Abstract: Because the pressure angle ?° (=12°) of teeth (47) of a worm wheel (46) is larger than the pressure angle ?° (=11°) of teeth (45) of a worm (44), tips of the teeth (47) of the worm wheel (46) can be more tapered as compared with a case in which the pressure angle of the teeth of the worm and the pressure angle of the teeth of the worm wheel are the same angle (the conventional case). Thereby, it is possible to ensure non-contact of teeth, which had been variable in terms of contact and non-contact in the case of the conventional form, even if there has been non-uniformity in the teeth (47) of the worm wheel (46).

Abstract: A progressing cavity pump has: a stator; a rotor; the rotor having a first axial operating position within the stator in which a first axial part of the rotor aligns with a first axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator; the rotor having a second axial operating position within the stator in which the first axial part of the rotor aligns with a second axial part of the stator to form an active pump section adapted to generate a pumping force on rotation of the rotor in the stator. A related method is disclosed.

Abstract: A transmission speed reduction device, comprising: a worm assembly (1) which is located within a container body (2), a worm wheel assembly (3) and an output axle (4); an input axle (11) is provided on the worm assembly (1), while the worm assembly (1) and the worm wheel assembly (3) achieve primary stage mesh transmission there between by means of worm teeth which are provided on the worm assembly (1) and a first worm wheel tooth (34) which is provided on the worm wheel assembly (3); the worm wheel assembly (3) and the output axle (4) achieve secondary stage mesh transmission by means of an intermediate rotary body (32) which is provided on the worm wheel assembly (3) and a rotary disc assembly (5) which is fixed on the output axle (4).

Abstract: Pressure changing devices and methods of making and using the same are disclosed. One pressure changing device includes an elliptic cylinder and a piston that has an external surface with a trochoid cross-section. Another pressure changing device includes a piston and a rotating cylinder that has an internal surface with a trochoid cross-section. Another pressure changing device includes two fixed axes, one for rotation of one component and another for orbiting or oscillation of the other component. The devices and methods include stacked pressure changing devices with one or more common shafts. The pressure changing device may be easier and less expensive to manufacture and repair than prior pressure changing devices of the same or similar functionality, and can provide efficient gap sealing in a high-pressure expansion part of a compression or expansion cycle.

Abstract: The invention relates to an adjustment mechanism for a vehicle disk brake, which is provided with an adjustment device for compensating the operation-induced wear on the brake linings and the brake disk, wherein the adjustment device has the following components: —a drive element (25) which is rotatably arranged within the housing of the disk brake on an axis (A) parallel to the axis of rotation of the brake disk and which can be set in rotation by a brake application device; —a shaft (40) which is arranged centrally on the axis (A), on which the drive element (25) is rotatably mounted; —a cardanic rotary bearing (45) which supports the shaft (40) in an opening (1A) of the housing in a pendulum-like manner and which is made at least partially of a deformable rubber or elastomer ring (46) and a steel ring (47) which is attached therein.

Abstract: The invention relates to a system for rotating a fan (2) of a turbojet engine (1) about a first rotation axis ?, including a reduction gear (3) made up of a planetary gearset placed at the centre of the fan (2), which includes: a central sun gear (31); an outer planet gear (33) attached to the fan (2); at least one satellite gear (32) arranged between the central sun gear (31) and the outer planet gear (33) in order to transmit a rotary movement between the central sun gear (31) and the outer planet gear (33); characterised in that the outer planet gear (33) includes an inner portion (33a) which meshes with the satellite gear (32), as well as an outer portion (33b) to which blades (21) of the fan (2) are directly attached.

Abstract: A thread-forming screw has a shank which, in a front region of the shank, has a tip for insertion into a bore in a substrate, and in a rear region of the shank, has a drive for transmitting a torque to the shank. The shank has a spiral-shaped groove and a thread spiral which is inserted into the spiral-shaped groove. The spiral-shaped groove has a front flank and a rear flank disposed opposite the front flank. The front flank, at least regionally, has a different part flank angle than the rear flank.

