Cat® Grade Control for D6T Track-Type Tractors Caterpillar

The Cat^® Grade Control system includes various features that complement or integrate with the system as a whole. Many Track Type Tractors share the same features with some slight variations but generally the features automate an implement function on the machine. The grade control system features are given below:

• The Grade Control system supports automatic control of the blade lift and tilt to maintain a desired elevation using the Grade Control Mode setting to determine how the feature interacts with the loaded design.

• The Grade Control system supports automatic lift and lower of the blade to maintain a desired Blade Load Factor with the AutoCarry feature.

• The Grade Control Mode allows operation in Rough Grade Control or Grade Control modes.

Grade Control Mode

The Grade Control Mode is one of two modes that the system use for controlling the blade. The grade control mode can be selected by clicking the "Setup Menu" > "Configuration" and selecting "Grade Control Settings" menu. The Grade Control Mode can also be selected by pressing and holding the "AutoCarry" softkey from the main screen which will directly open the "Grade Control Settings" menu. With this mode of operation selected, the grade control system becomes active when the left yellow button of the implement joystick is pressed.

When the machine is operating in Grade Control Mode, the blade lift and tilt are controlled by the Implement Electronic Control Module (ECM) in accordance with the selected guidance method. Grade Control Mode controls the blade along the design plan in accordance with the selected guidance method. Typically, "3D, 1 Point Center" is used as the guidance method when selected and operating in Grade Control Mode. The system will not allow either blade tip to pass through the design plane. Once a blade tip has been engaged with the design plan, the system will actively control the blade lift and tilt to maintain the blade on the design plan. There are some instances when the machine is working around design transitions and slope using the "Lane Guidance" feature or selecting "3D, 1 Point Focus" for the guidance method is helpful.

During Grade Control active operation:

• The CB460 Grade Control display will show the design plan for the work to be performed.

• The ECM will automatically begin controlling the lift and tilt of the blade when one tip touches the design plan.

• The ECM will control the lift and tilt of the blade to maintain the blade on the design plan in accordance with the selected guidance method.

• The system will ignore operator commands to force the blade beneath the design plan through lower or tilt commands.

• The operator may raise or tilt the blade above the design plan using the joystick, but as long as one blade tip is still touching the design surface, the system will resume automatic control. If both blade tips are above the design surface after a manual blade up lever command, the system will not resume automatic control until one of the blade tips again touches the design surface.

• AutoCarry can be active.

When operating in Grade Control mode with the AutoCarry feature active:

• AutoCarry controls blade lift to meet AutoCarry machine load setting configured in the "AutoCarry Settings" menu of the CB460 Grade Control display.

• Grade Control will take over blade lift and tilt control if a blade tip touches the design plan.

• When the blade is being controlled by the Grade Control system and AutoCarry blade load setting is met, the AutoCarry feature will have priority to lift the blade off the design plan to maintain the proper blade load.

• When circumstances reduce the blade load on a machine, the AutoCarry feature will lower the blade to maintain the blade load, up until the blade load setting is met or the blade comes in contact with the design plan.

• AutoCarry will be deactivated when the machine is shifted into reverse gear and will automatically become active when a forward gear is selected.

Note: The engine must be running at a speed above low idle speed, the parking brake released, and the implement lockout switch must be released before any of the Grade Controls features can be activated. Depressing the Decel pedal will deactivate the AutoCarry feature. Manual commands are used whenever the blade is above the design plane.

When in Grade Control Mode, regardless of the selected guidance method, the system monitors the left and right blade tip. Grade Control Mode will control the blade tip that is first to hit the design. The blade will then be commanded to tilt to place the other tip on the design.

If both blade tips are on design, the system will monitor both tips and ensure that the tips are both controlled to stay on the design. The system will ensure that both tips are stopped from going through the design, if the operator commands to lower the blade.

During a fill situation, the blade tip that is first to cross the control range threshold will initiate the automatic control and continue to drive the blade to the design even if it is in the air. The blade tips will stay on the design surface unless a manual command lifts the blade. In cases where the severity of the terrain or track movement causes the blade to lift above the design surface before the hydraulics are able to respond, the system will drive the blade back to the design surface.

In some cases when operating in rough terrain, the operator may unknowingly cause a small lever command that brings the system out of automatic control.

Note: A manual override command by the operator to raise the blade will result in manual operation until the blade contacts the design plane again.

Rough Grade Control Mode

Rough Grade Control is an operating mode of Grade Control system. Rough Grade Control, controls blade height at the center of the blade but does not control blade tilt. Blade tilt is controlled by the operator for steering and digging tasks without interference from Grade Control.

Rough Grade Control Mode is best used when removing difficult material or large amounts of material. Rough Grade Control can be used with AutoCarry by selecting Rough Grade Control from the Grade Control Mode and toggling the AutoCarry softkey to the ON position. Rough Grade Control is suited for removing large amounts of material prior to grading operations.

Note: AutoCarry will only function with the integrated Grade Control system and not Blade Mounted Global Navigation Satellite System (GNSS) Receiver systems.

