The drilling machine includes a frame that is supported for movement over the ground and a tower that is mounted on the frame. A rotary head is movable along the tower and engageable with a drill string for rotating the drill string. A pull down cable is connected to the rotary head for pulling the rotary head downward for pushing the drill string into the ground. A pull back cable is connected to the rotary head for pulling the rotary head upward for pulling the drill string out of the ground. The pull back cable is subject to a slack condition in response to elastic stretch of the pull down cable. A slack take-up device is connected to the pull back cable to remove the slack created in the pull back cable by the elastic stretch of the pull down cable.
A top drive power swivel assembly for well drilling rigs having a travelling frame for moving along a drilling tower. The travelling frame has at least two lower and two upper travelling frame extensions. A housing has at least two upper and two lower housing extensions each with an opening. A first connector penetrates openings of upper travelling frame extensions and openings of an upper housing extensions engaging the travelling frame to the housing. A second connector penetrates openings of lower travelling frame extensions and openings of lower housing extensions to securely engage the travelling frame to the housing. A top drive power swivel mounts to the housing and the top drive power swivel receives power from hydraulic motors. Various sheave assemblies mounted to the travelling frame engage a hoisting means. Guide wheel assemblies disposed on the travelling frame engage the tubulars.
