Abstract: In a power tool, a tubular gear case is disposed frontwardly of a motor and configured to accommodate a planetary gear speed reduction mechanism, a tubular motor bracket is attached to the motor and configured to connect the motor and the gear case together, and at least one pin is pierced through the motor bracket and the gear case to connect the motor bracket and the gear case together. The pin is engaged with a first-stage internal gear located at a first stage of the planetary gear speed reduction mechanism whereby the first-stage internal gear is restrained from rotating and located in position in an axial direction thereof.

Abstract: In a clutch mechanism of a percussion driver drill, a plurality of engageable members held in a gear case is configured to be engageable with an end face of a final-stage internal gear, and a coil spring is configured to press the engageable members against the end face of the internal gear. The coil spring is disposed frontwardly of the engageable members between a switch member and an operating member of a vibration mechanism. A coupling member connected with the switch member and the operating member is disposed to pass through a gap between the plurality of engageable members and detour around a rear end of the coil spring.

Abstract: In a speed change device of an electrical power tool, a reset arm is provided separately from a switch lever, which arm is operated by a reset motor. Due to tilting motion of the reset arm, a lock ring can be returned to an unlocking position in which a second stage internal gear can be rotated, so that the speed change device can be rest to a high speed low torque mode.

Abstract: Three battery cells can be arranged such that one battery cell is situated on the front side of a handle portion and that the remaining two battery cells are situated on the rear side thereof while being arranged laterally side by side. Also, a handle portion can be generally of a triangular cross-sectional configuration whose apex portion is situated on the front side of the handle portion and whose base portion is situated on the rear side thereof; and the handle portion is grasped by bringing fingertips into contact with the apex portion (11a) on the front side.

Abstract: A portable electric power tool powered by a battery pack, which includes: a motor that operates the tool; the housing that houses the motor; at least one elastic member that is supported by the housing; and a battery pack holder supported by the elastic member. The battery pack holder is provided with an engaging portion that is detachably engaged with the case of the battery pack and connecting terminals that are electrically connected to the output terminals of the battery pack installed by the engaging portion. Thus, vibration of the battery pack is prevented even when the electric power tool vibrates.

Abstract: A power tool includes a tool bit, a tool holder, a bit holding member, a bit mounting hole, a through hole, an outside opening, a bit mounting hole side opening, an engaging member, a cylindrical operating member, a movement preventing portion, a biasing member, a first engaging region, a second engaging region, and a third engaging region. As the first, the second and the third engaging regions respectively cooperate, the tool bit can be automatically secured to the bit holding member by inserting the tool bit into the bit mounting hole of the bit holding member. Mounting and removing of the tool bit can be achieved without a ring spring.

Abstract: A portable electric power tool powered by a battery pack, which includes: a motor that operates the tool; the housing that houses the motor; at least one elastic member that is supported by the housing; and a battery pack holder supported by the elastic member. The battery pack holder is provided with an engaging portion that is detachably engaged with the case of the battery pack and connecting terminals that are electrically connected to the output terminals of the battery pack installed by the engaging portion. Thus, vibration of the battery pack is prevented even when the electric power tool vibrates.

Abstract: It is an object of the invention to provide an effective technique for simplifying the structure while maintaining the, ease of operation for mounting and removing a tool bit in a tool holder of a power tool. The representative power tool may include tool bit, a tool holder, a bit holding member, bit mounting hole, a through hole, an outside opening, a bit mounting hole side opening, an engaging member, a cylindrical operating member, a movement preventing portion, a biasing member, a first engaging region, a second engaging region, and a third engaging region. With such construction, as the first, second and third engaging regions respectively cooperate, the tool bit can be automatically secured to the bit holding member simply by inserting the tool bit into the bit mounting hole of the bit holding member. Thus, mounting and removal of the tool bit can be achieved without a ring spring needed in the known tool holder.

