Patent ID: 7429060

Claim:
A telescopic shaft for steering of a vehicle, assembled in a steering shaft and including a male shaft and a female shaft that are so fitted as to be capable of transferring torque and to be movable in an axial direction relative to each other, characterized in that a rolling member is fitted through an elastic body for pre-load between at least a pair of axially-extending grooves formed in an outer peripheral surface of said male shaft and in an inner peripheral surface of said female shaft, a slide member is fitted in between at least another pair of axially-extending grooves formed in the outer peripheral surface of said male shaft and in the inner peripheral surface of said female shaft, and when a steering torque is equal to or smaller than a predetermined level, said elastic body for the pre-load exhibits a low rigidity characteristic as said elastic body performs pre-load action; when the steering torque is equal to or larger than the predetermined level, said slide member exhibits a high rigidity characteristic as said slide member engages with said pair of axially extending grooves; and two-staged torsional rigidity characteristics of the low rigidity characteristic and the high rigidity characteristic, are thereby provided.