A radial wedge clutch, including: an axis of rotation; a shaft; an outer ring located radially outward of the shaft; a cage radially disposed between the shaft and the outer ring; a plurality of circumferentially aligned wedge plate segments radially disposed between the shaft and the outer ring; at least one resilient element urging the plurality of circumferentially aligned wedge plate segments radially outwardly; and an actuation plate axially displaceable in a first axial direction to engage the cage and rotate the cage and the plurality of circumferentially aligned wedge plate segments.

A centrifugal clutch 200 includes a first drive plate 210 rotationally driven directly by a driving force of an engine and a second drive plate 220 frictionally in contact with the first drive plate 210. The first drive plate 210 includes a bulging body 215 on a supporting portion 214 bulging toward the second drive plate 220. The second drive plate 220 is rotationally driven together with the first drive plate 210 while allowing rotational displacement relative to the first drive plate and includes clutch weights 230. The bulging body 215 is made of a cylindrical roller. The clutch weight 230 is formed with a driven portion 232. The driven portion 232 has a pressing body 232a in contact with the bulging body 215. The pressing body 232a obliquely extends rearwardly and outwardly in a rotational drive direction of the first drive plate 210.

A centrifugal clutch 200 includes a first drive plate 210 rotationally driven directly by a driving force of an engine and a second drive plate 220 frictionally in contact with the first drive plate 210. The first drive plate 210 includes a bulging body 215 on a supporting portion 214 bulging toward the second drive plate 220. The second drive plate 220 is rotationally driven together with the first drive plate 210 while allowing rotational displacement relative to the first drive plate and includes clutch weights 230. The bulging body 215 is made of a cylindrical roller. The clutch weight 230 is formed with a driven portion 232. The driven portion 232 has a pressing body 232a in contact with the bulging body 215. The pressing body 232a obliquely extends rearwardly and outwardly in a rotational drive direction of the first drive plate 210.

In a predetermined first state, a distance (D.sub.1) in a second direction between a contact portion (P.sub.in) between a input-side engaging part (9) and an input-side engaging part (17) and a rotation center (O) is larger than a distance (D.sub.2) in the second direction between a contact portion (P.sub.out) between an output-side engaging part (12) and an output-side engaged part (14) and the rotation center (O). In a locked state or a semi-locked state, a contact portion (C.sub.1) between the output-side engaging part (12) and the output-side engaged part (14) is located closer to the rotation center (O) of the output member (4) in a first direction than an imaginary straight line (L) connecting a contact portion (C.sub.2) between one pressing surface (13) of the pair of pressing surfaces (13) and a pressed surface (6) to the rotation center (O) of the output member (4).

In a predetermined first state, a distance (D.sub.1) in a second direction between a contact portion (P.sub.in) between a input-side engaging part (9) and an input-side engaging part (17) and a rotation center (O) is larger than a distance (D.sub.2) in the second direction between a contact portion (P.sub.out) between an output-side engaging part (12) and an output-side engaged part (14) and the rotation center (O). In a locked state or a semi-locked state, a contact portion (C.sub.1) between the output-side engaging part (12) and the output-side engaged part (14) is located closer to the rotation center (O) of the output member (4) in a first direction than an imaginary straight line (L) connecting a contact portion (C.sub.2) between one pressing surface (13) of the pair of pressing surfaces (13) and a pressed surface (6) to the rotation center (O) of the output member (4).

A high performance synchronous transmission to be used aboard a motorcycle for transmitting the motion generated by an engine to a driving wheel, between a crankshaft and a hub shaft parallel therebetween and perpendicular to the median plane of the motorcycle, comprising on the crankshaft a centrifugal clutch, for the automatic engagement of the first speed above a predetermined rotation regime, and a driving pulley apt to transmit the motion through a subsequent kinematic chain, is provided with a coupling between crankshaft and driving pulley which connects them directly, by determining with its own engagement the exclusion of said centrifugal clutch, said coupling being controlled in disengagement when a control lever is in active position.

In a predetermined first state, a distance (D.sub.1) in a second direction between a contact portion (P.sub.in) between a input-side engaging part (9) and an input-side engaging part (17) and a rotation center (O) is larger than a distance (D.sub.2) in the second direction between a contact portion (P.sub.out) between an output-side engaging part (12) and an output-side engaged part (14) and the rotation center (O). In a locked state or a semi-locked state, a contact portion (C.sub.1) between the output-side engaging part (12) and the output-side engaged part (14) is located closer to the rotation center (O) of the output member (4) in a first direction than an imaginary straight line (L) connecting a contact portion (C.sub.2) between one pressing surface (13) of the pair of pressing surfaces (13) and a pressed surface (6) to the rotation center (O) of the output member (4).

In a predetermined first state, a distance (D.sub.1) in a second direction between a contact portion (P.sub.in) between a input-side engaging part (9) and an input-side engaging part (17) and a rotation center (O) is larger than a distance (D.sub.2) in the second direction between a contact portion (P.sub.out) between an output-side engaging part (12) and an output-side engaged part (14) and the rotation center (O). In a locked state or a semi-locked state, a contact portion (C.sub.1) between the output-side engaging part (12) and the output-side engaged part (14) is located closer to the rotation center (O) of the output member (4) in a first direction than an imaginary straight line (L) connecting a contact portion (C.sub.2) between one pressing surface (13) of the pair of pressing surfaces (13) and a pressed surface (6) to the rotation center (O) of the output member (4).

A high performance synchronous transmission to be used aboard a motorcycle for transmitting the motion generated by an engine to a driving wheel, between a crankshaft and a hub shaft parallel therebetween and perpendicular to the median plane of the motorcycle, having a primary shaft of mechanical gearbox equipped with a primary gearwheel, and a pair of secondary gearwheels equipped with one or more secondary shafts for transmitting the motion to a hub shaft, wherein the primary shaft receives the motion through a driven pulley which receives the motion by a driving pulley connected to the crankshaft, an input clutch being provided on the primary shaft.

A centrifugal clutch that can suppress the inclination of a clutch weight, realize smooth oscillation, and suppress the uneven wear of a clutch shoe is provided. A drive plate (210) slidably supports a clutch weight (230) and also supports a projection body (218) via a projection body support pin (216). The clutch weight (230) includes a first spring attachment part (231) and a second spring attachment part (234) to which two clutch springs (235) are attached formed, and a driven part (238) that comes into contact with the projection body (218) formed. The projection body (218) and the driven part (238) are formed in a manner that a projection body range (TE) where the projection body (218) and the driven part (238) come into contact overlaps action positions (FP1) and (FP2) of forces (F1) and (F2) of the clutch spring (235) acting on the clutch weight (230) in the thickness direction of the clutch weight (230).