SEAL 5276591 - Caterpillar

The Working Window
Before you pave, the operator will use the control box in order to calibrate a control region or a zone around the control reference. This process is also called nulling.
Illustration 10 g00815450
The working window is a zone that is 6 cm (2.4 inch) above and 6 cm (2.4 inch) below the On Grade distance. The screed can be controlled automatically if the distance that is measured by the Sonic Tracker II® is within the working window. If the distance that is measured is outside of the working window, the control is switched to the MANUAL position. No corrections are sent to the control valve until the distance that is measured is returned within the working window. This prevents the system from diving. This would occur if the Sonic Tracker II moves off the control reference. Examples of these control references would be skis, stringlines, or curbs. In the AUTO mode, the control box tries to keep the control reference at a constant distance from the Sonic Tracker II. The Sonic Tracker II measures the distance to the control reference. The control box will determine the orientation between the working window and the control reference. This occurs if the control box determines that the system is not On Grade. Once the orientation is determined, the control box displays the appropriate correction symbol on the grade adjustment LED that is located on the control box and on the Sonic Tracker II LED. The control box sends correction signals to the solenoid valves for the tow point cylinders in order to adjust the screed to On Grade.
Illustration 11 g00815337
The LED display on the Sonic Tracker II will flash in two second intervals. One of the LED arrows above the grade correction knob will flash. To bring the working window around the control reference, adjust the arrows that are located above the grade adjustment knob. Turn the knob in the same direction of the arrow. The system will also be placed under manual control.Interlock for Travel
The interlock relay opens the circuits to the solenoid valves on both