... eddy current brake for auxiliary brake.3. For oil drilling rigs over 4000m in drilling depth, rig floor is in two levels ... , easy for assemble and disassembly.5. ZJ70/4500LDB/LD oil drilling rig is fitted with bailing drum, mechanical friction cathead and ... service, inspections and maintenance of oil drilling rigs, inspection and maintenance of rigs, inspections of drilling tools, casing at home and ...