A power transmission device includes a pinion gear having a large pinion gear and a small pinion gear, a carrier that supports the pinion gear, a ring gear that engages with the small pinion gear, an oil supply unit positioned above a horizontal line that passes through a revolution center of the pinion gear, and a downstream side wall part facing a gear surface of the large pinion gear. The downstream side wall part is arranged to be adjacent to the oil supply unit further downstream in a revolution direction of the pinion gear than the oil supply unit when viewed from an axial direction.

A power transmission device includes a pinion gear having a large pinion gear and a small pinion gear, a carrier that supports the pinion gear, a ring gear that engages with the small pinion gear, an oil supply unit positioned above a horizontal line that passes through a revolution center of the pinion gear, and a downstream side wall part facing a gear surface of the large pinion gear. The downstream side wall part is arranged to be adjacent to the oil supply unit further downstream in a revolution direction of the pinion gear than the oil supply unit when viewed from an axial direction.

An apparatus and method for reducing edge contact stress concentrations in a press-fit. The apparatus and method of the present disclosure specifically provide for a press-fit collar having a channel circumscribing a collar axis. The channel having an asymmetrical cross-sectional profile in a radial face. The asymmetrical cross-sectional profile being configured to reduce an edge contact pressure.

A structure includes a transmission axle rotatably mounted at a center of a housing. The transmission axle includes a sun gear mounted thereon. An internally-toothed ring track is fixed to an inner circumference of the housing. A planetary gear set is arranged between the sun gear and the internally-toothed ring track. The planetary gear set includes a plurality of stepped planetary gears arranged around the sun gear for self-spinning and orbiting around the sun gear. Each stepped planetary gear includes a first toothed portion meshing with both the sun gear and the internally-toothed ring track and a second toothed portion rotatable in unison with the first toothed portion. An output member is fit over the planetary gear set and includes an inner circumference formed with an internal toothed circumference meshing with the second toothed portion of each stepped planetary gear.

Disclosed herein are actuator, planetary-gear apparatus, and structural-unit embodiments configured to reduce noise and vibration caused by operation of planetary gears. An embodiment may include a ring gear having an outer peripheral surface that extends in the axial direction. A first raised portion may be formed on said outer peripheral surface; and a housing having an inner peripheral surface that is provided facing, and with a gap from, the outer peripheral surface of the ring gear. A second raised portion may be formed on said inner peripheral surface. Movement of the ring gear in the circumferential direction is limited by linear contact or point contact between the first raised portion and the second raised portion, for example. The outer peripheral surface and/or the inner peripheral surface may be a surface of a crowned shape that is bowed in the outer radial direction, according to some further embodiments.

A gear-based mechanical metamaterial with continuously adjustable elastic parameters in a large range is provided. The gear-based mechanical metamaterial includes a gear array, a frame and connecting shafts. The gear array is formed by periodically extending mechanical metamaterial cells along an x direction and a y direction. Each of the mechanical metamaterial cells is formed by arranging a multiple gears. Adjacent gears of the multiple gears are meshed with each other. Each of the multiple gears includes a center hole and two centrosymmetric irregularly-shaped holes. A thickness of an elastic arm between the each of two centrosymmetric irregularly-shaped holes and an outer wall of a corresponding one of the multiple gears is uniformly increased or decreased. Each of the connecting shafts is arranged in a center hole of a corresponding one of the multiple gears.

A gear-based mechanical metamaterial with continuously adjustable elastic parameters in a large range is provided. The gear-based mechanical metamaterial includes a gear array, a frame and connecting shafts. The gear array is formed by periodically extending mechanical metamaterial cells along an x direction and a y direction. Each of the mechanical metamaterial cells is formed by arranging a multiple gears. Adjacent gears of the multiple gears are meshed with each other. Each of the multiple gears includes a center hole and two centrosymmetric irregularly-shaped holes. A thickness of an elastic arm between the each of two centrosymmetric irregularly-shaped holes and an outer wall of a corresponding one of the multiple gears is uniformly increased or decreased. Each of the connecting shafts is arranged in a center hole of a corresponding one of the multiple gears.

An electric parking brake actuator assembly is proposed. The electric parking brake actuator assembly includes: an outer housing including an inner space in which a gear installation space and a motor installation space are formed; an inner housing installed in the inner space of the outer housing, and including a brush card part and a gear installation part integrated together; a motor assembly coupled to the brush card part to be electrically connected thereto, and installed in the motor installation space; a gear assembly installed at the gear installation part and at the gear installation space, and changing and transmitting the rotational speed of the motor assembly; and a cover housing coupled to the outer housing with the inner housing interposed therebetween, and including a shaft insertion portion.

An electric parking brake actuator assembly is proposed. The electric parking brake actuator assembly includes: an outer housing including an inner space in which a gear installation space and a motor installation space are formed; an inner housing installed in the inner space of the outer housing, and including a brush card part and a gear installation part integrated together; a motor assembly coupled to the brush card part to be electrically connected thereto, and installed in the motor installation space; a gear assembly installed at the gear installation part and at the gear installation space, and changing and transmitting the rotational speed of the motor assembly; and a cover housing coupled to the outer housing with the inner housing interposed therebetween, and including a shaft insertion portion.

A compact geared reduction unit for application with transmission shaft subjected to radial loads, comprising a box-like body inside which a gear system is accommodated for the transmission of rotary motion from a driving shaft to a transmission shaft, which is provided with an output reduction stage of the epicyclic type; the output reduction stage comprises a driving sun gear which rotates about a main axis and a ring gear which is integrally associated with the box-like body, between which multiple planet gears are engaged which are supported in rotation about respective longitudinal axes which are parallel to the main axis by a transmission planet carrier, which in turn rotates about the main axis and is associated so as to be integral in rotation with the transmission shaft at a connection region. The reduction unit furthermore provides for rolling means adapted to support radial loads associated with the transmission shaft.