Abstract: A plastic helical gear has a three-dimensional tooth surface modification section on a tooth surface of each of involute-shaped teeth. The three-dimensional tooth surface modification section is a combined surface of a tooth top modification surface and an arc crowning surface. The tooth top modification surface is reduced in tooth thickness from a position between a tooth top and a tooth root toward the tooth top. The arc crowning surface is reduced in tooth thickness from a position between one end in the tooth width direction and the other end in the tooth width direction toward both ends in the tooth width direction. A line extending from an intersection point P0 between the starting position of the tooth top modification surface and the apex position of the arc crowning surface to the tooth root is aligned with a line on the tooth surface of the involute-shaped tooth.

Abstract: A resin helical gear is formed by setting a first machining reference line obliquely coupling a tooth tip side of a first tooth to a tooth root side of a second tooth on another end side in the tooth width direction along a tooth surface, and a second machining reference line obliquely coupling a tooth tip side of the second tooth to a tooth root side of the first tooth along the tooth surface. Then, the tooth surface is cut out from the first machining reference line to the tooth root of the first tooth while the tooth surface is cut out from the second machining reference line to the tooth root of the second tooth. Then, an involute tooth profile form is left on a tooth tip side of the tooth with respect to the first machining reference line and the second machining reference line.

Abstract: A slew drive includes a housing, a worm shaft having a worm thread carried within the housing for rotational movement, and a torque tube having an outer diameter and a central socket. The torque tube is carried by the housing for rotational movement perpendicularly to the worm shaft and worm thread. A ring gear section having teeth, is carried by the torque tube so that the teeth extend beyond the outer diameter of the torque tube and engage the worm threads. Rotation of the worm shaft rotates the worm threads engaging the teeth of the ring gear section, thereby rotating the ring gear section which rotates the torque tube relative the housing.

Abstract: A drive transmission mechanism includes plural gears having meshing teeth and a recessed or projecting portion provided on a side surface of at least one of the gears. The side surface crosses a rotation axis of the at least one of the gears. The recessed or projecting portion is at least one of a cavity and a protrusion having a ridge that extends so as to follow an outline of at least one of the teeth and that serves as a marking for measuring wear of the at least one of the teeth.

Abstract: There is provided a tool for efficiently cutting a face gear to be meshed with a helical gear. When a circular tooth thickness of a tooth tip of a cutting edge portion is represented as SatSC, a circular tooth thickness on a virtual outside diameter of a tooth profile of the helical gear in a cross-sectional view perpendicular to an axis is represented as Sat, a helix angle on the virtual outside diameter of the tooth profile of the helical gear in a cross-sectional view by a plane perpendicular to the axis is represented as ?a, and a face width of the cutting edge portion is represented as bsc, b SC ? s at - s atSC tan ? ? ? a is satisfied.

Abstract: An internal-circulation-type ball screw includes a nut, a screw shaft, and two returning members. The nut has an internal-thread groove. The screw shaft passes through the nut and has an external-thread groove. The internally and external-thread grooves are aligned to form a helix channel. The screw shaft has a returning channel and two opposite receiving recesses. Each of the receiving recesses is radially communicated between the external-thread groove and the returning channel. The returning members are received in the receiving recesses of the screw shaft and each have a redirecting channel. The redirecting channel is connected between the helix channel and the returning channel, so that balls are allowed to circulate along the helix channel, the redirecting channel and the returning channel. Thereby, the internal-circulation-type ball screw provides good durability, reliability and smoothness in use.

Abstract: A recirculating-ball style gearbox for a vehicle steering system is provided. The gearbox has a rack with rack-teeth that are capable of providing variable ratio steering, where the rack-teeth are in mesh with the involute-teeth of a tapered sector gear. The involute-teeth of the sector gear have arrays of helical meshing lines extending across the meshing surfaces of the teeth, wherein the array of helical meshing lines have leads that decrease in length moving radially outward across the meshing surfaces.

