Patent ID: 7520702

Claim:
A drilling machine comprising: a stand; a carriage guided on said stand along a guide provided on said stand; a drive supported on said stand and being engagable with said carriage for generating a feed motion moving said carriage in a working direction along said guide; an axially-fixed intermediate shaft arranged on said stand and engaging said carriage for translating a rotary motion of said intermediate shaft into a linear motion of said carriage along said guide; wherein said drive is engagable with said intermediate shaft for moving said carriage along said guide via a worm gear pair for driving said intermediate shaft and being engagable with said drive for rotating said intermediate shaft, wherein said worm gear pair comprises a worm gear screw driven by said stepper motor and engaging a worm gear wheel which is engagable with said intermediate shaft for transferring a rotation of said worm gear screw into a rotation of said intermediate shaft, a plurality of roller bodies arranged displaceably between said first and second positions, said roller bodies engaging said worm gear screw and said intermediate shaft when being in said first position for transferring a rotation of said drive into a rotation of said intermediate shaft and for allowing free rotation of said intermediate shaft independently from said drive when being in said second position; a plunger being supported on said intermediate shaft and being axially displaceable between first and second positions; a lever being engagable with said plunger for shifting said plunger between said first and second positions, wherein said lever is configured as a star handle having three articulated gripping parts, each handle part having an end engaging one end of said plunger to thereby allow to axially shift said plunger between said first and second positions when tilting said gripping parts; a spring element held between said plunger and said intermediate shaft for biasing said roller bodies for engaging into catching recesses provided on said worm gear wheel for positively catching the intermediate shaft when being in said first position; wherein said lever is movable between an engaging position in which said plunger is located in said first position, and between a disengaged position, in which said plunger is in said second position allowing for a manual rotation of said intermediate shaft when rotating said lever; and a drilling unit supported on said carriage and comprising a spindle being driven by a motor for driving a drilling tool; wherein said drive comprises a stepper motor.