Abstract: A gear transmission device for a power tool. The device transmits rotation of an input shaft to an output shaft, which are coaxially rotated. The input shaft includes a distal portion, and the output shaft includes a basal portion facing towards the distal portion of the input shaft. The gear transmission device includes a support arranged on one of the distal portion of the input shaft and the basal portion of the output shaft. A socket is arranged in the other one of the distal portion of the input shaft and the basal portion of the output shaft. The socket includes a hollow portion for rotatably accommodating the support.

Abstract: In an earth drill rig wherein an upwardly and downwardly moving drill-string-turning rotary table is rotated by a kelly bar connected at its lower end to a vertical drive shaft, the kelly bar being journaled for rotation in and the rotary table being mounted for axial movement on a drill frame assembly, the drill frame assembly being mounted on a vehicle for pivoting between an upright position and a substantially horizontal position for transportation, a frame assembly pivot is positioned below the lower end of the kelly bar and a universal coupling connects the lower end of the kelly bar and the vertical drive shaft.