Abstract: A combustion gas powered fastener driving tool includes inlet and outlet openings through which the combustion gases are discharged from a combustion chamber. These openings are located above the uppermost driving position (top dead center) of a slidable piston, so that an air and fuel mixture is fully trapped in the combustion chamber until after it is combusted. Since an outflow of the unburnt air and fuel mixture is completely prevented, the rate of fuel consumption of the fastener driving tool is high and there is no danger of accidental explosion of unburned fuel even when the fastener driving tool is used in a badly ventilated working place or site. An electric fan for forcing fresh air into the combustion chamber is disposed outside the cylinder and isolated from high temperatures. The fan is durable in structure and reliable in operation.

Abstract: A pneumatic fastener driving tool including a start valve adapted to be open for start a fastener driving operation by pneumatically driving a driving rod forwardly, and a vent hole for connecting to start valve to atmospheric air to let compressed air escape to atmosphere when compressed air is accidentally supplied through the start valve after one cycle of fastener driving operation is completed due to bouncing of the piston, for example.

Abstract: A vibroisolating handle joint structure for a power tool such as a disc grinder has a vibratable power tool unit, a tubular handle holder fastened to the power tool unit and having first axial surfaces, a grip handle having on one end thereof a larger-diameter cup disposed radially around the handle holder and having second axial surfaces extending in substantially axially confronting relation to the first axial surfaces, and elastic members disposed between and joined to the first and second axial surfaces. The power tool unit and the handle are thus interconnected by the elastic members in a vibroisolating manner without using metallic plates. Even when some of the elastic members are torn apart, the power tool unit and the handle are prevented from being separated from each other by the first and second axial surfaces which are engageable with each other.

Abstract: A stator assembly for use in an electric motor includes a stator core, a coil wound in the stator core and having terminal ends connected to leads, two sheets of insulation paper interposed between the stator core and the coil, and two auxiliary insulation plates extending between ends of the sheets of insulation paper and pole tongue ends of the stator core. The auxiliary insulation plate has engaging portions held in abutting engagement with the pole tongue ends. The engaging portions comprise opposite edge portions cut and bent from opposite ends of the auxiliary insulation plate toward one side thereof.

Abstract: A fastener driving tool such as a pneumatic nailing machine drives a fastener into a workpiece under a fluid pressure supplied into an upper chamber in a cylinder and applied to a piston reciprocally movably disposed in the cylinder. When the fastener being driven is stopped in a power stroke of the piston due to a pressure shortage, the fluid flows from the upper chamber into a lower chamber in the cylinder to make the pressure in the lower chamber equal to or higher than the pressure in the upper chamber. No reactive forces are thus applied by the high pressure in the upper chamber to the fastener driving tool, and the fastener driving tool is prevented from being repelled back when the fastener is stopped. The fastener can then be driven home into the workpiece in successive power strokes of the piston.

Abstract: A power-driven impact drill includes a spindle extending at a right angle to the axis of rotation of a drill bit, a rotational first hammer slidably mounted on the spindle for co-rotation therewith, and a reciprocal second hammer slidably disposed in front of the drill bit. When the rotation of the first hammer is arrested by the second hammer, the first hammer is caused by a cam mechanism to retract along the spindle in a direction away from the second hammer against the force of a first hammer spring. Upon disengagement with the second hammer, the first hammer is permitted by the cam mechanism to slide back into engagement with the second hammer under the force of the first hammer spring while it is rotated by the spindle. In this instance, the angular velocity of the first hammer received by the spindle is enhanced by the force stored in the compressed first hammer spring so that a large impact power is imposed to the rotating drill via the second hammer without substantial loss.

Abstract: An electrically powered tool such as a drill has a gear holder drivable by a motor shaft and having a larger-diameter gear and a smaller-diameter gear, a transmission shaft rotatable by the gear holder for rotating an output shaft, the transmission shaft having a splined disc having first splines, a high-speed gear rotatably mounted on the transmission shaft and held in mesh with the larger-diameter gear, the high-speed gear having second splines, a low-speed gear rotatably mounted on the transmission shaft and held in mesh with the smaller-diameter gear, the low-speed gear having third splines, a pair of springs for normally urging the high- and low-speed gears to be axially held against opposite surfaces of the splined disc, and a clutch plate having internal axial teeth and axially slidably mounted on the splined disc.

