Abstract: A combustion gas powered tool includes a member defining a part of cylindrical combustion chamber having an axis. A piston is movable in a direction along the axis of the combustion chamber. The piston defines the combustion chamber in conjunction with the member. A mixture of air and fuel is generated in the combustion chamber. The air-fuel mixture in the combustion chamber is burned to drive the piston. An orifice grille extends in the combustion chamber, and is parallel to the axis of the combustion chamber.

Abstract: An electric-powered tool comprises: a housing; and a brush motor contained in the housing, having: brush holders, each of brush holders holding a carbon brush; and brush terminals, made of an electrical conductive and elastic material having at least one blade portion, a palm portion, and an arm portion, for providing electrical connection thereof to the brushes through the brush holder by catching and griping the brush holder by the blade and the palm portions, the arm portion extending from the palm portion to an end where a fixing portion is provided, each of the brush terminals being fixed by the fixing portion with a positional offset to develop a contact pressure between the palm portion and the brush holder. Further, the arm portion is further extending over the fixing portion to form a connecting portion. On the other hand, one end of a field coil is connected to a connector. Thus, the brush holder is connected to the field coil through the connection portion and the connector.

Abstract: A vacuum pump includes a rotatable cylinder rotatably disposed coaxially around an inner stationary cylinder and in an outer stationary cylinder. The rotatable cylinder has a plurality of recesses defined in inner and outer circumferential surfaces thereof. The outer stationary cylinder has a helical groove defined in an inner circumferential surface thereof. The inner stationary cylinder has a helical groove defined in an outer circumferential thereof. The rotatable cylinder is rotated by a motor to deliver a gas axially along the helical grooves. The recesses are effective to produce turbulent flows in the gas to increase the rate at which the gas is discharged. The recesses have an axial length smaller than the transverse width of helical threads on the outer circumferential surface of the inner stationary cylinder and the inner circumferential surface of the outer stationary cylinder, to minimize any gas leakage across the helical threads.

Abstract: A power tool includes an internal wiring structure having a first terminal board secured to a commutator motor stator and a second terminal board releasably engaged with the first terminal board to electrically connect terminals on the first and second terminal board. The second terminal board includes first and second conductive resilient brush terminals respectively resiliently engaged with first and second conductive brush holders when the stator is installed in a housing of the power tool. Internal wiring of the power tool is thereby automatically completed upon installation of the stator in the housing.

Abstract: A power operated screwdriver including a support shaft firmly secured to a motor housing, a gear driven by a motor shaft and rotatably mounted on the support shaft, a main spindle slidably mounted on the supported shaft and holding a detachable drill bit, and an intermediate clutch disc slidably mounted on the support shaft between the gear and the main spindle. The gear and the intermediate clutch disc are selectively connected and separated by a first clutch, while the intermediate clutch disc and the main spindle are always connected together by a second clutch. A compression coil spring acts between the support shaft and the intermediate clutch disc and urges the intermediate clutch disc toward the main spindle to disengage the first clutch. With this construction, the a rotational driving force of the gear is transmitted to the main spindle via the intermediate clutch disc and first and second clutches only when the screwdriver is performing a screw-driving operation.

Abstract: A pneumatic fastener driving tool includes a main valve operable to cause compressed air to be alternately introduced into and discharged from the upper piston chamber, a first passage leading the compressed air into the main valve chamber, a repeat valve disposed in the first passage for opening and closing the same, and a second passage extending between the lower piston chamber and a repeat valve chamber in which the repeat valve is reciprocably received. With this construction, the repeat valve is reciprocally movable in response to a change of pressure in the lower piston chamber to cause the main valve to reciprocate, thereby reciprocating the piston repeatedly. Since the reciprocating fastener driving movement of the piston is directly related to the reciprocating movement of the repeat valve, the fastener driving work can be achieved reliably without causing any operational failure such as a non-load striking.

Abstract: An electric hammer drill including a vacuum dust collecting device for collecting dust from an area of an article being drilled by a drill bit wherein a hose extending from a body of the hammer drill is directly connected to an end of a movable first pipe which is slidably received in a stationary second pipe. A fan for transporting the dust by vacuum is fixed on a shaft extending across a dust collecting chamber in the body. The shaft is coaxial with, and releasably coupled with, an armature shaft of a motor. With this releasable coupling, the armature shaft is relatively short and unlikely to bend or flex, so that vibration produced during a drilling operation is small. During the drilling operation, the first pipe slides back and forth along the second pipe as a suction hood moves in a direction opposite to the direction of movement of the drill bit.

Abstract: A quick-return motion mechanism for use in an automatic magnetic drilling machine including a feed motor for generating power transferred through a worm wheel and a high-ratio reduction gear to a handle shaft to drive an electric drill. A one-way clutch is provided inside the worm wheel so that the handle shaft races on feed and is locked on return. The high-ration reduction gear is composed of elements which are arranged to cause the input and output sides of the high-ratio reduction gear to rotate in the same direction. The quick-return motion mechanism consists of an arrangement for restraining the input side element of the high-ratio reduction gear on feed and for releasing it on return to race the high-ratio reduction gear.

Abstract: An electric circular saw of the type including a mechanism for tilting a base relative to the plane of a blade is provided wherein a side knob for being gripped by the user during cutting operation pivotally connects the base and a body of the circular saw through a base attachment portion and a bevel plate having an arcuate guide groove extending through an angular distance corresponding to a tilt angle of the base relative to the blade. The side knob is threaded to the base attachment portion and movable together with the base when the base is tilted. The side knob is spaced from a guide surface of the base by a distance at least larger than a maximum radius of the side knob. The distance between the base and the side knob is constant regardless of the relative angular position of said base and the blade, so that circular saw can be held stably and hence is capable of performing an accurate cutting operation.

Abstract: A molecular drag pump for delivering a gas under molecular flow conditions comprises a pair of parallel, helically threaded rotors rotatably mounted in a stationary housing. The rotors have respective helical threads and respective helical grooves, and are held in close mesh with each other. The helical threads are helically inclined in one direction to the axes of the rotors, and have a flank angle such that the helical threads are closely received in the respective helical grooves while keeping the threads out of contact with each other. The rotors are rotated in one direction about their respective axes to move a gas introduced through an inlet port toward an exhaust port axially along the rotors.

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.