A friction clutch with a clutch plate having a hub member, a rim portion and a plurality of rib members. The hub member has a plurality of female hub teeth. The rim portion is disposed concentrically about the hub member and has a rim member and a friction material that is coupled to the rim member. Each of the rib members extend radially between the hub member and the rim member to couple the hub member and the rim member to one another. Each one of the rib members is intersected by at least three of the other rib members. Each of the other rib members intersecting the one of the rib members at a distinct location such that the distinct locations are spaced apart from one another along the one of the rib members.

A one-way clutch, including: an outer race; an inner race; and a rocker assembly. The outer race includes: a first outer race plate defining a first rocker pocket; and a second outer race plate non-rotatably connected to the first outer race plate and defining a second rocker pocket. The inner race is axially disposed between the first and second outer race plates. The rocker assembly is at least partly disposed in the first and second rocker pockets and includes a rocker arranged to contact the inner race, a spring guide including a spring arm, and a spring wrapped around the spring arm and urging the rocker in a pivot direction. The one-way clutch includes: a first annular thrust washer axially disposed between the first outer race plate and the inner race; or a friction-reducing coating adhered to the first outer race plate and facing the inner race.

A constant velocity universal joint includes an inner ring and an outer ring. A cage is disposed between an outer spherical surface of the inner ring and an inner spherical surface of the outer ring, and has windows in which respective balls are received. The cage has ball contact surface areas with which the balls come into contact, and includes soft portions that are lower in hardness than the ball contact surface areas. The soft portions are formed by local heat treatment at portions of the windows that are kept out of contact with the balls or surface portions around the windows.

A speed-reducing or -increasing apparatus, with first and second crown gears facing one another, with a cam unit that causes the first crown gear to incline with respect to the second crown gear so that the first crown gear meshes with the second crown gear, that causes the first crown gear to precess in such a manner as to move the meshing position, and couples to an input or output shaft. A rolling element is between the cam unit and the first crown gear, and the cam unit includes a first member that couples to the input or output shaft and a second member made of steel and including a rolling element rolling portion where the rolling element rolls, the second member configured to be incapable of rotating relatively to the first member, and at least part of the first member having a lower specific gravity than the second member.

A torque limiter includes a friction mechanism, a pressure plate, a first side plate, an urging member, and a second side plate. The friction mechanism includes a first friction member and a second friction member. The pressure plate includes a first contact surface and a plurality of first drainage grooves. The first contact surface is a surface that makes contact with the first friction member. The first drainage grooves radially extend. The second side plate includes a second contact surface that makes contact with the second friction member. The second side plate is disposed on a second side with respect to the second friction member in an axial direction. The second side plate is attached to the first side plate to be unitarily rotated therewith.

A one-way clutch, including: an outer race; an inner race; and a rocker assembly. The outer race includes: a first outer race plate defining a first rocker pocket; and a second outer race plate non-rotatably connected to the first outer race plate and defining a second rocker pocket. The inner race is axially disposed between the first and second outer race plates. The rocker assembly is at least partly disposed in the first and second rocker pockets and includes a rocker arranged to contact the inner race, a spring guide including a spring arm, and a spring wrapped around the spring arm and urging the rocker in a pivot direction. The one-way clutch includes: a first annular thrust washer axially disposed between the first outer race plate and the inner race; or a friction-reducing coating adhered to the first outer race plate and facing the inner race.

A clutch includes a clutch disk that rotates by receiving motive power from an engine and a clutch plate switched between an engaged state in which it is engaged with the clutch disk and a disengaged state in which it is not engaged with the clutch disk. A controller calculates a coefficient of friction μ between the clutch disk and the clutch plate based on a time period Δt elapsed from a first time point when the number of relative rotations of the clutch disk and the clutch plate attains to a first number of rotations to a second time point when a second number of rotations smaller than the first number of rotations is attained, in a state in which the clutch disk rotates while transfer of motive power from the engine to the clutch disk is cut off and in the engaged state.

In a power transmission apparatus, a centrifugal clutch includes a holder, a press, and springs to urge masses from a radially outer position to a radially inner position. The masses are each housed in an associated one of housing portions arranged in a circumferential direction of the holder such that the masses are radially movable. More than one spring is provided in the circumferential direction between an inner peripheral wall surface of each of the housing portions and an associated one of the masses to urge the associated mass from the radially outer position to the radially inner position.

In a power transmission apparatus, an auxiliary clutch plate different in diameter from driving and driven clutch plates located in a clutch housing. When the driving and driven clutch plates are pressed against each other, the auxiliary clutch plate is pressed to enable transmission of a driving force of an engine to a driving wheel. When a pressing force exerted on the driving and driven clutch plates is released, a pressing force exerted on the auxiliary clutch plate is released to cut off transmission of the driving force of the engine to the driving wheel.

Provided are a wet friction plate and a wet multiplate clutch device capable of reduction drag torque while suppressing a decrease in the area of a friction member. The wet friction plate includes multiple friction members through oil grooves on a flat plate annular core metal. The friction member has first fine grooves opening at an inner peripheral edge of the friction member and extending to an outer peripheral edge side and second fine grooves opening at an outer peripheral edge of the friction member and extending to an inner peripheral edge side. The first fine groove and the second fine groove are formed to have a groove width of equal to or greater than 0.1 mm and equal to or less than 0.8 mm, and overlap portions overlapping with each other in a circumferential direction at the same position in a radial direction of the core metal.