| 摘要 |
PROBLEM TO BE SOLVED: To enhance safety by checking whether or not the reflected wave exists generated by an ultrasonic wave generation means, by determining whether or not the surface of the ground exists, and lowering the optical axis of a working lamp downward if the surface of the ground does not exist ahead. SOLUTION: When the engine of a hydraulic shovel 1 is started, an ultrasonic wave sensor 11 starts to operate, transmitting transmitted waves toward the surface of the ground that is always at a fixed distance ahead and receiving the reflected waves. Then a working lamp 9 is turned on to initiate traveling action or a digging operation on bad roads or in mountainous areas, etc. Then if no reflected waves are read from the ultrasonic wave sensor 11 although a fixed period of time has elapsed, a controller determines whether or not the reflected waves are received. When determining that no waves are received, the controller determines that the hydraulic shovel 1 is approaching the top of a slope. The controller further drives a working-lamp drive mechanism 10 to set the optical axis of the working lamp 90 to a downward position L where it is lowered byθ1 from a normal position N, thus lowering the reflection range of light by the working lamp 9.
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