Abstract: A portable electric tool including an electric motor for driving a cutter to cut an object to be machined. The electric tool comprises a bracket for supporting the electric motor and handles attached to handle-mounting sections of the bracket for keeping the electric tool in cutting operation. Also included in the electric tool is a coupling mechanism for mechanically coupling each of the handles to each of the handle-mounting sections of the bracket. The coupling mechanism includes first and second annular members which are respectively attached to the handle-mounting section thereof and the handle so as to be coaxially arranged in confronting relationship to each other. Each of the first and second annular members has elongated recess portions and elongated projection portions which are alternately and successively arranged at a predetermined angular interval with respect to its own center.

Abstract: A dot-line printer has a hammer bank carrying a plurality of printing hammers arranged in groups, each group having a predetermined number of printing hammers displaced from one another by predetermined numbers of dot-lines in the direction of paper feed. A shuttle mechanism causes the hammer bank to undergo reciprocating shuttle movements with a reversing period between successive shuttle movements. A character line, covering a predetermined number of dot-lines, is printed over a plurality of shuttle movements, a paper feed mechanism causing the paper to move a predetermined number of dot-lines in the reversing period between shuttle movements. A number of blank dot-lines separate a printed character line from the beginning of the first dot-line of the next character line to be printed.

Abstract: In a control device for an impact printer for performing a printing operation at a first printing speed, a temperature sensing element, provided such that the temperature of an electromagnet unit can be directly or indirectly detected, is operated at a first temperature and restored at a second temperature lower than the first temperature. A controller changes the printing speed to a second printing speed lower than the first printing speed when the temperature sensing element is operated, returns the printing speed to the first printing speed when the element is restored, and changes the operating speed to a third printing speed lower than the second printing speed when the element is operated for a predetermined period of time, whereby the printer is made high in reliability.

Abstract: A beam deflector device in which two light beams from two light sources are simultaneously applied through movable reflectors to a beam deflector scanning a drum. The beams are also applied, through a beam splitter to two photodetectors used to control the position of the respective reflector. The two beams are separated before they are applied to the photodetectors by means of polarization plates, color filters, diffraction gratings or prisms.

Abstract: A drive motor connected to a drill bit serves to actuate the drill bit. An electric current is allowed to flow through the drive motor to activate the drive motor. A mechanism serves to feed the drill bit with respect to a workpiece. The current flowing through the drive motor is sensed. A device stores a value of the current which is sensed when the drill bit is out of engagement with the workpiece. A determination is made as to whether or not a drilling process is completed in accordance with a value of the present sensed current and the stored value of the sensed current.

Abstract: In an electrophotographic developing device, its doctor blade disposed adjacent to a magnetic roll so as to control the thickness of a layer of magnetic developing agent conveyed by the magnetic roll has an edge which is curved in such a manner that the gap between the edge and the magnetic roll is a minimum in the vicinity of the middle of the magnetic roll, whereby the layer of magnetic developing agent is made uniform in thickness and the printing density is made uniform despite gravitational sagging of the roll.

Abstract: A cooled print hammer assembly in which a plurality of hammer coils are formed in a resin member having a recess in which is placed a cooling fin. The opened faces of the fins are placed adjacent a plate of the frame of the print hammer assembly so that closed forced-air ducts are defined by the fins and the frame plate. Additionally, partitions may be placed on the sides of the fins so that the external sides of the fins are cooled.

Abstract: Cut paper electrophotographic printers with continuous paper feed mechanisms including a pickup roll, a photosensitive drum, a charging unit, an optical unit, a host controller, a developing unit, a transfer unit and fixing rolls. Further included are first and second branch passages for providing alternate feeding paths to continuously feed cut paper sheets to the photosensitive drum.

Abstract: A method for pretreating a biological material for observation by scanning electron microscope which comprises: placing a biological material in a vacuum, supplying an inert gas to a predetermined level of pressure; and energizing the inert gas for ionization for a time sufficient to cause the surface of the biological material to be activated whereby when an electron beam is irradiated on the treated surfaces, secondary electrons are emitted in a high efficiency. The apparatus for carrying out the above method is also described.