Abstract: A tool storage drum which is adapted to receive and store a plurality of toolholders is rotatably mounted on top of the upright of a horizontal machining center behind the spindle thereof. A tool changer carriage carrying a tool change arm is pivotally mounted on the upright above the spindle and is pivotable between a parked position in which an end of the tool changer arm is adjacent to the tool storage drum and an exchange position in which an end of the tool changer arm is adjacent to the spindle. The tool changer arm is slidably mounted on the carriage for movement between an extended and a retracted position to remove toolholders from their sockets or insert them therein and is rotatable through 180.degree. to interchange its ends for the purpose of exchanging a tool in the spindle for a tool previously removed from the tool storage drum.

Abstract: The bed and upright of a machine tool are made of structural steel tubes which are welded together to form unitary structures. Each of the structural steel tubes is substantially rectangular in cross-sectional shape.

Abstract: The worktable and pallet shuttle of a machine tool are driven by a common motor which is mounted on the worktable base. The motor is coupled to the worktable by gears which engage when the worktable is raised to be indexed and disengage when the worktable is lowered. The motor is coupled to the pallet shuttle by gears which engage when the worktable base is moved into the shuttle position and disengage when the worktable base is moved out of the shuttle position.

Abstract: A tool storage drum which is adapted to receive and store a plurality of toolholders is rotatably mounted on top of the upright of a horizontal machining center behind the spindle thereof. A tool changer carriage carrying a tool change arm is pivotally mounted on the upright above the spindle and is pivotable between a parked positon in which an end of the tool changer arm is adjacent to the tool storage drum and an exchange position in which an end of the tool changer arm is adjacent to the spindle. The tool changer arm is slidably mounted on the carriage for movement between an extended and a retracted position to remove toolholders from their sockets or insert them therein and is rotatable through 180.degree. to interchange its ends for the purpose of exchanging a tool in the spindle for a tool previously removed from the tool storage drum.