Abstract: A planetary variator applicable in a variable transmission for realizing a variable speed and torque ratio includes: a ring wheel; at least two planet wheels, the at least two planet wheels including a shaft portion and a wheel portion that is rotatable about the shaft portion, the shaft portion having a longitudinal central axis, the longitudinal central axis also being the rotation axis of the wheel portion, each planet wheel being freely rotatable about a hinge axis that is oriented essentially perpendicularly with respect to a plane defined by the common central axis and the rotation axis of the wheel portion of the planet wheel; and a sun wheel. The ring wheel and the sun wheel are axisymmetric bodies positioned with respect to a common central symmetry axis. Interaction between the ring wheel, the at least two planet wheels, and the sun wheel takes place through a rolling motion.

Abstract: A toroidal continuously variable transmission including input and output discs disposed to face each other so that a rotational axis of the input disc and a rotational axis of the output disc conform, each of the discs having a concave contact surface; a power roller sandwiched between the contact surfaces of discs so that the power roller is tiltable, the power roller transmitting a rotational driving force of the input disc to the output disc with a transmission ratio corresponding to a tilt motion angle; and a pressing device which presses one of the discs toward the other. When viewed from a direction of a tilt motion axis lof the power roller, the contact surface of at least one of discs has a region with a curvature that is larger than a curvature of a tilt motion trajectory of a contact surface of the power roller.

Abstract: Power roller-side concave grooves are opposed to disk-side concave grooves 19, 19 so as to have angles therebetween in a rolling contact area between a peripheral surface of the power roller and a one-side surface 17 of a disk 16 in an axial direction regardless of a transmission gear ratio of a toroidal continuously variable transmission. Accordingly, the disk-side concave grooves 19, 19 are formed so as to have angles with respect to a circumferential direction of the disk 16 when viewed from a normal direction relative to the one-side surface 17 in the axial direction. Meanwhile, the power roller-side concave grooves are formed into a concentric shape (or a spiral shape) about a central shaft of the power roller. As a result, it is possible to prevent a decrease of a contact area in the rolling contact area regardless of the transmission gear ratio.

Abstract: A roller frictional transmission unit includes: a first roller; a second roller; an input shaft connected with a driving system of main driving wheels, and connected with one of the first roller and the second roller; an output shaft connected with a driving system of auxiliary driving wheels, and connected with the other of the first roller and the second roller; a thrust bearing arranged to position an input shaft side rotation section including the one of the first roller and the second roller and the input shaft, or an output shaft side rotation section including the other of the first roller and the second roller and the output shaft, with respect to a unit housing in an axial direction; and a low rigidity structure disposed in a thrust transmission path to the thrust bearing, and arranged to buffer a thrust.

Abstract: The use of powder metal components in a variator is disclosed. Traction fluid of various sorts may be used in the variators, not just high performance synthetics or application specific lubricants.

Abstract: In order to absorb loadings on friction faces in bevel friction ring gear mechanisms in an improved manner, the invention proposes a bevel friction ring gear mechanism having at least two friction cones which are arranged spaced apart from one another and a friction ring which is arranged displaceably in the spacing and transmits a torque from one of the two friction cones to the other of the two friction cones, wherein at least one friction face varies axially and the axial variation of the friction face has a radius above 0.1 mm in at least two convex regions.

Abstract: In a toroidal continuously variable transmission, rolling contact portions of an input disc 4, an output disc 7, and roller 13 are formed of bearing steel, which contains C: 0.8-1.5 wt %; Si: 0.5-2.5 wt %; Mn: 0.3-2.0 wt %; Cr: 1.9-2.5 wt %; Mo: 0.3-1.0 wt %; and a total of 1.0 wt % or more of Si and Mo; with the balance being iron and unavoidable impurities. A residual austenite in a range of depth Z=1.0L, where L is the major axis of a contact ellipse of the traction contact portion, from the surface of the rolling contact portion is 15 wt % or less, and the hardness of the range is HRC 58-62 by tempering a blank with a predetermined shape at a temperature of 250° C. or more after quenching the blank.

