| 摘要 |
<p>The laser alignment system (49) of the apparatus for leveling flowable material, in which two radiant energy beam detectors (51, 53) mounted on opposite ends of an elongated leveling member (15) are responsive to a projected radiant energy beam establishing a leveling plane (59), is modified for operation when one of the detectors (51, 53) is blocked from receiving the projected beam by an obstruction such as a support column (68), equipment or personnel. Whereas, each detector signal is normally used to generate a separate adjustment signal for an adjustment device such as a hydraulic cylinder (31, 37) to raise and lower the associated end of the elongated leveling member (15), when one detector is blocked from receiving the radiant energy beam the detector elevation signal generated by the other, unblocked detector, is used to generate the adjustment signals for both ends of the elongated leveling member (15).</p> |
