Abstract: The disclosure pertains to a space-conserving integrated fluid delivery system which is particularly useful for gas distribution in semiconductor processing equipment. The present invention also pertains to an integrated fluid flow network architecture, which may include, in addition to a layered substrate containing fluid flow channels, various fluid handling and monitoring components. The layered substrate is diffusion bonded, and the various fluid handling and monitoring components may be partially integrated or fully integrated into the substrate, depending on design and material requirements.

Abstract: A micromachined capacitive acoustic transducer including an electrode formed by a perforated plate and another electrode formed by a shallowly corrugated membrane anchored at one or more positions on the substrate which also supports the said perforated plate is described. Also disclosed includes: a fixed perforated plate; a movable shallowly corrugated membrane having holes to form acoustic filter to a certain frequency or a range of frequencies spaced from the perforated plate that is anchored in one or more location but loose at other locations; a support structure in the perforated plate maintaining the minimum separation between the membrane and the perforated plate near the perimeter.

Abstract: A pressure and sensing element is provided that includes one piezo-resistive sensing element configured as a single light implant square, and may produce outputs relating to both a pressure and temperature that has been sensed. The piezo-sensing element may operate as a piezo-resistive radial element when a constant current is conducted through the element in the radial direction with respect to the diaphragm. Conversely, the piezo-sensing element may operate as a piezo-resistive tangential element when a constant current is conducted through the element in the tangential direction to the edge of the diaphragm. A difference in the radial and tangential resistances and a corresponding difference in voltage drop are proportional to an applied pressure, while a sum of the same two resistances is a function of temperature.

Abstract: A pressure gauge is provided for monitoring pressure within a reservoir, such as air within a vehicle tire. The gauge is particularly configured to allow it to remain upon a valve stem of the tire even when the tire is in operation. A receiver of the gauge can be coupled to the valve stem. A valve core is preferably provided through which air can pass from a compressed air source, so that the tire can be filled without removing the gauge. A Bourdon tube is located within a sensor chamber and measures pressure within the reservoir. A shroud or other support surface is located adjacent a central opening of the Bourdon tube so that the Bourdon tube is supported sufficiently to avoid damage from forces including centrifugal forces encountered when the tire is spinning and the gauge is mounted on the valve stem of the tire.

Abstract: A method and system of providing power to a pressure and temperature sensing element is provided. Polarity switching is added to a current source for a sensor, which includes one piezo-resistive sensing element configured as a single implant square located at an edge of a diaphragm of the element, and which produces pressure and temperature outputs. The piezo-sensing element operates as a piezo-resistive radial element when current is conducted through the element radially with respect to the diaphragm. Conversely, the piezo-sensing element operates as a piezo-resistive tangential element when current is conducted through the element tangentially to the edge of the diaphragm. A difference in the radial and tangential resistances is proportional to an applied pressure, while a sum of the resistances is a function of temperature. By alternating the polarity of power applied to the sensor, a build up of ions resulting from PUD is minimized.

Abstract: A pressure sensor housing and configuration is provided for a single-square-sensor (SSS) sensing die. A sensor includes a glass wafer hermetically bonded to the SSS chip. The SSS chip is then positioned between a header and a cover, which can be glued together using an epoxy, for example. A tube, such as a pyrex tube, is connected to the SSS chip through which pressure is sensed. After bonding the wafer to the SSS chip, a vacuum seal is created and thus less emphasis is placed on hermetically sealing the remainder of the sensor.

Abstract: A method and apparatus for measuring the force applied by a first member coupled to a second member by a connecting body, by: transmitting a cyclically-repeating energy wave through the connecting body from a first location thereon to a second location thereon; measuring the transit time of the cyclically-repeating energy wave from the first location to the second location; and utilizing the measured transit time to produce a measurement of the force. In the preferred described embodiment, the connecting body is a fastening plate which fastens a drive shaft to a driven shaft and measures the torque output of the drive shaft.

Abstract: A method for estimating transmission input torque is provided. The method includes identifying a plurality of measurable characteristics that influence transmission input torque. Thereafter, transmission input torque values are measured on a sample powertrain operating at a plurality of different combinations of the measurable characteristics. A look-up table including the measured input torque values corresponding to each combination of the measurable characteristics is established and saved onto a vehicle memory device. The vehicle is configured to monitor the status of the measurable characteristics during operation. At any given time, the vehicle can retrieve the measured transmission input torque value corresponding to the status of the monitored measurable characteristics wherein the measured transmission input torque value provides an estimate of the transmission input torque of the vehicle.

