| 摘要 |
PROBLEM TO BE SOLVED: To automatically detect a desired rake angle by inputting a detected value and a desired rake angle instruction value to a control device, controlling a rake angle control solenoid valve having a hydraulic circuit via an arithmetic operation circuit used for comparative operation, and feeding pressure oil to a ram elevating drive cylinder. SOLUTION: A dog and an oscillatable lever fitted to a rake angle adjustment device convert the vertical motion of a ram 23 to a rotary motion, and the turning displacement of a rotary shaft connected to the lever is directly detected with an encoder. A rake angleθis thereby detected automatically. Furthermore, a value detected with the encoder and the prescribed value of a desired rake angle are simply and electrically compared with each other via an arithmetic operation circuit 67, and the rake angle control solenoid valve 87 of a hydraulic circuit 61 is controlled, thereby automatically changing the rake angleθ.
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