Variable ratio range set for a transfer case

A transfer case comprising:

• an input shaft;
• an output shaft;
• a gear reduction unit having a first component driven by said input shaft;
• a second component driving said output shaft, and a rotatable third component;
• a worm gearset having a worm gear fixed to said third component of said gear reduction unit, and a worm meshed with said worm gear;
• and
• a variable speed motor for driving said worm so as to control the rotary speed of said third component relative to said input shaft for varying the speed ratio between said input shaft and said output shaft;
• wherein said gear reduction unit includes a sun gear fixed to said input shaft, a carrier to which said worm gear is fixed, and planet gears meshed with said sun gear and which drive said output shaft, wherein a direct drive ratio is established between said input shaft and said output shaft when said worm gearset is held against rotation, and wherein a continuously variable reduction drive ratio is established between said input shaft and said output shaft when said motor is actuated to rotate said worm gear for varying the relative speed between said input shaft and said carrier.

A transfer case for a four-wheel drive vehicle having a power source and front and rear drivelines comprising:

• an input shaft adapted to receive rotary power from the power source;
• a rear output shaft adapted to drive the rear driveline;
• a front output shaft adapted to drive the front output driveline;
• a transfer assembly for transferring rotary power from said rear output shaft to said front output shaft;
• a planetary gearset having a first sun gear driven by said input shaft, a second sun gear driving said rear output shaft, planet gears meshed with said first and second sun gears, and a carrier rotatably supporting said planet gears;
• a worm gearset having a worm gear fixed to said carrier and a worm meshed with said worm gear;
• a motor having a rotary output member fixed to said worm;
• and
• a control system for controlling variable speed actuation of said motor which acts to vary the relative rotary speed between said input shaft and said carrier.

A transfer case for a four-wheel drive vehicle having a power source and front and rear drivelines comprising:

• an input shaft adapted to receive rotary power from the power source;
• a rear output shaft adapted to drive the rear driveline;
• a front output shaft adapted to drive the front output shaft;
• a transfer assembly for transferring rotary power from said rear output shaft to said front output shaft;
• a bevel gearset having a first side gear driven by said input shaft, a second side gear driving said rear output shaft, pinion gears meshed with said first and second side gears, and a carrier rotatably supporting said pinion gears;
• a worm gearset having a worm gear fixed to said carrier and a worm meshed with said worm gear;
• a motor having a rotary output member fixed to said worm;
• and
• a control system for controlling variable speed actuation of said motor which acts to vary the rotary speed differential between said input shaft and said carrier.