Patent ID: 8439788

Claim:
A vehicle differential unit comprising: a first gear member rotatably supported by a support member formed of a rotatable member; and a second gear member and a third gear member that mesh with the first gear member, and that distribute a driving force from a drive source of a vehicle to a pair of output shafts via the first gear member, the second gear member, the third gear member, and the support member, wherein the support member is formed of a plurality of separate elements that are able to rotate relative to each other on an axis of the pair of output shafts, wherein the plurality of separate elements of the support member define a helical spline that receives the driving force and generates a thrust force in one direction or another direction parallel to the axis of the pair of output shafts between the plurality of elements, in response to a relative rotation; and a relative movement limiting portion that limits a relative movement between at least two adjacent elements among the plurality of elements in the one direction parallel to the axis of the pair of output shafts, due to the thrust force when the vehicle is in one of a drive mode and a coast mode, but does not limit the relative movement between the at least two adjacent elements among the plurality of elements in the another direction parallel to the axis of the pair of output shafts, due to the thrust force when the vehicle is in the other of a drive mode and a coast mode, wherein the relative movement limiting portion comprises a first contact face and a second contact face that contact each other when the relative movement between the at least two elements in the one direction is limited by the relative movement limiting portion; and the first contact face is formed in one of the at least two elements, and the second contact face is formed in the other element.