Abstract: Exemplary embodiments provide a progressive cavity pump or motor including a stator having a longitudinal bore and a rotor rotatably disposed within the longitudinal bore of the stator. The rotor includes a rotor core and a resilient outer layer formed of a resilient material bonded onto the outer surface of the rotor core. The resilient outer layer sealably connects the helical configurations on the outer surfaces of the rotor and the stator as the rotor rotates within the longitudinal bore of the stator.

Abstract: The invention relates to an eccentric screw pump (100), in particular for conveying viscous, highly viscous and abrasive media, having a longitudinal direction L, having a conical, helically wound, at least single-start rotor (1) having a gradient h, having at least one eccentricity (e1, e2, e3, . . . en) and at least one cross-section d that is rotatably arranged in a single or multi-start conical stator (2) wherein a plurality of chambers (3, 4, 5 . . . n) each having a volume (V3, V4, V5 . . . Vn) is formed between the rotor (1) and stator (2) that serve to convey the medium and wherein the chambers (3, 4, 5 . . . n) between the stator and the rotor are limited by a sealing line D. The volumes (V3, V4, V5 . . . Vn) of each individual chamber (3, 4, 5 . . . n) between the stator (2) and the rotor (1) are equal.

Abstract: A process and an apparatus for generating control data, wherein a first tooth flank geometry is determined which corresponds to a geometry of a first tooth flank of the herringbone gearing, a second tooth flank geometry is determined which corresponds to a geometry of a second tooth flank of the herringbone gearing, a transition section geometry is determined which corresponds to a geometry of a transition section between the first tooth flank and the second tooth flank, an overall tooth flank geometry is determined which comprises the first tooth flank geometry, the transition section geometry and the second tooth flank geometry, and the control data is generated based on the overall tooth flank geometry and machining paths are indicated, each extending transversely to the profile direction of the tooth flanks and along the first tooth flank geometry, the transition section geometry and the second tooth flank geometry.

Abstract: Each tooth of a worm wheel has a first tooth flank in which a helical surface portion is arranged on one side in a rotational axis direction of the worm wheel and a concavely curved surface portion is arranged on the other side in the rotational axis direction, and a second tooth flank in which a concavely curved surface portion is arranged on the one side in the rotational axis direction and the helical surface portion is arranged on the other side in the rotational axis direction.

Abstract: In a gear mechanism that includes a gear in which a tooth trace is twisted at a predetermined angle with respect to an axial direction, a curvature radius along a line of contact at a meshing position where a line of contact does not intersect a pitch circle is formed larger than a curvature radius along a line of contact at a meshing position where a line of contact intersects a pitch circle, on a plane of action of the gear.

Abstract: A gear structure is configured to support vertical motion of an electric pop-up monitor. More specifically, a double rack gear structure is configured to support a pop-up monitor. The rack gear structure includes an outer gear and an inner gear. The outer gear is coupled at a side of the monitor frame to operate integrally with the monitor frame, and enables the vertical motion of the monitor frame with an ascending or descending motion. The inner gear is received inside the outer gear. The inner gear performs an ascending or descending motion simultaneously with the outer gear, and supports forward and rearward or right and left shaking, which occurs in the outer gear, by maximizing a portion overlapping with the outer gear when the outer gear has ascended to the maximum.

Abstract: A retainer made of a synthetic resin for use in a deep groove ball bearing is proposed of which the lubricity has been improved. The retainer includes a cylindrical first split retainer member (41) having a first axial side, and a cylindrical second split retainer member (42) having a second axial side coupled to the first axial side of the first split retainer member (41). Circumferentially spaced apart first and second cutouts (45 and 50) are formed in the first axial side of the first split retainer member (41) and the second axial side of the second split retainer member (42), respectively, which define respective pockets for receiving balls with the split retainers (41 and 42) coupled together.