When active, the Implement ECM will not allow the center of the blade to travel below design plan. The rough grade feature controls the blade height at the center of the blade but does not control the blade tip height. Blade tilt may still be adjusted by the operator to help steer or dig. Rough Grade mode prevents the center cutting edge of the blade from traveling below design plan based on algorithms in the Implement ECM. The Implement ECM software calculates blade center cutting edge height based on inputs from measure up, lift cylinder position sensor signals, blade rotation cylinder position sensor signals (if applicable), and machine pitch and roll angles from the chassis Inertial Measuring Unit (IMU).

During rough grade active operation:

• The CB460 Grade Control display will show the design plan for the work to be performed.

• The operator always controls blade tilt.

• The rough grade controller will automatically control blade lift cylinders when the center of the blade is engaged with the design plan.

• The operator may manually lift the blade off the design plan using the implement joysticks at any point in time.

• The operator must manually lower the blade to the design plan to reengage the rough grade feature after lifting the blade with the joystick.

• AutoCarry may be active.

Grade Control Mode and Guidance Method Interaction

The Guidance Method and the Grade Control Mode (Grade Control or Rough Grade Control) interact to allow the operator full control of the blade in various applications with both simple and complex design features. Expected operation may change based on the selected combination of these two settings.

In Rough Grade Control Mode, guidance for the center of the blade will be obtained from the selected Guidance Method. The different guidance methods are given below:

• If Guidance Method "3D, 1 Point Center" is selected, the system will control the center of the blade based on a center guidance point.

• If Guidance Method "3D, 1 Point Focus" is selected, the system will control the center of the blade based on a focus point located guidance point.

• If Guidance Method "3D, 2 Points Tips" is selected, the system will control the center of the blade based on a design plan established by the two guidance points established from the blade tips.

Note: Guidance method is discussed in Operation and Maintenance Manual, SEBU8851, "Cat^® Grade Control 3D for the D6T Track Type Tractor".

Grade Control with AutoCarry Feature

The AutoCarry feature automatically raises or lowers the blade to ensure more productive blade loads. When AutoCarry is used with Grade Control, the system ensures that the cutting edge does not go below the design plane. AutoCarry will maintain a productive blade load.

Cat Grade Control Settings and Configuration

The Grade Control system and the AutoCarry feature use many of the same configuration settings, measurements, and calibrations.

Note: Incorrect settings, measurements, or calibrations may adversely affect the performance of the machine when utilizing Grade Control, Rough Grade Control, or AutoCarry.

Machine Measurements and Calibrations

Machine dimensions and Grade Control calibrations must be completed prior to attempting to tune the system. Both Machine dimensions and Grade Control calibrations can severely affect the system accuracy and performance.

Note: REHS9783, "Cat^® Grade Control Calibration and Measure-Up Procedure for Certain Track Type Tractors" provides detailed instructions on completing an initial measurement and calibrations on the machine for the Cat Grade Control system or if servicing the machine indicates that measurement and calibrations are required.

Cat Grade Control Software Enabled Attachment

All Grade Control tractors delivered from the factory should come with the Software Enabled Attachment (SEA) installation status for the Grade Control system set to Installed.

Note: If the Grade Control System installation status is not set to installed, the Grade Control system will not function and the CB460 Grade Control display will not connect properly to the ECM.

The Grade Control System installation status should show "Installed" and the Grade Control System enablement status should show "Enabled" for the system to function properly. The system may be disabled to suppress any Grade Control diagnostic codes from faulty components without the necessity to obtain a factory password from the feature protection system.

Cat Grade Control Valve Speed Settings

The Grade Control system supports valve speed settings to allow the user to adjust the system to achieve desired system performance under various conditions. The Grade Control system may perform differently depending on the material type and conditions. System response with gravel will be different from clay.

Note: The behavior of the system will change based on whether the material is wet muddy dirt or loose dry dirt.

Illustration 1	g06056328

The Grade Control valve speed may be changed through the onboard CB460 Grade Control display by accessing the "Configuration Setup Menu" and selecting "Valve Speed". There will be options to select the valve speed setting for the"Lift valves" or the "Tilt valves".

Within the menu, the valve speed value may be adjusted higher to get a faster blade response by moving the slider to the right. Similarly, the valve speed value may be adjusted lower to get a slower blade response by moving the slider to the left.

The lift valve speed has been split into a raise speed and a lower speed to allow finer custom tuning of the Grade Control system. Gravity and blade weight can affect system responsiveness differently for the blade raise movements and the blade lower movements.

Note: The valve speed in the CB460 Grade Control display will not affect manual response of the machine when Implement Joystick commands are given.

Note: The Valve Speed settings are intended for system adjustments after Lift, Lower, and Tilt Solenoid Calibrations and Tool Automation Implement Valve Calibration have been properly completed. Although adjusting the valve speed may achieve a stable Grade Control system response, it will be unlikely to provide the best performance. Having a valve speed value set to a different value from the default 50 value will not affect the completion of either Solenoid Calibrations or the Tool Automation Implement Valve Calibration.

More details regarding the relationship between the Valve Speed and Grade Control calibrations are discussed in the Cat Grade Control Performance Troubleshooting section.