| 摘要 |
A control system controls movement of individual hydraulically moveable ends of a screed head carried by a boom of a machine so as to maintain a selected elevational position between each end of the screed head and a reference in a concrete paving application. One of a pair of elevation receivers is mounted at each end of the screed head, providing a first and second signals indicating the position of the first and second ends of the screed head in relation to the reference. A sensor, mounted on the screed head, senses the orientation of the screed head along its length from the first end to the second end and providing a third signal indicating such orientation. A control circuit, responsive to the elevation receivers and to the sensor, controls the hydraulically moveable ends of the screed head using the first and second signals from the elevation receivers when the first and second signals are available, and controls the hydraulically movable ends of the screed head using the third signal from the sensor and one of the first and second signals from the elevation receivers when the other of the first and second signals is not available.
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