Abstract: A method of determining the crack growth life of a thin, polymeric material is provided. The method includes the steps of providing a sample of the thin, polymeric material having a predetermined length, width and thickness. A groove is then formed in the sample followed by the formation of a crack in the groove. The sample is then secured in a test apparatus that cycles the sample in a bending mode at a predetermined frequency. The crack length is measured in the sample after a predetermined number of cycles. The crack growth data is collected over a period of cycles to determine the crack growth life in the sample.

Abstract: The present invention a method and apparatus for measuring the compression of a stator core 10 that comprises attaching a measuring device 22 to a tensioner 20, placing the tensioner on an end of a through-bolt 12 of the stator core, and performing at least one act of tensioning the stator core 10 with the tensioner. Then measuring a compression state of the stator core by the measuring device registers determining the amount of relative compression achieved by the act of tensioning, the relative compression is the amount of actual compression of the core and the amount of stretch of the through-bolt. Finally determining an actual compression state of the stator core based on the measuring.

Abstract: Disclosed herein is a shear application system for applying substantially uniform amounts of shear throughout a powder sample. The shear application system preferably includes a cylinder assembly having an inner cylinder, a housing, an inner set of lugs, and an outer set of lugs. The inner cylinder has an external cylindrical surface and the housing has an internal cylindrical surface concentric with said external cylindrical surface. The internal and external cylindrical surfaces form an annular chamber therebetween. Each one of the lugs of the inner set extend radially outward from the external cylindrical surface, and each one of the lugs of the outer set extend radially inward from the internal cylindrical surface and are substantially uniformly spaced. The shear application system preferably includes drive means mechanically connected to the inner cylinder and control means electrically connected to the drive means.

Abstract: A system for measuring, recording, and evaluating a deformation and/or wear of structures and positioning the structures with respect of their axis. The system includes at least one sensor for measuring a vector with respect of planes X and Y. The sensor evaluates a point of a form of the structure. The at least one sensor interacts synchronically with a software to integrate a data from the at least one sensor to reveal the form of the structure. Then, the at least one sensor evaluates and records the deformation of the structure in order to draw its form.

Abstract: A circuit board clamping mechanism and a testing device using the same. The circuit board clamping mechanism is for clamping a main circuit board and an extending circuit board. The extending circuit board is coupled with the main circuit board, and there is a titling angel between the extending circuit board and the main circuit board. The circuit board clamping mechanism includes a substrate board and a clamping element. The main circuit board is disposed on the substrate board. The clamping element includes a clamping part and a fixing part. The clamping part is for clamping the extending circuit board. The fixing part is disposed on the substrate board and is coupled with the clamping part. The clamping part and the fixing part form an L-shaped structure.

Abstract: A method and apparatus for measuring in situ flow of non-aqueous phase liquids (NAPLs) through a porous medium is described. A tracer is introduced into a well or boring located in the medium and the tracer concentration in the well kept uniform by mixing. The rate at which the tracer is depleted from the well has been determined to be proportional to the flow rate of the NAPL through the well or boring and surrounding formation.

Abstract: The invention relates to an arrangement for signal processing in ultrasonic transducers in flow meters, wherein the ultrasonic transducer is acted upon by a drive signal, the ultrasonic transducer being connected to a resonant circuit matched to the frequency of the drive signal. The resonant circuit can be, in particular, a component of a network, which makes possible a switching over of an ultrasonic transducer from a transmitting operation to a receiving operation. The present invention further relates to an ultrasonic flow meter according to the time-of-flight principle, with means for transmitting and receiving ultrasonic signals as well as means for signal post-processing of the received ultrasonic signals.

Abstract: A method of testing a mass flow rate meter functioning on the Coriolis principle, in which an apparatus of the mass flow rate meter is subjected to a predetermined oscillation excitation and the associated oscillation response is recorded. Then the recorded oscillation response is compared with a previously recorded oscillation response. Testing of the Coriolis mass flow rate meter with regard, for example, to error tolerances in the manufacturing or with regard to a calibration condition is thereby enabled.

