and GPS controls as well as systems with total station from all current manufacturers can be installed
on Liebherr crawlers. The fi nal installation is made by the respective system manufacturer or their dealer.
Pre-installation kits for PR 724 and PR 734
In practice, predominately small or medium sized crawler tractors are used for work with automatic grade control systems. Liebherr supplies installation kits for machine control systems from various manufacturers.
These kits, which are preinstalled at the factory, are available as optional equipment and include all the machine preparations required for subsequent installation of an automatic control system. This applies to electrical and hydraulic
installations as well as all mounts and plug connections.
With the factory installed pre-installation kit, the mounting of machine controls in the fi eld is signifi cantly simplifi ed.
The respective control components, such as masts, slope sensors, displays or control unit, GPS antenna, receiver
prism or data transmitters can be simply installed or plugged in without requiring access into the interior of the machine. Since these kits support all below listed systems of a manufacturer, a crawler can be subsequently upgraded,
for example from 2D to 3D at any time.
Pre-installation kit Installable control systems
TRIMBLE
PR 724, PR 734
TOPCON
PR 724, PR 734
LEICA
PR 724, PR 734
Grade control systems
6
2D-Laser control: GCS 300, GCS 400
3D-GPS control: GCS900 with single GPS or Dual GPS
3D- control with Total station: GCS900 with Tachymeter ATS/UTS
2D-Laser control: LS-B2 or LS-B110 Laser receiver
3D-GPS control: 3D-MC GPS or Millimeter-GPS
3D- control with Total station: 3D-MC LPS
2D-Laser control: Mikrofyn Mikrograde 2D / Leica Powergrade 2D
3D-GPS control: Mikrofyn Mikrograde 3D / Leica Powergrade 3D
3D- control with Total station: Mikrofyn Mikrograde 3D / Leica Powergrade 3D
Components of the pre-installation kits
Electrical preparation
Complete wiring in the inside of the machine including
plug connections, power supply connections and control
module.
Mounting brackets on the blade
Welded-on mounting brackets for the masts, as well as a
suitable mount for the slope sensor.
Hydraulic components
All required hydraulic valves and the complete hydraulic
hose system in the inside of the crawler.
Mounts and wiring for data receiver or radio antenna
Connector cable as well as installation possibility on the
cab for the data radio receiver, for operation with GPS or
total station.
Mounting for monitor, interface for control unit
Installation base and plug connection for control unit
(monitor) in the cab. For ergonomic operation, the automatic switch is integrated into the joystick.
Grade control systems
7
The Liebherr Group of Companies
Wide product range
The Liebherr Group is one of the largest construction
equipment manufacturers in the world. Liebherr’s highvalue products and services enjoy a high reputation in
many other fields, too. The wide range includes domestic appliances, aerospace and transportation systems,
machine tools and maritime cranes.
Exceptional customer benefit
Every product line provides a complete range of models
in many different versions. With both their technical excellence and acknowledged quality, Liebherr products offer
a maximum of customer benefits in practical application.
State-of-the-art technology
To provide consistent, top quality products, Liebherr
attaches great importance to each product area, its
components and core technologies. Important modules
and components are developed and manufactured inhouse, for instance the entire drive and control technology for construction equipment.
Worldwide and independent
Hans Liebherr founded the Liebherr family company in
1949. Since that time, the enterprise has steadily grown to
a group of 100 companies with over 32,000 employees
located on all continents. The corporate headquarters of
the Group is Liebherr-International AG in Bulle, Switzerland.
The Liebherr family is the sole owner of the com pany.
www.liebherr.us
Printed in Germany by Eberl BK-RP LWT/VM 11000766-0.5-12.09_enUS Subject to change without notice.
Liebherr Construction Equipment Co.
4100 Chestnut Avenue, Newport News, VA 23607, USA
콯 (757) 2 45 5251, Fax (757) 9 28 8701
www.liebherr.us, E-Mail: info.lce@liebherr.com
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