| 摘要 |
1,205,109. Graders. BALDWIN-LIMA-HAM ILTON CORP. 6 Nov., 1968 [8 Nov., 1967], No. 52515/68. Heading E1F. [Also in Division G3] A steerable power-driven vehicle supports a ground levelling tool the vertical position of which is automatically adjusted by power means electrically controlled in dependence on the relative vertical position of a horizontal reference band of a detector carried by the tool and a collinated beam of electromagnetic radiation which determines the path of travel of the tool. In Fig. 1, the scraper blade 11 of an earthlevelling vehicle is carried by a ring 21 which is adjustable vertically, or about a fore and aft axis, by control of hydraulic actuators 17, 18. The vertical position of one end of blade 11 relative to a laser beam emitted from a source 30 is determined by a photo-voltaic detector 31 which controls actuator 18 in the appropriate sense to correct vertical deviation of the end of blade 11 from a position in which the laser beam falls on a narrow null zone of detector 31. A pendulum operated potentiometer 41 mounted on the vehicle to determine its transverse inclination is included with a preset potentiometer in a balanced circuit controlling actuator 17 to maintain transverse inclination of the blade at a value determined by the preset potentiometer. Further resistors vary with, and compensate for, changes in attitude of the ring relative to the chassis and the blade relative to the ring. Transverse inclination may alternatively be determined by controlling actuator 17 by a detector 61 responsive to a second laser beam, from a source 60, which need not be parallel to the other laser beam if it is desired that the inclination shall vary as the vehicle travels forward. Simultaneous control of actuators 17, 18 from one detector to determine the height of the blade is also referred to. Detector 31 also responds to the transverse position of the vehicle relative to the laser beam when it is in the null zone of vertical control. Hydraulic steering is then controlled automatically in a progressive manner to maintain the vehicle on a desired course. Further hydraulic actuators may be provided, e.g. to alter the cutting angle of the blade or shift it longitudinally. |