Abstract: A torque measuring apparatus is described that comprises a chassis, a reversible electrical motor having a motor housing and a rotatable output shaft projecting from one end of said motor housing, motor mounting means mounting said motor housing for rotation relative to said chassis, means for connecting said motor output shaft to a rotatable component of a device to be tested, whereby energization of said motor will cause said output shaft to rotate and apply a torque to said rotatable component and the resistance to rotation offered by said rotatable component will result in a reactionary torque that causes said motor housing to rotate relative to said chassis, means responsive to rotation of said motor housing for generating a signal representative of said reactionary torque, and means for converting that signal into a measure of the torque applied by said motor output shaft to said rotatable component.

Abstract: An apparatus and method for noncontact, optical measuring of any of torque, torque angle, shaft speed, and shaft direction by at least one of a rotatable or non-rotatable flexure with input and output ends, a light source for generating a light signal, a field mask carrying a pattern of opaque and transparent lines adapted to form an image of overlaid lines on the field mask and reflected from lines on the input and output ends of the flexure, and a detector for receiving a light signal from the overlaid lines in the image, the detector generating an output light signal waveform proportional to the torque, and comparing amplitude variations between input and output end waveforms to provide a measurement of torque.

Abstract: A spatial pressure distribution sensor comprises a sensor array and a processor. The sensor array comprises an array of pressure sensors. Each of the pressure sensors is operable to generate a respective pressure signal in response to pressure applied to it. The pressure signal quantifies the pressure with greater than single-bit resolution. The processor is operable in response to the pressure signals to generate an information signal representing the spatial distribution of pressure applied to the sensor array.

Abstract: A device for determining the actual reversal of the direction of rotation of a rotational drive continuing to operate after previous switching of the direction of rotation, in particular for window lifting systems or sliding roof drives in a motor vehicle, has a sensor wheel (1) with a coding structure (9) configured asymmetrically in respect of distribution along the periphery of the sensor wheel (1); a single detector (2), which generates a rotor speed-dependent pulse signal during rotation of the sensor wheel (1) by scanning the coding structure (9); and an evaluation unit (4), to which the pulse signal is fed and which determines the actual reversal of the direction of rotation by evaluating the pulse edges; wherein the coding structure (9) is formed by coding sectors (10) of a first sector width (11) and a reference coding sector pair (12) with a second sector width (13).

Abstract: A torque sensor includes a shaft and a magnetic sensor. The shaft may have at least one active region having an elliptical magnetization. The magnetic sensor may be configured to sense a magnetic field about the shaft, where the magnetic field is representative of a torque applied to the shaft. The elliptical magnetization may have a nonzero axial component directed along a center line axis of said shaft at zero torque.

Abstract: Provided is a method and apparatus for generating and sensing torsional vibrations using magnetostriction, in order to perform modal testing on a bar, a pipe, a shaft, a beam, or the like. The apparatus includes a torsional vibration generating part transmitting torsional vibrations to a test part having an arbitrary cross-section and a predetermined length, and a torsional vibration sensing part sensing the torsional vibrations generated from the torsional vibration generating part.

Abstract: Apparatus and methods for detecting the presence of an airborne chemical or biological analyte utilize: a substantially gas- and liquid-impermeable container; means for introducing a substantially analyte-free collection liquid into said container; means for rapidly sampling ambient air and transferring said analyte therefrom into said collection liquid, said sampling means comprising an air intake means and and an air venting means; and means for removing from said container an analyte-enriched collection liquid; wherein said volume of air passes through a substantially horizontal air inlet and downward through a substantially vertical collector electrode tube with means for applying an electric field between said tube and a co-axial spiked wire- or rod-shaped discharge electrode.

Abstract: An air monitoring system includes a tubing having a metallic inner layer and an outer jacket to provide optimal transport of air samples.

Abstract: The simultaneous taking of water samples from the bottom of a column of water in the bed water above a water bed is of use for scientific investigation of the transition zone between the water bed and the water column lying above the same, for the determination of parameter gradients. Conventional bed water sampling devices with an arrangement of horizontally oriented sample containers at different water levels do not generally permit a non-invasive sampling. According to the invention, said ground water sampling device thus comprises central retainer rod (2) for the sample containers (3), which permanently rotate freely and easily in the bottom currents by means of a flow vane (6). All sample containers (3) comprise sealing devices (16) on both front surfaces (14, 15) and are flushed through with bed water originating from the corresponding level before the sampling.

