Abstract: Two guide members cooperatively constitute a chuck portion for holding a screw head. Opening and closing of the chuck portion is regulated depending on a mutual position between a machine body and a member into which a screw is driven. Guide pin portions of respective guide members engage with a stopper portion of a push lever until a screw is driven to a predetermined depth. The chuck potion tightly holds the screw head until a screw fastening operation is substantially finished, thereby suppressing the lifting of a machine body.

Abstract: In an image forming apparatus, the developing unit includes two developing rollers whose rotational directions are different from each other, and a bias potential of the developing roller (first developing roller) located upstream in the rotational direction of the photosensitive member is selected to be a potential, which is in value between a bias potential of the developing roller (second developing roller) located downstream in the same direction and a background potential.

Abstract: There are disposed optical sensors (S1, S2, S3,S4, S5, and S6) outside sheet trays (1, 2, 3). The optical axes of the optical sensors are respectively set in such a manner that they are parallel to their associated up-down tables (1a, 2a, and 3a) and pass upwardly of contact positions (A, B and C) between sheets (P) and sheet supply rollers (20, 21, and 22).

Abstract: An improved structure of an impact screwdriver is provided which achieves a low-noise screw-driving operation. The impact screwdriver includes a clutch assembly for transmitting torque provided by a motor to a tool bit. The clutch assembly includes a toque-transmitting member, a torque-outputting member, and a clutch coil spring. The clutch coil spring is selectively wound around the torque-transmitting member and the torque-outputting member according to a rotational difference therebetween to establish torque transmission for providing the torque to the tool bit intermittently.

Abstract: A rotor temperature control system for a centrifuge is provided. This system includes an ambient temperature sensor for detecting ambient temperature around the system, a temperature regulating device for regulating temperature of a rotor of the centrifuge according to an operation factor which is variable within a range of preselected maximum to minimum values, and an operation factor controller for controlling a value the operation factor of the temperature regulating device in a preselected relation to the ambient temperature and a given target rotor temperature to modify the temperature of the rotor to the target rotor temperature. With this arrangement, the temperature of the rotor is modified to a desired value quickly regardless of an initial temperature of the rotor.

Abstract: A high-frequency motor comprises a squirrel-cage rotor. The rotor comprises an iron core having a plurality of circular slots, a plurality of conductive rods inserted into the slots, and short-circuit rings disposed at both ends of the conductive rods. The conductive rods are made of copper. A ratio of a product of the number N2 of the conductive rods and a diameter d2 of each conductive rod to an outer diameter D of the rotor is in an optimized range of 1.1 to 1.5, namely, 1.1.ltoreq.N2.multidot.d2/D.ltoreq.1.5. With this optimization, it becomes possible to achieve a maximum rotational speed of more than 120,000 min.sup.-1 and obtain an excellent motor efficiency.

Abstract: A percussion hammer tool comprises a spindle 1 causing rotation about an axis thereof. The spindle 1 is driven by a motor M. A hammer 3, slidably coupled with the spindle 1, generates a percussion force to rotate and hit an anvil. The anvil is divided into an engaging portion 7 engageable with the hammer 3 and a tip tool holding portion 8 holding a tip tool 16. The engaging portion 7 and the tip tool holding portion 8 are locked with each other. A torque transmitting mechanism 11 makes the engaging portion 7 and the tip tool holding portion 8 displaceable with each other telescopically in an axial direction. A cushion member 10 is provided in a clearance 9a between the engaging portion 7 and the tip tool holding portion 8, thereby transmitting an angular component of the percussion force while absorbing an axial component of the percussion force. An additional cushion member 13 may be interposed between the spindle 1 and the anvil.

Abstract: A grinder has a grinding member. The grinder includes a rotatable spindle having an engagement portion. A first flange engages the engagement portion of the spindle. The first flange and the engagement portion of the spindle define a given play therebetween in a direction of rotation. The grinding member is held between the first flange and a second flange. A lubricant solid material is provided between the first flange and the engagement portion of the spindle.

Abstract: A vibration-damping apparatus for an electric hammer unit is provided. This vibration-damping apparatus is provided with the so-called transatory unit including elastic bars disposed between elastic damper members connected to a tool body and a handle of the electric hammer unit, respectively, for absorbing relative displacement of the elastic damper members caused by vibrations produced by the tool body during use. The vibration-damping apparatus further includes a stopper member attached to the elastic damper member attached to the handle so as to engage a chamber formed in the elastic damper member attached to the tool body for preventing the handle from being dislodged from the tool body even when the handle is swung laterally by a hammer operator.

Abstract: A percussion hammer for a tool includes a rotational drive source. A motion converting mechanism is connected to the rotational drive source for convening rotational movement of the rotational drive source into reciprocating movement. A striking mechanism is connected to the motion converting mechanism, and has a drive cylinder. A rotation transmitting mechanism is operative for transmitting rotational movement from the rotational drive source to the tool. A drive wheel is connected to the rotational drive source, and extends around the drive cylinder. A coupling member is connected to the drive cylinder, and extends around the drive cylinder. The coupling member is movable in a percussion axis direction. A movable adjustment member is connected to the coupling member for selectively connecting and disconnecting the coupling member to and from the drive wheel. Teeth are formed on an outer circumferential surface of the drive cylinder.

Abstract: A slipping torque changing mechanism for an impact tool includes a driving source for generating a rotational motion. A motion converting mechanism is connected with this driving source for converting the rotational motion of the driving source into a reciprocating motion. An impact mechanism is connected with this motion converting mechanism for transmitting the reciprocating motion to a tool end. A rotational motion transmitting mechanism is disposed separately from the motion converting mechanism for transmitting the rotational motion of the driving source to the tool end. A plurality of clutches, having different slipping torques, are disposed at different portions on the rotational motion transmitting mechanism.

Abstract: A management system for use in a centrifuge equipped with a detachable rotor which is rotatable so as to separate density-different samples by a centrifugal force due to the rotation. The management system is for managing the lifetime of the rotor on the basis of the detection results of an operated-condition detector for detecting operated conditions such as the number of times of rotation, running time and rotational speed of the rotor. The management system includes a data storing device which is provided on the rotor to be rotatable therewith and is composed of a magnetic recording medium to allow keeping data relating to the operated conditions of the rotor. Also included in the management system is a data processing unit coupled through a data reading and writing device such as a magnetic head to the data keeping device and also coupled to the operated-condition detector to be responsive to the operated conditions.

Abstract: An optical system is provided with a laser device for emitting a multiplet laser beam with two types of frequencies F1, F2, and a sample rotator on which a reference sample and a test sample containing substances are set for rotating both the test sample and the reference sample to separate the substances contained in the test sample. The test sample and the reference sample are irradiated with the multiplet laser beam one after another to shift the phase of the laser beam. The optical system is further provided with a polarizer for polarizing the multiplet laser beams transmitting through the test sample and the reference sample to produce both a test sample signal with a frequency .DELTA.F=F1-F2 and a reference sample signal with the frequency .DELTA.F, and a signal analyzer for analyzing a phase difference between the sample signals to determine an index of refraction of the test sample. Therefore, the substances containing in the test sample are specified.