Abstract: A worm wheel including first toothing regions transitioning into and on either side of a second toothing region and a complete annular surface on both ends of the worm wheel. The first toothing regions may have a constant outer diameter and the second toothing region may be depressed relative to the first toothing region. The first toothing regions may be globoid toothing regions and the second toothing region may be a cylindrical toothing region.

Abstract: A method of manufacturing a gear by a skiving process, the skiving process utilizing a cutter including a rotational axis inclined to a rotational axis of a work to be processed into the gear, the skiving process feeding the cutter in a tooth trace direction of a tooth to be formed at the work in a state where the cutter rotates in synchronization with the work, the method includes a surface hardening process for hardening a work surface of the work before the skiving process is performed.

Abstract: A gear structure comprising: a reinforcement member fixed onto a side surface of a gear; and a fixation section configured to fix the reinforcement member onto the side surface of the gear, the fixation section being provided on a line of contact action of the gear.

Abstract: An eccentrically cycloidal gear engagement of tooth profiles having curvilinear teeth is disclosed. One of the engaging profiles represents a gearwheel with at least two helical teeth. The flanks of each tooth of the first tooth profile are outlined, in a principal cross-section of the gearwheel, by corresponding arcs of circular curves, eccentrically shifted from a center of rotation of the gearwheel. The second tooth profile, which is conjugated with the first tooth profile, has helical cycloidal teeth. The teeth of the second tooth profile are outlined, in the same cross-section, by segments of front edges of intersecting cycloidal curves. Tips and troughs between teeth can have any shape, not intersecting with the gearwheel teeth.

Abstract: A rotational-to-linear conversion mechanism inhibits interference from occurring in places except for an engagement site to increase the efficiency of conversion mechanism and reliability, which has: a rack rod 1 including thread on its outer peripheral face; a holder member 3 provided on the outer periphery of the rack rod, rotating about the rack rod and moving in the axis direction; and revolving rollers 21 rotatably supported in the holder member, each having ring-shaped grooves formed in its outer peripheral face to be engaged with the thread, and placed at an axis angle with respect to a center axis of the rack rod to allow the ring-shaped grooves to be engaged with the thread on the rack rod. A contact face of the thread with each ring-shaped groove in an engagement site of the thread and the ring-shaped groove is formed as a convex face having different curvatures in a radial direction.

Abstract: A roller transmission and gearing mechanism with a driving body, one or more rollers, and a driven body coupled to the driven body via the rollers. The bodies define at least one pair of respective roller guide tracks thereon. The guide tracks start and terminate at respective pairs of limit surfaces. The rollers contact the guide tracks along rolling curves, and distances between points of the rolling curve on the driving body and the respective rolling curve on the driven body are different such that: for all contacting point-pairs on the rolling curves, the respective tangential planes are parallel to each other; the velocities of the contacting pairs of points are identical but have opposite signs; in the contacting points, the action lines of forces intersect the central axes of the rollers; and the lengths of the rolling curves of the driving and driven bodies are equal.

Abstract: A transmission gear has a tooth surface formed of a free-form surface instead of an involute surface and a root area formed of a free-form surface instead of a trochoid surface. With such a transmission gear, the fatigue strength against contact pressure can be increased by reducing the Hertzian stress in the area around the meshing point of the tooth surface. The tooth surface is formed of a free-form surface in which the smallest radius of curvature in an area around a mating pitch point is maximized, and the fatigue strength against bending can be increased by reducing the bending stress at a tooth root portion of the bottom land. In addition, the gear noise can be reduced. The bottom land is formed of a free-form surface in which the smallest radius of curvature in an area around a tooth root is maximized.

