A motor-driven machine tool includes a drive unit and a tool changing magazine with tool chambers that are placed into a transfer position adjacent to a tool receptacle to be loaded. The machine tool includes a tool changing device with a slide element that is arranged in operative connection with a tool. The slide element is moved by an operating element into a first position for accepting a tool from or transferring a tool to the tool chamber and into a second position to drive the tool. The slide element is fixed in the second position by a blocking element that is brought out of operative connection with the slide element by a transfer element to move the slide element from the second position to the first position. The slide element is arranged in indirect contact with the blocking element to move the blocking element by the transfer element.

An electronic drill with revolving replaceable drilling heads includes a housing, a driving unit, a rotary cover, and a plurality of drill heads. The housing has an opening, a through hole, a containing room connected therebetween. A motor container is disposed within the containing room to contain a motor of the driving unit. The rotary cover is assembled to the housing and is rotatable so that the plurality of drill heads coupled to the rotary cover is moveable freely in a rotary track between the motor container and the housing. One of the drill heads may be rotated to be aligned with a rotary hole of a gear set driven by the motor and pushed forward for use. The drill head can also be retracted backward and replaced in the electronic drill by rotating the rotary cover, so that another drill head can be pushed outward for use.