A structure is achieved capable of ensuring excellent transmission efficiency while preventing the occurrence of gross slipping at traction portions.

A pressing device 9 rotationally drives a cam disk 21 by a pressing force adjusting motor 23, which causes an annular roller element 6a of a pair of annular roller elements 6a, 6b to displace in the axial direction. A controller 31, by adjusting the rotational drive of the pressing force adjusting motor 23, adjusts the surface pressure at the traction portions between rolling surfaces 16 of planetary rollers 7 and an inner-diameter side rolling contact surface 5 of an input shaft 3 and outer-diameter side rolling contact surfaces 12a, 12b of the pair of annular roller elements 6a, 6b to a target value.

A planetary gearbox with two rows of planets, at least some of the planets including magnets. The planets are driven by a stator to drive the gearbox as a motor. The planets may be geared with axial portions with different helix angle to position the gears and avoid the need for a planet carrier or bearings. Gears with small heights and/or high pressure angles may be used to avoiding or reduce negative effects of conventional gearing.

A planetary gearbox with two rows of planets, at least some of the planets including magnets. The planets are driven by a stator to drive the gearbox as a motor. The planets may be geared with axial portions with different helix angle to position the gears and avoid the need for a planet carrier or bearings. Gears with small heights and/or high pressure angles may be used to avoiding or reduce negative effects of conventional gearing.

A prosthetic elbow includes a fixed member structure and a powered gearbox mechanism housed in a housing structure for rotating the forearm portion to varying angular positions. The powered gearbox mechanism includes a motor attached to the housing structure, a planetary frictional drive connected to a motor shaft of the motor and the housing structure, and a strain wave gear set having an input driven by the planetary fictional drive and an output attached to the fixed member structure, where the powered gearbox mechanism is configured to convert an output of the motor into a rotation of the housing structure relative to the fixed member structure, thereby causing the rotation of the forearm portion to varying angular positions relative to the upper arm. The fixed member structure and the housing structure each are connected to one of a forearm portion and an upper arm portion and rotatable relative to one another about an axis of rotation of the forearm portion.

A prosthetic elbow includes a fixed member structure and a powered gearbox mechanism housed in a housing structure for rotating the forearm portion to varying angular positions. The powered gearbox mechanism includes a motor attached to the housing structure, a planetary frictional drive connected to a motor shaft of the motor and the housing structure, and a strain wave gear set having an input driven by the planetary fictional drive and an output attached to the fixed member structure, where the powered gearbox mechanism is configured to convert an output of the motor into a rotation of the housing structure relative to the fixed member structure, thereby causing the rotation of the forearm portion to varying angular positions relative to the upper arm. The fixed member structure and the housing structure each are connected to one of a forearm portion and an upper arm portion and rotatable relative to one another about an axis of rotation of the forearm portion.

A landing gear system includes a drive shaft extending through an axle. A wheel with a drive surface is rotatably coupled to the axle. A drive assembly, which has disengaged and engaged states, includes a drive element and an idler element. The drive element, which has an engagement feature, is coupled to the drive shaft for rotation about an axis. The engagement feature has first and second diameters when the drive assembly is in the disengaged and engaged states, respectively. The idler element is frictionally engaged with the engagement feature of the drive element to transfer rotation of the drive element to the wheel when the drive assembly is in the engaged state. The idler element is disengaged from at least one of the engagement feature of drive element and the wheel when the drive assembly is in the disengaged state.

A spacer includes a first surface and a second surface. The first surface and the second surface respectively have two opposite first roller accommodating grooves and two opposite second roller accommodating grooves. The first and second roller accommodating grooves of the first surface correspond to the second and first roller accommodating grooves of the second surface. The spacer defines a reference plane, which is perpendicular to a horizontal direction and passes through a center point of the maximum thickness of the spacer. The horizontal distance from the reference plane to the center of each first roller accommodating groove is different from the horizontal distance from the reference plane to the center of each second roller accommodating groove. By flipping the spacer of the present invention, the spacing of two adjacent rollers can be adjusted. In addition, the present invention further provides a cycloidal reducer with the aforementioned spacer.

A spacer includes a first surface and a second surface. The first surface and the second surface respectively have two opposite first roller accommodating grooves and two opposite second roller accommodating grooves. The first and second roller accommodating grooves of the first surface correspond to the second and first roller accommodating grooves of the second surface. The spacer defines a reference plane, which is perpendicular to a horizontal direction and passes through a center point of the maximum thickness of the spacer. The horizontal distance from the reference plane to the center of each first roller accommodating groove is different from the horizontal distance from the reference plane to the center of each second roller accommodating groove. By flipping the spacer of the present invention, the spacing of two adjacent rollers can be adjusted. In addition, the present invention further provides a cycloidal reducer with the aforementioned spacer.

A rolling-element bearing transmission includes a first rolled-on element, at least one second rolled-on element and a third rolled-on element. Each of the rolled-on elements has a raceway configured to support a plurality of rolling elements. A first set of rolling elements is disposed between the first rolled-on element and the at least one second rolled-on element and a second set of rolling elements is disposed between the at least one second and the third rolled-on elements. Each of the rolled-on elements comprises or supports at least one transmission element, and the at least one transmission elements are disposed and configured to form a transmission.

A rolling-element bearing transmission includes a first rolled-on element, at least one second rolled-on element and a third rolled-on element. Each of the rolled-on elements has a raceway configured to support a plurality of rolling elements. A first set of rolling elements is disposed between the first rolled-on element and the at least one second rolled-on element and a second set of rolling elements is disposed between the at least one second and the third rolled-on elements. Each of the rolled-on elements comprises or supports at least one transmission element, and the at least one transmission elements are disposed and configured to form a transmission.