Abstract: A planetary gear transmission gear system comprises a main planetary gear train composed of a main sun gear, a main ring gear, and main planet gears. The main sun gear is driven by an input rotary shaft to rotate. A sub planetary gear train is included to have a sub sun gear, a sub ring gear, and sub planet gears, and has a different gear ratio from the main planetary gear train. The sub sun gear is connected to rotate together with the main sun gear. A common carrier supporting the main and sub planet gears is rotatable about a common center axis and is drivingly connected to rotate an output shaft. A lock mechanism releasably fixes the main ring gear in order to allow the main planet gears to rotate about the center axis as the main sun gear rotates with the main ring gear fixed. A one-way clutch is connected to permit the sub ring gear to rotate in a first direction and to prohibit the sub ring gear from rotating in a second direction opposite to the first direction.

Abstract: An electrically powered squeezer such as a caulking gun for dispensing a viscous substance such as a caulking or sealing compound. The gun comprises a housing carried by an operator and incorporating an electric motor and a switch for energizing and deenergizing the motor. The housing is formed with a holder for receiving therein a cartridge filled with the above viscous substance and having a discharge nozzle. Incorporated within the housing is a pressing element driven by the motor to compress the cartridge wall so as to force the viscous substance out of the cartridge through the nozzle. A release mechanism is included to disengage the driving connection between the motor and the pressing element when the switch deenergizes the motor, in such a way as to allow the pressing element to retract to a position where the pressing element no longer exerts pressure upon the viscous substance.

Abstract: A hand-held electric tool comprising an elongated housing having a first longitudinal axis and provided with a motor-driven chuck projecting from the forward end thereof, an elongated grip having a second longitudinal axis and connected at its forward end to the rearward end of the housing. An electric motor is positioned within the housing for rotatably driving a suitable bit held in the chuck to perform fastening or drilling operation. The grip is connected to the housing in such a way as to be selectively switched between two positions, that is, a straight position where the first and second longitudinal axes are in alignment and an angled position where the first axis crosses the second axis. In the preferred embodiment, the grip and the housing are pivotally interconnected at a pivot axis to permit the grip to swing about the pivot axis between the straight and angled positions.

Abstract: A gear shifting speed change apparatus for a rotary electric tool such as a drill having an electric motor driving a first pair of unequal diameter pinion gears which are in continuous driving engagement with a second pair of pinion gears. The gears of second pair are independently mounted next to each other for free rotation on a shaft having an axial keyway. An axially sliding key is manually shifted to engage either one, but not both, of the second pair of gears by means of a pair of projections extending radially outwardly from the sliding key, one projection being axially outside the outer face of each gear and engageable with a recess in the outer face of the adjacent gear.