OIL DRILLING RIG,ZJ70DBS OEM of NOV corporation ... , gear transmission, stepless speed regulating, the brake adopts hydraulic disk brake and dynamic brake together, with simple structure ... system for working s tatus of mechanical, electric, hydraulic and pneumatic implements, failure alarm and failure self-diagnosis ... control modeAC-DC-ACone to onedrilling rig,oil drilling rig,drill rig,rig,driling machine ...