An overload protection mechanism for use with an electrically hedge trimmer includes a transmission ring gear, a roller disposed in the transmission ring gear, a transmission shaft disposed in the transmission ring gear and eccentrically connected with two rocker arms, and a clutch member movably sleeved on the transmission shaft. When excessive resistance is applied to the rocker arms, the clutch member is pushed by the roller to compress an elastic member. This allows the transmission ring gear to be idled. When the resistance applied to the rocker arms is smaller than the rebound force provided by the elastic member, the clutch member is engaged with the roller, such that the transmission ring gear drives the transmission shaft to rotate through the clutch member.

Thus, the overload protection mechanism of the present invention carries out overload protection to the motor for extending the life of the motor.

Uncoupling pulley having a longitudinal axis, and including a wheel rim having a first zone, to receive a belt connecting the wheel rim to a first power transmission element, and second zone situated in the axial extension along the direction defined by the longitudinal axis of the pulley, of the first zone; a hub to be secured to a second power transmission element; one of the power transmission elements being driving, and the other being driven; a ring mounted below the second zone of the wheel rim and around the hub, so the ring can rotate, around the longitudinal axis, relative to the wheel rim and/or the hub; an elastically deformable element mounted between the hub and the ring; and a unidirectional clutch having an end fastened to the ring and the remaining part of which is mounted below the second zone of the wheel rim and above the ring.

A torque-limiting fastener and a method of assembling the same includes a drive shell, a driven fastener carried by the drive shell, and a clutch axially between the fastener and the drive shell. The drive shell may have a shell base wall including drive-off surfaces, drive-on surfaces, and a shell skirt extending axially away from the shell base wall. The driven fastener may have a fastener base wall including driven-on surfaces, driven-off surfaces, drive tang pockets between the driven-on and driven-off surfaces, and driven-on beam pockets, and a radially outer wall extending in an axial direction away from the fastener base wall. The clutch may have a plate, a driven beam, and a driven tang, wherein the driven beam and the drive tang are cantilevered with respect to the plate. A drive shell, driven fastener, and clutch are individually disclosed.

A torque-limiting fastener and a method of assembling the same includes a drive shell, a driven fastener carried by the drive shell, and a clutch axially between the fastener and the drive shell. The drive shell may have a shell base wall including drive-off surfaces, drive-on surfaces, and a shell skirt extending axially away from the shell base wall. The driven fastener may have a fastener base wall including driven-on surfaces, driven-off surfaces, drive tang pockets between the driven-on and driven-off surfaces, and driven-on beam pockets, and a radially outer wall extending in an axial direction away from the fastener base wall. The clutch may have a plate, a driven beam, and a driven tang, wherein the driven beam and the drive tang are cantilevered with respect to the plate. A drive shell, driven fastener, and clutch are individually disclosed.

An image forming apparatus includes a development cartridge having a developing roller. The developing roller includes a roller body, and a shaft to pass through a central axis of the roller body. A coupling structure is disposed at an end part of the shaft, is movable from a first position to a second position, and includes a first coupling piece and a second coupling piece. Positions of the first coupling piece and the second coupling piece are maintained with respect to one another by a static frictional force between surfaces of the first coupling piece and the second coupling piece to hold the coupling structure in the first position. When a predetermined force overcomes the static frictional force, the first coupling piece and the second coupling piece disengage from one another to allow the coupling structure to move from the first position to the second position.

An image forming apparatus includes a development cartridge having a developing roller. The developing roller includes a roller body, and a shaft to pass through a central axis of the roller body. A coupling structure is disposed at an end part of the shaft, is movable from a first position to a second position, and includes a first coupling piece and a second coupling piece. Positions of the first coupling piece and the second coupling piece are maintained with respect to one another by a static frictional force between surfaces of the first coupling piece and the second coupling piece to hold the coupling structure in the first position. When a predetermined force overcomes the static frictional force, the first coupling piece and the second coupling piece disengage from one another to allow the coupling structure to move from the first position to the second position.

Provided, in one aspect, is a downhole torque limiter, comprising a tubular housing; a pipe positioned within the tubular housing, the pipe transitioning from a larger inside diameter (ID.sub.L) to a smaller inside diameter (ID.sub.S), thereby forming a venturi profile having a first pressure zone (Z.sub.1) and a second pressure zone (Z.sub.2); a tubular valve plate radially positioned between the tubular housing and the pipe and rotationally fixed with the pipe; a lower sub rotationally fixed relative to the tubular housing and rotationally coupled to the tubular valve plate via a clutch mechanism; and a valve assembly positioned within a longitudinal opening extending along at least a portion of a sidewall of the tubular valve plate, the valve assembly configured to be activated by a pressure drop created by fluid flowing through the venturi profile.

The protection system (5) comprises a first tubular member (13) and a second tubular member (15) which can be slidably inserted into each other and a protection (8) at one end of the first tubular member (13). The protection comprises a protective boot (40) and a first annular element (21) fixed to the first tubular member (13). Further provided for is a second annular element (33) which can be torsionally coupled to the first annular element (21) and which can be decoupled therefrom by means of a mutual movement between the first annular element (21) and the second annular element (33) in a direction approximately parallel to the axis (A-A) of the first tubular member (13). The second annular element (33) is coupled to the protective boot (40) which is provided with members (49) for coupling to a stationary plate (51) which can be connected to a power take-off (9). A drive shaft provided with such a protection system is also described.

A drill string system includes a drill bit disposed at a distal end of a drill string. A clutch is coupled with the drill bit. A mud motor is coupled to the clutch, and the mud motor is operable to receive a drilling fluid therein and transfer torque to the drill bit through the clutch. The clutch disengages upon application of a torque exceeding a predetermined threshold.

A balanced motorcycle powertrain is described. Embodiments of the balanced motorcycle powertrain include components mounted to a frame of a motorcycle such that the powertrain can be evenly balanced about a centerline of the frame. The balanced motorcycle powertrain can include, but is not limited to, a motor, a transmission, a pair of clutches, a clutch shaft, a crank shaft, a pair of superchargers, a pair of chains, a pair of rear sprockets, and a rear wheel. Each of the components can be oriented such that the powertrain is substantially balanced about the centerline of the frame.