Abstract: A method for manufacturing a variator component of a continuously variable transmission having a plurality of cylindrical sections and a plurality of ball spline grooves, which are provided alternately in an inner radial region of the variator component. The method includes: simultaneously finishing the cylindrical sections and the ball spline grooves through use of a hard broaching tool; and finishing functional surfaces provided on side surfaces of the variator component while taking the cylindrical sections as a machining reference.

Abstract: A toroidal type continuously variable transmission has an input shaft to which a rotation torque is input, an input side disk and an output side disk that are concentrically and rotatably supported by the input shaft in a state that an inner peripheral surface of the input side disk opposes to an inner peripheral surface of the output side disk, a power roller held between the input side disk and the output side disk and a hydraulic loading device applying predetermined pressing force so that the power roller is pressed between the input and output side disks. Fine grooves are formed on at least a radially inner part of the inner peripheral surface of the input side disk and at least radially outer part of the inner peripheral surface of the output side disk, respectively.

Abstract: A transmission belt is formed by annularly arranging elements including a plate-shaped first element and a plate-shaped second element, and annularly connecting the elements using a ring. The first element includes a first edge surface on which a burr is formed when the first element is formed by a press operation. The second element includes a second edge surface on which a burr is formed when the second element is formed by the press operation. The first and second edge surfaces face in directions opposite to each other in a direction in which the elements are arranged. The first edge surface includes a first rocking edge that contacts the element adjacent to the first element when the elements are arranged in an arc. The second edge surface includes a second rocking edge that contacts the element adjacent to the second element when the elements are arranged in the arc.

Abstract: A rolling element including a base metal, and a nickel coat formed on a surface of the base metal and cooperating with the base metal to constitute a rolling contact surface satisfying condition that a mean value of ratios of L1 to L2 as measured in at least three optional observation areas is in a range of from 1.2 to 2.4, where each observation area is disposed in a cross section taken in a vertical direction relative to the surface of the base metal and is defined by two parallel vertical lines; lengths L1 and L2 respectively represent a length of an interface between the base metal and the nickel coat, and a length of a reference line segment extending perpendicular to the vertical direction, in same observation area.

Abstract: What is proposed is a variator disk for a toroidal variator, in particular for a motor vehicle toroidal transmission. The variator disk has a curved running surface which is oriented coaxially with respect to a variator axis and on which rollers of the toroidal variator can roll. The variator disk having furthermore at least two partial disks which are designed as a traction disk, on which the running surface is formed, and as a supporting disk, respectively. The supporting disk is designed for supporting axial forces applied to the running surface. The traction disk is supported on the supporting disk in the radial direction to the variator axis.

Abstract: A half toroidal CVT disk having an inner surface portion, an outer surface portion and a toroidal surface having a given machining allowance is centered with said inner surface portion worked prior to the heat treatment of said half toroidal CVT disk as the standard thereof, and then is chucked by a chuck mechanism. The toroidal surface of the chucked half toroidal CVT disk is ground by a grinding mechanism with the grinding wheel for grinding the half toroidal CVT disk in a state that one of said half toroidal CVT disk and said tool is inclined at a given angle with respect to the other.

Abstract: A friction transmission unit for transmitting power between input and output members by means of friction and capable of loss reduction and large torque transmission. Power is transmitted between a planar disk (16) and a roller (10), which contacts the upper surface of the planar disk (16). The profile of the peripheral surface (14) of the roller (10) which actually contacts the upper surface (20) of the disk (16) is expressed as z=a·sin h(bx2). This profile realizes a contact stress distribution which is constant over an area corresponding to approximately 80% in the width direction of the entire contact region. This profile also prevents formation of peak stresses near and at the edges of the contact region and, instead, enables formation of monotonic decrease of stress in areas near the edges.

