Abstract: A wheel assembly includes a wheel portion and a pair of drive assemblies opposing each other with the wheel portion interposed therebetween. One of the pair of drive assemblies includes a first motor and a first deceleration assembly. The other of the pair of drive assemblies includes a second motor and a second deceleration assembly. The first deceleration assembly includes a first input shaft connected to the first output shaft. The first rotation axis and the second rotation axis are parallel to the rotation axis of the wheel portion and disposed outside the wheel portion in the radial direction of the wheel portion. The first output shaft, the first input shaft, the second output shaft, and the second input shaft extend in a direction away from the wheel portion in a direction along the rotation axis.

Abstract: A driving force transmission device includes drive rollers, roller support portions, and a roller arrangement portion. The drive rollers transmit a driving force to a main wheel. The roller support portions rotatably support the drive rollers. The roller arrangement portion includes a base, an outer frame, and an inner frame. The base expands radially outward with respect to a rotation axis. The outer frame extends in a circumferential direction around the rotation axis and protrudes from the base in an axial direction along the rotation axis. The inner frame is radially inside the outer frame and protrudes from the base in the axial direction. The roller support portions are fitted between the inner circumferential surface of the outer frame and the outer circumferential surface of the inner frame.

Abstract: A gear includes a tubular portion and a diaphragm portion. The diaphragm portion extends in a direction including a radial component from one axial end portion of the tubular portion. The portion includes a first portion and a second portion. The first portion is on one axial side of the portion. The second portion is on another axial side relative to the first portion. The second portion includes teeth protruding radially outward. A maximum value of a thickness of the diaphragm portion is equal to or less than twice a distance from radially outer ends of the teeth to a radially inner surface of the second portion, and a minimum value of a thickness of the first portion is equal to or less than half the maximum value of the thickness of the diaphragm portion.

Abstract: A gear includes a tubular portion and a diaphragm portion. The diaphragm portion extends in a direction including a radial component from one axial end portion of the tubular portion. The portion includes a first portion and a second portion. The first portion is on one axial side of the portion. The second portion is on another axial side relative to the first portion. The second portion includes teeth protruding radially outward. A maximum value of a thickness of the diaphragm portion is equal to or less than twice a distance from radially outer ends of the teeth to a radially inner surface of the second portion, and a minimum value of a thickness of the first portion is equal to or less than half the maximum value of the thickness of the diaphragm portion.

Abstract: A rotary drive device includes a pair of drive force transmissions, a pair of decelerators, a pair of carriers, and at least one coupler. Driving rollers are included in the pair of drive force transmissions. Driving rollers transmit drive force to a main wheel. The main wheel includes driven rollers. The pair of drive force transmissions are rotatable about a rotation axis. The pair of carriers accommodate at least a portion of the decelerators. The pair of carriers oppose each other in an axial direction along the rotation axis. The pair of carriers include a first carrier and a second carrier that are directly or indirectly coupled by the at least one coupler.

Abstract: A rotary drive device in a mobile body includes a main wheel and a pair of drive assemblies opposing each other and each driving the main wheel. The main wheel includes driven rollers. One of the pair of drive assemblies includes a motor, a motor case, a drive force transmission, and driving rollers. The driving rollers are in the drive force transmission along a circumferential direction, and contact at least a portion of the driven rollers from one side of the rotary drive device of the axial direction. The drive force transmission rotates to transmit a drive force of the motor to the main wheel via the driving rollers. At least a portion of the motor case opposes at least a portion of the driving rollers in the axial direction.

Abstract: A speed reducer includes an input shaft member including a sun rotor arranged to rotate about a central axis; one or more planetary rolling elements each of which is supported to be capable of rotating around the sun rotor; a tubular eccentric shaft including an outer circumferential surface eccentric with respect to the central axis, and arranged to rotate about the central axis along with the rotation of the one or more planetary rolling elements; an eccentric oscillating gear including a plurality of external teeth in an outer circumferential surface thereof, and supported by the eccentric shaft through a first bearing; a housing including internal teeth arranged to mesh with the external teeth of the eccentric oscillating gear in an inner circumferential surface thereof; an output flange arranged to rotate about the central axis together with the eccentric oscillating gear, and including an eccentric oscillating carrier pin arranged to pass through the eccentric oscillating gear in an axial direction; and

Abstract: A speed reducer includes an input shaft member including a sun rotor arranged to rotate about a central axis; one or more planetary rolling elements each of which is supported to be capable of rotating around the sun rotor; a tubular eccentric shaft including an outer circumferential surface eccentric with respect to the central axis, and arranged to rotate about the central axis along with the rotation of the one or more planetary rolling elements; an eccentric oscillating gear including a plurality of external teeth in an outer circumferential surface thereof, and supported by the eccentric shaft through a first bearing; a housing including internal teeth arranged to mesh with the external teeth of the eccentric oscillating gear in an inner circumferential surface thereof; an output flange arranged to rotate about the central axis together with the eccentric oscillating gear, and including an eccentric oscillating carrier pin arranged to pass through the eccentric oscillating gear in an axial direction; and