... to the requirements of industry standard SY/T5527.There are two designed kinds of bumper in hook cylinder, mechanical and hydraulic ... DG225 DG315DG450Max. hook load kN (lbs) 2250 (500000 31507000004500 (1000000Spring stroke mm(in)2007 7/8200 7 7/82007 7/8Opening ... ,DG225,DG315,DG450,hook for drilling,drilling rig,oil drilling machine,drilling rig square parts,