Abstract: The flexible external gear of a strain wave gearing is provided with: a cylindrical body part capable of flexing in the radial direction; external teeth formed on the outer circumferential surface thereof with a constant pitch; and grooves formed on the inner circumferential surface of the cylindrical body section along the circumferential direction thereof with the same pitch as the external teeth. The grooves are grooves with a wave-shaped cross-sectional shape having the center line of the tooth crest of the external tooth as the center and extend in the width direction of the external teeth. It is possible to increase the tooth bottom fatigue strength of the flexible external gear by increasing the tooth bottom thickness, while maintaining ease of flexing and a tooth shape that can withstand tangential forces due to meshing.

Abstract: A strain wave gearing has a wave generator provided with a plug and a roller bearing. The roller bearing is provided with flange plates fixed to both sides of the plug, and outer circumferential edge portions of the flange plates protrude outwardly from a plug outer circumferential surface so as to locate on both sides, in an axial line direction, of the raceway of rollers. The movements of the rollers in the axial line direction are constrained by the outer circumferential edge portions. The movement of retainer in the axial line direction is constrained by engaging with the rollers. The movement of each component part of the roller bearing in the axial line direction can be constrained without using additional components.

Abstract: A boss-side fastening surface formed in a boss of a flexible externally toothed gear of a strain wave gearing and a shaft-side fastening surface of an output shaft are coaxially fastened with bolts. The boss-side fastening surface is a convex-side fastening surface defined by two symmetrical inclined surfaces that are intersected at a prescribed angle to form a ridge line on a diameter line of the surface. The shaft-side fastening surface is a concave-side fastening surface defined by two symmetrical inclined surfaces that are intersected at a prescribed angle to form a trough line on a diameter line of the surface. The inclination angle of the inclined surfaces is set in the range of 2° to 16°. Transmission torques equal to or larger than those for combined bolt and pin fastening can be secured with bolt-only fastening.

Abstract: A flat strain wave gearing (1) has a mechanism for preventing a flexible externally toothed gear (4) from moving in the direction of the device center axis (1a) with respect to a rigid internally toothed gears (2, 3). The mechanism has an inner-peripheral groove (11) formed on inner teeth (3a) of the internally toothed gear (3), an outer-peripheral groove (12) formed on outer teeth (4a) of the externally toothed gear (4), and a flexible ring (13) mounted between the inner-peripheral groove (11) and the outer-peripheral groove (12). The ring (13) is engageable with groove inner-peripheral surfaces (11a, 11b, 12a, 12b), from the direction of the device center axis (1a), at meshing positions of the both gears (2, 4).

Abstract: The wave generator of the strain wave gear device comprises: a rigid plug; a roller bearing fitted on the elliptical outer circumferential surface thereof; and first and second cylindrical springs, which press loose rollers that have some play in the radial direction between the outer race and the inner race of the roller bearing against the outer raceway surface. The loose rollers are pressed against the outer raceway surface with a linear contact and roll according to the outer raceway surface. Skewing of the rollers is limited, ensuring smooth rotation of the roller bearing.

Abstract: The flexible external gear of a strain wave gearing is provided with: a cylindrical body part capable of flexing in the radial direction; external teeth formed on the outer circumferential surface thereof with a constant pitch; and grooves formed on the inner circumferential surface of the cylindrical body section along the circumferential direction thereof with the same pitch as the external teeth. The grooves are grooves with a wave-shaped cross-sectional shape having the center line of the tooth crest of the external tooth as the center and extend in the width direction of the external teeth. It is possible to increase the tooth bottom fatigue strength of the flexible external gear by increasing the tooth bottom thickness, while maintaining ease of flexing and a tooth shape that can withstand tangential forces due to meshing.

Abstract: An externally toothed gear of a strain wave gearing is made to flex into a shape conforming to an ellipsoidal curve. The externally toothed gear meshes with an internally toothed gear at the major-diameter position of the ellipsoidal curve. These two meshing positions gradually change in the circumferential direction of the both gears along the tooth trace direction. The number of external teeth of the externally toothed gear participating in meshing with the internally toothed gear can be increased. A strain wave gearing which has a high rigidity and is capable of reducing vibrational noise, can be realized.

