Telescopic drive shaft

DETAILED DESCRIPTION What is claimed is: 1.
Telescopic drive shaft comprising an axially extending inner shaft member, an axially extending outer shaft member laterally enclosing and spaced radially outwardly from said inner shaft member, roll bodies in contact with and positioned between said inner shaft member and outer shaft member for transmitting torque therebetween, said roll bodies disposed in at least two axially extending rows spaced angularly apart around said inner shaft member, and support means for said roll bodies, wherein the improvement comprises that said support means comprises at least one guide ring extending around said inner shaft member within said outer shaft member and located at one end of the rows of said roll bodies, said guide ring having a radially outer surface and a radially inner surface, said outer shaft member having a first thread on the inner surface thereof, said inner shaft member having a second thread on the outer surface thereof, said guide ring having a third thread on said radially outer surface in meshed engagement with said first thread and a fourth thread on said radially inner surface thereof in meshed engagement with said second thread, and the pitch of said first and third threads being opposite to the pitch of said second and fourth threads.
2.
Telescopic drive shaft, as set forth in claim 1, wherein said support means comprises a pair of said guide rings each positioned at an opposite end of the rows of said roll bodies.
3.
Telescopic drive shaft, as set forth in claim 1, wherein the pitch of said first and third threads and the pitch of said second and fourth threads is in the range of one to three times as large as the mean diameter of said guide ring.
4.
Telescopic drive shaft, as set forth in claim 1, wherein said support means includes a cage extending in the axial direction of and located between said inner and outer shaft members, said cage extending circumferentially around said inner shaft member, said cage connected to said guide ring at one end of the rows of said roll bodies and extending therefrom toward the other end of the rows of said roll bodies, said cage being rigid in the axial direction and rotatable in the circumferential direction