Control system of an excavator

An excavator which comprises:

• a working device having a plurality of links comprising a boom attached to a tip of an upper pivoting body pivoting with respect to a lower running body, an arm attached to a tip of the boom, and a bucket attached to a tip of an arm;
• a pivoting device for driving and pivoting the upper pivoting body with respect to the lower running body;
• a running device for driving left and right chain belts of the lower running body;
• hydraulic cylinders and hydraulic motors for actuating the working device, the pivoting device, and the running device;
• hydraulic control valves for controlling quantities of hydraulic fluid supplied to the hydraulic cylinders and the hydraulic motors;
• a boom angle detecting sensor installed between the upper pivoting body and the boom, for detecting a relative angular position of the boom with respect to the upper pivoting body;
• an arm angle detecting sensor installed between the boom and the arm, for detecting the relative angular position with respect to the boom,
• a bucket angle detecting sensor installed between the boom and the bucket, for detecting the relative angular position with respect to the arm;
• a control system having a pair of manipulating devices each of which can be manipulated in at least three directions so as to output electrical signals proportional to deviated amounts in selected directions among the directions from a neutral position thereof, a switch board on which a plurality of function switch are installed, for transferring a signal in accordance with a selected function and displaying the selected function, a control section for controlling quantities of hydraulic fluid supplied to the hydraulic cylinders and the hydraulic motors by receiving signals from the manipulating device, the switch board, and the angle detecting sensors and transferring the signals to the hydraulic control valves.