The AccuGrade GPS system, developed by Caterpillar and Trimble provides grade control accuracy dual antennae, the proper receiver, and a base station range within one mile. GPS grade control systems are currently available for dozers, motor graders, excavators, and scrapers available for other types of machines in the future. AccuGrade is designed for Caterpillar ARO (Option) machines, but it is fully compatible with current Trimble-brand equipment. Grade-control systems can be used to guide the operator, or they can be integrated into the machine control the blade hydraulics.

The Global Positioning System (GPS) is a highly accurate three-dimensional positioning system reference points. It works in any weather, anywhere in the world as long as there is no overhead reception, and a single GPS base station can support multiple machines.

Reference Station and Total Station

Total Station Systems can be used for both Site Positioning and Grade Control. Instead of a GPS base station communicating with satellites, a sophisticated electronic surveying instrument known as a total station is used to measure the site and provide guidance for grading equipment.

A Total Station system is preferred over a GPS system in applications with overhead obstructions that could interfere with GPS. A key advantage of this system is its ability to take remote measurements of surfaces that are inaccessible or dangerous to access by foot.

When properly calibrated, the total station can achieve a higher level of accuracy than GPS—3mm tolerance as compared to 10mm. It must, however, be calibrated periodically to deliver the specified accuracy.

Other potential disadvantages include a shorter range and a limitation of one rover or machine per total station.

Machine Control Systems

Laser-based controls systems consist of one or two antennae mounted on masts and a control box with two-dimensional display. The GPS— System consists of two mast-mounted GPS receivers, a communications radio, an angle sensor, and a three-dimensional display box.

The laser or GPS systems can supply blade guidance to the operator via left-right or up-down indicator units mounted in the cab, or they can be integrated into the machine’s hydraulics to automatically adjust blade height and tilt, leaving the operator free to steer and watch the work site.

The display boxes enable the operator to see where the machine is relative to the site and to the site plans at all times, and tell the operator (or machine hydraulics) where the blade should be at all times.

Caterpillar AccuGrade Ready machines (ARO Ready) are pre-wired to support this equipment and will provide the best performance and reliability. Caterpillar engineers designed the electronics and electro-hydraulic valves for each machine model and size class. The machines are wired ready for Laser, GPS, and ATS as they are going down the assembly line in the factory. This is far superior to an aftermarket install.

Altorfer can retrofit other machines as well. If your Dozer, Motorgrader, Hydraulic Excavator, or Scraper is not ARO ready, we can wire and set up the machine for you with a Trimble machine control system.


AccuGrade Dual Mast GPS Machine Kit will work on any Caterpillar Dozer, or Motor Grader with the attachment ready option (ARO).
Please call 319-365-0551 ext.285 for more information, pricing and availability.