Patent ID: 8893820

Claim:
A drive system for releasably interconnecting a motor shaft of a rotary hand held power tool and an input shaft of an attachment device that is mounted thereon, said system comprising: an elongated flexible drive shaft connected to the input shaft of the attachment device, said flexible drive shaft having an outer end portion with a non-circular cross-section configured to engage a complementarily shaped cavity of an output shaft operatively attached to the power tool motor shaft; and an elongated output shaft operatively connected to the motor shaft of the power tool, said output shaft having a cylindrical outer configuration along its length and having a rearward mounting portion for attachment to said motor shaft, an intermediate portion having said complementarily shaped cavity for receiving said flexible drive shaft and a forward portion with an enlarged concentric opening for receiving and guiding the outer end portion of said flexible drive shaft into said cavity during mounting the attachment device on the power tool, wherein said enlarged concentric opening of said forward portion includes an inwardly tapering surface sized and configured to receive a collet when the flexible drive shaft is not received therein, and said forward portion includes an outside surface defining screw threads configured for engagement with a collet nut when the collet is received within said enlarged concentric opening to thereby clamp a tool bit within the collet.