PURPOSE: To lighten labor of an operator by linking connecting members through a coupling pin and a shock absorbing member to a three-point ring hitch of tractor and installing a stopper to regulate an amount of the shock absorbing member bent.

CONSTITUTION: Left and right connecting members 4 such as vibration type subsoiler are linked to low rinks 5 and the connecting members at the top of a mast are coupled with a top rink. The connecting members 4 are cylinders through which coupling pins 12 are passed. The connecting members are provided with a pair of left and right ring-shaped rubbers 13 as shock absorbing members and vibration transmitted to the low rinks is damped. Ring-shaped stoppers 14 are installed at the outside of the ring-shaped rubbers 13, application and overload to the ring-shaped rubbers and large bending of the ring-shaped rubber are prevented.