Abstract: A worm wheel gear for a BLDC motor transmits the operation of a shift gear of an armature unit in a BLDC motor. The worm wheel gear may include a worm wheel-threaded portion formed on the outer circumferential surface with one side of a thread groove recessed and open and the other side of the thread groove closed, a worm wheel central shaft formed at the center portion, and internal support members protruding from the worm wheel central shaft and connected to the inner circumferential surface of the worm wheel-threaded portion to support the worm wheel-threaded portion. Therefore, it is possible to improve efficiency of transmitting operation and reduce operational noise by increasing the contact surface between the worm wheel-threaded portion and the shift gear.

Abstract: A gear assembly includes a single piece gear body having a first axis of rotation and including opposing first and second surfaces each having spiroid gear teeth formed therein. The gear teeth radially extend outward from the first axis of rotation. The gear teeth on the first surface also extend from the first surface toward the second surface and the gear teeth on the second surface also extend from the second surface toward the first surface. The gear teeth on the first surface and the gear teeth on the second surface are configured to concurrently engage teeth of a pinion such that rotation of the pinion is translated to rotation of the gear body around the first axis of rotation.

Abstract: A worm wheel including an annular worm wheel main body formed from a resin material; teeth on an outer periphery of the worm wheel main body in a circumferential direction of the worm wheel main body a; a first region on respective tooth flanks of the teeth and offset from a mid-position of a whole depth of the respective teeth in a radially outward direction of the worm wheel main body; a first region; and a second region.

Abstract: A spindle (242; 414; 542; 642) for driving a bung of a cartridge is provided. The spindle includes a generally circular shaft having an outer surface (560). The generally circular shaft extends from a distal end to a proximal end of said circular shaft. A first helical groove (219; 519; 619) is provided along a first portion of the outer surface. The first helical groove having a first pitch. A second helical groove (221; 521; 621) provided along a second portion of the outer surface of the generally circular shaft. The second helical groove overlapping the first helical groove. The second helical groove having a second pitch.

Abstract: A helical gear having helical tooth portions of the helical gear being worked by a punch and a die having a land of a smaller distance between opposed working surfaces formed to be inclined than that of other portion, formed on predetermined portions in tooth directions of respective opposed working surfaces thereon, in which worked surfaces on both side of the helical tooth portions on the helical gear as a work are ironed by the land in response to the helical tooth portions passing through the land when the work is forged by the punch.

Abstract: An electric power steering apparatus 10 has an electric motor 46 for supplying an auxiliary force to a steering force inputted from a steering wheel 16, and transmits the steering force including the auxiliary force to a steered road-wheel 14 at least partially via a rack-and-pinion mechanism 30, thereby performing steering of a vehicle 12. The rack-and-pinion mechanism 30 includes: a pinion 38 provided at a pinion shaft 28 connected to the steering wheel 16; a rack 40 that is provided over a predetermined width at a rack shaft 32 connected to the steered road-wheel 14, and that is engaged with the pinion 38; and a rack guide 70 for urging the rack shaft 32 toward the pinion 38. A pressure angle ?1 of a tooth root of the rack 40 is set to be greater than a pressure angle ?0 of a tooth tip of the rack 40.

Abstract: A method of improving working of grooves of a screw rotor, in particular, working of grooves side in working efficiency, a working apparatus, a working tool, and a method of manufacturing a screw compressor are provided. A method of controlling rotation of a work and turning of a tool at a time to form a screw tooth space based on a five-axis NC machine, and a special end mill having a cutting edge of a short length and a neck portion provided between the cutting edge and a shank portion to be made thin is used to perform working in grooves side finish working process.

Abstract: A roller bearing comprises at least two rows of rollers disposed between an inner ring and an outer ring. At least two tracks guide the respective rows of roller and are defined in the axial direction of the inner ring or the outer ring. At least one flange abuts axial ends of axially-adjacent rows of rollers and extends radially from a radially outer side or a radially inner side of the inner ring or the outer ring. At least one recess is defined on the side of the inner ring or the outer ring that is opposite of the radially outer side or the radially inner side of the inner ring or the outer ring, from which the at least one flange radially extends. The at least one recess at least partially overlaps the at least one flange in the axial direction.

