Patent ID: 7289896

Claim:
A working unit control apparatus of an excavating and loading machine comprising: a boom cylinder controlling a lift of a boom; a boom control valve controlling extension and compression of the boom cylinder; a boom lever instructing an extension and compression speed of the boom cylinder; a boom lever operating amount detector detecting an operating amount of the boom lever; a bucket cylinder controlling a tilt of a bucket, said bucket being rotatably attached to said boom for lifting by said boom; a bucket control valve controlling an extension and compression of the bucket cylinder; a bucket lever instructing an extension and compression speed of the bucket cylinder; a bucket lever operating amount detector detecting an operating amount of the bucket lever; and a controller outputting a boom control command value to the boom control valve on the basis of the boom lever operating amount input from the boom lever operating amount detector, and outputting a bucket control command value to the bucket control valve on the basis of the bucket lever operating amount input from the bucket lever operating amount detector, wherein said working unit control apparatus is additionally provided with an engine rotational speed detector detecting an engine rotational speed, and wherein said controller has automatic excavation control means setting and outputting an automatic excavation command value to each of the control valves on the basis of any one of a manual command and a judgement of a load judging portion judging whether or not the vehicle is under excavation, and at a time of operating the boom to lift the bucket, said automatic excavation control means outputs a boom control command value to the boom control valve, which becomes a smaller value as the engine rotational speed becomes larger so as to reduce the lifting speed of the bucket.