A garden tool power system comprises a motor, a reducer and a transmission shaft. The motor transmits the power to the transmission shaft through the reducer to drive wheels on the transmission shaft. The reducer comprises a pinion connected to an output end of the motor and a gear engaged with the pinion. The transmission shaft includes left and right shafts connected with each other through a connecting shaft. The gear mounted on the connecting shaft has at least two guiding rods transversely located thereon and two centrifugal blocks located between the guiding rods. Each guiding rod has a spring surrounded therearound and each spring located between two centrifugal blocks has two opposite ends respectively abutted against the corresponding portions of the centrifugal blocks. A fixing sleeve provided on the periphery of the centrifugal blocks is mounted on the transmission shaft and has buckle structures matching with the centrifugal blocks.

A clutch includes a rotatable inputting member, a rotatable outputting member, a stationary member, and a contact member. The outputting member includes an output contact portion. The contact member is positioned between the outputting member and the stationary member and includes an arcuate first contact surface and a second contact surface. When the input torque for rotating the inputting member is inputted, the outputting member and the contact member rotate in contact with the inputting member. When a reverse input torque for rotating the outputting member is inputted, the outputting member is spaced from the inputting member, and the output contact portion of the outputting member urges the first contact surface against the stationary member by urging the second contact surface of the contact member thereby to prevent rotation of the outputting member.

A clutch includes a rotatable inputting member, a rotatable outputting member, a stationary member, and a contact member. The outputting member includes an output contact portion. The contact member is positioned between the outputting member and the stationary member and includes an arcuate first contact surface and a second contact surface. When the input torque for rotating the inputting member is inputted, the outputting member and the contact member rotate in contact with the inputting member. When a reverse input torque for rotating the outputting member is inputted, the outputting member is spaced from the inputting member, and the output contact portion of the outputting member urges the first contact surface against the stationary member by urging the second contact surface of the contact member thereby to prevent rotation of the outputting member.

An agricultural header includes: a header frame; at least one cutting unit carried by the header frame and including a cutting element and a driveshaft coupled to the cutting element; and a gearbox configured to drive the cutting element. The gearbox includes a gearbox output rotatably coupled to the driveshaft; and a clutch including an intermediate shaft and at least one clutch shoe rotatably coupled to the intermediate shaft and displaceable between a non-engaging position where the at least one clutch shoe does not engage the gearbox output and an engaging position where the at least one clutch shoe engages the gearbox output. The clutch is configured such that the at least one clutch shoe displaces to the engaging position when a rotational speed of the intermediate shaft reaches a threshold value.

An agricultural header includes: a header frame; at least one cutting unit carried by the header frame and including a cutting element and a driveshaft coupled to the cutting element; and a gearbox configured to drive the cutting element. The gearbox includes a gearbox output rotatably coupled to the driveshaft; and a clutch including an intermediate shaft and at least one clutch shoe rotatably coupled to the intermediate shaft and displaceable between a non-engaging position where the at least one clutch shoe does not engage the gearbox output and an engaging position where the at least one clutch shoe engages the gearbox output. The clutch is configured such that the at least one clutch shoe displaces to the engaging position when a rotational speed of the intermediate shaft reaches a threshold value.

A wedge clutch includes first and second races supported for rotation about a common axis. The first race defines a cam surface and circumferentially arranged pockets recessed into the cam surface. A wedge element is formed of circumferentially arranged wedges each having an ear disposed in one of the pockets. Resilient members are disposed in the pockets and act between the ears to bias the wedge element to a contracted position in which the wedge elements collectively contract towards the axis and the clutch is engaged. A cage is axial movable towards the wedge element to engage with the ears to compress the resilient members and move the wedge element to an expanded position in which the wedge elements collectively expand away from the axis and the clutch is disengaged.

A wedge clutch includes first and second races supported for rotation about a common axis. The first race defines a cam surface and circumferentially arranged pockets recessed into the cam surface. A wedge element is formed of circumferentially arranged wedges each having an ear disposed in one of the pockets. Resilient members are disposed in the pockets and act between the ears to bias the wedge element to a contracted position in which the wedge elements collectively contract towards the axis and the clutch is engaged. A cage is axial movable towards the wedge element to engage with the ears to compress the resilient members and move the wedge element to an expanded position in which the wedge elements collectively expand away from the axis and the clutch is disengaged.

A wedge clutch includes an inner race and an outer race circumscribing the inner race. A wedge element is radially disposed between the inner and outer races and actuatable to couple and decouple the inner and outer races. An actuator is operably coupled with the wedge element and is configured to actuate the wedge element to decouple the inner and outer races.

A self-contained switchable wedge plate clutch, consisting of: a housing arranged to receive rotational torque; and a clutch assembly. The clutch assembly includes: an outer race non-rotatably connected to the housing; an output hub; a plurality of circumferentially aligned wedge plate segments, enclosed by the housing, radially disposed about the output hub; and an activation assembly at least a portion of which is enclosed by the housing. The activation assembly is arranged to displace the plurality of circumferentially aligned wedge plate segments to switch the self-contained switchable wedge plate clutch between: a locked mode for the sell-contained switchable wedge plate clutch, in which the housing and the output hub are non-rotatably connected; and an unlocked mode for the self-contained switchable wedge plate clutch, in which the housing and the output hub are rotatable with respect to each other.

A self-contained switchable wedge plate clutch, consisting of: a housing arranged to receive rotational torque; and a clutch assembly. The clutch assembly includes: an outer race non-rotatably connected to the housing; an output hub; a plurality of circumferentially aligned wedge plate segments, enclosed by the housing, radially disposed about the output hub; and an activation assembly at least a portion of which is enclosed by the housing. The activation assembly is arranged to displace the plurality of circumferentially aligned wedge plate segments to switch the self-contained switchable wedge plate clutch between: a locked mode for the sell-contained switchable wedge plate clutch, in which the housing and the output hub are non-rotatably connected; and an unlocked mode for the self-contained switchable wedge plate clutch, in which the housing and the output hub are rotatable with respect to each other.