PURPOSE: To provide the subject detector so designed that a standard member stuck at the target revolving center is constructed in a flexible way to deteect the deviation of a vehicle body from its target revolving locus and whose supporting structure is simplified despite smooth sticking of the standard member into the ground.
CONSTITUTION: A lift operating means M is provided to make vertical movement of the standard member 1 relative to a vehicle body 5 over the range from the action position at which the standard member is stuck into the ground and retreat position above, where the standard member 1 is stood in a stuck way into the ground corresponding to the target revolving center position prier to the revolving movement from the terminal end of one working stroke toward the initial and of the next working stroke. Based on the flexural displacement at a flex part K provided at a vertical midway point of the standard member 1, the deviation of the vehicle body from the target movement locus around the target revolving center is detected. In this detector equipped with a revolving state detecting means to detect the deviations, such an engaging part (k) is provided as to allow a relative vertical movement within the set range between the upper side part 1b and lower side part 1a for the flex part K in the standard member 1, to check flex displacement in such a state that the lower side part 1a is descended relative to the upper side part 1b, and allow the flex displacement in such a state the lower side part 1a is ascended relative to the upper side part 1b.
MASUTOME ATSUSHI
YOSHIKAWA KOJI
KUROIWA RYOZO
