Telescopic shaft for vehicle

A telescopic shaft comprising:

• a male shaft including a plurality of first grooves, a couple of fixing grooves, and a couple of derail prevention protrusions, which are formed on an outer circumferential surface of the male shaft, wherein the couple of fixing grooves are formed in an outer circumferential direction of the male shaft at an end portion and a middle portion of the male shaft in a longitudinal direction of the male shaft, the couple of derail prevention protrusions are formed at the end portion and the middle portion of the male shaft, wherein the plurality of first grooves are formed in an axial direction of the male shaft between the couple of fixing grooves;
• a female shaft including a hollow space therein and a plurality of second grooves formed on an inner circumferential surface of the female shaft, wherein the plurality of second grooves are corresponding to the plurality of first grooves;
• a plurality of balls disposed between the plurality of first grooves and the plurality of second grooves;
• a recess formed at a bottom of the plurality of the first grooves;
• a leaf spring inserted into the plurality of first grooves to support the plurality of balls within the plurality of first grooves, wherein a central portion of the leaf spring is positioned over the recess while both sides of the leaf spring are supported by the bottom, wherein the central portion of the leaf spring supports the plurality of balls;
• and
• a couple of fixing rings inserted to the couple of fixing grooves and surrounding ends of the leaf spring to prevent the leaf spring from derailing.