Abstract: A power roller bearing of a toroidal-type continuously variable transmission unit that is used for a transmission of an automobile or the like comprises a power roller, an outer race, balls, a retainer, etc. Annular raceway grooves are formed individually on the respective opposite end faces of the outer race and the power roller. Treated-surface layers for enhancing the endurance of the power roller bearing are formed individually on the respective surfaces of the raceway grooves. The treated-surface layers include super-finished surfaces with the surface roughness of 0.05 Rad or less, formed individually on the raceway grooves, and low-friction layers formed individually on the super-finished surfaces. Alternatively, the treated-surface layers include residual compression stress layers formed on the respective surface layer portions of the raceway grooves by shot-preening.

Abstract: An inner surface 16a of a torque transmitting disc of a toroidal type continuously variable transmission can be finish-worked without also enhancing accuracy of a cylindrical surface as an outer peripheral surface of the disc. The inner surface is finish-worked with super finish while urging a working surface of a grindstone against the inner surface. In this case, roller shoes are rollingly contacted with the inner surface to prevent the disc from being radially displaced under force from the working surface.

Abstract: A toroidal type continuously variable transmission comprises input and output discs coaxially and rotatably arranged about a common axis. The input and output discs have respective toroidal concave surfaces which face each other. Power rollers are arranged each having a rounded outer surface and being interposed between the toroidal concave surfaces of the input and output discs. A loading cam is provided that presses the input disc against the power rollers by a force that is proposal to an input torque. Trunnions are provided each supporting the corresponding power roller in such a manner that the power roller is inclinable relative to a center of curvature of the input and output discs. Power roller bearings are arranged to rotatably support the power rollers relative to the respective trunnions.

Abstract: A toroidal-type continuously variable transmission component, such as an input disk, an output disk, an inner ring of a power roller bearing, and an outer ring of the power roller bearing, which is functioned as a rolling member, has a layer a depth of which is 0.5 mm or less from the surface thereof. The layer does not include a non-metallic inclusion having a maximum diameter of up to 0.1 mm in the area thereof having a depth of 0.5 mm or less from the surface thereof.

Abstract: For extension of service lives of rollers and discs of a toroidal continuously variable transmission, input discs, output discs and rollers are formed of a heat-resisting bearing steel. At least a roller has its peripheral surface subjected to a shot peening for achieving a compressive residual stress of 0.6 to 1.2 GPa and a hardness of HRC 63 to 66 at the outermost surface.

Abstract: A rotary assembly for traction drives, including a plurality of rolling elements having a rotation axis and traction contact surfaces around the rotation axis and associating with each other to transmit a motive power between the rolling elements via a traction oil film formed between the traction contact surfaces, in which at least one of the traction contact surfaces has a microstructure with irregularities which sizes are larger than a thickness of the traction oil film. The process for the traction contact surface is also disclosed.

Abstract: A blank for disc is heat treated for adjusting a surface hardness thereof to not less than Hv700. The blank has a spline hole thereof heated by high frequency heating while cooling a race thereof. Subsequently, the spline hole is subjected to slow cooling. Thus is obtained a disc having a surface hardness of not less than Hv700 at the race, and a surface hardness of not more than Hv600 at the spline hole, the disc wherein at least a thin portion is varied in hardness between a hardened layer of a bottom of the spline hole and a hardened layer of the race by an amount of not less than Hv20 per 1-mm depth.

Abstract: A toroidal continuously variable transmission is characterized by comprising an input disk, an output disk, trunnions, power rollers, and thrust rolling-element bearing, in which at least one of the input disk, output disk and power rollers of a power roller bearing is formed of an alloy steel and subjected to either carburizing processing and polishing or carbonitriding processing and polishing, and at least one of the input disk, output disk and the inner ring of the power roller bearing has an efficient hardened layer of Hv 653, which has a depth of 2.0 mm or more and 4.00 mm or less from the surface.

