Range shift arrangement for four-wheel drive vehicles

Abstract

A synchronized shift arrangement is disclosed for shifting a planetary-type gear reduction assembly from a low-range operating mode to a high-range operating mode. This arrangement is particularly adapted for use in vehicular power transfer devices, such as four-wheel drive transfer cases, for allowing the vehicle operator to shift 'on-the-fly' from a four-wheel low-range drive mode to a four-wheel high-range drive mode without the need of stopping the motor vehicle. In a preferred embodiment, the power transfer apparatus includes a housing, a first member supported for rotation in the housing, a second member supported in the housing for rotation relative to the first member, a planetary gear assembly coupled to the first member for rotatably driving an output member thereof at a reduced ratio relative to the first member, and a clutch sleeve supported for rotation with the second member and which is movable between a first position for coupling the second member to the output member of the planetary gear assembly for rotatably driving the second member at the reduced ratio, and a second position for coupling the second member for rotation with the first member. The power transfer apparatus further includes a synchronizer for causing speed synchronization between the first and second members in response to movement of the clutch sleeve from the first position to said second position.