Abstract: A retainer made of a synthetic resin for use in a deep groove ball bearing is proposed of which the lubricity has been improved. The retainer includes a cylindrical first split retainer member (41) having a first axial side, and a cylindrical second split retainer member (42) having a second axial side coupled to the first axial side of the first split retainer member (41). Circumferentially spaced apart first and second cutouts (45 and 50) are formed in the first axial side of the first split retainer member (41) and the second axial side of the second split retainer member (42), respectively, which define respective pockets for receiving balls with the split retainers (41 and 42) coupled together.

Abstract: A gear train is provided that includes at least one side gear comprising a helical face gear and a plurality of helical pinions in meshing engagement with the helical face gear. The gear train may further include an absorber configured to provide an axial force on at least one of the plurality of helical pinions. A differential may also be provided including a differential case and a gear train disposed in the differential case. The gear train includes at least one side gear comprising a helical face gear and a plurality of helical pinions in meshing engagement with the helical face gear. The gear train in the differential may further include a means for providing an axial force on at least one of the plurality of helical pinions.

Abstract: The invention relates to a gear transmission having at least one gear wheel stage (1), wherein at least one of the gear wheels (2a; 2b) is fastened coaxially on a hollow shaft (3) that is rotatably mounted in a transmission housing (5) via at least two shaft bearings (4a, 4b). An outside-radial stage offset (8) is formed on the hollow shaft (3) as a seat for a broad rim gear wheel (2a) that approaches the plant radially on the inside.

Abstract: A hybrid spiroid and worm gear is formed as a gear body having an axis of rotation. The gear body has a plurality of spiroid gear teeth formed in opposing surfaces of the body formed generally radially relative to the axis of rotation. The gear body further has a plurality of worm gear teeth formed in a hub portion, between, separate and apart from the spiroid teeth. The worm gear teeth are formed generally longitudinally relative to the axis of rotation. A method for making the hybrid spiroid and worm gear is also disclosed.

Abstract: A planetary gear device having two sun gears with different diameters that engage with double planet gears having a first gear teeth area, which interacts with the fist sun gear, and a second gear teeth area, which interacts with the second sun gear. The double planet gears are continuous helical gear wheels. The crown circle diameters of the gear teeth areas of the double planet gears and the crown circle diameters of the sun gears are adapted such that the pitch circle diameters between the double planet gears and the sun gears are arranged in the center between the crown circle diameters and the effective root diameters of the gear teeth areas of the double planet gears and the sun gears.

Abstract: As for the gears, this invention makes the transmission angle error and the backlash very small, and reduces vibration and mechanical sound. If form of the teeth in gears are made into the circle, at the angle which the peak of a tooth top and the peak of a tooth bottom overlap, the backlash of the gears will be made to zero. As for the other mesh angle, the correct degree of transmission angle is included in the range of the backlash. If it sets it as 1 cycle to become mesh of the same condition, as for one half of cycles, it will be in the condition which the tooth top and the tooth bottom replaced, and will become the same mesh. If the slice of the gears of the circle-tooth is made as the helical gear by the detailed lamination, the mesh from which the phase shifted exists in that pitch point, and the action of the gears are limited at a zero-backlash-part.

Abstract: A rotor gear includes a rotor gear body having involute teeth that each have an involute surface that extends between a tooth tip and a tooth base. The involute surface includes at least reference points A-D, with reference point A near the base, reference point D near the tip, reference point B between reference points A and D, and reference point C between reference points B and D. The reference points A-D have associated respective roll angles, ?A-D, between a corresponding first line that is perpendicular to the involute surface at the given reference point A-D and a second line that is tangent at a reference point that lies on a terminal end of the involute surface at the tooth base to a reference base circle having a center origin at the center axis.