Abstract: A toroidal type continuously variable transmission includes a pair of discs (5, 10) in opposed relation, and a rotary element (17) interposed in a toroidal clearance (S) defined between these discs (5, 10). Torque is transmitted between the pair of discs (5, 10) via the rotary element (17). Sensing the velocity of the rotary element (17) permits the determination of, for example, how much the rotary element (17) slips on the discs (5, 10). This assists the prevention of heat-up of the rotary element (17) and also provides an optimal traction between the rotary element (17) and the discs (5, 10).

Abstract: A toroidal continuously variable transmission system of the present invention is provided with an input disk, an output disk and power rollers. The input and output disks have traction surfaces defined between a small-diameter portion and a large-diameter portion and having an arc-shaped concave section. The input and output disks are coaxially arranged in such a manner that the traction surfaces face each other. The power roller are frictionally engagement with the traction surfaces of the input and output disks and transmit a driving force. At least one of the input disk, the output disk and the power rollers is formed of an alloy steel which contains 0.15 to 2.0% by weight of Mo. The alloy steel is subjected first to carburization or carbonitriding processing executed at a temperature not lower than 1,000° C., and then to hardening and tempering. The alloy steel has a surface carbon content of 0.8 to 1.4%.

Abstract: A traction drive rotary assembly including a plurality of rolling elements having traction contact surfaces associating with each other to transmit power between the rolling elements. At least one of the traction contact surfaces has a surface microstructure including grooves and protrusions alternately arranged. The surface microstructure is represented by an unfiltered primary profile curve including recesses and projections corresponding to the grooves and the protrusions. Each projection includes a portion located higher than a center line of the unfiltered primary profile curve and having a shape selected from a generally trapezoidal shape with rounded corners, a generally crowning shape, a generally elliptic arc shape, a generally sinusoidal shape and a generally triangular shape with a rounded apex. A ratio &lgr;/AMP of a wavelength &lgr; of the unfiltered primary profile curve to a half depth AMP of the recess is in a range of 50-400.

Abstract: In a method of fabricating a variator disc, an outer periphery (5) of the input disc (D1), with a spline hole (4) thereof meshed with an input shaft (6), is finished using the input shaft (6) as a working reference. Subsequently, a race (2) is finished with high precisions using the outer periphery (5) as a working reference. There is an alternative method wherein a spline hole (4) with a machining allowance is precisely formed by means of a broach (X) prior to the heat treatment of a blank (B); after hardening the blank (B) by the heat treatment, tooth flanks (4a) of the spline hole (4) are precisely finished by means of a finishing broach (Y); and then, a race (2) of an input disc (D1) is precisely finished using the tooth flanks (4a) as a working reference.

Abstract: A rotary assembly for traction drives, including a plurality of rolling elements having a rotation axis and traction contact surfaces around the rotation axis and associating with each other to transmit a motive power between the rolling elements via a traction oil film formed between the traction contact surfaces, in which at least one of the traction contact surfaces has a microstructure with irregularities which sizes are larger than a thickness of the traction oil film. The process for the traction contact surface is also disclosed.

Abstract: The toroidal-type continuously variable transmission comprises an input shaft, an input disk, an output disk, a plurality of trunnions, a plurality of power rollers, and power roller bearings, wherein the mutually opposed inner surfaces of the input and output disks are respectively formed as concave surfaces each having an arc-shaped section, the peripheral surfaces of the power rollers are respectively formed as spherical-shaped convex surfaces, and these peripheral surfaces are contacted with the above-mentioned inner surfaces. The retainer of the power roller bearing is formed of high strength brass, and the high strength brass has a micro structure in which the &agr; phase thereof is 40% or more in the area ratio thereof, and the hardness of said retainer is set at HB80 or higher.