Abstract: A measurement system including a staging unit including a substrate having piezoelectric properties and a conductive electrode formed on the substrate, the conductive electrode including an area adapted to receive a sample, and an oscillator coupled to the conductive electrode. A method including in a tissue sample having a mass of less than about one microgram and that exerts a high osmotic pressure, calculating an osmotic pressure value for the tissue sample from a plurality of measurements of changes in the mass due to swelling.

Abstract: Systems and methods are presented for determining a transfer characteristic of welding electrodes, flux, or other welding consumable, or materials used in producing welding consumables, in which an analytical scale or other weight measurement instrument is situated within an environmental chamber to weigh welding consumable test items while the atmospheric conditions inside the chamber are controlled. A data acquisition system is located outside the chamber and is operatively coupled with the scale to obtain a number of measurements at different times while the atmospheric condition in the interior of said environmental chamber is controlled to a test condition.

Abstract: A system for the nondestructive evaluation of aircraft comprising a plurality of positional transmitters forming a perimeter around a test airplane and an inspection station within the perimeter. The inspection station includes a moveable cart, a nondestructive testing device coupled the cart, and a computer coupled to the cart and nondestructive testing device. The computer configured to receive aircraft positional data from positional receivers mounted on an aircraft and overlay a model of the aircraft on the received aircraft positional data to determine a coordinate system for the aircraft. The computer is further operable to determine the location of the cart from data received from onboard positional receivers, the location of the cart referenced to the coordinate system for the aircraft.

Abstract: Variables such as injection pressure and injection velocity are detected at a predetermined sampling cycle for each molding cycle and the variables for a plurality of past molding cycles starting from the latest molding cycle are stored. Change patterns of the stored variables of the respective molding cycles are displayed in the form of graphs in which the first axis represents time (the number of times of sampling), the second axis represents the variable values, and the third axis represents the molding cycle.

Abstract: A fault diagnosis section activates a driving component alone, measures an operation state signal and a paper passage time, and stores feature values (Vm, ?v, Tqs, ?ts) extracted as a determination reference in a storage medium. A paper passage fault determination section determines whether or not a fault has arisen on the basis of the paper passage time when an apparatus is under normal operating conditions. A diagnosis target block determination section determines an order to operate a detail fault diagnosis when it is determined that there is a plurality of diagnosis target blocks.

Abstract: A multi-speed transmission includes first and second output gear sets having co-planar intermeshing gears axially-spaced from one another. Each has a first gear intermeshing with a second gear, one of which is connected for common rotation with an output shaft or a first countershaft and the other of which is connected for rotation about and selectively engagable with the other of the output shaft and first countershaft by a respective output torque-transmitting mechanism. A direct drive torque-transmitting mechanism is selectively engageable for transferring torque from the input shaft to the output shaft when neither of the output torque-transmitting mechanisms is engaged. The first output torque-transmitting mechanism is engaged during underdrive gear ratios and the second output torque-transmitting mechanism is engaged during overdrive gear ratios. The order of engagement of torque-transmitting mechanisms during the underdrive gear ratios may be repeated during the overdrive gear ratios.

Abstract: A gear change control device and a method for a work vehicle for reducing a heat quantity generated by gear shift clutches of a transmission and a gear shift shock to reduce a load on the clutches without inducing elongation of a cycle time or deterioration of a work efficiency. A clutch pressure (Pm) of an input clutch(10) is reduced to switch from a connected state to a power-transmittable sliding state at a time (tE) after a time (tA) at which a cut-off operation of a gear shift clutch used before gear shifting (reverse clutch 22) is started and before a time (tD) at which the connecting operation of a selected gear shift clutch to be used after the gear shifting (forward clutch 21) is completed.

Abstract: The invention relates to a transmission module, especially a transmission module in countershaft design, having at least one input and one output which are connected with each other by way of at least one speed-torque converter device, with a reverse gear which is arranged between a countershaft and the transmission output, with a hydrodynamic retarder. The hydrodynamic retarder having at least one rotor blade wheel and a stator. The rotor blade wheel is connected via a high gear with the transmission output. The high gear is a component of the reverse gear.

