As the boom position detecting means there may be used {HEAD ~ a detector} which detects the angle of the boom 3, but in this embodiment there is used a stroke meter 71 which detects the length of {TAIL ~ the cylinder} 50 shown in FIG 7 and which is attached to the cylinder 50 
As the boom position detecting means there may be used { HEAD ~ a detector } which detects the angle of the boom 3 , but in this embodiment there is used a stroke meter 71 which detects the length of { TAIL ~ the cylinder } 50 shown in FIG 7 and which is attached to the cylinder 50
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH