FULLY TURNING TYPE BACK HOE

PURPOSE:To obtain a fully turning type back hoe which eliminates the need for immediately stopping the operation of the machine even when an external worker enters an invasion blocking area, and avoids possible contact accident. CONSTITUTION:This machine is provided with ultrasonic sensors S1 and S2 which have areas for blocking the invasion of external workers set as a plurality of zones to transmit ultrasonic signals for searching different in characteristics toward the respective zones while receiving replies from a transmitter/receiver 16 carried by an external worker in surrounding areas. The transmitter/receiver 16 makes a responce when receiving the searching signals from the ultrasonic sensors S1 and S2 of the machine. This machine is equipped with a judging means which computes distances between the ultrasonic sensors S1 and S2 and the transmitter/receiver 16 to judge whether the invasion occurs or not and a working speed deceleration mechanism 21 which reduces the working speed lower than the normal value thereof invasion by an external worker is determined to occur in any of the invasion blocking areas.