Abstract: A synchronizer-controlled transmission has a plurality of input shafts, which are selectively connectible with a transmission input shaft, at least one countershaft, which rotatably supports a plurality of ratio gears, and an output shaft. A plurality of synchronizers is disposed along the countershaft and at least one input shaft to provide power transmission connections between the countershaft and the ratio gears disposed thereon. At least one ratio is established through direct connection between at least one input shaft and the output shaft.

Abstract: A power delivery system of a hybrid vehicle realizes a speed reduction route and a speed increase route, and thereby enhances fuel economy.

Abstract: A steel bar for a steering rack that contains 0.50 to 0.60% by mass of C, 0.05 to 0.5% by mass of Si, 0.2 to 1.5% by mass of Mn, 0.0005 to 0.003% by mass of B, 0.005 to 0.05% by mass of Ti, 0.0005 to 0.1% by mass of Al, and 0.002 to 0.02% by mass of N is provided. Given D as a diameter of the steel bar, then the steel bar is adjusted in such a manner that quenched and tempered structures in a portion of the steel bar at a depth of D/4 from a surface satisfy conditions I), II), and III) as follows: I) a sum of a tempered bainitic structure and a tempered martensitic structure accounts for 30 to 100% in area percentage; II) a regenerated perlite structure accounts for 0 to 50% in area percentage; and III) a sum of the tempered bainitic structure, the tempered martensitic structure, and the regenerated perlite structure accounts for 50 to 100% in area percentage.

Abstract: The present invention provides parallel, cable based robotic manipulators, for use in different applications such as ultra high-speed robots or positioning devices with between three to six degrees of freedom. The manipulators provide more options for the number of degrees of freedom and also more simplicity compared to the current cable-based robots. The general structure of these manipulators includes a base platform, a moving platform or end effector, an extensible or telescoping central post connecting the base to moving platform to apply a pushing force to the platforms. The central post can apply the force by an actuator (active), or spring or air pressure (passive) using telescoping cylinders. The robotic manipulators use a combination of active and passive tensile (cable) members, and collapsible and rigid links to maximize the benefits of both pure cable and conventional parallel mechanisms.

Abstract: The present invention provides parallel, cable based robotic manipulators, for use in different applications such as ultra high-speed robots or positioning devices with between three to six degrees of freedom. The manipulators provide more options for the number of degrees of freedom and also more simplicity compared to the current cable-based robots. The general structure of these manipulators includes a base platform, a moving platform or end effector, an extensible or telescoping central post connecting the base to moving platform to apply a pushing force to the platforms. The central post can apply the force by an actuator (active), or spring or air pressure (passive) using telescoping cylinders. The robotic manipulators use a combination of active and passive tensile (cable) members, and collapsible and rigid links to maximize the benefits of both pure cable and conventional parallel mechanisms.

Abstract: The invention provides an energy absorbing apparatus for a steering column. The energy absorbing apparatus includes a first member having a telescoping end and a side wall. The energy absorbing apparatus also includes a second member having a telescoping end and a side wall. The second member is disposed for collapsing telescoping movement with the first member. The energy absorbing apparatus also includes a bushing extending annularly between the first member and the second member. The bushing is fixed to one of the first member and the second member. The energy absorbing apparatus also includes at least one projection integrally formed with the bushing and extending longitudinally and radially along the side wall of the one of the first member and the second member.

Abstract: In one illustrative embodiment, an isolator for an inertial measurement unit (IMU) is provided that includes an inner ring with an outer surface and an outer ring with an inner surface. The inner ring of the isolator may have a recessed portion and the outer ring may have a protruding portion, wherein the protruding portion is interlocked with at least part of the recessed portion to prevent excessive rotation of the inner ring relative to the outer ring during high rotational events. The isolator may also include an elastomer position between at least a portion of the inner ring and at least a portion of the outer ring to provide enhanced vibration and/or shock isolation during operation of the IMU, and to provide dampening of shock events during bottoming out of isolator during high shock events.

Abstract: A gear and clutch cluster receives rotational input from a bi-rotational input gear. The gear and clutch cluster produces rotational output in a driveshaft of a drive train in a single direction for both rotation directions of the bi-rotational input.

Abstract: Nanometer to micrometer sized particles containing platinum and having selected morphologies are prepared by a sonochemical process. A compound of platinum is dissolved, suspended, or diluted in a suitable liquid medium at a predetermined concentration and the liquid is maintained at a predetermined temperature from sub-ambient temperatures to above ambient temperatures. A reducing gas is bubbled through the liquid as it is subjected to cavitation at a controlled power to affect the reductive decomposition of the platinum compound. The morphology of the precipitated platinum particles can be varied widely by varying the described concentration, temperature and power parameters.

