A cam transmission mechanism includes a rotary disk, a camshaft, contact members and a housing. The rotary disk has a periphery formed with equidistant projections, any two adjacent ones of which define an accommodating recess. The camshaft includes a shaft rod and a cam body that has at least one groove communicated with some of the recesses of the rotary disk. The groove and the recesses cooperate to form a plurality of confining spaces, within which the contact members are accommodated freely rollably for rotation transfer from the camshaft to the rotary disk. The housing is connected to the rotary disk for confining the contact members in the confining spaces, respectively.

A cam transmission mechanism includes a rotary disk, a camshaft, contact members and a housing. The rotary disk has a periphery formed with equidistant projections, any two adjacent ones of which define an accommodating recess. The camshaft includes a shaft rod and a cam body that has at least one groove communicated with some of the recesses of the rotary disk. The groove and the recesses cooperate to form a plurality of confining spaces, within which the contact members are accommodated freely rollably for rotation transfer from the camshaft to the rotary disk. The housing is connected to the rotary disk for confining the contact members in the confining spaces, respectively.

A harmonic drive assembly and fluid-powered linear motors with both axial pistons are rotary piston arrangements incorporating the harmonic drive assembly are disclosed. The motors may be used in downhole drilling applications, but the drive assembly and/or motors may be used in other applications. The assembly, motors and methods use advanced harmonic drives, advanced helical drives, and combinations thereof with 1) motors with axial pistons and reciprocating linear rings to convert reciprocative axial motion to continuous rotary motion, and 2) motors with rotary pistons and reciprocating linear rings to rectify reciprocative rotary motion to continual rotary motion to improve performance over prior configurations. Axial pistons provide a robust simple solution for generating rotation; Rotational pistons provide increased torque generation as the torque generated is proportional to motor length. Since downhole drills are long, a high-torque motor can be produced using this method.

A transmission, including an outer shell (1), an inner shell (2), a drive disk (3), a plurality of T-shaped teeth (4), a gear (5), a tooth seat (6), an adjustable nut (7), balls (8), inner balls (9), outer balls (10), an inner protective frame (11), an outer protective frame (12), rollers (13), a first sealing ring (14), a second sealing ring (15) and a third sealing ring (16). Transmission clearance can be adjusted freely at any time, the meshing of the T-shaped tooth and the gear is a real surface meshing, and almost all the teeth participate in force transmission simultaneously. Therefore, the transmission has high precision, high mechanical properties, and long service life.

A rolling-element bearing transmission includes a rotor configured to rotate a shaft relative to a stator and a rotatable output ring that includes a first rolled-on surface element. The shaft includes at least one second rolled-on surface element, and the stator includes a third rolled-on surface element. First and second pluralities of rolling elements are located between the shaft and the stator and between the shaft and the output ring. Also, a transmission mechanism transmits a rotary motion of the shaft to the output ring with a speed reduction such that the output ring rotates at a lower speed than the shaft.

A harmonic drive assembly and fluid-powered linear motors with both axial pistons are rotary piston arrangements incorporating the harmonic drive assembly are disclosed. The motors may be used in downhole drilling applications, but the drive assembly and/or motors may be used in other applications. The assembly, motors and methods use advanced harmonic drives, advanced helical drives, and combinations thereof with 1) motors with axial pistons and reciprocating linear rings to convert reciprocative axial motion to continuous rotary motion, and 2) motors with rotary pistons and reciprocating linear rings to rectify reciprocative rotary motion to continual rotary motion to improve performance over prior configurations.

The retainer is provided so as to be prevented from being rotatable with respect to the rotary shaft, and rotation of the input-side rotary member is reduced in speed and transmitted to the output-side rotary member through intermediation of the balls which engage with both of the ball engagement grooves. A raceway center line of the second ball engagement groove is formed of a wave-shaped curve. When a speed reduction ratio of the speed reducer is represented by i, the wave-shaped curve has such a shape that the balls which engage with the first ball engagement groove engage with the second ball engagement groove at a given rotation angle () of the input-side rotary member in a state in which the output-side rotary member is at a rotation angle (i).

A ball type speed reducer includes: an eccentric disk cam that turns integrally with an input-side rotating body; a shaking body shaken by the eccentric disk cam; a plurality of balls supported by the shaking body; a fixing member; a first output-side rotating body facing one side face of the fixing member; and a second output-side rotating body facing the other side face of the fixing member. A plurality of radial grooves guide the ball along the radial direction in the fixing member. A corrugated groove spirally guiding the ball along the circumferential direction is formed across the first output-side rotating body and the second output-side rotating body. The groove depth at the top of a wave of the corrugated groove is greater than that at the bottom of the wave, in an alternating manner on the first output-side rotating body side and the second output-side rotating body side.

A harmonic drive assembly and fluid-powered linear motors with both axial pistons are rotary piston arrangements incorporating the harmonic drive assembly are disclosed. The motors may be used in downhole drilling applications, but the drive assembly and/or motors may be used in other applications. The assembly, motors and methods use advanced harmonic drives, advanced helical drives, and combinations thereof with 1) motors with axial pistons and reciprocating linear rings to convert reciprocative axial motion to continuous rotary motion, and 2) motors with rotary pistons and reciprocating linear rings to rectify reciprocative rotary motion to continual rotary motion to improve performance over prior configurations. Axial pistons provide a robust simple solution for generating rotation; Rotational pistons provide increased torque generation as the torque generated is proportional to motor length. Since downhole drills are long, a high-torque motor can be produced using this method.

A ball type speed reducer includes: an eccentric disk cam rotating in synchronization with an input-side rotating body; a shaking body fitted relatively rotatably to an outer circumference side of the eccentric disk cam to be shaken; balls rollably housed in a ball holding portion of the shaking body; and a fixing member having a first side face portion facing one side face of the shaking body. Radial grooves for radially guiding the balls are formed in the first side face portion. An output-side rotating body has a second side face portion facing the other side face of the shaking body. An annular corrugated groove for guiding the balls circumferentially in an undulating manner is formed in the second side face portion. The balls are engaged with the radial grooves and the corrugated groove and are rolled inside the radial grooves and the corrugated groove as the shaking body is shaken.