| 摘要 |
For breaking out a drill rod joint, a hydraulic chuck is mounted by a housing for clampingly engaging a drill rod and for rotation to break a rod joint, the chuck being rotated by a first gear that is bolted to a drive tube which mounts the chuck. A hydraulic motor drives a second gear within the housing for rotating the first gear. A rack is mounted for tangential movement by a rack mount which is movable radially inwardly to move the rack teeth for engaging the first gear teeth while a first spring mechanism constantly resiliently urges the rack mount to a retracted position so that the rack teeth are not engagable with the gear teeth even though the rack is tangentially moved by a first hydraulic ram that is operable for moving the rack to a tangential advance position. A second spring mechanism urges the rack radially outwardly, a second ram being operated to radially move the rack mount and thereby the rack to have the rack teeth engagable with the gear teeth. Hydraulic controls automatically operate the second ram to move the rack inwardly and thereafter the first ram tangentially to apply a rotary force to the gear teeth in the event the motor is not able to initially start the rotation of the second gear to start the breaking out of a rod joint. |
