| 摘要 |
PURPOSE:To alleviate loads on a blade by lifting it when stopped by overloading as well as exactly restore the blade to its original value by a method which two systems of set-value inputting means for determining the height of the blade are provided and the second set value is input while the first set value is stored. CONSTITUTION:Levels are input by the level setter 12 of a light receiver control system A, and the rod of the light receiver 4 is shrunk or extended to the level set value by a light receiver rod elevator 6. When light 19 from a light projector 18 is out of the center of the light receiver 4, the difference is transmitted to a cylinder control ststem B and the blade 3 is moved vertically. When operation is impossible due to overloading, a switch S2 is switched to the contact (b) side by an input unit 7, the elevator 6 is driven by the signal of the input unit 7 to lower the light receiver 4, the light 19 is out of the center of the light receiver, the blade 3 goes up, and loads on the blade 3 are alleviated. When the switch S2 is reset on the contact (a) side by a return switch 11a, the blade 3 is restored to the height of set indication value by the setter 12. |
