... parts,such as a crown block,traveling block,hook,swivel, rotary table,mast & substructure are in compliance with API standards, ... for AC/VFD drive drawworks, with simple structure and reliable performance.ParametersmodelZJ30/1700 D/DB/L/LDB/Nominal drilling depth(114mm ... opening mm(in) 520(20 1/2)Shift number of rotary tableMechanical driven2+2RCombination driven2 +2RDC2 +2RAC+R stepless variableRated ...