Tool holding attachment

An attachment removably mounted to a spindle head of a machine tool for holding a tool removably attached thereto comprising:

• a pull stud which can be inserted into a main spindle from its tip and gripped by drawing with a collet arranged inside the main spindle;
• a shank member which has the pull stud fixed at its upper end, a flange and a central shaft at its lower end face, and a shank side coupling on a lower end face of the flange;
• a sleeve into which the central shaft is slidably inserted, and which has a gear at its lower end for transmitting the driving torque of the main spindle to a tool held by the attachment;
• an attachment body which holds the sleeve rotatably, which has a small diameter coupling at the inner side of the upper end face engaging with the shank side coupling, and has a large diameter coupling at the outer side of the upper end face for engaging with a head side coupling provided on the spindle head of the machine tool for fixing the attachment body to the spindle head;
• and
• an elastic member which is arranged between the sleeve and the central shaft, and forcedly fixes the large diameter coupling to the head side coupling in a compressed state, and fixes the shank member by forcedly pushing the central shaft in such a direction that the shank side coupling engages with the small diameter coupling in an expanded state.