A three-dimensional tooth profile of internal teeth in a strain wave gearing is a basic internal-teeth tooth profile at an internal-teeth outer end, and is a reduced tooth profile, in which the basic internal-teeth tooth profile is proportionally reduced only in the lateral direction, at other tooth-trace-direction positions. A three-dimensional tooth profile of external teeth is a basic external-teeth tooth profile at an external-teeth outer end, and is an increased tooth profile, in which the basic external-teeth tooth profile is proportionally increased only in the lateral direction, at other tooth-trace-direction positions. The tooth tip circle of an internal-teeth inner-end-side portion of the internal teeth is larger than that of other portions and does not interfere with the external teeth. The external teeth and the internal teeth mesh three-dimensionally, the teeth do not interfere at the internal-teeth inner-end side.

One aspect of the present disclosure provides a strain wave gear device including an internal gear, an external gear and a wave generator. The wave generator has a cam and a fourth bearing. The cam has a non-circular outer peripheral surface, and the fourth bearing is positioned between the inner peripheral surface of the external gear and the outer peripheral surface of the cam. The fourth bearing has an outer ring, an inner ring, a plurality of balls, and a retainer. The strain wave gear device includes a restricting portion provided such that the restricting portion can avoid touching the retainer. The restricting portion can restrict the fourth bearing from moving in the direction extending along the axis of rotation.

A pulley pulling device for removing a harmonic damper pulley having at least two spoke portions from a crankshaft comprises a hub including at least two clevis portions. A plurality of legs are pivotably connected to respective ones of the clevis portions, with the legs each including a body portion and a foot portion protruding laterally therefrom. The body and foot portions are contoured and oriented relative to each other such that the foot portion is adapted to engage a corresponding one of the spoke portions and to selectively pivot relative thereto as achieves optimized contact therebetween.

A three-dimensional tooth profile of internal teeth in a strain wave gearing is a basic internal-teeth tooth profile at an internal-teeth outer end, and is a reduced tooth profile, in which the basic internal-teeth tooth profile is proportionally reduced only in the lateral direction, at other tooth-trace-direction positions. A three-dimensional tooth profile of external teeth is a basic external-teeth tooth profile at an external-teeth outer end, and is an increased tooth profile, in which the basic external-teeth tooth profile is proportionally increased only in the lateral direction, at other tooth-trace-direction positions. The tooth tip circle of an internal-teeth inner-end-side portion of the internal teeth is larger than that of other portions and does not interfere with the external teeth. The external teeth and the internal teeth mesh three-dimensionally, the teeth do not interfere at the internal-teeth inner-end side.

A rotary actuator assembly includes a gearbox disposed within a cavity of a housing. The gearbox includes a fixed gear with elevations arranged on an outer surface that are designed to engage the housing and fix the gear to the housing.

The flat strain wave gearing is provided with an axially arranged rigid gear, flexible gear and wave generator. The flexible gear forms a flat truncated cone shape, has a tooth formation portion connected via a bellows-shaped cross-sectional diaphragm to a rigid boss which is an output shaft linking part. The flat strain wave gearing can ensure axial flexibility of the tooth formation portion, and can enable teeth of the flexible gear to mesh favorably with teeth of the rigid gear in the axial direction in each position in the tooth trace direction. Local bias of the load torque in the meshing portion in the tooth formation portion can also be suppressed.

An externally toothed gear of a dual-type strain wave gearing is provided with first and second external teeth having different teeth numbers, and a gap formed between these teeth as a cutter clearance area for tooth cutters. Where L1 is the maximum width of the gap, t1 is a depth from the tooth top land of the first external teeth to the deepest part of the gap, h1 is the tooth depth of the first external teeth, t2 is a depth from the tooth top land of the second external teeth to the deepest part, and h2 is the tooth depth of the second external teeth, any one of the following conditions 1 to 3 is satisfied:
L1=0.1L−0.35L, t1=0.9h1−1.3h1, and t2=0.3h2−0.9h2  Condition 1:
L1=0.1L−0.35L, t1=0.3h1−0.9h1, and t2=0.9h2−1.3h2  Condition 2:
L1=0.1L−0.35L, t1=0.3h1−0.9h1, and t2=0.3h2−0.9h2  Condition 3: It is possible to obtain a dual-type strain wave gearing in which wear resistance and tooth bottom fatigue strength are increased.

The present invention relates to a harmonic gear device in which a first similarity curve obtained by similarly transforming a reference curve representing a moving locus of an external tooth with respect to an internal tooth in a non-deflected state and a second similarity curve generated by similarly transforming the first similarity curve are used as a criterion for generating a tooth profile, wherein the present invention may provide the harmonic gear device that enlarges a first curve represented by a moving locus of positive deflection located above the apex of the reference curve among the moving loci of positive deflection of the external teeth on the basis of the reference curve to approximate an approximate reference point arranged on the second similarity curve to create a second curve, and uses the second curve as the top of the tooth profile of the external tooth.

A gearing includes an internal gear, a flexible external gear partially meshing with the internal gear and relatively rotating about a rotation axis to the internal gear, and a wave generator provided inside of the external gear and moving a mesh position between the internal gear and the external gear in a circumferential direction about the rotation axis, wherein the external gear includes an external tooth having an external tooth surface, the external tooth surface has an external tooth convex pattern including a first convex portion and a second convex portion extending in directions crossing directions of a tooth trace of the external tooth and arranged adjacent to each other in the directions of the tooth trace, and a distance between the first convex portion and the second convex portion is from 80 μm to 520 μm.

An externally toothed gear of a dual-type strain wave gearing is provided with first and second external teeth having different teeth numbers, and a gap formed between these teeth as a cutter clearance area for tooth cutters. The maximum width L1 of the gap is 0.1 to 0.3 times the width L of the externally toothed gear. The depth from the tooth top land of the first external teeth to the deepest part of the gap is 0.9 to 1.3 times the depth of the first external teeth, and the depth from the tooth top land of the second external teeth to the deepest part of the gap is 0.9 to 1.3 times the depth of the second external teeth. The tooth bottom fatigue strength of the externally toothed gear provided with differing numbers of first and second external teeth is increased.