Abstract: In the thus structured toroidal-type continuously variable transmission, at least one of the concave surface of the input side disk, the concave surface of the output side disk, the convex surfaces of the power rollers, the raceway surfaces of the inner races of the power roller bearings, and the raceway surfaces of the outer races of the power roller bearings is, after heat treatment, subjected to grinding, superfinishing and shot-peening and then surperfinishing again, and the resultant surface residual compression stress is in the range from −780 to −1800 MPa.

Abstract: A toroidal continuously variable transmission is characterized by comprising an input disk, an output disk, trunnions, power rollers, and thrust rolling-element bearing, in which at least one of the input disk, output disk and power rollers of a power roller bearing is formed of an alloy steel and subjected to either carburizing processing and polishing or carbonitriding processing and polishing, and at least one of the input disk, output disk and the inner ring of the power roller bearing has an efficient hardened layer of Hv 653, which has a depth of 2.0 mm or more and 4.00 mm or less from the surface.

Abstract: A toroidal continuously variable transmission system of the present invention is provided with an input disk, an output disk and power rollers. The input and output disks have traction surfaces defined between a small-diameter portion and a large-diameter portion and having an arc-shaped concave section. The input and output disks are coaxially arranged in such a manner that the traction surfaces face each other. The power roller are frictionally engagement with the traction surfaces of the input and output disks and transmit a driving force. At least one of the input disk, the output disk and the power rollers is formed of an alloy steel which contains 0.15 to 2.0% by weight of Mo. The alloy steel is subjected first to carburization or carbonitriding processing executed at a temperature not lower than 1,000° C., and then to hardening and tempering. The alloy steel has a surface carbon content of 0.8 to 1.4%.

Abstract: A toroidal-type continuously variable transmission (CVT), including rolling elements having traction surfaces cooperating with each other to transmit a power between the rolling elements via a traction oil film formed between the traction surfaces. The traction surfaces have the microstructure that is defined with respect to a thickness of the traction oil film formed when the temperature of the traction portion of the traction surface is high, to thereby exhibit high traction coefficient even in the high-temperature operating condition.

Abstract: For extension of service lives of rollers and discs of a toroidal continuously variable transmission, input discs, output discs and rollers are formed of a heat-resisting bearing steel. At least a roller has its peripheral surface subjected to a shot peening for achieving a compressive residual stress of 0.6 to 1.2 GPa and a hardness of HRC 63 to 66 at the outermost surface.

Abstract: A disk for a half toroidal type continuously variable transmission is manufactured through the following processes. In step S1, a work as a base material mass is heated to a temperature suitable for forging. In step S2, the work is forged into the work having a portion corresponding to a protrusion of the disk using a first die set. In step S3, the work is forged into the work which has a hole corresponding to a mounting hole of the disk using a second die set. In step S4, the work is forged into the work which has a portion corresponding to a skirt portion of the disk using a third die set. In step S5, the work receives punching, machining and the like to finally obtain the disk product.

Abstract: The present toroidal-type continuously variable transmission comprises input and output disks coaxially disposed so as to be opposed to each other, and a pair of power roller bearings, each power roller bearing including an inner race, an outer race, and power rollers disposed so as to roll on the toroidal surfaces of the input and output disks. At least one of the input and output disks and power rollers are made of medium-carbon steel containing carbon in an amount ranging from 0.3 wt %-0.5 wt %, to thereby have a very long life.

Abstract: A blank for disc is heat treated for adjusting a surface hardness thereof to not less than Hv700. The blank has a spline hole thereof heated by high frequency heating while cooling a race thereof. Subsequently, the spline hole is subjected to slow cooling. Thus is obtained a disc having a surface hardness of not less than Hv700 at the race, and a surface hardness of not more than Hv600 at the spline hole, the disc wherein at least a thin portion is varied in hardness between a hardened layer of a bottom of the spline hole and a hardened layer of the race by an amount of not less than Hv20 per 1-mm depth.

