Abstract: A spring-set, electromagnetically released brake that requires a relatively small amount of current to release is provided. The brake includes a magnet shell disposed about a first axis. The shell includes a radially outwardly extending pole. The brake also includes an armature disposed radially outwardly of the pole and pivotable at a first axial end and a first engagement element, such as a brake shoe, coupled to the armature proximate a second axial end of the armature. The brake further includes a spring disposed about the pole. The spring biases the armature radially outwardly to urge the first engagement element towards a second engagement element such as a friction surface in a brake drum. Finally, the brake includes a coil disposed about the pole and means for selectively energizing the coil to urge the armature radially inwardly and the first engagement element away from the second engagement element. A bobbin for use in the brake is also provided.

Abstract: An electromagnetically actuated friction clutch includes a rotatably driven input gear. A rotatable armature is connected to the input gear and includes a friction face and nitrocarburized outer surfaces. A pole piece has a pole face for engaging the friction face of the armature and nitrocarburized outer surfaces. An electromagnet generates an electromagnetic field to shift the armature from a disengaged position to an engaged position wherein the friction face of the armature and the pole face of the pole piece are frictionally engaged. An output shaft is driven by the input gear when the armature is in the engaged position. The nitrocarburized outer surfaces of the armature and the pole piece resist wear, while interior portions of the armature and pole piece direct magnetic flux flow along a desired path.

Abstract: A vehicle drive train transfer case includes a differential with an input and two outputs, a normally disengaged electromagnetic first clutch, and a normally engaged second clutch adapted to be electromagnetically disengaged. When the first and second clutches are disengaged and engaged, respectively, torque is transmitted via the differential to the rear axle of the vehicle without torque being transmitted to the front axles so as to propel the vehicle in a two-wheel drive mode. When both clutches are engaged, the differential is locked so as to cause torque to be transmitted to both the front and rear axles and effect propelling of the vehicle in a conventional four-wheel drive mode. When the first and second clutches are engaged and disengaged, respectively, the differential is unlocked to enable torque to be transmitted to both the front and rear axles in an all-wheel drive mode.

Abstract: An electromagnetic clutch includes a fixed field shell with a multiple turn coil, a rotor rotatable with and slidable along a splined input shaft, and a rotatable armature disposed in axially opposing relation with the rotor. An internally splined locking ring is coupled to rotate with the armature and is supported to rotate with and slide along a splined output shaft. When the coil is first energized, the armature is drawn into engagement with the rotor by magnetic flux and acts through the locking ring to cause the output shaft to rotate at substantially the same speed as the input shaft. Thereafter, the magnetic flux causes the rotor and the armature to move axially as a unit toward the field shell so as to shift the locking ring into meshing engagement with the input shaft and thereby couple the output shaft for rotation with the input shaft via the splined coupling.

Abstract: An armature is attracted to an electromagnetic field and moves axially of a rotary shaft when the field is excited. As the armature moves toward the field, it causes a movable pressure plate to shift along the shaft toward a fixed pressure plate and to press the discs of a disc pack into frictional engagement with one another. The disc pack is located between the two pressure plates and, when the discs are pressed into frictional engagement, they transmit torque from the shaft to an output member. The movable pressure plate is splined to the shaft and is tied rigidly to the armature to prevent the armature from cocking relative to the shaft.