Abstract: A strain wave gearing has a wave generator provided with a plug and a roller bearing. The roller bearing is provided with flange plates fixed to both sides of the plug, and outer circumferential edge portions of the flange plates protrude outwardly from a plug outer circumferential surface so as to locate on both sides, in an axial line direction, of the raceway of rollers. The movements of the rollers in the axial line direction are constrained by the outer circumferential edge portions. The movement of retainer in the axial line direction is constrained by engaging with the rollers. The movement of each component part of the roller bearing in the axial line direction can be constrained without using additional components.

Abstract: A boss-side fastening surface formed in a boss of a flexible externally toothed gear of a strain wave gearing and a shaft-side fastening surface of an output shaft are coaxially fastened with bolts. The boss-side fastening surface is a convex-side fastening surface defined by two symmetrical inclined surfaces that are intersected at a prescribed angle to form a ridge line on a diameter line of the surface. The shaft-side fastening surface is a concave-side fastening surface defined by two symmetrical inclined surfaces that are intersected at a prescribed angle to form a trough line on a diameter line of the surface. The inclination angle of the inclined surfaces is set in the range of 2° to 16°. Transmission torques equal to or larger than those for combined bolt and pin fastening can be secured with bolt-only fastening.

Abstract: First and second external tooth gear parts of a strain wave gearing are bent in an elliptic shape by a wave generator to engage with first and second internal tooth gears, respectively. The first and second external tooth gear parts are bent so as to have elliptic shapes the phases of which are rotated 90 degrees from each other about a rotational center line. A coupling external tooth gear part that maintains a circular cross-sectional shape which does not deform is formed in between the first and second external tooth gear parts. The coupling external tooth gear part is maintained so as to be coupled with a coupling internal tooth gear in an engaged manner. The strain wave gearing has high engagement rigidity and is capable of transmitting large torque.

Abstract: The wave generator of the strain wave gear device comprises: a rigid plug; a roller bearing fitted on the elliptical outer circumferential surface thereof; and first and second cylindrical springs, which press loose rollers that have some play in the radial direction between the outer race and the inner race of the roller bearing against the outer raceway surface. The loose rollers are pressed against the outer raceway surface with a linear contact and roll according to the outer raceway surface. Skewing of the rollers is limited, ensuring smooth rotation of the roller bearing.

Abstract: A flat strain wave gearing (1) has a mechanism for preventing a flexible externally toothed gear (4) from moving in the direction of the device center axis (1a) with respect to a rigid internally toothed gears (2, 3). The mechanism has an inner-peripheral groove (11) formed on inner teeth (3a) of the internally toothed gear (3), an outer-peripheral groove (12) formed on outer teeth (4a) of the externally toothed gear (4), and a flexible ring (13) mounted between the inner-peripheral groove (11) and the outer-peripheral groove (12). The ring (13) is engageable with groove inner-peripheral surfaces (11a, 11b, 12a, 12b), from the direction of the device center axis (1a), at meshing positions of the both gears (2, 4).

Abstract: A fastening friction plate is wedged between the fastening surfaces of two fastening members in order to increase the fastening force between them. The fastening friction plate has a friction plate main body of a fixed thickness, and engaging protuberances having an approximately truncated cone shape formed on the both surfaces of the friction plate main body at a fixed pitch. The friction plate main body and the engaging protuberances are integrally formed by photo-etching into the both surfaces of a steel plate material having a fixed thickness. The hardness of the fastening friction plate is equal to or greater than that of the fastening surfaces of the fastening members.

Abstract: An externally toothed gear of a strain wave gearing is made to flex into a shape conforming to an ellipsoidal curve. The externally toothed gear meshes with an internally toothed gear at the major-diameter position of the ellipsoidal curve. These two meshing positions gradually change in the circumferential direction of the both gears along the tooth trace direction. The number of external teeth of the externally toothed gear participating in meshing with the internally toothed gear can be increased. A strain wave gearing which has a high rigidity and is capable of reducing vibrational noise, can be realized.