Abstract: A continuously variable transmission including discs made of heat-resisting bearing steel, and rollers made of ceramics. The heat-resisting bearing steel contains 0.8-1.5 wt % of C, 0.5-2.0 wt % of Si, 0.3-2.0 wt % of Mn, 1.3-1.98 wt % of Cr, and 0.3-1.0 wt % of Mo, (Si+Mo) being 1.0 wt % or more. Because the rollers are made of ceramics superior in heat resistance, the toroidal type continuously variable transmission, even if used under high load and high rotational speed, is free from occurrence of sticking between discs and rollers and damage of the raceway surfaces.

Abstract: A roller transmission, in particular toroidal transmission, with infinitely variable transmission ratio, includes a friction wheel (6) disposed between a driving disk (2) and driven disk (3) and rotatably mounted to a swingable carrier (7). The friction wheel has a circumferential friction surface (8) for interaction with confronting end faces (4, 5) of both disks (2, 3). The friction wheel (6) is made of two sheet metal parts (9, 10) interconnected outside the friction surface (8) and defining a partition plane which is disposed substantially transversely to the rotation axis of the friction wheel (6), wherein at least one cavity (15) is arranged between both sheet metal parts (9, 10).

Abstract: An infinitely variable transmission comprising a pair of rotary, generally conical, torque-transmitting members, each being mounted for rotation on its geometric axis, the angularity of the axes, one with respect to the other, being variable, the outer surfaces of each member having torque-transmitting needles extending outwardly from the generally conical surface, the needles of one member meshing with the needles of its companion member, the needles being capable of flexing whereby torque may be transmitted through the rotary members without frictional sliding motion at the area of meshing engagement of the needles, the angularity of one member with respect to the other permitting a wide torque-transmitting ratio range.

Abstract: A toroidal continuously variable transmission including input and output disks having a common first rotation axis about which the disks are rotatable, and a power roller swingably interposed between the disks and having a second rotation axis intersecting the first rotation axis, about which the power roller is rotatable. The input and output disks and the power roller have traction surfaces cooperating with each other to transmit rotation therebetween. At least one of the input and output disks and the power roller has a surface roughness on the traction surface thereof which varies in a direction of the rotation axis thereof.

Abstract: A loading cam mechanism of a toroidal type continuously variable transmission is provided with a cam disc that rotates together with an input shaft. A cam surface is formed on the cam disc. The cam disc includes a disc portion having the cam surface formed thereon and a cylindrical portion protruding from the central portion of the cam surface. The cam disc further includes a lathe-turned portion formed by lathe turning, a milled surface formed by means of an end mill, and a ground surface formed by means of a grindstone. Formed on a corner portion between the cylindrical portion and the disc portion are a first corner curved surface worked by means of an arcuate portion on the distal end portion of the end mill and a second corner curved surface worked by means of an arcuate portion on the distal end portion of the grindstone.

Abstract: A power roller assembly for a toroidal-type CVT, including a pair of races formed with bearing surfaces opposed to each other, a plurality of rolling elements rotatably disposed between the races in contact with the bearing surfaces, and an iron phosphate-based coat formed on at least one of bearing surfaces.

Abstract: An inner surface 16a of an output transmitting disc of a toroidal type continuously variable transmission can be finish-worked without enhancing accuracy of a cylindrical surface as an outer peripheral surface of the disc. The inner surface is finish-worked with super finish while urging a working surface of a grindstone against the inner surface. In this case, roller shoes are rollingly contacted with the inner surface to prevent the disc from being retarded from the working surface.

Abstract: A power roller of a power roller bearing in a half-toroidal type continuously variable transmission is manufactured as follows. In step S1, a work used as material is heated up to a temperature suitable for forging. In step S2, the work is pressed by using a first die set, with its end face being held. In step S3, the work is forged by using a second die set. The work is formed into a work having a curved face corresponding to a traction surface, a hole corresponding to a center hole, and a recess corresponding to a raceway groove. In step S4, the work is punched by using a third die set. In step S5, the work is subjected to a cutting process and a heating process, thereby obtaining the power roller.

