Abstract: A tool mounting mechanism for a machine tool, particularly for surface grinding machines, comprises a spindle sleeve, in which a tool spindle, such as a grinding wheel spindle, is mounted without a backlash. The tool spindle has mutually opposite end portions protruding from the sleeve. A tool, such as a grinding wheel, is adapted to be fixed to one of said end portions. A belt pulley is mounted on the other of said end portions. A spindle carrier comprises at least two sleeve guiding means, in which the sleeve is axially slidably mounted. For guiding the sleeve without a backlash, the sleeve is provided on its outside peripheral surface with at least three and particularly with four longitudinal ribs, each of which is movably mounted in two linear roller bearings provided in the sleeve guiding means on both sides of the rib. As a result, any changes of the biasing forces acting on the bearings for the spindle and the means for guiding the sleeve will not influence each other.