A friction clutch having an electromagnet assembly including a coil and a magnet connected to the coil. When the coil is energised, a magnetic field is generated and passes through the magnet and a magnetisable conductive body adjacent to the magnet, such that a displaceable magnetisable armature portion can be brought from one position into another position. The coil has a plurality of outer portions each having an associated outer dimension of the outer portion. The magnet completely covers an outer portion of the coil by a magnet side. Two further outer portions of the coil are not covered by the magnet or are not covered by more than 20% of an outer dimension of the further outer portion, or wherein, in the case a single further outer portion covered by the magnet, the outer portion is not covered by more than 70%.

A friction clutch having an electromagnet assembly including a coil and a magnet connected to the coil. When the coil is energised, a magnetic field is generated and passes through the magnet and a magnetisable conductive body adjacent to the magnet, such that a displaceable magnetisable armature portion can be brought from one position into another position. The coil has a plurality of outer portions each having an associated outer dimension of the outer portion. The magnet completely covers an outer portion of the coil by a magnet side. Two further outer portions of the coil are not covered by the magnet or are not covered by more than 20% of an outer dimension of the further outer portion, or wherein, in the case a single further outer portion covered by the magnet, the outer portion is not covered by more than 70%.

A wet friction disc includes a lubrication groove and a plurality of lands defined by the lubrication groove. The lubrication groove has a plurality of circumferential groove portions that extends in a circumferential direction and has a predetermined groove width in a radial direction, and a plurality of intersecting groove portions that extends in directions intersecting the circumferential direction. At least some of the circumferential groove portions have an arc shape such that an end in the circumferential direction is located adjacent to one of the lands in the circumferential direction and that the groove width is entirely contained within a range in the radial direction spanned by that land.

There is provided a power transmission device to switch a coupled state and an uncoupled state between a first member and a second member which are arranged in a transmission path of a driving force to thereby control transmission of the driving force. The device includes a movable body having ferromagnetic property, a first magnetic path and a second magnetic path, and a permanent magnet. The device also includes a driving portion to excite the electromagnet in the forward direction and then increases an attraction force on a side on which a magnetic flux is increased or decreased.

There is provided a power transmission device to switch a coupled state and an uncoupled state between a first member and a second member which are arranged in a transmission path of a driving force to thereby control transmission of the driving force. The device includes a movable body having ferromagnetic property, a first magnetic path and a second magnetic path, and a permanent magnet. The device also includes a driving portion to excite the electromagnet in the forward direction and then increases an attraction force on a side on which a magnetic flux is increased or decreased.

One embodiment is a system comprising an internal combustion engine including an output shaft, a pulley system structured to be driven by the output shaft, a first alternator and a second alternator structured to be driven by the pulley system, and an electromagnetic clutch integrated within one of the pulley system, the first alternator and the second alternator and structured to selectably couple and decouple at least one of the first alternator and the second alternator from the output shaft. The system includes a controller in operative communication with the internal combustion engine system and structured to evaluate power demand and power production capability parameters of the system and to control the electromagnetic clutch to engage or disengage in response to the evaluation.

One embodiment is a system comprising an internal combustion engine including an output shaft, a pulley system structured to be driven by the output shaft, a first alternator and a second alternator structured to be driven by the pulley system, and an electromagnetic clutch integrated within one of the pulley system, the first alternator and the second alternator and structured to selectably couple and decouple at least one of the first alternator and the second alternator from the output shaft. The system includes a controller in operative communication with the internal combustion engine system and structured to evaluate power demand and power production capability parameters of the system and to control the electromagnetic clutch to engage or disengage in response to the evaluation.

A torque limiter device includes an input shaft having a first contact surface and an output shaft having a second contact surface. The input and output shafts are operable in an engaged position and a disengaged position A biasing mechanism provides a bias force that mechanically biases the input and output shafts in one of the positions and sets a threshold torque. An electromagnet is arranged to selectively provide an electromagnetic force that opposes the bias force when an activation current is supplied. A controller determines a difference in rotations of the shafts and selectively supply the activation current to the electromagnet so as to disengage the input and output shafts when the rotation difference exceeds a threshold. Each of the contact surfaces comprises one or more grooves, wherein at least one rotatable member is disposed in at least one of said grooves.

A torque limiter device includes an input shaft having a first contact surface and an output shaft having a second contact surface. The input and output shafts are operable in an engaged position and a disengaged position A biasing mechanism provides a bias force that mechanically biases the input and output shafts in one of the positions and sets a threshold torque. An electromagnet is arranged to selectively provide an electromagnetic force that opposes the bias force when an activation current is supplied. A controller determines a difference in rotations of the shafts and selectively supply the activation current to the electromagnet so as to disengage the input and output shafts when the rotation difference exceeds a threshold. Each of the contact surfaces comprises one or more grooves, wherein at least one rotatable member is disposed in at least one of said grooves.

A clutch assembly includes a stationary journal bracket assembly having a base, a stub shaft that extends axially from the base, and a passage, a threaded bracket journal coupled to the stub shaft and accessible through the passage, pulley bearings supported on the threaded bracket journal, an integrated pulley/shaft including a pulley and a center shaft, and a clutch mechanism. The center shaft includes a cup-like hub and a distal portion that extends axially from the cup-like hub. The cup-like hub is supported on the pulley bearings, located at least partially within a blind hollow interior area of the cup-like hub. The threaded bracket journal is located at least partially within the hollow interior area of the cup-like hub.