Abstract: A cam disk for use in a loading cam mechanism of a toroidal type continuously variable transmission comprises a first projecting portion, a second projecting portion, a flange portion, a cam surface, a bearing raceway and a corner section. The cam disk has metal flows along the cam surface, metal flows along a surface of the raceway, and metal flows along a surface of the corner section. To produce the cam disk, material is shaped into a predetermined form through a first forging step using a first die unit, a second forging step using a second die unit, a third forging step using a third die unit, a finishing step, etc. The metal flows are also formed in these steps.

Abstract: The disk has a traction surface having a concave-arc-shaped cross section which is interposed between a small diameter end portion and a large diameter end portion. In the central portion of the end face of the disk on the small diameter end portion side, there is formed a through hole which extends through the disk up to the large diameter end portion side end face of the disk, while the inner peripheral surface of the through hole is used as an inside diameter surface of the disk. Here, when, among metal flows existing in the disk, a metal flow, which has such a positional relationship with respect to the surface of the disk that an angle .theta. formed between a metal flow on the traction surface side and the tangent of the traction surface is smaller than or equal to 30 degrees, is defined as a "metal flow along the disk surface", the disk is structured such that the "metal flow along the disk surface" exists at least in the traction surface.

Abstract: A method of manufacturing a traction roller for a continuously variable transmission comprises placing a layer on a hollow cylindrical material having the volume substantially equal to the traction roller, performing axial pressure forging of the cylindrical material to obtain a work having the axial length substantially equal to that of the traction roller, performing axial die forging of the work to form side wall and outer peripheral surface of the traction roller, and grinding the work subjected to die forging to obtain a finished product of the traction roller.

Abstract: A toroidal type continuously variable transmission includes an input disk mounted on an input shaft; an output disk mounted on an output shaft; and a pair of power roller bearings each of which includes an inner race, an outer race, and a plurality of rolling elements. The inner races are engaged with the input and output disks to transmit the power of the input shaft to the output shaft. The inner races, outer races, input disk and output disk are made of case hardening steel, and are each subjected to a heat treatment in which carburizing or carbonitriding, hardening and tempering are performed sequentially, and then to shot peening, and finished by grinding of a predetermined grinding portion.

Abstract: A toroidal-type continuously variable transmission provides an input side disk disposed on an input shaft, an output side disk disposed on an output shaft, and a power roller for transmitting motive power of the input shaft to the output shaft while engaging both the input side disk and the output side disk, in which the input side disk, the output side disk, and the power roller made of a material are subjected to either a carburizing and grinding process or to a carbonitriding and grinding process so that effective carburized depths of the input side disk, the output side disk, and the power roller are limited to a range between 2.0 mm and 4.0 mm. The toroidal-type continuously variable transmission is capable of improving not only the rolling contact lives of the traction surfaces of the input and output side disks as well as the traction surfaces of the power rollers, but also the fatigue fracture lives of the input and output side disks and power rollers.

Abstract: The disk has a traction surface having a concave-arc-shaped cross section which is interposed between a small diameter end portion and a large diameter end portion. In the central portion of the end face of the disk on the small diameter end portion side, there is formed a through hole which extends through the disk up to the large diameter end portion side end face of the disk, while the inner peripheral surface of the through hole is used as an inside diameter surface of the disk. Here, when, among metal flows existing in the disk, a metal flow, which has such a positional relationship with respect to the surface of the disk that an angle ? formed between a metal flow on the traction surface side and the tangent of the traction surface is smaller than or equal to 30 degrees, is defined as a “metal flow along the disk surface”, the disk is structured such that the “metal flow along the disk surface” exists at least in the traction surface.