Abstract: A wave generator of a hollow strain wave gearing has a rigid plug and a needle roller bearing. The needle roller bearing has an inner ring trajectory surface formed in the plug external peripheral surface, a flexible outer ring, an outer ring trajectory surface formed in an inner peripheral surface of the outer ring, and needle rollers. An inner ring trajectory groove is formed in the plug external peripheral surface, and the inner ring trajectory surface is formed in a groove bottom surface of the inner ring trajectory groove. Inner-ring-side restricting surfaces for restricting the needle rollers from moving in the center axis direction are formed in groove side surfaces on both sides of the inner ring trajectory groove. A wave generator can be obtained, which is suitable for increasing the hollow diameter of a strain wave gearing.

Abstract: A strain wave gearing (1) has a flexible externally toothed gear (3) with a boss (7). A boss-side fastening surface (16) formed on the boss is coaxially superposed with a member-side fastening surface (15) of an output member (11), and the boss (7) and the output member are fastened by fastening bolts (13). The bolt tension of the fastening bolts (13) causes the engaging protuberances (20) of the boss-side fastening surface (16) to dig into the member-side fastening surface (15) by a predetermined dig-in depth. A large frictional force is produced in the fastening portions between the flexible externally toothed gear (3) and the output member (11). It is thereby possible to transmit the necessary torque by the bolt tension alone without using pins or a friction sheet together with the fastening bolts.

Abstract: A wave generator of a strain wave gearing has a rigid plug and a needle roller bearing mounted on the plug external peripheral surface. The plug external peripheral surface has a retainer engaging part for engaging with a retainer that would move in an axis line direction and for restricting the movement thereof along the axis line direction. The retainer has an outer ring engaging part for engaging with an outer ring that would move in the axis line direction and for restricting the movement thereof along the axis line direction. The movements of the retainer and the outer ring can be restricted without providing a separate member. A wave generator of a strain way gearing can be realized, which is provided with a roller bearing capable of restricting the movement of the outer ring with a simple structure.

Abstract: A wave generator of a strain wave gearing has a rigid plug and a needle roller bearing mounted on the plug external peripheral surface. The plug external peripheral surface has a retainer engaging part for engaging with a retainer that would move in an axis line direction and for restricting the movement thereof along the axis line direction. The retainer has an outer ring engaging part for engaging with an outer ring that would move in the axis line direction and for restricting the movement thereof along the axis line direction. The movements of the retainer and the outer ring can be restricted without providing a separate member. A wave generator of a strain way gearing can be realized, which is provided with a roller bearing capable of restricting the movement of the outer ring with a simple structure.

Abstract: A wave generator of a hollow strain wave gearing has a rigid plug and a needle roller bearing. The needle roller bearing has an inner ring trajectory surface formed in the plug external peripheral surface, a flexible outer ring, an outer ring trajectory surface formed in an inner peripheral surface of the outer ring, and needle rollers. An inner ring trajectory groove is formed in the plug external peripheral surface, and the inner ring trajectory surface is formed in a groove bottom surface of the inner ring trajectory groove. Inner-ring-side restricting surfaces for restricting the needle rollers from moving in the center axis direction are formed in groove side surfaces on both sides of the inner ring trajectory groove. A wave generator can be obtained, which is suitable for increasing the hollow diameter of a strain wave gearing.

Abstract: First and second external tooth gear parts of a strain wave gearing are bent in an elliptic shape by a wave generator to engage with first and second internal tooth gears, respectively. The first and second external tooth gear parts are bent so as to have elliptic shapes the phases of which are rotated 90 degrees from each other about a rotational center line. A coupling external tooth gear part that maintains a circular cross-sectional shape which does not deform is formed in between the first and second external tooth gear parts. The coupling external tooth gear part is maintained so as to be coupled with a coupling internal tooth gear in an engaged manner. The strain wave gearing has high engagement rigidity and is capable of transmitting large torque.