Abstract: Liquid crystalline compounds having a large negative ?? low viscosity, a large K33/K11 value, a small ??/?? and mutually excellent solubility even at low temperature, compositions containing at least one of the compounds and liquid crystal display devices containing such a liquid crystal compositions are disclosed.

Abstract: The present invention provides a process for producing a difluoromethyl ether derivative simple and efficient process for producing the difluoromethyl ether derivative represented by Formula (1d?) or a difluoromethyl ether derivative represented by Formula (1c?): wherein all the variables are defined in the specification.

Abstract: A liquid crystalline compound represented by Formula (1c′): wherein R1 and R2, rings A1, A2, A3, A4 and A5, Z1, Z2, Z3 and Z4, Y1, Y2, Y3 and Y4, and k, l, m and n are as defined in the specification. Also provided is a liquid crystal composition containing at least one of these liquid crystalline compounds.

Abstract: There are provided a liquid crystalline compound having a large negative &Dgr;&egr;, low viscosity, a large K33/K11 value, a small &Dgr;&egr;/&egr;L and mutually excellent solubility even at extremely low temperature; a liquid crystal composition prepared from a liquid crystalline compound; and a liquid crystal display device fabricated from such a liquid crystal composition.

Abstract: Liquid crystalline compounds having a large negative &Dgr;∈ low viscosity, a large K33/K11 value, a small &Dgr;∈/&Dgr;⊥ and mutually excellent solubility even at low temperature, compositions containing at least one of the compounds and liquid crystal display devices containing such a liquid crystal compositions are disclosed.

Abstract: The present invention provides a difluoromethyl ether derivative which shows various suitable physical properties as a liquid crystal compound, a liquid crystal composition comprising the compound and a liquid crystal display element containing the composition, and also provides a simple and efficient process for producing the difluoromethyl ether derivative.

Abstract: The present invention provides a difluoromethyl ether derivative which shows various suitable physical properties as a liquid crystal compound, a liquid crystal composition comprising the compound and a liquid crystal display element containing the composition, and also provides a simple and efficient process for producing the difluoromethyl ether derivative.

Abstract: The present invention provides a difluoromethyl ether derivative which shows various suitable physical properties as a liquid crystal compound, a liquid crystal composition comprising the compound and a liquid crystal display element containing the composition, and also provides a simple and efficient process for producing the difluoromethyl ether derivative. According to the present invention, a process for producing a difluoromethyl ether derivative represented by Formula (1d): wherein the variables are defined in the specification, is characterized by using an &agr;&agr;-difluorocyclohexylidene derivative represented by Formula (1a): wherein R1, rings A1 and A2, Z1, Z2, k and l have the same meanings as defined in the specification, as a starting material.

Abstract: There is provided a liquid crystalline compound having a high voltage holding ratio which has a very small degree of temperature dependence, a low threshold voltage which has a very small degree of temperature dependence, a high &Dgr;n, and excellent miscibility with other liquid crystal materials at low temperature; a liquid crystal composition; and a liquid crystal display element, and the liquid crystalline compound is a substituted benzene derivative represented by general formula (1), where, R represents a straight chain or branched alkyl group having 1 to 20 carbon atoms in which each of optional and nonadjacent methylene groups (—CH2—) may be substituted by an oxygen atom; X represents a halogen atom, —CF3, —CF2H, —CFH2, —OCF3 or —OCF2H; each of Z1 and Z2 independently represents —(CH2)2—, —(CH2)4—, —CH2O—, —OCH2— or a covalent bond, but Z1 and Z2 are not covalent bonds simultaneously; each of Y1

Abstract: There is provided a liquid crystalline compound having a high voltage holding ratio which has a very small degree of temperature dependence, a low threshold voltage which has a very small degree of temperature dependence, a high &Dgr;n, and excellent miscibility with other liquid crystal materials at low temperature; a liquid crystal composition; and a liquid crystal display element, and the liquid crystalline compound is a substituted benzene derivative represented by general formula (1), 1