Abstract: A process for recycling composite materials includes the steps of feeding a quantity of composite material composed of at least one polymer and aluminum into at least one first reactor; heating the composite material in a non-oxidizing environment at a temperature sufficient to volatilize the at least one polymer and form a hydrocarbon by-product and aluminum in the at least one first reactor; feeding the aluminum free of the at least one polymer into a second reactor; and heating the aluminum in a non-oxidizing environment at a temperature sufficient to melt the aluminum in the second reactor.

Abstract: A method of handling liquid non-ferrous metals after smelting. The liquid metal is in contact with a solid refractory material, and in the absence of electrical currents passing through the liquid-metal-contacting surfaces. The solid material is Ti3SiC2. The liquid non-ferrous material can be aluminum or an aluminum alloy, magnesium or a magnesium alloy, or other non-ferrous materials as to which the Ti3SiC2 material is stable.

Abstract: Dental prostheses are fabricated as a metallic alloy body by a technique that produces scrap alloy. Suitable gold base alloys have only base metal alloying additions which are more readily oxidized than gold and when combined with the gold can be age hardened. Exemplary metals include titanium, zirconium, yttrium and chromium. Scrap from fabricating a dental prosthesis is melted in air so that the base metals are all oxidized and substantially pure gold is reclaimed for reuse in new alloys.

Abstract: The present invention provides a process that is useful in producing ferronickel having a high Ni content at low cost with high efficiency and reproducibility even if a low-grade feedstock containing nickel oxide is used. In particular, a feedstock containing nickel oxide and iron oxide is mixed with a carbonaceous reductant, the mixture is formed into agglomerates with an agglomerator, and the agglomerates are heated and reduced in a moving hearth furnace, whereby reduced agglomerates in which the Ni metallization degree is 40% or more and the Fe metallization degree is at least 15% less than the Ni metallization degree are prepared by adjusting the retention time of the agglomerates placed in the moving hearth furnace. The reduced agglomerates, in which the Ni component has been primarily reduced as compared with the Fe component, are smelted in a smelting furnace, whereby ferronickel having a high Ni content is obtained.

Abstract: Deadblow hammers capable of minimizing or eliminating recoils when the hammers impact their targets are discussed. These hammers have easy access anti-recoil chambers, at least one insert element placed inside the anti-recoil chamber, and improved openings for inserting the insert element. The insert element or elements function to negate the effects of the hammer recoils. Golf clubs with anti-recoil chamber and insert elements are also discussed.

Abstract: A ratchet wrench includes a metal rod member, an outer layer and a grip. The outer layer surrounds an upper portion of the metal rod member, and the outer layer is combined with the grip that can be chosen from a variety of grips having different shapes, colors and patterns. The grip and the outer layer are separately made for enhancing the percentage of qualified finished products so as to lower producing cost.

Abstract: A ratchet wrench with a quick-rotated element which has a blocking function, includes a shank and a ratchet wheel pivotally received in one end of the shank. The ratchet wheel includes a polygonal hole centrally and longitudinally defined therein. The polygonal hole extends through the ratchet wheel. An annular groove is laterally defined in an inner periphery of the polygonal hole. A disk is attached to a top of the ratchet wheel and has a through hole defined therein. The through hole has a diameter smaller than that of the polygonal hole. A retainer partially is received in the annular groove in the ratchet wheel, wherein the retainer is adapted to position a tool bit that is partially and longitudinally received in the polygonal hole.

Abstract: A ratchet wrench with clamping and blocking functions includes a shank having an enlarged head formed on one end thereof. A through hole is defined in the enlarged head and a ratchet wheel is pivotally received in the through hole. A first annular groove is defined in an inner periphery of the through hole. The ratchet wheel has a polygonal hole longitudinally defined therein. The polygonal hole extends through the ratchet wheel. A second annular groove and a second annular groove are respectively defined in an inner periphery of the polygonal hole. A stopper is partially received in the second annular groove and adapted to prevent a tool bit overly extending through the ratchet wheel and a retainer is partially received in the third annular groove and adapted to position the tool bit in the ratchet wheel.