Automatic control systems for rippers for use in civil works

An automatic control system for a ripper utilized in a civil work comprising a switch circuit for selecting and commanding the raising and lowering of the shank of the ripper when entering into a digging region from a piercing region and the raising and lowering of the shank when entering into the piercing region from the digging region;

• first detecting means for detecting the fact that the shank is in the piercing region or in the digging region;
• second detecting means for detecting the fact that the shank angle is at a preset piercing angle or a preset digging angle;
• third detecting means for detecting an overload condition of the shank;
• fourth detecting means for detecting upper and lower limit positions of the shank;
• an electric control signal generating circuit for generating a first control signal for commanding the tilting and lifting of said shank in accordance with the output from said first to fourth detecting means at the time of said lowering command, and a second command signal which effects extension, contraction and stop of a tilting cylinder for the shank at the time of a tilting command, and effects the contraction of said tilting cylinder only at the time of overload and at the time of a lifting command;
• said electric control signal generating circuit generating said first control signal that commands the lifting and tilting of said shank in response to the output from respective detecting means at the time of said raising command, and generating said second control signal that commands the extension, contraction and stop of the tilting cylinder for said shank at the time of said tilting command, and commands the contraction and stop of said lifting cylinder at the time of the lift command;
• a tilt-lift transfer controlling fluid pressure circuit including a first electromagnetic transfer valve actuated by said first control signal, and a lift-tilt transfer valve actuated by the operating fluid supplied by said first electromagnetic transfer valve for supplying the operating fluid to the selected one of said lifting cylinder and said tilting cylinder;
• and a fluid pressure circuit for controlling the direction of flow of the operating fluid including a second electromagnetic transfer valve actuated by said second control signal, and a main transfer valve actuated by the operating fluid supplied by said second electromagnetic transfer valve for switching the direction of the operating fluid supplied to respective cylinders thereby selectively performing the lowering control and the raising control of said shank.