A clutch includes a clutch housing, a driving rotating body, a driven rotating body, a roller arranged between the clutch housing and the driven rotating body, a support member that holds the roller between the clutch housing and the driven rotating body, and grease arranged between the clutch housing and the roller. The support member includes a guiding portion that guides grease, which has been moved from a space between the clutch housing and the roller, to the space between the clutch housing and the roller during rotation.

A clutch includes a clutch housing, a driving rotating body, a driven rotating body, a roller arranged between the clutch housing and the driven rotating body, a support member that holds the roller between the clutch housing and the driven rotating body, and grease arranged between the clutch housing and the roller. The support member includes a guiding portion that guides grease, which has been moved from a space between the clutch housing and the roller, to the space between the clutch housing and the roller during rotation.

A driving force transmission mechanism includes a worm gear unit as a brake disposed between a driving motor and an electrically driven input gear, and is configured such that when a driving force is applied from the driving motor to the electrically driven input gear through the worm gear unit, an outer ring which rotates together with the electrically driven input gear becomes locked to an inner ring through rollers so that the driving force is transmitted to an output gear, which rotates together with the inner ring, and when a driving force is applied to a manually driven input shaft, the outer ring and the inner ring are unlocked from each other by an unlocking piece which rotates together with the manually driven input shaft, and thereafter, the driving force is transmitted to the inner ring and the output shaft.

A driving force transmission mechanism includes a worm gear unit as a brake disposed between a driving motor and an electrically driven input gear, and is configured such that when a driving force is applied from the driving motor to the electrically driven input gear through the worm gear unit, an outer ring which rotates together with the electrically driven input gear becomes locked to an inner ring through rollers so that the driving force is transmitted to an output gear, which rotates together with the inner ring, and when a driving force is applied to a manually driven input shaft, the outer ring and the inner ring are unlocked from each other by an unlocking piece which rotates together with the manually driven input shaft, and thereafter, the driving force is transmitted to the inner ring and the output shaft.

A drive transmission device includes a clutch mechanism. The clutch mechanism includes a drive transmission member that is coupled to a first rotation member via a torque limiter and is arranged in a fitting part of a second rotation member and a third rotation member, and a transmission member moving part that includes a first gap and a second gap, the first gap being formed in the fitting part and having a width wider than the thickness of the drive transmission member and the second gap being formed in the fitting part and having a width that is equal to or smaller than the thickness of the drive transmission member, the transmission member moving part being formed in such a way that the width thereof becomes smaller about a rotation axis in the fitting part.

A one-way clutch, disposed between an input rotating body and an output rotating body, is used to connect the input and output rotating bodies so that the rotating bodies are rotatable integrally in a state in which the rotation speed of the input rotating body is higher than that of the output rotating body and to cut off the connection between the input and output rotating bodies in a state in which the rotation speed of the input rotating body is lower than that of the output rotating body. A plurality of engaging elements or an inner ring and an outer ring constituting the one-way clutch are made of a base material obtained by subjecting a martensitic stainless steel material to soft nitriding treatment, and the Vickers hardness of the portion up to 20 μm from the surface of the contact portion thereof is 1000 to 1500 Hv.

A one-way clutch, disposed between an input rotating body and an output rotating body, is used to connect the input and output rotating bodies so that the rotating bodies are rotatable integrally in a state in which the rotation speed of the input rotating body is higher than that of the output rotating body and to cut off the connection between the input and output rotating bodies in a state in which the rotation speed of the input rotating body is lower than that of the output rotating body. A plurality of engaging elements or an inner ring and an outer ring constituting the one-way clutch are made of a base material obtained by subjecting a martensitic stainless steel material to soft nitriding treatment, and the Vickers hardness of the portion up to 20 μm from the surface of the contact portion thereof is 1000 to 1500 Hv.

An roller clutch assembly that includes an outer race with a plurality of cam surfaces circumferentially spaced apart from each adjacent cam surface having a shallow end and a deep end further radially recessed into the outer race and an inner race having circumferentially spaced splines on an inner surface. A roller clutch assembly is disposed adjacent the inner race, and at least two spiral lock snap rings, wherein one spiral lock snap ring is disposed adjacent the outer race.

When relative positions of cages are changed from first positions to second positions, rollers are moved toward each other against an elastic biasing force of an elastic member such that an off state is achieved in which the rollers are disengaged from a cam surface or an inner peripheral surface portion to have a clearance therefrom. When the relative positions of the cages are changed from the second positions to the first positions, the rollers are moved away from each other by the elastic biasing force such that an on state is achieved in which one of the rollers on a downstream side engages with the cam surface or the inner peripheral surface portion without any clearance while the other of the rollers on an upstream side has a clearance from the cam surface or the inner peripheral surface portion.

When relative positions of cages are changed from first positions to second positions, rollers are moved toward each other against an elastic biasing force of an elastic member such that an off state is achieved in which the rollers are disengaged from a cam surface or an inner peripheral surface portion to have a clearance therefrom. When the relative positions of the cages are changed from the second positions to the first positions, the rollers are moved away from each other by the elastic biasing force such that an on state is achieved in which one of the rollers on a downstream side engages with the cam surface or the inner peripheral surface portion without any clearance while the other of the rollers on an upstream side has a clearance from the cam surface or the inner peripheral surface portion.