One-way or selectable clutch with multiple rows of ratchet elements

A method of operating a single selectable clutch unit with reduced backlash and bi-directional capacity, comprising:

• providing a clutch unit including first, second, and third races, each coaxially positioned with respect to the other races, a first plurality of ratchet elements extending radially between the first and second races, the first plurality of ratchet elements being mounted in the second race;
• wherein the clutch unit further includes a second plurality of ratchet elements mounted in the third race, the second plurality of ratchet elements extending between the second race and the third race;
• providing a locking arm on each ratchet element;
• providing a cam surface and a shoulder on one of the races to selectively accommodate one ratchet element;
• rotating either of the first and third races clockwise relative to the second race, such rotation causing the locking arm to slide along the cam surface, thereby allowing one of the first and third races to move freely;
• and
• rotating one of the first and third races counterclockwise relative to the second race to selectively cause the locking arm to engage the shoulder to prevent further rotation of one of the first and third races.

A motor vehicle transfer case, comprising:

• a housing formed by a case and a cover, the case being operatively coupled to an output of a transmission;
• an input shaft rotatably supported by an input roller bearing and the case;
• a primary output shaft rotatably supported by a rear output roller bearing in the cover;
• a secondary output shaft rotatably supported at the lower portion of the housing by a front output roller bearing, the secondary output shaft having a bell-shaped flange operatively coupled to a bulge joint to transmit torque;
• a drive sprocket splined to the primary output shaft and operatively coupled to a lower driven sprocket, the lower driven sprocket being rotatably supported by a rear roller bearing to selectively transmit torque to the secondary output shaft;
• and
• a selectable clutch unit axially situated between the input shaft and the primary output shaft, the clutch unit comprising a first race, a second race coaxially positioned with respect to the first race, and a first plurality of ratchet elements extending radially between the first and second races, the first plurality of ratchet elements being mounted in the second race;
• wherein the clutch unit further comprises a third race coaxially positioned with respect to the first and second races;
• and
• wherein the clutch unit further includes a second plurality of ratchet elements mounted in the third race, the second plurality of ratchet elements extending between the second race and the third race, the first and second plurality of ratchet elements being disposed circumferentially in multiple rows between the first, second, and third races, and wherein each of the ratchet elements includes a pivot axle from which extends a locking arm.