EXTENSION AND RETRACTION DETECTOR FOR CRAWLER

摘要

PROBLEM TO BE SOLVED: To execute work properly even if crawlers are extended or retracted unevenly between the right and left. SOLUTION: Pressure reducing valves 19L and 19R are variable in the degree of pressure reduction in dependence on the extension/retraction of the left and right crawlers 15L and 15R. A shuttle valve 34 selects such a secondary pressure from those past the pressure reducing valves as is for the smaller extension/ retraction of the crawlers 15L and 15R, and the pressure is detected by a pressure sensor 36. A moment limiter 38 stores a plurality of rated load curves corresponding to levels of extension/retraction of the crawlers 15L and 15R, and on the basis of the detection value from the pressure sensor 36, a controller 37 selects one from the rated load curves.