Hydraulic drilling-machine drive

The invention pertains to a hydraulic rotary drive for the rotating rod assembly of a drilling machine which contains at least two hydraulic motors ( 1 - 3 ) with the motor shafts ( 34 - 36 ) that are connected to a common output shaft ( 11 ) by means of a gear, with a clutch ( 4 - 6 ) being arranged between the motor shaft ( 34 - 36 ) of each hydraulic motor ( 1 - 3 ) and the gear such that the rotational movement of each hydraulic motor ( 1 - 3 ) can be disengaged from the rotational movement of the output shaft ( 11 ). The invention aims to develop a highly variable rotary drive for ground and rock drilling machines. According to the invention, this objective is attained due to the fact that: (1) the gear is formed by pinions ( 7 - 9 ) that are each connected to a corresponding motor shaft ( 34 - 36 ) by means of a corresponding clutch ( 4 - 6 ), with said pinions engaging a toothed wheel ( 10 ) arranged on the output shaft ( 11 ), and (2) the housings of the hydraulic motors ( 1 - 3 ) have identical connection dimensions, with the hydraulic motors having different intake volumes.