US Patent 7175375 Structure of a spindle of a machining center

A spindle of a machining center is equipped with a clutch, which is fitted to a main spindle housing, and directly connected to a power source for separable engagement with a shaft coupling sleeve, and which is guided by sloping guiding trenches of a clutch disk such that a pull rod of the spindle is actuated for a tool shank housing to be changed between a clamped position and a released one; thus, power of the power source can be usually provided to the spindle to effect rotation of the spindle for machining a work piece, and the clutch can be operated for allowing the pull rod to be directly actuated with power of the power source without hydraulic mechanisms.