TRACK FRAME FOR CONSTRUCTION MACHINE

PURPOSE: To increase an expansion contraction stroke by a method wherein a bolt insertion hole for increasing a surplus expansion contraction stroke not used in such a state to stretch a side frame are formed on the center frame side, in a device to increase or decrease a distance between right and left side frames on which respective tracks are mounted. CONSTITUTION: In a track frame 30, the coupling part 31b of a center frame 31 is fixed to a coupling plate 33, fixed to a side frame 32, by means of bolts 34... A plurality of approximately U-shaped bolt insertion holes are formed in a coupling part 31b for the bolt coupling and a plurality of screw holes are formed in the coupling plate 33. In this case, in bolt insertion holes A (A1 -A5 ) and screw holes B (B1 -B5 ) formed in the direction of the width of a car a distance between the bolt insertion holes A1 and A2 and a distance between the screw holes B3 and B4 set to D2 and a distance between the bolt insertion holes A1 and A5 is set to D1 +D2 . The bolt insertion hole A1 is used for increasing the expansion contraction stroke of the side frame 32.