Abstract: It is an object of the present invention to approximate of life of each resin double helical gear of a gearing resin double helical gear pair to each other by effectively increasing the strength of the tooth of the resin double helical gear with the higher rotational speed; and to lengthen life of the gearing resin double helical gear pair by effectively increasing the strength of the tooth of the resin double helical gear that comes to the end of its life earlier due to stress concentration out of the gearing resin double helical gear pair. A resin double helical gear pair includes a first resin double helical gear and a second resin double helical gear with the larger diameter gearing into the first double helical gear. The first double helical gear is formed so that at least an addendum modification coefficient of a peak of a chevron tooth is larger than addendum modification coefficients of other sections.

Abstract: A gear structure comprising: a reinforcement member fixed onto a side surface of a gear; and a fixation section configured to fix the reinforcement member onto the side surface of the gear, the fixation section being provided on a line of contact action of the gear.

Abstract: A self service terminal having a slot; at least one shutter for selectively opening and closing the slot and a gear drive for moving the shutter between open and closed positions, the gear drive having a first gear that interacts with a second gear, at least one of the first and second gears defining a stop that is engagable with the other of the first and second gears to stop or prevent non-gear driven movement of the shutter.

Abstract: An image heating apparatus comprising a heating rotatable member for heating an image on a recording material; a pressing rotatable member for contacting the heating rotatable member to form a nip therebetween; a driving source; a first helical gear rotatable by a driving force supplied from the driving source; a second helical gear rotatable by a driving force supplied from the driving source, the second helical gear has a twisting direction which is different from that of the first helical gear; a first switching member for switching between rotation transmission and non-transmission from the driving gear to the first helical gear; a second switching member for switching between rotation transmission and non-transmission from the driving gear to the second helical gear; a third helical gear provided on the heating rotatable member in meshing engagement with the first helical gear; a fourth helical gear provided on the heating rotatable member in meshing engagement with the second helical gear; and switching

Abstract: A gear set is provided including a side gear comprising a helical face gear with at least one helical tooth and a helical pinion. The helical pinion may have at least one helical tooth and may have an apex angle that is less than about 20°. The helical pinion may be configured for meshing engagement with the side gear. A differential may also be provided. The differential comprises a differential case and a gear set. The differential may further include a torque ring configured to support the helical pinion.

Abstract: A worm wheel is provided in which a step is not formed near a tooth face meshing with a worm, and noise does not easily occur during power transmission. A worm wheel 1 includes a circular arc-shaped tooth section 5 that is a portion meshing with a worm 101 and configuring a circular tube worm gear, and a helical tooth section 4 that is connected to one end side of the circular arc-shaped tooth section 5. An angle of torsion at an arbitrary reference point 14 in a tooth depth direction of a tooth 3 on a boundary 7 between the circular arc-shaped tooth section 5 and the helical tooth section 4 is equal to an angle of torsion at a second reference point 15 corresponding to the first reference point 14 in the tooth depth direction of the tooth 3 in a diameter portion P0 of a throat of the circular arc-shaped section 5. As a result, a step is not formed on a tooth face on the boundary 7 between the circular arc-shaped tooth section 5 and the helical tooth section 4.

Abstract: In optimum number of teeth setting method for a helical gear pair and the helical gear pair manufactured on the basis of the set optimum number of teeth of each helical gear of the helical gear pair, a sound pressure level of a gear sound is compared with the sound pressure level of an audible limit with respect to a meshing frequency of the helical gear pair at a predetermined vehicle speed of an automotive vehicle in which the helical gear pair is mounted to select a frequency region in which the calculated sound pressure of the gear sound is relatively low to the sound pressure level of the audible limit, and number of teeth of each helical gear of the helical gear pair corresponding to the selected frequency region is set to an optimum number of teeth of each helical gear of the helical gear pair.